Semiconductor nanoparticle composite, liquid dispersion of semiconductor nanoparticle composite, and curable composition

Abstract

To provide a semiconductor nanoparticle composite improved in quantum yield and dispersibility in a solvent after being stored in a powder state in the atmosphere.SOLUTION: A semiconductor nanoparticle composite comprising: a semiconductor nanoparticle; and a ligand layer provided on a surface of the semiconductor nanoparticle, wherein the ligand layer contains a compound represented by Formula (I). (In the formula, R1 is a branched-chain hydrocarbyl group, and R2 is a linear or branched-chain divalent hydrocarbyl group having 2 to 8 carbon atoms between carbonyl and mercapto groups.). ) SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a semiconductor nanoparticle composite. More specifically, the present invention relates to a semiconductor nanoparticle composite having a semiconductor nanoparticle and a ligand layer containing a compound represented by a predetermined general formula on the surface of the semiconductor nanoparticle. [Background technology]

[0002] Semiconductor nanoparticles, also known as quantum dots, absorb light and emit light corresponding to the band gap energy thereof, and thus have been widely used to date. However, improvements in luminescence efficiency (quantum yield) and durability remain issues. To address these issues, for example, studies have been conducted to cover the surface of semiconductor nanoparticles with a ligand layer containing a carboxylic acid ester compound having a specific chemical structure (e.g., Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-153915 [Patent Document 2] Patent Publication No. 2021-128341 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the quantum yield of the semiconductor nanoparticle composites described in Patent Documents 1 and 2 is insufficient. Furthermore, the semiconductor nanoparticle composites described in Patent Documents 1 and 2 have the problem that, after being stored in the air as a powder, the quantum yield decreases and the composites aggregate during storage, making it difficult to disperse them in an organic solvent after storage.

[0005] The present invention has been made in view of these conventional problems, and aims to provide a semiconductor nanoparticle composite that has improved quantum yield after storage in powder form in the atmosphere and improved dispersibility in a solvent. [Means for solving the problem]

[0006] As a result of extensive research aimed at solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by providing a ligand layer containing a compound represented by a specific chemical formula on the surface of semiconductor nanoparticles, and have completed the present invention. Specifically, the present invention relates to the following semiconductor nanoparticle composites, semiconductor nanoparticle composite dispersions, and curable compositions.

[0007] (1) A semiconductor nanoparticle composite comprising a semiconductor nanoparticle and a ligand layer provided on the surface of the semiconductor nanoparticle, the ligand layer containing a compound represented by formula (I). [ka] (In the formula, R 1 is a branched hydrocarbon group, and R 2 is a linear or branched divalent hydrocarbon group having 2 to 8 carbon atoms between the carbonyl group and the mercapto group.

[0008] With this configuration, the quantum yield of the semiconductor nanoparticle composite is less likely to decrease even when stored in a powder state under air.

[0009] (2)R 1 The semiconductor nanoparticle composite according to (1) above, wherein is a branched hydrocarbon group having 6 to 30 carbon atoms.

[0010] With this configuration, the semiconductor nanoparticle composite can be further prevented from decreasing in quantum yield when stored in a powder state under air.

[0011] (3)R 1 The semiconductor nanoparticle composite according to (1) above, wherein is a branched hydrocarbon group having 14 to 30 carbon atoms.

[0012] With this configuration, the semiconductor nanoparticle composite not only prevents a decrease in quantum yield when stored in a powder state under air, but also exhibits excellent dispersibility when redispersed in an organic solvent after storage.

[0013] (4) The semiconductor nanoparticle composite according to any one of (1) to (3) above, wherein the semiconductor nanoparticle has a core containing zinc.

[0014] Cadmium, lead, indium, and the like, which are commonly used in the cores of semiconductor nanoparticles, are toxic and carcinogenic, so the semiconductor nanoparticle composite according to the above feature (4) is excellent in safety.

[0015] (5) A semiconductor nanoparticle composite dispersion liquid in which the semiconductor nanoparticle composite according to any one of (1) to (4) above is dispersed in an organic solvent.

[0016] According to this configuration, the semiconductor nanoparticle composite has excellent durability when dispersed in an organic solvent. Furthermore, the semiconductor nanoparticle composite has excellent redispersibility in an organic solvent even after being stored in the form of a powder in the air. Therefore, the semiconductor nanoparticle composite dispersion liquid can be suitably used.

[0017] (6) The semiconductor nanoparticle composite dispersion liquid according to (5) above, wherein the organic solvent contains an aliphatic hydrocarbon.

[0018] According to this configuration, the semiconductor nanoparticle composite is dispersed in an aliphatic hydrocarbon solvent, and thus has superior durability.

[0019] (7) A curable composition comprising the semiconductor nanoparticle composite according to any one of (1) to (4) above.

[0020] According to this configuration, the semiconductor nanoparticle composite has a high quantum yield, and the curable composition containing the semiconductor nanoparticle composite has high light-emitting properties. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a semiconductor nanoparticle composite that has improved quantum yield after being stored in the form of a powder in the atmosphere and improved dispersibility in a solvent. DETAILED DESCRIPTION OF THE INVENTION

[0022] A semiconductor nanoparticle composite according to one embodiment of the present invention comprises a semiconductor nanoparticle and a ligand layer provided on the surface of the semiconductor nanoparticle. The ligand layer comprises a compound represented by formula (I). [ka] (In the formula, the symbols have the same meanings as defined above.)

[0023] [Semiconductor nanoparticles] Semiconductor nanoparticles are nano-sized crystals that absorb ultraviolet or visible light (e.g., blue light) and emit fluorescence or phosphorescence. Semiconductor nanoparticles are also called quantum dots. The wavelength (emission color) of light emitted by semiconductor nanoparticles depends on the size (e.g., particle diameter) of the semiconductor nanoparticles and the energy gap of the semiconductor nanoparticles. Therefore, the emission color of semiconductor nanoparticles can be selected (adjusted) by changing the constituent materials used and the size. The semiconductor nanoparticles of this embodiment are, for example, crystals having a maximum particle diameter of 100 nm or less as measured by a transmission electron microscope or a scanning electron microscope.

[0024] For example, semiconductor nanoparticles can absorb light of a predetermined wavelength and emit light (fluorescence or phosphorescence) of a wavelength different from the absorbed wavelength. The semiconductor nanoparticles may be semiconductor nanocrystalline particles that emit light having an emission peak in the wavelength range of 605 to 665 nm (red light), semiconductor nanocrystalline particles that emit light having an emission peak in the wavelength range of 500 to 560 nm (green light), or semiconductor nanocrystalline particles that emit light having an emission peak in the wavelength range of 420 to 480 nm (blue light). The half-width of the light emitted by the semiconductor nanoparticles is preferably, for example, 45 nm or less, and more preferably 40 nm or less. In this embodiment, the semiconductor nanoparticles are preferably semiconductor nanocrystalline particles that emit light having an emission peak in the wavelength range of 500 to 560 nm (green light). The emission peak wavelength of the semiconductor nanoparticles can be confirmed, for example, from a fluorescence spectrum or phosphorescence spectrum measured using a spectrofluorometer.

[0025] The semiconductor nanoparticles are not particularly limited as long as they are particles that can emit light when stimulated by light. The semiconductor nanoparticles may be, for example, a compound selected from the group consisting of II-VI group semiconductor compounds; III-V group semiconductor compounds; I-III-VI group semiconductor compounds; IV-VI group semiconductor compounds; Group IV elements or compounds containing them; and combinations thereof. The semiconductor nanoparticles may be a single semiconductor compound or a mixture of two or more semiconductor compounds.

[0026] Specifically, the II-VI semiconductor compound is a binary compound selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, and mixtures thereof; CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdH and ternary compounds selected from the group consisting of ZnSeSTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, and mixtures thereof. The II-VI group semiconductor compounds may be used singly or in combination of two or more.

[0027] The III-V semiconductor compound may be selected from the group consisting of binary compounds selected from the group consisting of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, and mixtures thereof; ternary compounds selected from the group consisting of GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNPs, AlNAs, AlNSb, AlPAs, AlPSb, InNPs, InNAs, InNSb, InPAs, InPSb, and mixtures thereof; and quaternary compounds selected from the group consisting of GaAlNPs, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNPs, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNPs, InAlNAs, InAlNSb, InAlPAs, InAlPSb, and mixtures thereof. The III-V semiconductor compounds may be used alone or in combination.

[0028] The I-III-VI semiconductor compound may be selected from the group consisting of ternary compounds selected from the group consisting of CuGaS, CuGaSe, CuInS, CuInSe, AgGaS, AgGaSe, AgInS, AgInSe, and mixtures thereof; or quaternary compounds selected from the group consisting of CuGaInS, CuGaInSe, AgGaInS, AgGaInSe, CuAgGaS, CuAgGaSe, CuAgInS, CuAgInSe, CuGaSSe, CuInSSe, AgGaSSe, AgInSSe, and mixtures thereof. The I-III-VI semiconductor compounds may be used alone or in combination of two or more.

[0029] The IV-VI semiconductor compound may be selected from the group consisting of binary compounds selected from the group consisting of SnS, SnSe, SnTe, PbS, PbSe, PbTe, and mixtures thereof; ternary compounds selected from the group consisting of SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, and mixtures thereof; and quaternary compounds selected from the group consisting of SnPbSSe, SnPbSeTe, SnPbSTe, and mixtures thereof. The IV-VI semiconductor compounds may be used alone or in combination of two or more.

[0030] The semiconductor nanoparticles of this embodiment are preferably semiconductor nanoparticles of a core-shell structure. Semiconductor nanoparticles of a core-shell structure include semiconductor nanoparticles having multiple shells. Specifically, the semiconductor nanoparticles may have a structure consisting of a core, a first shell, and a second shell (core / shell / shell structure), or may have a structure consisting of a core, a first shell, a second shell, and a third shell (core / shell / shell / shell structure). In this embodiment, the semiconductor nanoparticles preferably have a core / shell structure, a core / shell / shell structure, or a core / shell / shell / shell structure.

[0031] Furthermore, the semiconductors constituting the core and the shell may be different semiconductor compounds selected from the semiconductor compounds described above. For example, the core may contain one or more selected from InP, InZnP, InGaP, CdSe, CdS, CdTe, ZnS, ZnSe, ZnTe, ZnSeS, ZnSTe, ZnSeTe, ZnSeSTe, CdSeTe, CdZnS, CdZnSe, CdZnTe, CdSeS, PbSe, PbS, PbTe, AgInZnS, AgGaInS, HgS, HgSe, HgTe, GaN, GaP, GaAs, InGaN, InAs, and ZnO. The shell may also contain one or more selected from ZnS, ZnSe, ZnTe, ZnSeS, ZnO, CdS, CdSe, CdTe, CdO, InP, InS, GaP, GaN, GaO, InZnP, InGaP, InGaN, InZnSCdSe, PbS, TiO, SrSe, and HgSe.

[0032] The semiconductor nanoparticles of this embodiment preferably contain zinc in the core. Specifically, the semiconductor nanoparticles preferably contain one or more selected from ZnS, ZnSe, ZnTe, ZnSeTe, ZnSeS, ZnSTe, and ZnO in the core. Furthermore, the semiconductor nanoparticles of this embodiment preferably contain zinc in the shell. Specifically, the semiconductor nanoparticles preferably contain one or more selected from ZnS, ZnSe, ZnTe, ZnSeTe, ZnSeS, ZnSTe, and ZnO. Cadmium, lead, indium, and the like, which have traditionally been widely used as cores for semiconductor nanoparticles, are toxic and carcinogenic, which raises concerns about their potential. Therefore, the semiconductor nanoparticle composite of this embodiment has excellent safety.

[0033] Furthermore, the semiconductor nanoparticles of this embodiment may be a mixed crystal in which the core and shell each contain two or more semiconductor materials (for example, InP+GaP, ZnS+ZnSe, InP+ZnS, AgInS+ZnS, etc.).

[0034] The shape of the semiconductor nanoparticles is not particularly limited. The shape of the semiconductor nanoparticles may be, for example, spherical, ellipsoidal, pyramidal, disc-like, branched, net-like, rod-like, or the like. However, the particle shape of the semiconductor nanoparticles is preferably less directional (for example, spherical, tetrahedral, or the like). This can further improve the uniformity and fluidity of the curable composition containing the semiconductor nanoparticle composite of this embodiment.

[0035] The average particle size of the semiconductor nanoparticles is preferably 1.0 nm or more, more preferably 1.5 nm or more, and even more preferably 2.0 nm or more. The average particle size of the semiconductor nanoparticles is preferably 40.0 nm or less, more preferably 30.0 nm or less, and even more preferably 20.0 nm or less. When the semiconductor nanoparticles have the above average particle size, the semiconductor nanoparticles can easily emit light of a desired wavelength, and also have excellent dispersibility and storage stability.

[0036] The average particle diameter of semiconductor nanoparticles is determined by directly observing any number of semiconductor nanoparticles using a transmission electron microscope (TEM) or a scanning electron microscope (SEM), calculating the diameter of each particle from the ratio of their long and short axes in a projected two-dimensional image, and then averaging the results. The size and shape of semiconductor nanoparticles are thought to depend on their chemical composition, structure, manufacturing method, manufacturing conditions, etc.

[0037] [Compound represented by formula (I)] The compound represented by formula (I) has a mercapto group and an ester structure in the molecule, and therefore has a strong covalent bond with metal elements and a strong coordinating ability (bonding strength) to semiconductor nanoparticles containing metal elements, making the compound represented by formula (I) suitable for the ligand layer.

[0038] In the compound of formula (I), R 1 is a branched hydrocarbon group, preferably a branched hydrocarbon group having 6 to 30 carbon atoms. Such a semiconductor nanoparticle composite is less likely to decrease in quantum yield even when stored in a powder state under air. 1is more preferably a branched hydrocarbon group having a carbon number of 14 to 30. Such a semiconductor nanoparticle composite can further suppress the decrease in quantum yield when stored in a powder state under air.

[0039] The hydrocarbon group is not particularly limited as long as it is branched. The hydrocarbon group is preferably a branched saturated hydrocarbon group. Specifically, the hydrocarbon group is preferably a branched alkyl group, more preferably a branched alkyl group having 6 to 30 carbon atoms. Examples of such groups include an ethylhexyl group, a butyloctyl group, a hexyldecyl group, a decyltetradecyl group, and a dodecylhexadecyl group.

[0040] The branching position of the hydrocarbon group is not particularly limited. The branched hydrocarbon group may be a hydrocarbon group branched at any position. In particular, the branched hydrocarbon group is preferably a hydrocarbon group branched at the 2-position (R 1 Preferably, the branched alkyl group is a hydrocarbon group branched at a carbon atom at the β-position from the oxygen atom to which the oxygen atom is bonded. Therefore, the branched alkyl group having 6 to 30 carbon atoms is preferably an alkyl group having 6 to 30 carbon atoms branched at the 2-position. If such a group is represented by a partial structural formula, it can be represented by the following formula (II).

[0041] [ka] (In the formula, R 11 is C m H 2m+1 , R 12 is C n H 2n+1 , m and n are natural numbers, and m+n is between 4 and 28.

[0042] In the formula (II), it is preferable that m+n is 12 or more and 28 or less.

[0043] In addition, in the compound represented by formula (I), R 1Suitable examples of the alkyl group include a 2-ethylhexyl group, a 2-butyloctyl group, a 2-hexyldecyl group, a 2-decyltetradecyl group, and a 2-dodecylhexadecyl group.

[0044] In addition, in the compound represented by formula (I), R 2 R is a linear or branched divalent hydrocarbon group having 2 to 8 carbon atoms between the carbonyl group and the mercapto group. Here, the "number of carbon atoms between the carbonyl group and the mercapto group" does not include the number of carbon atoms in the branched chain portion. The linear or branched divalent hydrocarbon group is not particularly limited. The divalent hydrocarbon group is preferably a linear or branched divalent saturated hydrocarbon group. More specifically, the linear or branched divalent hydrocarbon group is preferably a linear or branched alkylene group. Even more specifically, the linear or branched divalent hydrocarbon group is preferably a linear or branched alkylene group having 2 to 8 carbon atoms between the carbonyl group and the mercapto group. Examples of such groups include an ethylene group, a propylene group, a trimethylene group, a tetramethylene group, and a pentamethylene group. 2 is particularly preferably an ethylene group or a propylene group.

[0045] R 2 When R is a branched divalent hydrocarbon group, the branching position is not particularly limited. Such a group is preferably a divalent hydrocarbon group branched at the carbon atom α-positioned to the carbonyl group. 2 The branched chain portion is preferably a hydrocarbon group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms.

[0046] The solubility parameter (SP value, (J / cm 3 ) 1 / 2 ) is preferably 15.0 or more, more preferably 16.0 or more, and even more preferably 16.5 or more. The SP value is preferably 18.5 or less, more preferably 18.0 or less, and even more preferably 17.5 or less. By using a compound having an SP value within the above range in the ligand layer, the dispersibility of the semiconductor nanoparticle composite in an organic solvent is improved.

[0047] Here, the SP value (δ) has a relationship with the dispersion force term (δD), polarity term (δP), and hydrogen bond term (δH) in the Hansen solubility parameters, as expressed by the following formula: δ 2 =δD 2 ×δP 2 ×δH 2 The method for calculating the Hansen solubility parameter is described in Charles M. Hansen, Hansen Solubility Parameters: A Users Handbook (CRC Press, 2007). Additionally, the Hansen solubility parameter can also be calculated using computer software (e.g., Hansen Solubility Parameters in Practice, HSPiP). Therefore, once the Hansen solubility parameter is obtained, the SP value can be calculated. An example of computer software for calculating the SP value is "SoluVision" by Material Doors Co., Ltd. In the present embodiment, it is preferable to use the SP value calculated by "SoluVision."

[0048] The compound of formula (I) can be, for example, a compound of formula (III): R 1 -OH (III) (In the formula, the symbols have the same meanings as defined above.) and a compound represented by formula (IV): HS-R 2 -COOH (IV) (In the formula, the symbols have the same meanings as defined above.) The compound represented by the formula (I) can be produced by dehydration condensation of the compound represented by the formula (I).

[0049] The dehydration condensation can be carried out by heating in an aromatic hydrocarbon solvent such as toluene using an acid catalyst such as p-toluenesulfonic acid while removing water produced in the reaction.

[0050] [Semiconductor nanoparticle composite] In the semiconductor nanoparticle composite of this embodiment, a ligand layer containing a compound represented by formula (I) is provided on the surface of the semiconductor nanoparticle.

[0051] In the semiconductor nanoparticle composite of this embodiment, the surface of the semiconductor nanoparticle is covered with a ligand layer containing the compound represented by formula (I), thereby protecting the surface of the semiconductor nanoparticle, and maintaining the quantum yield and durability are excellent. The semiconductor nanoparticle composite also has excellent dispersibility in organic solvents. Furthermore, the semiconductor nanoparticle composite of this embodiment can maintain a quantum yield of 90% or more of the initial quantum yield even after being stored in powder form in the air for 28 days. Therefore, the semiconductor nanoparticle composite can be stored stably for long periods of time and can be used for a variety of applications.

[0052] Here, quantum yield refers to the ratio of photons emitted by excitation with incident light to the number of photons of the incident light absorbed by the semiconductor nanoparticle composite. The quantum yield can be measured, for example, using an absolute luminescence quantum yield measurement device using an integrating sphere.

[0053] In the semiconductor nanoparticle composite of this embodiment, the content of the compound of formula (I) is not particularly limited as long as it does not affect the stability, dispersibility, and quantum yield of the semiconductor nanoparticle composite. For example, the content ratio of the compound represented by formula (I) relative to the semiconductor nanoparticles is preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more, by mass. Furthermore, the content ratio of the compound of formula (I) is preferably 60% or less, more preferably 55% or less, and even more preferably 50% or less, by mass. When the content ratio is within this range, the semiconductor nanoparticle composite can be advantageous in terms of maintaining stability, dispersibility, and quantum yield.

[0054] Furthermore, it is preferable that the compound represented by formula (I) covers 5% or more of the surface of the semiconductor nanoparticles relative to the total surface area.

[0055] In this case, the amount of the compound represented by formula (I) may be 0.1 to 10 moles per mole of the semiconductor nanoparticles.

[0056] Furthermore, the thickness of the ligand layer containing the compound represented by formula (I) is, for example, preferably 0.1 nm or more, more preferably 0.5 nm or more, and preferably 2.0 nm or less, more preferably 1.5 nm or less.

[0057] The semiconductor nanoparticle composite can be obtained by mixing semiconductor nanoparticles and a compound represented by formula (I) in an organic solvent. Specifically, the semiconductor nanoparticle composite of this embodiment can be obtained by dispersing semiconductor nanoparticles in an organic solvent, adding a compound represented by formula (I), and stirring the mixture at room temperature to 200°C for 30 minutes to 3 hours. Furthermore, by removing the organic solvent, the semiconductor nanoparticle composite can be obtained in powder form.

[0058] Furthermore, the semiconductor nanoparticle composite can be dispersed in an organic solvent to form a semiconductor nanoparticle composite dispersion. In this specification, the state in which the semiconductor nanoparticle composite is dispersed in a solvent refers to a state in which, when the semiconductor nanoparticle composite and the solvent are mixed, the semiconductor nanoparticle composite does not precipitate or does not remain as visible turbidity. Note that a semiconductor nanoparticle composite dispersed in a solvent is referred to as a semiconductor nanoparticle composite dispersion. When dispersed in an organic solvent, the semiconductor nanoparticle composite has better durability.

[0059] The organic solvent is not particularly limited. Examples of the organic solvent include aliphatic hydrocarbons such as pentane, hexane, cyclohexane, heptane, and octane, alcohols, ketones, esters, glycol ethers, glycol ether esters, aromatic hydrocarbons such as benzene, toluene, and xylene, and halogenated saturated hydrocarbons such as dichloromethane and chloroform. Among these, aliphatic hydrocarbons such as pentane, hexane, and octane are preferred. Dispersion of the semiconductor nanoparticle composite in an aliphatic hydrocarbon provides superior durability.

[0060] [Curable composition] The curable composition of this embodiment contains a semiconductor nanoparticle composite. The curable composition preferably contains a semiconductor nanoparticle composite and a polymerizable compound. The semiconductor nanoparticle composite and the polymerizable compound contained in the curable composition can each be used alone or in combination of two or more. For example, the curable composition may contain only one type of semiconductor nanoparticle composite that absorbs primary light and emits light of one color, such as green or red, or may additionally contain a different semiconductor nanoparticle composite that emits light of another color. Semiconductor nanoparticle composites have a high quantum yield, and curable compositions containing semiconductor nanoparticles have high light-emitting properties.

[0061] The content of the semiconductor nanoparticle composite in the curable composition is not particularly limited. When the total of all components other than the organic solvent contained in the curable composition is taken as 100% by mass, the content of the semiconductor nanoparticle composite is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. Furthermore, the content is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more.

[0062] A composition having a semiconductor nanoparticle composite content within the above range is preferred in that aggregation of the semiconductor nanoparticle composite is unlikely to occur and the quantum yield is also good.

[0063] (polymerizable compound) The polymerizable compound is not particularly limited. Examples of the polymerizable compound include resins such as (meth)acrylic resins, silicone resins, epoxy resins, maleic acid resins, butyral resins, polyester resins, melamine resins, phenolic resins, and polyurethane resins, and monomers having an ethylenically unsaturated bond such as methyl (meth)acrylate, butyl (meth)acrylate, benzyl (meth)acrylate, 1,6-hexanediol diacrylate, and pentaerythritol tetraacrylate. These polymerizable compounds can be used alone or in combination of two or more.

[0064] The method for curing the polymerizable compound is not particularly limited. The polymerizable compound can be cured using a curing method suitable for the polymerizable compound used, such as heat treatment or light irradiation.

[0065] The polymerizable compound is preferably a photopolymerizable compound that is cured by irradiation with light, such as a photoradical polymerizable compound that is cured by a radical polymerization reaction upon irradiation with light, or a photocationic polymerizable compound that is cured by a cationic polymerization reaction upon irradiation with light.

[0066] The photoradical polymerizable compound is preferably a compound having a polymerizable ethylenically unsaturated bond, etc. Specifically, the photoradical polymerizable compound is preferably a (meth)acrylic resin.

[0067] The polymerizable compound is preferably a thermally polymerizable compound that hardens when heated, such as melamine resin, phenolic resin, polyurethane resin, etc.

[0068] (Polymerization initiator) The curable composition preferably contains a polymerization initiator depending on the type of polymerizable compound. The polymerization initiator is a compound that generates active radicals, acids, etc. under the action of light or heat and can initiate polymerization of the polymerizable compound. One type of polymerization initiator can be used alone, or two or more types of polymerization initiators can be used.

[0069] Examples of the polymerization initiator include photopolymerization initiators such as oxime compounds, alkylphenone compounds, biimidazole compounds, triazine compounds and acylphosphine compounds, and thermal polymerization initiators such as azo compounds and organic peroxides.

[0070] A photopolymerization initiator is a compound that generates active radicals, acids, etc. under the action of light and can initiate polymerization of a photopolymerizable compound. The photopolymerization initiator is not particularly limited. Conventional photopolymerization initiators can be used as the photopolymerization initiator. Specific examples of the photopolymerization initiator include oxime compounds such as O-acyloxime compounds, alkylphenone compounds, and acylphosphine oxide compounds.

[0071] The curable composition may further contain other components, if necessary, in addition to the polymerizable compound and polymerization initiator. Examples of the other components include antioxidants, dispersants, resins, leveling agents, light scattering agents (inorganic particles, etc.), fillers, anti-aggregation agents, curing agents, etc. The other components may be contained alone or in combination of two or more.

[0072] In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. [Example]

[0073] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0074] <Synthesis of Compound of Formula (I)> Synthesis Example 1 6.5 g (50 mmol, Tokyo Chemical Industry Co., Ltd.) of 2-ethyl-1-hexanol, 6.5 g (60 mmol, Tokyo Chemical Industry Co., Ltd.) of 3-mercaptopropionic acid, 0.19 g (1 mmol) of p-toluenesulfonic acid monohydrate, and 25 g of toluene were added to a reaction flask, and the mixture was heated under reflux for 3 hours under a nitrogen atmosphere while adding an appropriate solvent. After the reaction solution was cooled to room temperature, 60 g of ethyl acetate was added, and the mixture was washed twice with a saturated aqueous solution of sodium bicarbonate. The organic layer was dried over sodium sulfate and concentrated to obtain a ligand represented by the following formula (Synthesis Example 1). The SP value of the compound of Synthesis Example 1 was calculated using the software "SoluVision" by Material Doors Co., Ltd., and was found to be 17.9 (J / cm 3) 1 / 2 It was.

[0075] [ka]

[0076] Synthesis Examples 2 to 5 and Comparative Synthesis Examples 1 to 5 Instead of 2-ethyl-1-hexanol in Synthesis Example 1, each of the alcohols shown in Table 1 (50 mmol each, all manufactured by Tokyo Chemical Industry Co., Ltd.), 6.5 g of each of the mercaptocarboxylic acids shown in Table 1 (60 mmol each, all manufactured by Tokyo Chemical Industry Co., Ltd.), 0.19 g (1 mmol) of p-toluenesulfonic acid monohydrate, and 25 g of toluene were used, and the ligands of Synthesis Examples 2 to 5 and Comparative Synthesis Examples 1 to 5 were obtained using the same procedure as in Synthesis Example 1. The structures of the ligands are as follows. The SP values ​​of Synthesis Examples 2 to 5 were calculated using the software "SoluVision" by Material Doors Co., Ltd., as in Synthesis Example 1.

[0077] [Table 1]

[0078] Synthesis Example 2 SP value: 17.6 (J / cm 3 ) 1 / 2 [ka]

[0079] Synthesis Example 3 SP value: 17.4 (J / cm 3 ) 1 / 2 [ka]

[0080] Synthesis Example 4 SP value: 17.1 (J / cm 3 ) 1 / 2 [ka]

[0081] Synthesis Example 5 SP value: 16.9 (J / cm 3 ) 1 / 2 [ka]

[0082] Comparative synthesis example 1 [ka]

[0083] Comparative synthesis example 2 [ka]

[0084] Comparative synthesis example 3 [ka]

[0085] Comparative Synthesis Example 4 [ka]

[0086] Comparative Synthesis Example 5 [ka]

[0087] <Synthesis of semiconductor nanoparticles> Semiconductor nanoparticles were synthesized based on the method described in the literature (Chem. Mater., 2020, 32, 13, 5768-5775).

[0088] Synthesis Example 6 (Preparation of precursor solution) (1) Selenium (Se), sulfur (S), or tellurium (Te) was dissolved in trioctylphosphine (TOP) or diphenylphosphine (DPP) to prepare 1.26 M Se-TOP precursor solution, 1.26 M S-TOP precursor solution, 0.24 M Te-TOP precursor solution, and 2.0 M Se-DPP precursor solution, respectively. (2) 2236 mg (12.2 mmol) of zinc acetate, 4.9 mL of octadecene (ODE), and 8.1 mL of oleic acid (OA) were heated at 120 °C under vacuum for 60 minutes, and then the reaction vessel was filled with inert gas to prepare a 0.94 M Zn(OA) precursor solution. (3) A Zn(St) precursor solution was prepared by dissolving 1898 mg (3.0 mmol) of zinc stearate (Zn(St)) in 5.7 mL of octadecene (ODE).

[0089] Synthesis Example 7 (Creation of Core Particles) A 100 mL three-neck flask was charged with 367 mg (2.0 mmol) of zinc acetate, 15 mL of octadecene (ODE), and 2 mL of oleic acid (OA) and heated to 120 °C under vacuum. After heating for 30 minutes, the reactor was filled with inert gas. The temperature was then raised to 230 °C, and 0.5 mL (0.35 mmol) of the Se-DPP precursor solution and 1.5 mL (1.0 mmol) of the Te-TOP precursor solution were rapidly injected. After the injection, the temperature was maintained at 230 °C for 30 minutes, then the temperature was raised to 270 °C and the reaction was allowed to proceed for 1 hour. This resulted in a ZnSeTe core dispersion.

[0090] Synthesis Example 8 (Shell Formation) (1) After the reaction, the ZnSeTe core dispersion was maintained at 270 °C. 3.2 mL (3.0 mmol) of the Zn(OA) precursor solution was added dropwise, followed by 1.0 mL (1.26 mmol) of the Se-TOP precursor solution. The resulting mixture was allowed to react for 1 hour to form a ZnSe shell. (2) Next, 3.2 mL of Zn(OA)2 precursor solution, 0.5 mL of Se-TOP precursor solution, and 0.5 mL of S-TOP precursor solution were added dropwise in the same manner as above, and the reaction was carried out again for 1 hour to form a ZnSeS shell. (3) Furthermore, 3.2 mL of Zn(OA)2 precursor solution and 1.0 mL of S-TOP precursor solution were added dropwise in the same manner, and then reacted for 1 hour to form a ZnS shell. (4) Then, 5.0 mL (2.6 mmol) of Zn(St)2 precursor solution was added dropwise and allowed to react for 30 minutes. After the reaction, the mixture was cooled to 230 °C, 1.0 mL of dodecanethiol was added dropwise, and the mixture was allowed to react for another 30 minutes. The reaction solution was then cooled to room temperature. Hexane and ethanol were added to the reaction solution, followed by centrifugation. The supernatant was removed, and the remaining precipitate was redispersed in toluene to obtain a ZnSeTe / ZnSe / ZnSeS / ZnS semiconductor nanoparticle dispersion. 16 μL of 2.5 M ZnCl2 ethanol solution was added to 2.0 mL of the resulting dispersion, and the mixture was heated and stirred at 80 °C for 30 minutes.

[0091] <Synthesis of semiconductor nanoparticle composites> Examples 1 to 5 and Comparative Examples 1 to 9 To the semiconductor nanoparticle dispersion obtained in Synthesis Example 8 above, 0.6 g of each of the ligands obtained in Synthesis Examples 1 to 5 or Comparative Synthesis Examples 1 to 5, or a commercially available reagent ligand, was added, and the mixture was heated and stirred at 80°C for 2 hours. After the reaction, acetonitrile was added, the mixture was centrifuged, and the supernatant was removed. The precipitate was re-dispersed in chloroform, and then acetonitrile was added again, and the mixture was centrifuged again. After the supernatant was removed after centrifugation, the precipitate was dried under reduced pressure to obtain the ZnSeTe / ZnSe / ZnSeS / ZnS semiconductor nanoparticle composites of Examples 1 to 5 and Comparative Examples 1 to 9 listed in Table 2 below.

[0092] Comparative Example 10 Acetonitrile was added to the semiconductor nanoparticle dispersion obtained in Synthesis Example 8, followed by centrifugation and removal of the supernatant. The precipitate was re-dispersed in chloroform, and acetonitrile was added again, followed by centrifugation. After removal of the supernatant following centrifugation, the precipitate was dried under reduced pressure to obtain ZnSeTe / ZnSe / ZnSeS / ZnS semiconductor nanoparticles of Comparative Example 10.

[0093] [Table 2]

[0094] <Luminescence measurement> (1) Each semiconductor nanoparticle composite of Examples 1 to 5 and Comparative Examples 1 to 10 was dispersed in chloroform to prepare a dispersion with a concentration of 0.2 mg / mL. The emission spectrum and internal quantum yield of each semiconductor nanoparticle composite dispersion were measured using an FP-8500 spectrofluorometer and an ILF-835 integrating sphere (both manufactured by JASCO Corporation) with excitation light at a wavelength of 400 nm. The peak wavelength and half-width were also derived from the measured emission spectrum. Subsequently, each ZnSeTe / ZnSe / ZnSeS / ZnS semiconductor nanoparticle composite of Examples 1 to 5 and Comparative Examples 1 to 10 was placed in a screw tube, capped, and stored at room temperature in a light-shielded environment. The emission spectrum and internal quantum yield of each semiconductor nanoparticle composite were measured immediately after production (after 0 days), and after storage for 7, 14, and 28 days, in the same manner as described above. The results are shown in Table 3.

[0095] (2) The semiconductor nanoparticle composites of each Example and Comparative Example listed in Table 4 were stored as powder under a nitrogen atmosphere, and the emission spectrum and internal quantum yield of each semiconductor nanoparticle composite were measured in the same manner as above immediately after production (after day 0), and after storage for 7, 14, and 28 days. The results are shown in Table 4.

[0096] (3) The semiconductor nanoparticle composites of each Example and Comparative Example listed in Table 5 were stored in powder form under air, and the emission spectrum and internal quantum yield of each semiconductor nanoparticle composite were measured in the same manner as above immediately after production (after day 0), and after storage for 7, 14, and 28 days. The results are shown in Table 5.

[0097] <Redispersibility> For the semiconductor nanoparticle composites of each Example and Comparative Example listed in Table 5, hexane was added to each semiconductor nanoparticle composite so that the concentration was 25 mg / mL immediately after production and after 28 days of storage in air as a powder, and the mixture was stirred by hand. The redispersion state of the semiconductor nanoparticle composite was then visually confirmed and evaluated according to the following criteria. The results are shown in Table 5. (Evaluation criteria) ○: The semiconductor nanoparticle composite was dispersed within 10 minutes after the addition of the solvent. △: The semiconductor nanoparticle composite was dispersed 10 minutes after the addition of the solvent. ×: The semiconductor nanoparticle composite was not dispersed.

[0098] [Table 3]

[0099] [Table 4]

[0100] [Table 5]

[0101] As can be seen from the above results, the semiconductor nanoparticle composite of the present invention has a high quantum yield, and the quantum yield was maintained even after storage for 28 days in a nitrogen atmosphere or in air, either in the form of a powder or dispersed in an organic solvent. Furthermore, even when dispersed in a solvent after storage for 28 days in air, the semiconductor nanoparticle composite of the present invention did not aggregate and exhibited excellent dispersibility. On the other hand, the comparative examples not containing the compound represented by formula (I) in the ligand layer had low quantum yields and did not meet the pass standard (quantum yield: 60%) (Comparative Examples 1, 3-5, and 7-9). Furthermore, when stored in powder form, it was difficult to maintain the quantum yield (Comparative Examples 2, 6, and 10).

Claims

1. A semiconductor nanoparticle and a ligand layer provided on the surface of the semiconductor nanoparticle, The semiconductor nanoparticle composite, wherein the ligand layer comprises a compound represented by formula (I): 【Chemistry 1】 (In the formula, R 1 is a branched hydrocarbon group, and R 2 is a linear or branched divalent hydrocarbon group having 2 to 8 carbon atoms between the carbonyl group and the mercapto group.

2. R 1 The semiconductor nanoparticle composite according to claim 1, wherein is a branched hydrocarbon group having 6 to 30 carbon atoms.

3. R 1 The semiconductor nanoparticle composite according to claim 1, wherein is a branched hydrocarbon group having 14 to 30 carbon atoms.

4. The semiconductor nanoparticle composite according to claim 1 or 2, wherein the semiconductor nanoparticle has a core containing zinc.

5. A semiconductor nanoparticle composite dispersion liquid in which the semiconductor nanoparticle composite according to claim 1 or 2 is dispersed in an organic solvent.

6. The semiconductor nanoparticle composite dispersion according to claim 5 , wherein the organic solvent comprises an aliphatic hydrocarbon.

7. A curable composition comprising the semiconductor nanoparticle composite according to claim 1 or 2.

Images