Quantum dot composition, method for manufacturing the same, cured product thereof, and display device containing the same

Abstract

To provide a quantum dot composition, a method of preparing the same, a cured product thereof, and a display device including the same.SOLUTION: The disclosure relates to a quantum dot composition, a method of preparing the same, a cured product thereof, and a display device including the same, and more particularly, to a quantum dot composition for electrohydrodynamic inkjet printing, a method of preparing the same, a cured product thereof, and a display device including the same.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a quantum dot composition, a method for producing the same, a cured product thereof, and a display device including the same, and specifically relates to a quantum dot composition for electrohydrodynamic inkjet printing, a method for producing the same, a cured product thereof, and a display device including the same. [Background Art]

[0002] Quantum dots (QDs) are so-called semiconductor nanocrystals. They can generate light of different wavelengths depending on particle size without changing the type of material, thereby producing various colors, and have the advantages of higher color purity and light stability than existing light emitters, so they are attracting attention as next-generation light-emitting devices.

[0003] In particular, quantum dots, which have become a new trend in the display field, are dispersed in a polymer matrix, and in the form of a composite, can be applied to various displays, electronic devices, etc. other than TVs and LEDs. Quantum dots represented by CdSe, InP, etc. have developed rapidly in terms of quantum yield, and synthesis methods with quantum yield close to 100% have been reported. Based on this, TVs applying quantum dot sheets are currently commercialized. In the next stage, quantum dot TVs are being developed in which quantum dots are included in the color filter layer of existing LED TVs (eliminating pigments and dyes), and are of a self-luminous version rather than a filtering method in the color filter layer. The core of the development of such quantum dot TVs is focused on how much the light efficiency of quantum dots can be maintained in the process of forming pixels with quantum dots and the manufacturing process.

[0004] On the other hand, materials for color filters require high sensitivity, adhesion to the substrate, chemical resistance, and heat resistance. Conventionally, color filters applied to displays were generally formed through a patterning process in which a desired pattern was formed through an exposure process using a photosensitive resist composition and a photomask, and then the unexposed areas were dissolved and removed through a development process. However, this process resulted in increased costs due to the wasteful use of materials.

[0005] Recently, in order to address the increased costs associated with the higher quality materials used in pixels, there has been growing interest in methods that minimize material usage by applying material only to desired areas, rather than using existing spin coating or slit coating methods for patterning. The most representative method is the inkjet method, which broadly includes the bubble jet method and the piezo method. The inkjet method prevents the waste of unnecessary materials because it applies material only to the desired pixels.

[0006] However, since quantum dot compositions used in inkjet methods are required to have a viscosity of 100 cps or less, preferably 50 cps or less, it has been difficult to apply high-viscosity inks exceeding 100 cps.

[0007] To compensate for the shortcomings of such inkjet methods, electrohydrodynamic (EHD) inkjet methods capable of fine patterning have been developed. EHD inkjet methods apply an electrical potential difference between the ink ejection nozzle and the substrate, enabling ink miniaturization and printing through an electric field.

[0008] As related prior art, Korean Patent Publication No. 10-2020-0137977 discloses a solution used in an electrohydrodynamic printing method.

[0009] The aforementioned prior art is characterized by improving optical efficiency by using microprinting to form a lens shape, which requires evaporating the solvent to increase viscosity and form a quantum dot polymer resin. Furthermore, while a high proportion of quantum dots results in good optical conversion efficiency, aggregation occurs between the quantum dots, and a low proportion of quantum dots leads to poor optical conversion efficiency.

[0010] To address this, we have suggested an appropriate ratio of polymer to quantum dots, but this ratio, approximately 1:100 to 1:1000 by weight, requires an excessively large amount of polymer. This results in the problem of the mixing process between quantum dots and polymer, and the quantum dot-polymer resin formation process, taking a considerable amount of time. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Korean Patent Publication No. 10-2020-0137977 [Overview of the project] [Problems that the invention aims to solve]

[0012] The problem that the present invention aims to solve is to provide a quantum dot composition and a method for producing the same that has high viscosity suitable for EHD inkjet systems, good electrical conductivity, does not cause aggregation between quantum dots, and has excellent ejectability and inkjetability.

[0013] Furthermore, the objective is to provide a quantum dot composition and a method for producing the same, which exhibit excellent optical properties without aggregation occurring between quantum dots.

[0014] Another problem that the present invention aims to solve is to provide a cured product of the quantum dot composition and a display device containing the same. [Means for solving the problem]

[0015] According to one aspect of the present invention for solving the aforementioned problems, the present invention comprises quantum dots, photopolymerizable monomers and oligomers, The present invention provides a quantum dot composition characterized in that the oligomer includes a compound containing a carbon-carbon double bond and a compound containing a thiol group.

[0016] Preferably, the oligomer is The present invention provides a quantum dot composition characterized by containing two or more compounds that include the carbon-carbon double bond.

[0017] Preferably, the quantum dot composition is characterized in that the compounds containing carbon-carbon double bonds include one compound containing 2 to 3 carbon-carbon double bonds per molecule and one compound containing 1 carbon-carbon double bond per molecule.

[0018] Preferably, the quantum dot composition is characterized in that the compound containing the carbon-carbon double bond contains one or more compounds containing a phenol group.

[0019] Preferably, the compound containing the thiol group provides a quantum dot composition characterized by containing 2 to 4 functional groups.

[0020] Preferably, the compound containing the carbon-carbon double bond includes triallyl isocyanurate and phenol acrylate. The present invention provides a quantum dot composition characterized in that the compound containing the thiol group contains ethylene glycol di(3-mercaptopropionate).

[0021] Preferably, the present invention provides a quantum dot composition characterized in that the molar ratio of the compound containing the carbon-carbon double bond to the compound containing the thiol group is 2.75:1 to 5:1.

[0022] Preferably, there is provided a quantum dot composition characterized in that the molar ratio of the compound containing 2 to 3 carbon-carbon double bonds per molecule to the compound containing 1 carbon-carbon double bond per molecule is 0.01:1 to 1.5:1.

[0023] Preferably, there is provided a quantum dot composition characterized in that the carbon-carbon double bond is one or more selected from the group consisting of a vinyl group, an allyl group, a (meth)acryl group, an isopropenyl group, and a 2-butenyl group.

[0024] Preferably, there is provided a quantum dot composition characterized in that the viscosity thereof at normal temperature ranges from 200 to 1000 cps.

[0025] Preferably, there is provided a quantum dot composition characterized in that the quantum dots are surface-modified with a primary ligand represented by the following Chemical Formula 1 and a secondary ligand having 3 to 40 carbon atoms containing a carboxyl group.

[0026]

Chemical Formula

[0027] Preferably, there is provided a quantum dot composition characterized in that it is used for electrohydrodynamic inkjet printing.

[0028] According to another aspect of the present invention, after modifying the surface of quantum dots, the modified quantum dots are dispersed in a photopolymerizable monomer to obtain a quantum dot dispersion, which is then mixed with an oligomer, there is provided a method for producing a quantum dot composition, characterized in that the oligomer is produced by mixing a compound containing a carbon-carbon double bond and a compound containing a thiol group.

[0029] Preferably, the oligomer is characterized by containing two or more compounds containing the carbon-carbon double bond, providing a method for producing a quantum dot composition.

[0030] Preferably, the present invention provides a method for producing a quantum dot composition characterized in that the compound containing the carbon-carbon double bond comprises one compound containing 2 to 3 carbon-carbon double bonds per molecule and one compound containing 1 carbon-carbon double bond per molecule.

[0031] Preferably, the compound containing the carbon-carbon double bond contains one or more compounds containing a phenol group, providing a method for producing a quantum dot composition.

[0032] Preferably, the compound containing the thiol group is characterized by containing 2 to 4 functional groups, and the present invention provides a method for producing a quantum dot composition.

[0033] Preferably, the present invention provides a method for producing a quantum dot composition, characterized by mixing a compound containing the carbon-carbon double bond with a compound containing the thiol group in a molar ratio of 2.75:1 to 5:1.

[0034] Preferably, the present invention provides a method for producing a quantum dot composition, characterized by mixing a compound containing 2 to 3 carbon-carbon double bonds per molecule with a compound containing 1 carbon-carbon double bond per molecule in a molar ratio of 0.01:1 to 1.5:1.

[0035] Preferably, the method for producing a quantum dot composition is characterized by modifying the surface of the quantum dot by adding a primary ligand represented by the following chemical formula 1 to perform primary surface modification, and then adding a secondary ligand having 3 to 40 carbon atoms and containing a carboxyl group to perform secondary surface modification.

[0036] [ka] (In the above chemical formula 1, M is a 2- to 4-valent metal. m is an integer from 1 to 4, and X is an organic group with 3 to 20 carbon atoms. n is an integer between 2 and 4.

[0037] Preferably, the oligomer further comprises a thermal initiator and a polymerization inhibitor. Before the oligomer is mixed with the quantum dot dispersion, it is stirred at room temperature, Radical addition The present invention provides a method for producing a quantum dot composition characterized by being manufactured as an oligomer through a reaction.

[0038] Preferably, the present invention provides a method for producing a quantum dot composition, characterized by further adding a photopolymerizable monomer and then adding and mixing a polymerization inhibitor, a photoinitiator, and a diffusing agent.

[0039] According to yet another aspect of the present invention, a cured film produced using the quantum dot composition is provided.

[0040] According to yet another aspect of the present invention, a light-emitting element comprising the quantum dot composition is provided.

[0041] According to yet another aspect of the present invention, a display device including the light-emitting element is provided. [Effects of the Invention]

[0042] Conventionally, it has been difficult to achieve excellent optical properties while preventing aggregation between quantum dot particles. However, the quantum dot composition and its manufacturing method according to the present invention have the advantage of making this possible, thereby simplifying the manufacturing process and reducing costs.

[0043] Furthermore, the quantum dot composition according to the present invention has good electrical conductivity, does not exhibit aggregation between particles, and is particularly excellent as a quantum dot ink composition for EHD inkjet printing, with suitable viscosity and excellent inkjetability.

[0044] Furthermore, the quantum dot composition exhibits excellent transparency and superior optical properties.

[0045] Furthermore, the quantum dot composition according to the present invention can reduce out-gas emissions during curing by ligands and the like, thereby improving the quality of the products manufactured therefrom. [Brief explanation of the drawing]

[0046] [Figure 1] This diagram shows some of the results from Experimental Example 1. [Modes for carrying out the invention]

[0047] The present invention will be described below.

[0048] All terms used herein (including technical and scientific terms) should, unless otherwise defined, be used in a way that is commonly understood by a person of ordinary skill in the art to which the invention pertains. Furthermore, terms defined in commonly used dictionaries should not be interpreted ideally or excessively unless explicitly defined otherwise.

[0049] Furthermore, throughout this specification, when a part of a section "includes" a certain component, this does not mean that other components are excluded, but rather that other components may be included, unless otherwise stated.

[0050] Furthermore, in this specification, "(meth)acrylate" means acrylate and methacrylate, "(meth)acrylic" means acrylic and methacrylic, and "(meth)acryloyl" means acryloyl and methacryloyl.

[0051] Furthermore, in this specification, "monomer" and "monomer" have the same meaning. In the present invention, a monomer is distinguished from oligomers and polymers and refers to a compound with a weight-average molecular weight of 1,000 or less. In this specification, "photopolymerizable monomer" refers to a group involved in polymerization reactions, such as a (meth)acrylate group.

[0052] In this specification, "substitution" means that hydrogen in a compound or active group is replaced by a C1-C30 alkyl group, C2-C30 alkenyl group, C2-C30 alkynyl group, C1-C30 alkoxy group, C1-C30 heteroalkyl group, C3-C30 heteroalkylaryl group, C3-C30 cycloalkyl group, C3-C15 cycloalkenyl group, C6-C30 cycloalkynyl group, C2-C30 heterocycloalkyl group, halogen (-F, -Cl, -Br or -I), or hydroxyl group (-OH). This means that the molecule is substituted with a substituent selected from a nitro group (-NO2), a cyano group (-CN), an ester group (-C(=O)OR, where R is a C1-C10 alkyl group or alkenyl group), an ether group (-OR, where R is a C1-C10 alkyl group or alkenyl group), a carbonyl group (-C(=O)-R, where R is a C1-C10 alkyl group or alkenyl group), a carboxyl group (-COOH), or a combination thereof.

[0053] In this specification, "organic group" means a C1-C30 linear or branched alkyl group, a C2-C30 linear or branched alkenyl group, or a C2-C30 linear or branched alkynyl group. Furthermore, the alkyl group, alkenyl group, and alkynyl group may be substituted or unsubstituted.

[0054] In this specification, "alkyl" means a monovalent substituent derived from a linear or branched saturated hydrocarbon having 1 to 40 carbon atoms. Examples include, but are not limited to, methyl, ethyl, propyl, isobutyl, sec-butyl, pentyl, iso-amyl, and hexyl.

[0055] In this specification, "alkenyl" means a monovalent substituent derived from a straight-chain or branched-chain unsaturated hydrocarbon having 2 to 40 carbon atoms and having one or more carbon-carbon double bonds. Examples include, but are not limited to, vinyl, allyl, isopropenyl, and 2-butenyl.

[0056] <Quantum dot composition> A quantum dot composition according to one embodiment of the present invention comprises quantum dots, a photopolymerizable monomer, and an oligomer, wherein the oligomer includes a compound containing a carbon-carbon double bond and a compound containing a thiol group.

[0057] A quantum dot composition according to one embodiment of the present invention is used for electrohydrodynamic inkjet printing and has a viscosity of 5000 cps or less, preferably in the range of 200 to 1000 cps, and more preferably in the range of 300 to 800 cps.

[0058] The composition of the quantum dot composition is described below in detail.

[0059] Quantum dots Quantum dots (QDs) are nanoscale semiconductor materials that can have different energy band gaps depending on their size and composition, allowing them to emit light at a variety of wavelengths.

[0060] Such quantum dots may have a homogeneous single-layer structure; a multi-layer structure such as a core-shell structure or a gradient structure; or a hybrid structure thereof. In a core-shell structure, the shell consists of multiple layers (e.g., core / shell / shell), in which case each layer may contain different components, such as (semi)metallic oxides.

[0061] Quantum dots can be freely selected from group II-VI compounds, group III-V compounds, group IV-VI compounds, group IV elements, group IV compounds, and combinations thereof. If the quantum dot has a core-shell structure, the core and shell can each be freely composed of the components exemplified below.

[0062] As an example, group II-VI compounds are diatomic compounds selected from the group consisting of CdO, CdS, CdSe, CdTe, ZnO, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, MgSe, MgS and mixtures thereof; CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdH Tri-element compounds selected from the group consisting of gSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, and mixtures thereof; and tetra-element compounds selected from the group consisting of CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, and mixtures thereof.

[0063] As another example, the group III-V compounds may be selected from the group consisting of two elemental compounds selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb and mixtures thereof; three elemental compounds selected from the group consisting of GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb and mixtures thereof; and four elemental compounds selected from the group consisting of GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb and mixtures thereof.

[0064] As another example, group IV-VI compounds may be selected from the group consisting of two elemental compounds selected from SnS, SnSe, SnTe, PbS, PbSe, PbTe and mixtures thereof; three elemental compounds selected from the group consisting of SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe and mixtures thereof; and four elemental compounds selected from the group consisting of SnPbSSe, SnPbSeTe, SnPbSTe and mixtures thereof.

[0065] As another example, Group IV elements can be selected from the group consisting of Si, Ge, and mixtures thereof. Group IV compounds are also two-element compounds selected from the group consisting of SiC, SiGe, and mixtures thereof.

[0066] Another example is alloy-type compounds, which are tri-element compounds selected from inZnP, etc.

[0067] The aforementioned two-element, three-element, or four-element compounds may exist within a particle at a uniform concentration, or they may be separated into states with partially different concentration distributions and exist within the same particle. Furthermore, a core / shell structure can exist in which one quantum dot surrounds another. The interface between the core and the shell may have a concentration gradient, where the concentration of the element present in the shell decreases towards the center.

[0068] The form of quantum dots is not particularly limited, as long as it is a form commonly used in the field. Examples include spherical, rod-shaped, pyramidal, disk-shaped, multi-arm, or cubic nanoparticles, nanotubes, nanowires, nanofibers, and nanoplate particles.

[0069] Furthermore, the size of the quantum dots is not particularly limited and can be appropriately adjusted within the usual range known in the field. For example, the average particle size (D50) of the quantum dots is about 2 to 10 nm. When the particle size of the quantum dots is controlled to the range of about 2 to 10 nm, light of a desired hue can be emitted. For example, if the particle size of a quantum dot core / shell containing InP is about 5 to 6 nm, it can emit light with a wavelength of about 520 to 550 nm, while if the particle size of a quantum dot core / shell containing InP is about 7 to 8 nm, it can emit light with a wavelength of about 620 to 640 nm. For example, non-cadmium (Cd) type III-V QDs (e.g., InP, InGaP, InZnP, GaN, GaAs, GaP) can be used as blue-emitting QDs.

[0070] Furthermore, the quantum dots can have a full width of half maximum (FWHM) of an emission wavelength spectrum of approximately 40 nm or less, and can improve color purity and color reproducibility within this range. In addition, since the light emitted through such quantum dots is emitted in all directions, a wide viewing angle can be improved.

[0071] According to one embodiment of the present invention, the content of the quantum dots is 1 to 60% by weight, preferably 20 to 50% by weight, based on the total weight of the quantum dot composition, depending on the properties of the quantum dots.

[0072] Oligomer In the quantum dot composition according to the present invention, the oligomer comprises a compound containing a carbon-carbon double bond and a compound containing a thiol group. Preferably, it contains two or more compounds containing carbon-carbon double bonds, for example, one compound containing 2 to 3 carbon-carbon double bonds per molecule and one compound containing 1 carbon-carbon double bond per molecule.

[0073] When the compound contains 2 to 3 carbon-carbon double bonds per molecule, the molecular weight is approximately 200 to 1000 g / mol, preferably approximately 200 to 800 g / mol, and more preferably approximately 200 to 500 g / mol. For example, triallyl isocyanurate can be used.

[0074] In this case, the compound containing the carbon-carbon double bond contains one or more compounds containing a phenol group, and preferably, the compound containing the phenol group may be a compound containing one carbon-carbon double bond per molecule. After curing the quantum dot composition, in subsequent processes, ligands and other substances on the surface of the quantum dots are discharged in gaseous form (hereinafter referred to as outgassing), which can cause product defects such as crack formation in the cured film, light-emitting element, and display device, and poor lamination. However, when one or more compounds containing a phenol group are included, there is an advantage in that the generation of outgassing can be reduced. For example, phenol acrylate can be used.

[0075] Compounds containing thiol groups contain 2 to 4 functional groups, preferably 2 to 4 thiol groups per molecule, and more preferably 2 to 3 thiol groups. For example, ethylene glycol di(3-mercaptopropionate) can be used.

[0076] The molar ratio of the compound containing a carbon-carbon double bond to the compound containing a thiol group is 2.75:1 to 5:1, preferably 2.75:1 to 4:1, and more preferably 2.75:1 to 3.5:1.

[0077] Furthermore, the molar ratio of a compound containing 2 to 3 carbon-carbon double bonds per molecule to a compound containing 1 carbon-carbon double bond per molecule is 0.01:1 to 1.5:1, preferably 0.1:1 to 1.5:1, and more preferably 0.3:1 to 1.2:1.

[0078] In compounds containing a carbon-carbon double bond, the carbon-carbon double bond is, but is not limited to, one or more groups independently selected from the group including an allyl group, a vinyl group, a (meth)acrylic group, an isopropenyl group, and a 2-butenyl group.

[0079] According to one embodiment of the present invention, the content of the oligomer is 1 to 50% by weight, preferably 10 to 45% by weight, based on the total weight of the quantum dot composition, depending on the properties of the quantum dots.

[0080] Ligand In the quantum dot composition according to the present invention, the ligand plays a role in modifying the surface of the quantum dot. Although the hydrophobic surface properties of quantum dots present a barrier to their dispersion with photopolymerizable monomers, the surface of the quantum dots can be modified with an appropriate ligand, thereby improving the miscibility of the quantum dots with the photopolymerizable monomers.

[0081] According to one embodiment of the present invention, the ligand may include a primary ligand represented by the following chemical formula 1, and a secondary ligand having 3 to 40 carbon atoms and containing a carboxyl group.

[0082] [ka] In the above chemical formula 1, M is a 2- to 4-valent metal. m is an integer from 1 to 4, and X is an organic group with 3 to 20 carbon atoms. n is an integer between 2 and 4.

[0083] Primary ligands are also metal-thiol compounds formed by reacting a metal salt with a thiol compound.

[0084] In the primary ligand described above, M is a metal with a valency of 2 to 4. For example, M is a metal from group 2 to group 14, and can be Mg, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Cd, In, or Sn. In chemical formula 1, n is determined by the valency of M and is an integer between 2 and 4.

[0085] Furthermore, in the above chemical formula 1, X is also an organic group having 3 to 20 carbon atoms. For example, X is an ester (-C(=O)O-), ether (-O-), carbonyl (-C(=O)-), carboxyl group (-C(=O)-OH), sulfonyl (-SO2-), sulfide (-S-), sulfoxide (-SO-), or alkoxy group (C n H 2n+1 It is also an alkylene group or alkenylene group having 3 to 20 carbon atoms, containing one or more active groups selected from the group consisting of (O-) and a hydroxyl group (-OH). Specifically, X is also an organic group having 4 to 20 carbon atoms, containing an ester (-C(=O)O-) active group.

[0086] In the primary ligand described above, the thiol group exhibits excellent affinity to the surface of the quantum dot, thereby improving the dispersibility of the quantum dot in photopolymerizable monomers. Furthermore, by including not only thiol groups but also ester, ether, carbonyl, carboxyl, alkoxy, cycloalkali, or hydroxyl groups in the primary ligand, the dispersibility of the surface-modified quantum dot in hydrophobic polar monomers can be maximized. Moreover, a quantum dot composition containing such quantum dots can have properties advantageous for display processes (e.g., low viscosity). On the other hand, when using thiol compounds with three or fewer carbon atoms, surface modification of quantum dots is possible, but the high polarity of the surface-modified quantum dots makes dispersion in common solvents and monomers difficult.

[0087] The secondary ligand has 3 to 40 carbon atoms and may contain a carboxyl group. Furthermore, according to one embodiment of the present invention, the secondary ligand does not contain a thiol group.

[0088] According to one embodiment of the present invention, the secondary ligand is represented by the following chemical formula 2. [ka] In the aforementioned chemical formula 2, L is selected from the group consisting of a single bond, or a substituted or unsubstituted C1-C20 alkylene group, and a substituted or unsubstituted C1-C20 alkenylene group. A is either a single bond or a C1-C20 alkylene group or alkenylene group containing one or more active groups selected from the group consisting of ester (-C(=O)O-), ether (-O-), carbonyl (-C(=O)-), sulfonyl (-SO2-), sulfide (-S-), and sulfoxide (-SO-). R is selected from the group consisting of hydrogen, substituted or unsubstituted C1-C20 alkyl groups, and substituted or unsubstituted C1-C20 alkenyl groups.

[0089] Preferably, in the secondary ligand, A may include an ester (-COO-), an ether (-O-), and combinations thereof. Alternatively, A may also be a C2-C15 alkylene group or an alkenylene group, preferably a C2-C10 alkylene group or an alkenylene group.

[0090] Generally, thiol ligands are known to be highly reactive with the surface of quantum dots. However, quantum dot compositions containing only thiol ligands can produce harmful odors or increase viscosity, leading to reduced storage stability, making them unsuitable for use in inkjet compositions. The quantum dot composition according to the present invention exhibits low viscosity and excellent storage stability by using both a primary ligand containing a thiol ligand and a secondary ligand that does not contain a thiol group. Furthermore, the secondary ligand contains active groups such as ester (-C(=O)O-), ether (-O-), carbonyl (-C(=O)-), and carboxyl group (-C(=O)-OH), resulting in excellent dispersibility with photopolymerizable monomers. On the other hand, if the secondary ligand has 16 or more carbon atoms, problems may arise such as failure to modify the surface of the quantum dots or impaired dispersibility with common solvents and monomers.

[0091] According to one embodiment of the present invention, the molar ratio of the primary ligand to the secondary ligand is 1:30 to 20:1, preferably 1:15 to 10:1, and more preferably 1:8 to 5:1, but is not limited thereto.

[0092] Furthermore, according to one embodiment of the present invention, the mixing ratio of the quantum dot and ligand is 1:1 to 20 by weight, preferably 1:1 to 10 by weight, and more preferably 1:5 to 10 by weight. Here, the ligand refers to the sum of the primary ligand and the secondary ligand.

[0093] Photopolymerizable monomers In the quantum dot composition according to the present invention, the photopolymerizable monomer plays a role in controlling the overall crosslinking density of the polymer matrix, i.e., the dosage form in which the quantum dots (QDs) are dispersed, thereby exhibiting the structure and various physical properties of the matrix. Furthermore, it can improve flexibility and adhesion to other materials.

[0094] The photopolymerizable monomer may include (meth)acrylate monomers. Any monomer commonly used in the art can be used without special restrictions.

[0095] For example, a (meth)acrylate monomer may contain at least one of a (meth)acrylic group, a vinyl group, and an allyl group. Specifically, these include 1,6-hexanediol diacrylate, 1,6-cyclohexanediol diacrylate, 2,2-dimethyl-1,3-propanediol diacrylate, diethylene glycol diacrylate, dipropylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, trimethylolpropane trimethacrylate, isobornyl acrylate, isobornyl methacrylate, tetrahydrofuryl acrylate, acryloylmorpholine, 2-phenoxyethyl acrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol mono(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexaacrylate, and dipentaerythritol hexamethacrylate. These may be used individually or in combination of two or more. In the present invention, 1,6-hexanediol diacrylate is preferred as a photopolymerizable monomer for achieving the viscosity characteristics of the quantum dot composition.

[0096] In the present invention, the content of the (meth)acrylamide monomer is 1 to 50% by weight, preferably 3 to 40% by weight, based on the total weight of the quantum dot composition, depending on the properties of the quantum dots.

[0097] Photoinitiator In the quantum dot composition according to the present invention, the photoinitiator is a component that plays a role in initiating photopolymerization when excited by a light source such as ultraviolet light (UV), and any conventional photopolymerization photoinitiator in the field can be used without limitation. For example, acetophenone compounds, benzophenone compounds, thioxanthone compounds, benzoin compounds, triazine compounds, oxime compounds, and the like can be used.

[0098] Non-restrictive examples of usable photoinitiators include ethyl(2,4,6-trimethylbenzoyl)phenylphosphine, Irgacure 184, Irgacure 369, Irgacure 651, Irgacure 819, Irgacure 907, benzione alkyl ether, benzophenone, benzyldimethylcatalyl, hydroxycyclohexylphenylacetone, chloroacetophenone, 1,1-dichloroacetophenone, diethoxyacetophenone, hydroxyacetophenone, 2-chlorothioxanthone, 2-ethylanthraquinone (2-ETAQ), 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, and methyl benzoylformate. These may be used individually or in combination of two or more.

[0099] The content of the photoinitiator can be appropriately adjusted within a range known in the art. For example, it is 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the total weight of the quantum dot composition. When the content of the photoinitiator falls within the above range, the photopolymerization reaction can be carried out sufficiently without deterioration of the matrix properties.

[0100] Diffusing agent In the quantum dot composition according to the present invention, the diffusing agent reflects light that is not absorbed by the photoconverting material, and the photoconverting material reabsorbs the reflected light. In other words, the diffusing agent can increase the amount of light absorbed by the photoconverting material and increase the photoconversion efficiency.

[0101] The aforementioned diffusion agent can be any diffusion agent component known in the art without limitation. Such a diffusion agent may be a solid diffusion agent powder or a dispersion in which the diffusion agent is dispersed.

[0102] Unrestricted examples of usable diffusing agents include barium sulfate (BaSO4), calcium carbonate (CaCO3), titanium dioxide (TiO2), zirconia (ZrO2), or combinations thereof. Furthermore, the average particle size and shape of the diffusing agent are not particularly limited and can be appropriately selected from configurations known in the art. For example, the average particle size (D50) is 150 nm to 250 nm, specifically 180 nm to 230 nm. When the average particle size of the diffusing agent falls within the aforementioned range, a superior light diffusion effect can be achieved, increasing the light conversion efficiency.

[0103] The content of the diffusing agent can be appropriately adjusted within a range known in the art. For example, it is 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the total weight of the quantum dot composition. When the content of the diffusing agent falls within the above range, an improvement in photoconversion efficiency can be achieved without a decrease in the physical properties of the matrix.

[0104] Polymerization inhibitors In the quantum dot composition according to the present invention, the polymerization inhibitor is a substance that reacts with a radical to form a low-reactivity radical or compound that does not undergo polymerization, and can control the rate of the photopolymerization reaction.

[0105] The polymerization inhibitor can be any substance known in the art without limitation. For example, quinone compounds, phenols or aniline compounds, aromatic nitros and nitroso compounds can be used as polymerization inhibitors. Specifically, these include hydroquinone (HQ), methylhydroquinone (THQ), hydroquinone monomethyl ether (MEHQ), hydroquinone monoethyl ether (EEHQ), 1,4-benzoquinone (BQ), 2,5-diphenylbenzoquinone (DPBQ), methyl-1,4-benzoquinone (MBQ), phenyl-1,4-benzoquinone (PBQ), 2,6-di-tert-butyl-4-methylphenol (BHT), 2,6-diphenyl-4-octadecyloxyphenol, catechol, phenothiazine, bis(α-methylbenzyl)phenothiazine, 3,7-dioctylphenothiazine, bis(α,α-dimethylbenzyl)phenothiazine, dimethyldithiocarbamic acid, diethyldithiocarbamic acid, dipropyldithiocarbamic acid, dibutyldithiocarbamic acid, and diphenyldithiocarbamic acid. These may be used individually or in combination of two or more.

[0106] The content of the polymerization inhibitor can be appropriately adjusted within a range known in the art. For example, it is 0.01 to 2% by weight, preferably 0.05 to 1 part by weight, based on the total weight of the quantum dot composition.

[0107] Other additives In addition to the components described above, the quantum dot composition of the present invention may use additives known in the art without limitation, as long as they do not impede the effects of the invention. In this case, the content of the additives can be appropriately adjusted within the range known in the art.

[0108] Examples of usable additives include silane compounds, siloxane compounds, antioxidants, polymerization inhibitors, lubricants, surface modifiers, surfactants, adhesion promoters, defoamers, slip agents, solvents, wetting agents, light stabilizers, anti-fouling agents, softeners, thickeners, and polymers. These may be used individually or in combination of two or more.

[0109] Silane compounds provide adhesion to the matrix, while siloxane compounds provide wetting properties. Such silane and siloxane compounds can be any known components in the art without limitation.

[0110] Antioxidants suppress discoloration caused by heat and light irradiation, as well as discoloration caused by various oxidizing gases such as ozone, reactive oxygen species, NOx, and SOx (where X is an integer). In this invention, by adding antioxidants, it is possible to prevent discoloration of the matrix and reduce the decrease in film thickness due to decomposition. Examples of usable antioxidants include hydrazides, hindered amine antioxidants, nitrogen-containing heterocyclic mercapto compounds, thioether antioxidants, hindered phenol antioxidants, ascorbic acids, zinc sulfate, thiocyanates, thiourea derivatives, sugars, nitrites, sulfites, thiosulfates, and hydroxylamine derivatives.

[0111] A leveling agent may be included to further increase the adhesive strength within the quantum dot composition by leveling it so that it is coated flat and smoothly when the quantum dot composition is coated. The leveling agent may include acrylic, silicone, etc., either alone or in a mixture of two or more. As an example, it may include a polyether-modified polydimethylsiloxane, in which a (meth)acryloyl group may be added to the polyether chain.

[0112] Surfactants may be included for the mixing and uniform application of the quantum dot composition. The surfactants can be conventional cationic, anionic, zwitterionic, or nonionic surfactants known in the art, and for example, one or more of fluorinated surfactants, silicone surfactants, and fluorosilicon surfactants may be used.

[0113] The light stabilizer is an ultraviolet absorber that enhances the weather resistance of the matrix. The softener is used to mitigate crack formation within the dried polymer matrix, thereby reducing crack formation in the cured matrix and improving impact resistance and flexural resistance.

[0114] <Method for manufacturing quantum dot compositions> In another embodiment of the present invention, a method for producing a quantum dot composition involves modifying the surface of the quantum dots, then dispersing them in a photopolymerizable monomer to obtain a quantum dot dispersion, which is then mixed with an oligomer. The oligomer can be produced by mixing a compound containing a carbon-carbon double bond and a compound containing a thiol group.

[0115] This may also include mixing the compound containing the carbon-carbon double bond with the compound containing the thiol group in a molar ratio of 2.75:1 to 5:1.

[0116] In this case, the mixture may contain two or more compounds containing carbon-carbon double bonds, and may include one compound containing 2 to 3 carbon-carbon double bonds per molecule and one compound containing 1 carbon-carbon double bond per molecule, and may also include mixing the compound containing 2 to 3 carbon-carbon double bonds per molecule and the compound containing 1 carbon-carbon double bond per molecule in a molar ratio of 0.01:1 to 1.5:1.

[0117] The oligomer may further contain a thermal initiator and a polymerization inhibitor, and after being stirred at room temperature before being mixed with the quantum dot dispersion, Radical addition It can be manufactured as an oligomer through a reaction.

[0118] Furthermore, with respect to the compounds containing the carbon-carbon double bond and the compounds containing the thiol group, the quantum dot composition is as described above to the extent of overlap.

[0119] Modifying the surface of a quantum dot may involve first modifying the primary surface by adding a primary ligand represented by the following chemical formula 1, and then modifying the secondary surface by adding a secondary ligand having 3 to 40 carbon atoms and containing a carboxyl group.

[0120] [ka] (In the above chemical formula 1, M is a 2- to 4-valent metal. m is an integer from 1 to 4, and X is an organic group with 3 to 20 carbon atoms. n is an integer between 2 and 4.

[0121] Specifically, quantum dots can be synthesized, a primary ligand can be added to the solution containing the synthesized quantum dots to perform primary surface modification, followed by centrifugation to obtain primary surface-modified quantum dots. After dispersing the primary surface-modified quantum dots in a photopolymerizable monomer, a secondary ligand containing a carboxyl group and having 3 to 40 carbon atoms can be added to perform secondary surface modification of the quantum dots.

[0122] Here, the method for manufacturing quantum dots can be one of the methods known from numerous publications (for example, high-temperature injection, microfluidic reactor, microwave radiation, etc.).

[0123] Quantum dots can be modified by first adding a primary ligand to a solution containing the synthesized quantum dots while maintaining the temperature at approximately 60°C, stirring for 30 minutes to 3 hours to allow the reaction to occur, and then adding a secondary ligand and stirring for 30 minutes to 3 hours to allow the reaction to occur, thereby further modifying the surface of the quantum dots.

[0124] The surface modification of the quantum dots is carried out in two stages, preventing the formation of addition products due to the reaction between the primary and secondary ligands. On the other hand, when the primary and secondary ligands are added to the quantum dots simultaneously, addition products may be formed by a thiol-ene reaction between the thiol group of the primary ligand and the acrylate of the secondary ligand. Such addition products can improve the viscosity of the quantum dot composition when the surface-modified quantum dots are dispersed in a photopolymerizable monomer.

[0125] After modifying the surface of the quantum dots using the method described above, the surface-modified quantum dots are obtained by centrifugation. Alternatively, a quantum dot dispersion can be prepared by dispersing the obtained surface-modified quantum dots in a photopolymerizable monomer.

[0126] In addition, the quantum dot dispersion and oligomer may be further mixed with a photopolymerizable monomer, a polymerization inhibitor, a photoinitiator, and a diffusing agent.

[0127] <Cured products, light-emitting elements, and display devices> The present invention can provide a cured product containing the aforementioned quantum dot composition. The cured product according to the present invention has excellent optical properties, specifically having a light absorption rate of 85% or more, preferably 90% or more. Furthermore, the cured product also has a light conversion rate of 30% or more, specifically 35% or more.

[0128] The cured product may be manufactured by a step of applying the aforementioned quantum dot composition onto a substrate by an EHD inkjet spraying method to form a pattern, and a step of curing the pattern.

[0129] The present invention provides a light-emitting element containing the aforementioned quantum dot composition. For example, a color filter is a thin-film optical component that extracts three colors—red, green, and blue—from white light emitted from a backlight source on a pixel-by-pixel basis, enabling the display of color in a liquid crystal display.

[0130] Such color filters are manufactured by methods such as dyeing, pigment dispersion, printing, and electrodeposition. Color filters containing quantum dot compositions are also manufactured by inkjet technology. Inkjet technology prevents waste of unwanted materials because it uses material only on the desired pixels.

[0131] Furthermore, the present invention provides a display device comprising the aforementioned quantum dot composition. Here, the display device includes, but is not limited to, liquid crystal displays (LCDs), electroluminescent displays (ELs), plasma displays (PDPs), field emission displays (FEDs), and organic light-emitting devices (OLEDs).

[0132] The present invention will be described in more detail below through examples. However, the following examples are for illustrative purposes only, and the scope of the present invention is not limited to these examples.

[0133] [Manufacturing Example 1-1] Manufacturing of Primary Ligand 1-1 1) Add approximately 280 g of polyoxyethylene glycol methyl ether 400 and approximately 50 g of mercaptosuccinic acid, raise the temperature to approximately 100°C, and allow to react for approximately 12 hours. After the reaction is complete, cool to room temperature to obtain 330 g of bis-(methoxypolyoxyethylene glycol)mercaptosuccinate-400). 2) In a round-bottom flask, 1.7 g of zinc chloride (ZnCl2) and 32 g of bis-(methoxypolyoxyethylene glycol) mercaptosuccinate-400 were placed in 134.5 g of hexyl acetate, and then stirred at approximately 60°C to dissolve. Subsequently, HCl was removed under vacuum for 2 hours to produce the primary ligand Zn-bis-(methoxypolyoxyethylene glycol) mercaptosuccinate-400).

[0134] [Manufacturing Example 1-2] Manufacturing of Primary Ligand 1-2 In a round-bottom flask, zinc chloride (ZnCl2) and the compound represented by chemical formula A-1 were placed in hexyl acetate in a molar ratio of approximately 1:3, and then dissolved by heating and stirring at approximately 60°C. Subsequently, HCl was removed under vacuum for approximately 2 hours to produce primary ligand 1-2.

[0135] [ka]

[0136] [Manufacturing Examples 1-3] Manufacturing of Primary Ligands 1-3 Primary ligand 1-3 was prepared in the same manner as in Preparation Example 1-2, except that the compound represented by chemical formula A-2 was used instead of the compound represented by chemical formula A-1.

[0137] [ka]

[0138] [Manufacturing Example 1-4] Manufacturing of Primary Ligand 1-4 Primary ligand 1-4 was prepared in the same manner as in Preparation Example 1-2, except that the compound represented by chemical formula A-3 was used instead of the compound represented by chemical formula A-1.

[0139] [ka]

[0140] [Manufacturing Examples 1-5] Manufacturing of Primary Ligands 1-5 Primary ligands 1-5 were prepared in the same manner as in Production Example 1-2, except that the compound represented by chemical formula A-4 was used instead of the compound represented by chemical formula A-1.

[0141] [ka]

[0142] [Manufacturing Examples 1-6] Manufacturing of Primary Ligand 1-6 Primary ligand 1-6 was prepared in the same manner as in Preparation Example 1-2, except that in Preparation Example 1-6, the compound represented by chemical formula A-5 was used instead of the compound represented by chemical formula A-1.

[0143] [ka]

[0144] [Manufacturing Example 2-1] Manufacturing of Secondary Ligand 2-1 The compound represented by chemical formula B-1 was placed in a round-bottom flask with hexyl acetate, and then stirred at room temperature for approximately 1 hour to produce secondary ligand 2-1.

[0145] [ka]

[0146] [Manufacturing Example 2-2] Manufacturing of Secondary Ligand 2-2 Secondary ligand 2-2 was prepared in the same manner as in Production Example 2-1, except that the compound represented by chemical formula B-2 was used instead of the compound represented by chemical formula B-1.

[0147] [ka]

[0148] [Manufacturing Example 2-3] Manufacturing of Secondary Ligand 2-3 Secondary ligand 2-3 was prepared in the same manner as in Production Example 2-1, except that the compound represented by chemical formula B-3 was used instead of the compound represented by chemical formula B-1.

[0149] [ka]

[0150] [Manufacturing Example 2-4] Manufacturing of Secondary Ligand 2-4 Secondary ligand 2-4 was prepared in the same manner as in Production Example 2-1, except that the compound represented by chemical formula B-4 was used instead of the compound represented by chemical formula B-1.

[0151] [ka]

[0152] [Manufacturing Example 2-5] Manufacturing of Secondary Ligand 2-5 Secondary ligand 2-5 was prepared in the same manner as in Production Example 2-1, except that the compound represented by chemical formula B-5 was used instead of the compound represented by chemical formula B-1.

[0153] [ka]

[0154] [Manufacturing Example 2-6] Manufacturing of Secondary Ligand 2-6 Secondary ligand 2-6 was prepared in the same manner as in Production Example 2-1, except that the compound represented by chemical formula B-6 was used instead of the compound represented by chemical formula B-1.

[0155] [ka]

[0156] [Manufacturing Example 3] Manufacturing of Quantum Dot (QD) Dispersion 1) 750 ml of InZnP / ZnSe / ZnS (core / shell / shell) quantum dot dispersion solution (Hansol, 20 wt% quantum dot solid powder; hexyl acetate) was heated to approximately 60°C under a nitrogen atmosphere and stirred. Approximately 9 g of the prepared primary ligand (1-1), Zn-bis-(methoxypolyoxyethylene glycol) mercaptosuccinate-400), was added and stirred for approximately 2 hours to modify the primary surface of the quantum dots. 2) To the solution containing the primary surface-modified quantum dots, approximately 30 g of the manufactured secondary ligand (2-2), mono(2-acryloyloxyethyl) succinate, was added and stirred for approximately 2 hours to modify the quantum dots' secondary surface. 3) The solution containing the surface-modified quantum dots was centrifuged twice with cyclohexane to obtain quantum dot powder, which was then dispersed at 60 wt% in 1,6-hexanediol diacrylate (manufactured by MIWON) to produce a QD dispersion.

[0157] [Manufacturing Example 4] Manufacturing of Oligomers Manufacturing Example 4-1. Manufacturing of Oligomer A Solution A was prepared by dissolving 1 part by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) and 0.1 parts by weight of methylhydroquinone in 100 parts by weight of triallyl isocyanurate as a base. 25 parts by weight of Solution A, 50 parts by weight of phenoxyethyl acrylate, and 25 parts by weight of ethylene glycol di(3-mercaptopropionate) were mixed and stirred at room temperature for 1 hour. After stirring, the reactor temperature was set to approximately 80°C. Radical addition Oligomer A was produced by the reaction.

[0158] Manufacturing Example 4-2. Manufacturing of Oligomer B Oligomer B was prepared in the same manner as in Production Example 4-1, except that approximately 42.9 parts by weight of solution A prepared in Production Example 4-1, approximately 28.6 parts by weight of phenoxyethyl acrylate, and approximately 28.6 parts by weight of ethylene glycol di(3-mercaptopropionate) were mixed.

[0159] Manufacturing Example 4-3. Manufacturing of Oligomer C Oligomer C was prepared in the same manner as in Production Example 4-1, except that approximately 29.2 parts by weight of solution A prepared in Production Example 4-1, approximately 41.7 parts by weight of phenoxyethyl acrylate, and approximately 29.2 parts by weight of ethylene glycol di(3-mercaptopropionate) were mixed.

[0160] Manufacturing Example 4-4. Manufacturing of Oligomer D Oligomer D was prepared in the same manner as in Production Example 4-1, except that 20 parts by weight of solution A prepared in Production Example 4-1, 40 parts by weight of phenoxyethyl acrylate, and 40 parts by weight of ethylene glycol di(3-mercaptopropionate) were mixed.

[0161] Manufacturing Example 4-5. Manufacturing of Oligomer E Oligomer E was prepared in the same manner as in Production Example 4-1, except that 50 parts by weight of solution A prepared in Production Example 4-1, 25 parts by weight of phenoxyethyl acrylate, and 25 parts by weight of ethylene glycol di(3-mercaptopropionate) were mixed.

[0162] <Example 1-1> Manufacturing of quantum dot composition After mixing 70 parts by weight of a surface-modified green quantum dot dispersion (Hansol, 60 wt% quantum dot polymer: 40 wt% 1,6-hexanediol diacrylate) and 17.5 parts by weight of oligomer A, a quantum dot composition was prepared by mixing 5.4 parts by weight of 1,6-hexanediol diacrylate (manufactured by MIWON), 0.1 parts by weight of methylhydroquinone, 2 parts by weight of ethyl (2,4,6-trimethylbenzoyl)phenyl phosphinate as a photoinitiator, and 5 parts by weight of titanium dioxide as a diffusing agent.

[0163] <Example 1-2> This is the same as Example 1, except that oligomer B, which was produced in Production Example 4-2, was used instead of oligomer A.

[0164] <Examples 1-3> This is the same as Example 1, except that oligomer C, which was produced in Production Example 4-3, was used instead of oligomer A.

[0165] <Examples 1-4> This is the same as Example 1, except that oligomer D, which was produced in Production Example 4-4, was used instead of oligomer A.

[0166] <Examples 1-5> This is the same as Example 1, except that oligomer E, which was produced in Production Example 4-5, was used instead of oligomer A.

[0167] <Comparative Example 1-1> This is the same as Example 1, except that a monomer of 1,6-hexanediol diacrylate (manufactured by MIWON) was used instead of oligomer A.

[0168] <Comparative Example 1-2> This example is the same as Example 1, except that MIRAMER PU2042 (manufactured by MIWON), an aliphatic urethane acrylate oligomer, was used instead of oligomer A.

[0169] <Comparative Example 1-3> This example is the same as Example 1, except that MIRAMER SC6300 (manufactured by MIWON), an epoxy acrylate-based oligomer, was used instead of oligomer A.

[0170] <Example 2-1> After mixing 46.5 parts by weight of surface-modified red quantum dot dispersion (Hansol, 60 wt% quantum dot polymer: 40 wt% 1,6-hexanediol diacrylate) and 35.5 parts by weight of oligomer A, a quantum dot composition was prepared by mixing 10.9 parts by weight of 1,6-hexanediol diacrylate, 0.1 parts by weight of methylhydroquinone, 2 parts by weight of ethyl (2,4,6-trimethylbenzoyl)phenyl phosphinate as a photoinitiator, and 5 parts by weight of titanium dioxide as a diffusing agent.

[0171] <Example 2-2> This is the same as Example 2-1, except that oligomer B, which was produced in Production Example 4-2, was used instead of oligomer A.

[0172] <Comparative Example 2-1> This is the same as Example 2-1, except that a monomer of 1,6-hexanediol diacrylate (manufactured by MIWON) was used instead of oligomer A.

[0173] The compositions of the examples and comparative examples are summarized in Table 1 below.

[0174] [Table 1]

[0175] Experimental Example 1. Evaluation of dispersibility and stability of QD dispersion and oligomer mixture. In Examples 1-1 to 1-5, Examples 2-1 to 2-2, and Comparative Examples 1-2 to 1-3, which included oligomers in their compositions, a mixture was prepared by mixing only the QD dispersion and the oligomer composition. The results are shown in Table 2 and Figure 1 below.

[0176] [Table 2]

[0177] In the mixed solutions of Examples 1-1, 1-2, 2-1, and 2-2, the QD dispersion and oligomer exhibit good miscibility, are uniformly dispersed, and do not harden or aggregate even after being left for a long time, demonstrating excellent stability of the mixed solution.

[0178] On the other hand, the mixtures of Examples 1-3 to 1-5 and Comparative Examples 1-2 and 1-3 were found to have insufficient dispersibility and stability. Specifically, in Examples 1-3 and 1-4, thermal curing occurred even at room temperature, and a phenomenon was observed where part of the mixture hardened like plastic. In the case of Example 1-5, a phenomenon occurred where quantum dots and oligomers intertwined and aggregated, indicating very insufficient dispersibility. Furthermore, although phenomena such as hardening and aggregation were not observed in Comparative Examples 1-2 and 1-3, the overall mixing was not good, and the mixture was found to be opaque.

[0179] Referring to Figure 1, it can be seen that the mixtures of Examples 1-1 and 1-2 are clear, while the mixtures of Comparative Examples 1-2 and 1-3 are cloudy.

[0180] Experimental Example 2. Evaluation of the light conversion rate and light absorption rate of quantum dot cured materials. 1) Among the examples, the green quantum dot compositions of Examples 1-1, 1-2, and Comparative Examples 1-1 to 1-3, which showed good dispersibility and stability, were coated to a thickness of 10 μm onto a 2 cm × 2 cm glass substrate using a spin coater (Mikasa, Opticoat MS-A150), and cured at 4000 mJ / cm using a 395 nm wavelength LED curing unit. 2 The samples were irradiated to produce a cured film. Next, a 2cm x 2cm single-film specimen was loaded into an integrating sphere apparatus (QE-2100, manufactured by Otsuka Electronics Co., Ltd.), and the initial light absorptivity and the light conversion rate (QE) after curing were measured. Subsequently, the samples were heat-treated (Post-bake) at 180°C for 30 minutes under a nitrogen atmosphere, and the light conversion rate (QE) was measured again. The results are shown in Table 3 below.

[0181] [Table 3]

[0182] The cured films produced in Examples 1-1, 1-2, and Comparative Examples 1-1 to 1-3 had a nearly uniform thickness in the range of 10 μm to approximately 0.2 μm.

[0183] In terms of light absorption rate, all examples showed values ​​of 87% or higher, and the light conversion rate was 35% or higher, confirming that they exhibited excellent optical properties.

[0184] On the other hand, with the exception of Comparative Example 1-1, the comparative examples did not exceed 87%, and even Comparative Example 1-1 showed a lower light absorption rate than the examples. Comparative Example 1-1, in which a monomer was used instead of an oligomer, showed a somewhat lower optical property with a light conversion rate of 32.8%. The oligomers used in Comparative Examples 1-2 and 1-3 did not disperse well with the quantum dot dispersion and showed lower light conversion rates of 30.7% and 27.6%, respectively, than Comparative Example 1-1.

[0185] Furthermore, in the example, the light conversion rate after heat treatment was maintained at 35% or higher, with changes of 0.1% and 0.9%, respectively, and the change rates before and after heat treatment were approximately 0.2% and 2.4%, respectively. On the other hand, in the comparative example, there was a decrease in light conversion rate of 0.1%, 0.3%, and 1.7%, respectively, and the change rates before and after heat treatment were approximately 0.3%, 0.9%, and 6.2%, respectively.

[0186] Therefore, since the excellent optical properties of Examples 1-1 and 1-2 are well maintained before and after heat treatment, if they are applied to light-emitting elements, displays, etc., and commercialized, the optical properties will be maintained for a longer period of time compared to the comparative examples.

[0187] 2) Using the red quantum dot compositions produced in Examples 2-1, 2-2 and Comparative Example 2-1, cured films were manufactured in the same manner as described above, and the light absorption rate and light conversion rate were measured. The light conversion rate after heat treatment was also measured in the same manner as described above. The results are shown in Table 4 below.

[0188] [Table 4]

[0189] The cured films produced in Examples 2-1, 2-2, and Comparative Example 2-1 had a nearly uniform thickness in the range of 10 μm to approximately 0.1 μm.

[0190] In the case of light absorption rate, all examples showed values ​​of 90% or higher, and the light conversion rate was 39% or higher, confirming that they exhibited extremely excellent optical properties.

[0191] On the other hand, the comparative example in which monomers were used instead of oligomers showed a light absorption rate of less than 90% and a light conversion rate of 35%, exhibiting slightly lower optical properties compared to the examples.

[0192] Furthermore, in the examples, the light conversion rate after heat treatment was maintained at 39% or higher, with changes of 0.1% and 0.4%, respectively, and the change rates before and after heat treatment were approximately 0.2% and 1.0%, respectively.

[0193] In the comparative example, even though the light conversion rate after heat treatment increased slightly, it remained at a level of 36%, and the optical properties were not as good as those of the example.

[0194] In summary, since the excellent optical properties of Examples 2-1 and 2-2 are well maintained before and after heat treatment, if they are applied to light-emitting elements, displays, etc., and commercialized, the optical properties will be maintained for a longer period of time compared to the comparative examples.

[0195] Experimental Example 3. Viscosity Evaluation of Quantum Dot Compositions The viscosity of the green quantum dot compositions of Examples 1-1 to 1-2 and Comparative Examples 1-1 to 1-3 was measured. The viscosity was measured at room temperature (25°C) using a rotational rheometer (HAAKE MARS, Thermo Scientific).

[0196] Furthermore, the viscosity of the red quantum dot compositions of Examples 2-1 to 2-2 and Comparative Example 2-1 was measured using the same method. The results are shown in Table 5 below.

[0197] [Table 5]

[0198] The viscosities of the green quantum dot composition in the examples were approximately 392 cps and 417 cps, and the viscosities of the red quantum dot composition in the examples were approximately 495 cps and 734 cps. This confirmed that the viscosities are suitable not only for inkjet printing but also for EHD inkjet printing.

[0199] On the other hand, Comparative Examples 1-1 and 2-1, which used monomers instead of oligomers, showed low viscosities of approximately 35 cps and 22 cps, respectively, confirming that they are unsuitable for EHD inkjet printing.

[0200] Furthermore, while Comparative Examples 1-2 and 1-3, which use oligomers, are suitable in terms of viscosity, considering the results of Experimental Examples 1 and 2, it is judged that their actual application would be difficult.

[0201] Experimental Example 4. Evaluation of EHD (electrohydrodynamic) inkjet printing (inkjetability). The inkjetability (discharge performance) of the green quantum dot compositions of Examples 1-1 to 1-2 and Comparative Example 1-1 was measured. Specifically, the EHD inkjetability was evaluated using an iEHD printer (manufactured by ENJET) with a nozzle diameter of 75 μm. Furthermore, the inkjetability of the red quantum dot compositions of Examples 2-1 to 2-2 and Comparative Example 2-1 was measured using the same method. The results are shown in Table 6 below.

[0202] [Table 6]

[0203] In the examples using the green quantum dot composition, it was confirmed that there was no nozzle clogging and that EHD inkjet printing was good at a delta voltage of 1.4kV (-0.6kV to -2kV). Similarly, in the examples using the red quantum dot composition, it was confirmed that there was no nozzle clogging and that EHD inkjet printing was good at a delta voltage of 0.8kV (-0.6kV to -1.5kV).

[0204] On the other hand, in Comparative Examples 1-1 and 2-1, where monomers were used instead of oligomers, we found that the low viscosity prevented proper jetting only to the desired locations during EHD printing.

[0205] However, in the case of Comparative Examples 1-2 and 1-3, which used oligomers, it was confirmed that they had a viscosity suitable for jetting based on the results of Experimental Example 3. However, when considering the results of Experimental Example 1 as a whole, the turbidity of the composition was high, and there was a possibility of raw material precipitation, so there was concern about nozzle clogging, and therefore the jetting performance was not evaluated.

[0206] It is obvious to a person with ordinary skill in the art to which the present invention pertains that the present invention is not limited to the embodiments described above and can be implemented in various ways by modification or alteration without departing from the technical spirit of the present invention.

Claims

1. The material comprises surface-modified quantum dots, photopolymerizable monomers, and oligomers. The photopolymerizable monomer is a photopolymerizable monomer having a (meth)acrylic group, The oligomer comprises a compound containing 2 to 3 carbon-carbon double bonds per molecule selected from the group consisting of allyl groups and (meth)acrylic groups, a compound containing a phenoxy group and one carbon-carbon double bond, and a compound containing 2 to 3 thiol groups per molecule. The molar ratio of a compound containing 2 to 3 carbon-carbon double bonds per molecule, selected from the group consisting of allyl groups and (meth)acrylic groups, to a compound containing 1 phenoxy group and the carbon-carbon double bond is 0.3:1 to 1.5:1, and The product is obtained by a radical addition reaction in which the molar ratio of the compound containing the carbon-carbon double bond to the compound containing the thiol group is in the range of 2.75:1 to 5:

1. The aforementioned quantum dot comprises a primary ligand represented by the following chemical formula 1, A quantum dot composition characterized by being a quantum dot surface-modified with a secondary ligand having 3 to 15 carbon atoms that contains a carboxyl group but does not contain a thiol group. 【Chemistry 1】 (In the above chemical formula 1, M is a divalent to tetravalent metal, m is an integer from 1 to 4, and X is an organic group with 4 to 20 carbon atoms. n is an integer between 2 and 4, corresponding to the valence of M.

2. The compound containing a carbon-carbon double bond selected from the group consisting of allyl groups and (meth)acrylic groups includes triallyl isocyanurate, and the compound containing a phenoxy group and one of the carbon-carbon double bonds includes phenoxyethyl acrylate. The quantum dot composition according to claim 1, characterized in that the compound containing 2 to 3 thiol groups per molecule contains ethylene glycol di(3-mercaptopropionate).

3. The quantum dot composition according to claim 1, characterized in that its viscosity at room temperature is in the range of 200 to 1000 cps.

4. The quantum dot composition according to claim 1, characterized in that it is used for electrohydrodynamic inkjet printing.

5. Chemical formula 1 below: 【Chemistry 2】 (In the above chemical formula 1, M is a divalent to tetravalent metal, m is an integer from 1 to 4, and X is an organic group with 4 to 20 carbon atoms. n is an integer between 2 and 4, corresponding to the valence of M. A primary ligand represented by, A step of modifying the surface of a quantum dot with a secondary ligand having 3 to 15 carbon atoms that contains a carboxyl group but does not contain a thiol group: and A step of dispersing surface-modified quantum dots in the photopolymerizable monomer to obtain a quantum dot dispersion, and further mixing it with the oligomer. A method for producing the quantum dot composition according to claim 1, characterized by including the following:

6. The method for producing a quantum dot composition according to claim 5, characterized in that the step of modifying the surface of the quantum dot includes, first, modifying the primary surface of the quantum dot by adding a primary ligand represented by the following chemical formula 1, and then modifying the secondary surface by adding a secondary ligand having 3 to 15 carbon atoms that contains a carboxyl group but does not contain a thiol group. 【Transformation 3】 (In the above chemical formula 1, M is a divalent to tetravalent metal, m is an integer from 1 to 4, and X is an organic group with 4 to 20 carbon atoms. n is an integer between 2 and 4, corresponding to the valence of M.

7. The process includes a step of preparing the oligomer by radical addition reaction of raw material monomers, wherein the raw material monomer mixture further comprises a thermal initiator and a polymerization inhibitor. The method for producing a quantum dot composition according to claim 5, characterized in that the oligomer is stirred at room temperature before being mixed with the quantum dot dispersion, and then produced as an oligomer by a radical addition reaction.

8. A cured film comprising a cured product of the quantum dot composition described in claim 1.

9. A light-emitting element comprising the quantum dot composition described in claim 1.

10. A display device including the light-emitting element described in claim 9.

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