Quantum dot ink composition, method for preparing same, cured film comprising same, color filter, and display device

Abstract

The present invention relates to a quantum dot ink composition, a method for preparing same, a cured film comprising same, a color filter, and a display device. The quantum dot ink composition of the present invention includes a ligand compound particularly suitable for AIGS-based quantum dots and thus can further improve the optical properties and stability of quantum dots. In addition, according to the method for preparing a quantum dot ink composition of the present invention, a quantum dot ink composition having excellent physical properties can be prepared by substituting, with high efficiency, a ligand compound on the surface of a quantum dot, and allowing the substituted ligand compound to bind more strongly to the surface of the quantum dot, thereby providing a high-quality display device with further improved optical properties.

Description

Quantum dot ink composition, method for producing the same, cured film, color filter, and display device including the same

[0001] The present invention relates to a quantum dot ink composition, a method for producing the same, a cured film including the same, a color filter, and a display device.

[0002] Quantum dots (QDs) are semiconductor nanostructures that can emit light of different wavelengths depending on their particle size, producing a variety of colors. They also have the advantage of higher color purity and light stability than existing light-emitting devices, and are attracting attention as next-generation light-emitting devices.

[0003] In particular, quantum dots, which have become a new trend in the display field, can be applied to various displays and electronic devices in addition to TVs and LEDs. Quantum dots, represented by CdSe and InP, are rapidly developing in terms of luminous efficiency (quantum yield), and synthesis methods with luminous efficiency close to 100% are being introduced. Based on this, TVs using quantum dot sheets are currently being commercialized. The next step is to develop a quantum dot TV that uses self-luminous light rather than a filtering method in the color filter layer by incorporating quantum dots into the color filter layer of existing LED TVs (excluding pigments and dyes). The key to the development of such quantum dot TVs is focusing on how well the luminous efficiency of quantum dots can be maintained during the process of forming pixels and the subsequent manufacturing process.

[0004] To address the recent advancements in pixel materials and the resulting cost increases, interest is growing in methods that minimize material usage by applying materials only to the desired areas, rather than using conventional spin coating or slit coating for patterning. The most representative method is inkjet printing, which prevents unnecessary material waste by applying materials only to the desired pixels.

[0005] Quantum dot compositions used in inkjet printing suffer from reduced processability when their viscosity is high. To address this issue, Korean Patent Publication No. 10-2022-0023000 discloses a solvent-free quantum dot composition that achieves low viscosity. However, this requires limiting the quantum dot content to a certain level, leading to increased pixel layer thickness to achieve the desired high luminous efficiency.

[0006] In order to solve the above-described problems, the present invention aims to provide a novel quantum dot ink composition of a solvent-free type including a ligand compound suitable therefor and a novel quantum dot capable of exhibiting improved optical properties and stability.

[0007] In addition, the present invention aims to provide a quantum dot ink composition that can be implemented with low viscosity and exhibits excellent light absorption rate and light conversion rate even at a thin thickness.

[0008] In addition, the present invention aims to provide a cured film, a color filter, and a display device including a cured product of the quantum dot ink composition.

[0009] In addition, the present invention aims to provide a method for producing the quantum dot ink composition.

[0010] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0011] To achieve the above object, the present invention provides a quantum dot ink composition comprising a quantum dot having a ligand layer on a surface and a photopolymerizable monomer, wherein the quantum dot comprises silver, indium, gallium and sulfur, and the ligand layer comprises a compound represented by the following chemical formula 1.

[0012] [Chemical Formula 1]

[0013]

[0014] (In the above chemical formula 1,

[0015] R 1 and R 2 are each independently a hydrogen atom or a methyl group,

[0016] L 1 , L 2 and L 3 are each independently a hydrocarbon group having 1 to 20 carbon atoms,

[0017] n is an integer from 1 to 20.)

[0018] In the above quantum dot ink composition, the compound represented by the chemical formula 1 has a weight average molecular weight (M w ) can be between 100 and 2000.

[0019] In the above quantum dot ink composition, the content of the quantum dot may be 1 to 50 wt% based on the total weight of the composition.

[0020] In the above quantum dot ink composition, the ligand layer may include a compound represented by the following chemical formula 2.

[0021] [Chemical Formula 2]

[0022]

[0023] (In the above chemical formula 2,

[0024] R 3 and R 4 are each independently a hydrogen atom or a methyl group,

[0025] o is an integer from 1 to 20.)

[0026] In the above quantum dot ink composition, the quantum dot ink composition may further include at least one selected from the group consisting of a photoinitiator and scattering particles.

[0027] In the above quantum dot ink composition, the photoinitiator may include at least one selected from the group consisting of a phosphine oxide compound, an acetophenone compound, a benzophenone compound, a triazine compound, a biimidazole compound, an oxime compound, and a thioxanthone compound.

[0028] In the above quantum dot ink composition, the scattering particles are Al2O3, SiO2, ZnO, ZrO2, CaCO3, It may include at least one selected from the group consisting of BaSO4, BaTiO3, TiO2, Ta2O5, Ti3O5, ITO, IZO, ATO, ZnO-Al, Nb2O3, SnO, and MgO.

[0029] In the above quantum dot ink composition, the viscosity of the quantum dot ink composition may be 30 cP or less, and the cured product of the quantum dot ink composition may exhibit a light conversion rate of 29% or more for a blue light source at a thickness of 7 μm.

[0030] In addition, the present invention provides a method for producing a quantum dot ink composition, comprising the steps of: (a) first surface-modifying a quantum dot containing silver, indium, gallium, and sulfur with an X-type ligand; (b) second surface-modifying the first surface-modified quantum dot with a compound represented by the chemical formula 1; and (c) dispersing the second surface-modified quantum dot in a photopolymerizable compound.

[0031] In addition, the present invention provides a cured film including a cured product of the quantum dot ink composition.

[0032] In addition, the present invention provides a color filter including the cured film.

[0033] In addition, the present invention provides a display device including the color filter.

[0034] The quantum dot ink composition according to the present invention includes a ligand compound particularly suitable for AIGS-based quantum dots, thereby providing an effect capable of further improving the optical properties and stability of quantum dots.

[0035] The method for producing a quantum dot ink composition according to the present invention provides an effect of producing a quantum dot ink composition having excellent physical properties by replacing a ligand compound on the surface of a quantum dot with excellent efficiency and allowing the substituted ligand compound to bind more strongly to the surface of the quantum dot.

[0036] The quantum dot ink composition according to the present invention has excellent processability for an inkjet process through low viscosity implementation, and at the same time exhibits improved light absorption rate and light conversion rate, so that it can be applied to a high-quality display device.

[0037] All terms (including technical and scientific terms) used in this specification, unless otherwise defined, may be used in their common sense by those of ordinary skill in the art to which the present invention pertains. Furthermore, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0038] Additionally, as used herein, the terms “comprises” and / or “comprising” are used to mean that they do not exclude the presence or addition of one or more other components and / or steps other than the mentioned components and / or steps.

[0039] Additionally, as used herein, “(meth)acrylate” means acrylate and methacrylate, “(meth)acrylic” means acrylic and methacrylic, and “(meth)acryloyl” means acryloyl and methacryloyl.

[0040] In addition, as used herein, "monomer" and "monomer" have the same meaning. In the present invention, the monomer is distinguished from oligomers and polymers, and refers to a compound having a weight average molecular weight of 1,000 or less. As used herein, the "photopolymerizable monomer" refers to a monomer containing a group involved in a photopolymerization reaction, such as a (meth)acrylate group.

[0041] < Quantum dot ink composition >

[0042] The quantum dot ink composition of the present invention is for use in an inkjet process and comprises a quantum dot having a ligand layer on its surface and a photopolymerizable monomer. Furthermore, the quantum dot ink composition may further comprise one or more additives selected from the group consisting of a photoinitiator, scattering particles, polymerization inhibitors, and other additives, as needed.

[0043] In one embodiment of the present invention, the quantum dot ink composition may be a solvent-free quantum dot ink composition, and even without a solvent, excellent quantum dot dispersibility and low viscosity can be achieved. In addition, the quantum dot ink composition may be suitable for inkjet printing in an inkjet process.

[0044] In one embodiment of the present invention, the quantum dot ink composition may substantially not contain a resin component. By not containing a resin component, a quantum dot ink composition exhibiting low viscosity and excellent inkjet processability can be provided.

[0045] In one embodiment of the present invention, the quantum dot ink composition may have a viscosity of 30 cP or less, and a cured product of the quantum dot ink composition may exhibit a light conversion rate of 29% or more for a blue light source at a thickness of 7 μm, preferably, the quantum dot ink composition may have a viscosity of 25 cP or less, and a cured product of the quantum dot ink composition may exhibit a light conversion rate of 30% or more for a blue light source at a thickness of 7 μm, and more preferably, the quantum dot ink composition may have a viscosity of 21 cP or less, and a cured product of the quantum dot ink composition may exhibit a light conversion rate of 31% or more for a blue light source at a thickness of 7 μm.

[0046] In one embodiment of the present invention, the cured product of the quantum dot ink composition may be heat-treated at 180°C for 30 minutes.

[0047] In one embodiment of the present invention, the blue light source may be a blue light source having a wavelength of 450 nm.

[0048] quantum dots

[0049] Quantum dots are nanocrystals (e.g., semiconductor-based) that exhibit quantum confinement or exciton confinement, and are a type of luminescent nanostructure (e.g., capable of emitting light upon energy excitation). In other words, quantum dots are nano-sized semiconductor materials that can have different energy bandgaps depending on their size and composition, and thus can emit light at various emission wavelengths.

[0050] These 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 mixture of these structures. If the shell is multi-layered, each layer may contain different components.

[0051] The shape of the quantum dot is not particularly limited as long as it is a shape commonly used in the field. For example, nanoparticles, nanotubes, nanowires, nanofibers, nanoplatelets, etc. in the shape of spherical, rod-shaped, pyramidal, disc-shaped, multi-armed, or cubic particles can be used.

[0052] In one embodiment of the present invention, the quantum dot may be an AIGS (Ag-In-Ga-S) quantum dot containing silver, indium, gallium, and sulfur. In addition, the quantum dot may include gallium and zinc on its surface.

[0053] In one embodiment of the present invention, the quantum dots may be free of cadmium, and may be free of mercury, lead, or a combination thereof.

[0054] In one embodiment of the present invention, the quantum dot may or may not further include copper.

[0055] In one embodiment of the present invention, the quantum dot may not contain lithium and may not contain an alkali metal such as sodium or potassium.

[0056] The molar ratio between each component of the above quantum dot can be adjusted so that the final quantum dot can exhibit the desired composition and optical properties.

[0057] In one embodiment of the present invention, the molar ratio of sulfur to the sum of silver, indium, and gallium of the quantum dot (S / (Ag+In+Ga)) may be 0.65 or more, 0.68 or more, 0.7 or more, 0.75 or more, 0.8 or more, 0.85 or more, 0.9 or more, 0.95 or more, 1 or more, 1.1 or more, 1.2 or more, 1.3 or more, 1.35 or more, 1.36 or more, 1.38 or more, 1.4 or more, or 1.45 or more. The molar ratio of sulfur to the total sum of silver, indium, and gallium (S / (Ag+In+Ga)) may be 3 or less, 2.5 or less, 2 or less, 1.9 or less, 1.88 or less, 1.6 or less, 1.55 or less, 1.5 or less, 1.45 or less, 1.4 or less, 1.35 or less, 1.33 or less, 1.3 or less, 1.25 or less, 1.2 or less, 1.17 or less, 1.15 or less, 1.09 or less, 1.05 or less, or 1.02 or less.

[0058] In one embodiment of the present invention, the molar ratio of the total sum of indium and gallium to silver of the quantum dot ((In+Ga) / Ag) may be 1.3 or more, 1.4 or more, 1.5 or more, 1.65 or more, 1.7 or more, 1.75 or more, 1.8 or more, 1.85 or more, 1.9 or more, 1.95 or more, 1.99 or more, 2 or more, 2.1 or more, 2.2 or more, 2.3 or more, or 2.35 or more. The molar ratio of the total sum of indium and gallium to the above silver ((In+Ga) / Ag) may be 7 or less, 6.5 or less, 6.3 or less, 6 or less, 5.9 or less, 5.7 or less, 5.66 or less, 5.5 or less, 5.3 or less, 5.1 or less, 4.5 or less, 4 or less, 3.5 or less, 3.2 or less, 3 or less, 2.8 or less, 2.6 or less, or 2.4 or less.

[0059] In one embodiment of the present invention, the molar ratio of gallium to the total sum of indium and gallium in the quantum dot (Ga / (In+Ga)) may be 0.5 or more, 0.55 or more, 0.6 or more, 0.65 or more, 0.7 or more, 0.75 or more, 0.8 or more, or 0.85 or more. The molar ratio of gallium to the total sum of indium and gallium (Ga / (In+Ga)) may be 0.99 or less, 0.98 or less, 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, 0.9 or less, or 0.83 or less.

[0060] In one embodiment of the present invention, the molar ratio of gallium to sulfur (Ga / S) of the quantum dot may be 0.1 or more, 0.15 or more, 0.2 or more, 0.25 or more, 0.3 or more, 0.31 or more, 0.32 or more, 0.33 or more, 0.34 or more, 0.35 or more, 0.38 or more, 0.4 or more, 0.47 or more, 0.5 or more, 0.53 or more, 0.55 or more, 0.56 or more, 0.58 or more, 0.6 or more, or 0.62 or more. The molar ratio of gallium to sulfur (Ga / S) may be 1 or less, 0.9 or less, 0.8 or less, 0.6 or less, 0.55 or less, 0.45 or less, 0.42 or less, 0.41 or less, or 0.4 or less.

[0061] In one embodiment of the present invention, the molar ratio of silver to sulfur (Ag / S) of the quantum dots may be 0.03 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.1 or more, 0.15 or more, 0.2 or more, 0.25 or more, 0.3 or more, 0.35 or more, 0.4 or more, or 0.45 or more. The molar ratio of silver to sulfur (Ag / S) may be 1 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.38 or less, 0.36 or less, 0.35 or less, 0.3 or less, 0.25 or less, 0.24 or less, or 0.23 or less.

[0062] In one embodiment of the present invention, the molar ratio of indium to sulfur (In / S) of the quantum dots may be 0.01 or more, 0.05 or more, 0.08 or more, 0.09 or more, or 0.1 or more. The molar ratio of indium to sulfur (In / S) may be 0.5 or less, 0.4 or less, 0.3 or less, 0.25 or less, 0.15 or less, 0.14 or less, 0.13 or less, or 0.12 or less.

[0063] In one embodiment of the present invention, the molar ratio of silver to indium (Ag / In) of the quantum dot may be 1.5 or more, 1.7 or more, 1.8 or more, 1.88 or more, or 2 or more. The molar ratio of silver to indium (Ag / In) may be 3.5 or less, 3 or less, 2.94 or less, 2 or less, 1.88 or less, or 1.8 or less.

[0064] In one embodiment of the present invention, the molar ratio of zinc to sulfur (Zn / S) of the quantum dots may be 0.01 or more, 0.05 or more, or 0.1 or more. The molar ratio of zinc to sulfur (Zn / S) may be 0.8 or less, 0.3 or less, or 0.25 or less.

[0065] In one embodiment of the present invention, the molar ratio of zinc to silver (Zn / Ag) of the quantum dots may be 0.3 or more, 0.35 or more, 0.4 or more, 0.45 or more, 0.5 or more, 0.55 or more, 0.6 or more, 0.65 or more, 0.7 or more, 0.75 or more, 0.8 or more, 0.85 or more, 0.9 or more, 0.95 or more, 1 or more, 1.2 or more, 1.4 or more, 1.6 or more, 1.7 or more, 1.9 or more, 2 or more, 2.5 or more, 3 or more, 3.5 or more, or 4 or more. The molar ratio of zinc to silver (Zn / Ag) may be 5 or less, 4.7 or less, 4.4 or less, 4.1 or less, 3.9 or less, 3.7 or less, 3.5 or less, 3 or less, 2.7 or less, 2.6 or less, or 2.3 or less.

[0066] In one embodiment of the present invention, the molar ratio of zinc to indium (Zn / In) of the quantum dots may be 0.1 or more, 0.3 or more, 0.5 or more, 0.7 or more, 0.75 or more, 0.78 or more, 0.9 or more, 1 or more, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, 1.6 or more, 1.7 or more, 1.72 or more, 1.9 or more, 2.1 or more, 2.3 or more, 2.5 or more, 2.7 or more, 2.9 or more, or 3 or more. The molar ratio of zinc to indium (Zn / In) may be 10 or less, 8 or less, 6 or less, 5 or less, 4.5 or less, 4 or less, 3 or less, 3.5 or less, 2 or less, 1.9 or less, 1.85 or less, 1.75 or less, 1.72 or less, or 1.6 or less.

[0067] In one embodiment of the present invention, the molar ratio of zinc to gallium (Zn / Ga) of the quantum dots may be 0.1 or more, 0.2 or more, 0.3 or more, 0.35 or more, 0.4 or more, 0.45 or more, or 0.5 or more. The molar ratio of zinc to gallium (Zn / Ga) may be 3 or less, 2.5 or less, 2 or less, 1.9 or less, 1.7 or less, 1.5 or less, 1.4 or less, 1.2 or less, 1.1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, or 0.49 or less.

[0068] In one embodiment of the present invention, the molar ratio of zinc to the sum of gallium, indium, and silver of the quantum dot (Zn / (Ga+In+Ag)) may be 0.05 or more, 0.1 or more, 0.2 or more, 0.25 or more, 0.3 or more, 0.35 or more, or 0.4 or more. The molar ratio of zinc to the sum of gallium, indium, and silver (Zn / (Ga+In+Ag)) may be 2 or less, 1.7 or less, 1.4 or less, 1.1 or less, 0.9 or less, 0.7 or less, 0.5 or less, or 0.45 or less.

[0069] In one embodiment of the present invention, the molar ratio of zinc to the sum of gallium and indium of the quantum dot (Zn / (Ga+In)) may be 0.05 or more, 0.1 or more, 0.2 or more, 0.25 or more, 0.3 or more, 0.35 or more, or 0.4 or more. The molar ratio of zinc to the sum of gallium and indium (Zn / (Ga+In)) may be 2 or less, 1.7 or less, 1.4 or less, 1.1 or less, 0.9 or less, 0.7 or less, 0.5 or less, or 0.45 or less.

[0070] In the above quantum dot, the indium content may have a concentration gradient that varies (e.g., decreases) in the radial direction (e.g., from the center to the periphery). In one embodiment, the indium content of a portion adjacent to the surface (e.g., a shell layer or an outermost layer) may be less than the indium content of an inner portion of the quantum dot. In one embodiment, the portion adjacent to the surface (e.g., a shell layer or an outermost layer) may not include indium.

[0071] In the above quantum dot, gallium may be on or exposed to the surface of the quantum dot, zinc may be on the surface of the quantum dot, and the ligand compound may be adjacent to or in contact with the surface of the quantum dot.

[0072] The quantum dot may have a core-shell structure. The core may have a different composition from the shell. The quantum dot or the shell may further include, for example, an inorganic layer comprising a zinc chalcogenide (e.g., comprising a third semiconductor nanocrystal) as an outermost layer. The zinc chalcogenide may include zinc; and selenium, sulfur, or a combination thereof. The zinc chalcogenide may include ZnSe, ZnSeS, ZnS, or a combination thereof.

[0073] The size or average size (hereinafter referred to as “particle size”) of the core may be 0.5 nm or more, 1 nm or more, 1.5 nm or more, 1.7 nm or more, 1.9 nm or more, 2 nm or more, 2.1 nm or more, 2.3 nm or more, 2.5 nm or more, 2.7 nm or more, 2.9 nm or more, 3 nm or more, 3.1 nm or more, 3.3 nm or more, 3.5 nm or more, 3.7 nm or more, or 3.9 nm or more. The particle size of the core may be 5 nm or less, 4.5 nm or less, 4 nm or less, 3.5 nm or less, 3 nm or less, 2.5 nm or less, 2 nm or less, or 1.5 nm or less.

[0074] The thickness or average thickness (hereinafter referred to as “thickness”) of the above shell may be 0.1 nm or more, 0.3 nm or more, 0.5 nm or more, 0.7 nm or more, 1 nm or more, 1.5 nm or more, 1.7 nm or more, 1.9 nm or more, 2 nm or more, 2.1 nm or more, 2.3 nm or more, 2.5 nm or more, 2.7 nm or more, 2.9 nm or more, 3 nm or more, 3.1 nm or more, 3.3 nm or more, 3.5 nm or more, 3.7 nm or more, or 3.9 nm or more. The thickness of the above shell may be 5 nm or less, 4.5 nm or less, 4 nm or less, 3.5 nm or less, 3 nm or less, 2.5 nm or less, 2 nm or less, or 1.5 nm or less.

[0075] In one embodiment of the present invention, the thickness of the inorganic layer can be appropriately selected. The thickness of the inorganic layer can be 0.1 nm or more, 0.3 nm or more, 0.5 nm or more, or 0.7 nm or more. The thickness of the inorganic layer can be 5 nm or less, 4 nm or less, 3.5 nm or less, 3 nm or less, 2.5 nm or less, 2 nm or less, 1.5 nm or less, 1 nm or less, or 0.8 nm or less. The thickness of the inorganic layer can be in the range of 0.1 nm - 5 nm, 0.3 nm - 4 nm, 0.5 nm - 3.5 nm, 0.7 nm - 3 nm, 0.9 nm - 2.5 nm, 1 nm - 2 nm, 1.5 nm - 1.7 nm, or a combination thereof.

[0076] The particle size of the above quantum dot may be 1 nm or more, 1.5 nm or more, 2 nm or more, 2.5 nm or more, 3 nm or more, 3.5 nm or more, 4 nm or more, 4.5 nm or more, 5 nm or more, 5.5 nm or more, 6 nm or more, 6.5 nm or more, 7 nm or more, 7.5 nm or more, 8 nm or more, 8.5 nm or more, 9 nm or more, 9.5 nm or more, 10 nm or more, or 10.5 nm or more. The size of the above quantum dots may be 50 nm or less, 48 ​​nm or less, 46 nm or less, 44 nm or less, 42 nm or less, 40 nm or less, 35 nm or less, 30 nm or less, 25 nm or less, 20 nm or less, 18 nm or less, 16 nm or less, 14 nm or less, 12 nm or less, 11 nm or less, 10 nm or less, 8 nm or less, 6 nm or less, or 4 nm or less. The particle size may be a particle diameter.

[0077] The content of the quantum dots may be 1 to 50 wt%, preferably 20 to 40 wt%, and more preferably 25 to 35 wt%, based on the total weight of the quantum dot ink composition.

[0078] ligand

[0079] The quantum dot has a ligand layer on its surface, and the ligand contained in the ligand layer serves to modify the surface of the quantum dot. Due to the hydrophobic surface characteristics of the quantum dot, there is a barrier to dispersion of the photopolymerizable monomer. However, by modifying the surface of the quantum dot with an appropriate ligand, the miscibility of the quantum dot with the photopolymerizable monomer can be improved.

[0080] The ligand included in the above ligand layer is not particularly limited as long as it can improve the compatibility of the quantum dot with the photopolymerizable monomer, but may include, for example, a compound represented by the following chemical formula 1.

[0081] [Chemical Formula 1]

[0082]

[0083] The compound represented by the above chemical formula 1 contains a (meth)acrylate group, an alkylene oxide group, an ester group, and a carboxylic acid group in the molecule, and is particularly characterized by containing multiple ester groups in the molecule.

[0084] The compound represented by the above chemical formula 1 has a weight average molecular weight (M w ) may be 100 to 2000, preferably 400 to 1500. When the compound represented by the chemical formula 1 satisfies the above weight average molecular weight range, it is preferable because it can improve the miscibility of the quantum dot with the photopolymerizable monomer of the quantum dot while appropriately maintaining the viscosity of the quantum dot ink composition, and exhibit excellent optical properties.

[0085] Also, in the above chemical formula 1, R 1 and R 2 Each independently can be a hydrogen atom or a methyl group.

[0086] Also, in the above chemical formula 1, L 1 , L 2 and L 3Each independently may be a hydrocarbon group having 1 to 20 carbon atoms.

[0087] In addition, in the above chemical formula 1, n may be an integer from 1 to 20, preferably an integer from 2 to 15, and more preferably an integer from 3 to 12.

[0088] The hydrocarbon group having 1 to 20 carbon atoms may be a divalent aliphatic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0089] The above aliphatic hydrocarbon group may be a saturated or unsaturated hydrocarbon group, and may be a chain or alicyclic hydrocarbon group. In addition, the above alicyclic hydrocarbon group may be a monocyclic or polycyclic hydrocarbon group.

[0090] Examples of the above divalent saturated hydrocarbon group include straight-chain alkylene groups such as a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, a dodecylene group, a hexadecylene group, and an icosylene group; branched-chain alkylene groups such as an isopropylene group, an isobutylene group, an isopentylene group, a neopentylene group, a 2-ethylhexylene group, a sec-butylene group, a 1,3-dimethylbutylene group, and a 2-ethylbutylene group; and alicyclic alkylene groups such as a cyclopropylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, and a tricyclodecylene group. The number of carbon atoms in the above-mentioned two-valent saturated hydrocarbon group is more preferably 1 to 10, further preferably 1 to 5, and still more preferably 1 to 3.

[0091] Examples of the above divalent aromatic hydrocarbon group include a phenylene group, a benzylene group, a tolylene group, a xylylene group, a naphthylene group, etc., and preferably a phenylene group, a benzylene group, or a tolylene group. The number of carbon atoms of the above divalent aromatic hydrocarbon group is preferably 6 to 15, more preferably 6 to 12, and still more preferably 6 to 10.

[0092] The ligand included in the above ligand layer may include a compound represented by the following chemical formula 2.

[0093] [Chemical Formula 2]

[0094]

[0095] In the above chemical formula 2, R 3 and R 4 Each independently can be a hydrogen atom or a methyl group.

[0096] In addition, in the above chemical formula 2, o may be an integer from 1 to 20, preferably an integer from 2 to 15, and more preferably an integer from 3 to 12.

[0097] In addition, the mixing weight ratio of the quantum dot and the ligand may be 1:0.05 to 1, preferably 1:0.1 to 0.5. When the quantum dot and the ligand satisfy the above weight ratio range, the surface of the quantum dot is modified, thereby improving the compatibility of the quantum dot with the photopolymerizable monomer, and at the same time, the optical properties and stability can be improved in a balanced manner, which is preferable.

[0098] photopolymerizable monomer

[0099] Photopolymerizable monomers control the overall crosslinking density of the polymer matrix, i.e., the formulation in which quantum dots are dispersed, thereby shaping the matrix's structure and overall physical properties. They can also improve flexibility and adhesion to other materials.

[0100] The above photopolymerizable monomer may include at least one selected from 1-6 functional (meth)acrylate compounds. The 1-6 functional (meth)acrylate compounds may be used without any particular limitation as long as they are monomers commonly used in the art.

[0101] Specific examples of the above monofunctional (meth)acrylate compound include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, octadecyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, or isobornyl (meth)acrylate.

[0102] Specific examples of the above-mentioned bifunctional (meth)acrylate compound include 1,6-hexanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methylpentanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, etc., and 1,6-hexanediol di(meth)acrylate can be preferably used.

[0103] Specific examples of the above 3 to 6 functional (meth)acrylate compounds include trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, ethoxylated dipentaerythritol hexa(meth)acrylate, propoxylated dipentaerythritol hexa(meth)acrylate, dipentaerythritol hexa(meth)acrylate, etc.

[0104] Meanwhile, while monofunctional (meth)acrylate compounds generally have small molecular weights, which are advantageous for controlling the viscosity of quantum dot ink compositions, their volatility increases at high temperatures, which may increase outgassing during high-temperature processes such as post-baking. This increase in outgassing may cause defects such as cracking within the coating film. Therefore, it may be preferable for the photopolymerizable monomer to include at least one selected from di- to hexafunctional (meth)acrylate compounds.

[0105] In addition, as the number of functional groups of the (meth)acrylate compound increases, the molecular weight generally increases, which has the advantage of reducing outgassing in a high-temperature process, but may increase the viscosity of the quantum dot ink composition, which may cause a decrease in inkjet processability and storage stability. In this respect, the photopolymerizable monomer may preferably include at least one selected from di- to trifunctional (meth)acrylate compounds, more preferably may include a difunctional (meth)acrylate compound, and most preferably may include 1,6-hexanediol diacrylate.

[0106] The content of the photopolymerizable monomer may be 35 to 80 wt%, preferably 45 to 70 wt%, based on the total weight of the quantum dot ink composition.

[0107] photoinitiator

[0108] A photoinitiator is a component that initiates photopolymerization by being excited by a light source such as ultraviolet (UV) light, and any conventional photoinitiator in the field can be used without limitation.

[0109] In one embodiment of the present invention, the photoinitiator may include at least one selected from the group consisting of a phosphine oxide compound, an acetophenone compound, a benzophenone compound, a triazine compound, a biimidazole compound, an oxime compound, and a thioxanthone compound.

[0110] Specific examples of the above phosphine oxide compounds include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, trimethylbenzoylphenylphosphine oxide, ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, etc., and a representative commercial product is TPO-L from IGM.

[0111] Specific examples of the above acetophenone compounds include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one, 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)butan-1-one, etc.

[0112] Specific examples of the above benzophenone compounds include benzophenone, o-benzoyl methyl benzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, etc.

[0113] Specific examples of the above triazine compounds include 2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxynaphthyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-piperonyl-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxystyryl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(5-methylfuran-2-yl)ethenyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)ethenyl]-1,3,5-triazine, Examples include 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)ethenyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(3,4-dimethoxyphenyl)ethenyl]-1,3,5-triazine, etc.

[0114] Specific examples of the above biimidazole compounds include 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole, 2,2'-bis(2,3-dichlorophenyl)-4,4',5,5'-tetraphenylbiimidazole, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetra(alkoxyphenyl)biimidazole, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetra(trialkoxyphenyl)biimidazole, 2,2-bis(2,6-dichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, or biimidazole compounds in which the phenyl group at the 4,4',5,5' position is substituted by a carboalkoxy group. Among these, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole, 2,2'-bis(2,3-dichlorophenyl)-4,4',5,5'-tetraphenylbiimidazole, and 2,2-bis(2,6-dichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole are preferably used.

[0115] Specific examples of the above oxime compounds include o-ethoxycarbonyl-α-oxyimino-1-phenylpropan-1-one, 2-((benzoyloxy)imino)-1-(4-(phenylthio)phenyl)octan-1-one, etc., and representative commercial products include Irgacure OXE 01 and OXE 02 from BASF.

[0116] Specific examples of the above thioxanthone compounds include 2-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, etc.

[0117] The content of the photoinitiator may be 0.01 to 10 wt%, preferably 0.1 to 5 wt%, based on the total weight of the quantum dot ink composition.

[0118] scattering particles

[0119] Scattering particles increase the path of light emitted from a light source, thereby increasing the overall light conversion efficiency of the light-scattering pixel.

[0120] As the above scattering particles, a typical inorganic material can be used, and preferably, a metal oxide can be used.

[0121] The above scattering particles are, for example, Al2O3, SiO2, ZnO, ZrO2, CaCO3, BaSO4, It may include at least one selected from the group consisting of BaTiO3, TiO2, Ta2O5, Ti3O5, ITO, IZO, ATO, ZnO-Al, Nb2O3, SnO and MgO, and preferably CaCO3, It may include at least one selected from the group consisting of BaSO4, TiO2, and ZrO2, and more preferably, it may include TiO2.

[0122] The primary average particle diameter (D90) of the above scattering particles may be 300 nm or less, preferably 150 to 250 nm, and more preferably 180 to 230 nm, but is not limited thereto.

[0123] The content of the scattering particles may be 0.01 to 10 wt%, preferably 0.1 to 5 wt%, based on the total weight of the quantum dot ink composition.

[0124] polymerization inhibitor

[0125] A polymerization inhibitor is a substance that forms a radical or compound with low reactivity that cannot cause a polymerization reaction by reacting with a radical, and can be added to control the speed of the photopolymerization reaction.

[0126] The polymerization inhibitor described above may be any material known in the art without limitation. For example, polymerization inhibitors may include quinone compounds, phenol or aniline compounds, and aromatic nitro or nitroso compounds. These may be used alone or in combination of two or more.

[0127] Specifically, examples of the quinone compounds 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), etc.

[0128] Examples of the above phenol or aniline compounds include 2,6-di-tert-butyl-4-methylphenol (BHT), 2,6-diphenyl-4-octadecyloxyphenol, and catechol.

[0129] Examples of the above aromatic nitro or nitroso compounds include phenothiazine, bis(α-methylbenzyl)phenothiazine, 3,7-dioctylphenothiazine, bis(α,α-dimethylbenzyl)phenothiazine, dimethyldithiocarbamic acid, diethyldithiocarbamic acid, dipropyldithiocarbamic acid, dibutyldithiocarbamic acid, and diphenyldithiocarbamic acid.

[0130] The content of the polymerization inhibitor may be 0.01 to 2 wt%, and preferably 0.05 to 1 wt%, based on the total weight of the quantum dot ink composition.

[0131] Other additives

[0132] In addition to the aforementioned components, the quantum dot ink composition may, as needed, utilize additives known in the art without limitation. The content of the additives may be appropriately adjusted within a range known in the art.

[0133] Examples of usable additives include silane compounds, siloxane compounds, antioxidants, lubricants, surface conditioners, surfactants, adhesion promoters, anti-foaming agents, slip agents, solvents, wetting agents, light stabilizers, stain inhibitors, softeners, thickeners, polymers, etc. These may be used alone or in combination of two or more.

[0134] Silane compounds provide adhesive properties to the matrix, and siloxane compounds provide wetting properties. Any known silane and siloxane compounds can be used without limitation.

[0135] Antioxidants play a role in suppressing discoloration due to heat or light irradiation and discoloration due to various oxidizing gases such as ozone, active oxygen, NOx, and SOx (X is an integer). In the present invention, by adding an antioxidant, it is possible to prevent discoloration of the matrix or reduce film thickness reduction due to decomposition. Examples of usable antioxidants include hydrazides, hindered amine antioxidants, nitrogen-containing heterocyclic mercapto compounds, thioether antioxidants, hindered phenol antioxidants, ascorbic acid, zinc sulfate, thiocyanates, thiourea derivatives, sugars, nitrites, sulfites, thiosulfates, hydroxylamine derivatives, and the like.

[0136] A leveling agent may be included to further increase the smoothness of the quantum dot ink composition by leveling it so that it can be coated evenly and smoothly. The leveling agent may include an acrylic agent, a silicone agent, or the like, either singly or in combination of two or more. For example, a polyether-modified polydimethylsiloxane may be included, and a (meth)acryloyl group may be added to the polyether chain.

[0137] A surfactant may be included to ensure mixing and uniform application of the quantum dot ink composition. The surfactant may be a cationic, anionic, zwitterionic, or nonionic surfactant known in the art. For example, at least one of a fluorinated surfactant, a silicone-based surfactant, and a fluorinated / silicon-based surfactant may be used.

[0138] Light stabilizers act as UV absorbers and enhance the weatherability of the matrix. Softeners mitigate cracking within the dried polymer matrix, thereby improving impact and flexural resistance by mitigating cracking within the cured matrix.

[0139] <Method for producing quantum dot ink composition>

[0140] The present invention provides a method for producing the quantum dot ink composition. The method may include: (a) a step of first surface-modifying a quantum dot including silver, indium, gallium, and sulfur with an X-type ligand; (b) a step of second surface-modifying the quantum dot subjected to the first surface modification with a compound represented by Chemical Formula 1; and (c) a step of dispersing the quantum dot subjected to the second surface modification in a photopolymerizable compound.

[0141] With respect to each component used in the method for manufacturing the quantum dot ink composition of the present invention, the contents of the above-described <quantum dot ink composition> can be applied without limitation.

[0142] The quantum dots comprising silver, indium, gallium, and sulfur of the above step (a) can be synthesized through methods known in the prior art in numerous documents (e.g., high-temperature injection, microfluidic reactor, microwave irradiation, etc.). For example, the quantum dots comprising silver, indium, gallium, and sulfur can be obtained by reacting a silver precursor, an indium precursor, a gallium precursor, and a sulfur precursor in a solution containing an organic ligand and an organic solvent at a predetermined reaction temperature (e.g., 20 to 300°C, 80 to 295°C, 120 to 290°C, 200 to 280°C), and then separating the reactants.

[0143] The type of the above silver precursor is not particularly limited and may be appropriately selected. The silver precursor may include silver powder, alkylated silver compound, silver alkoxide, silver carboxylate, silver acetylacetonate, silver nitrate, silver sulfate, silver halide, silver cyanide, silver hydroxide, silver oxide, silver peroxide, silver carbonate or a combination thereof, and preferably may include silver nitrate, silver acetate, silver acetylacetonate, silver chloride, silver bromide, silver iodide or a combination thereof.

[0144] The type of the above indium precursor is not particularly limited and may be appropriately selected. The indium precursor may include indium powder, alkylated indium compound, indium alkoxide, indium carboxylate, indium nitrate, indium percolate, indium sulfate, indium acetylacetonate, indium halide, indium cyanide, indium hydroxide, indium oxide, indium peroxide, indium carbonate, indium acetate, or a combination thereof, and preferably may include indium carboxylate such as indium oleate or indium myristate, indium acetate, indium hydroxide, indium chloride, indium bromide, indium iodide, or a combination thereof.

[0145] The type of the gallium precursor is not particularly limited and may be appropriately selected. The gallium precursor may include gallium powder, alkylated gallium compound, gallium alkoxide, gallium carboxylate, gallium nitrate, gallium percolate, gallium sulfate, gallium acetylacetonate, gallium halide, gallium cyanide, gallium hydroxide, gallium oxide, gallium peroxide, gallium carbonate, gallium chloride, gallium bromide, gallium iodide, or a combination thereof, and preferably may include gallium chloride, gallium iodide, gallium bromide, gallium acetate, gallium acetylacetonate, gallium oleate, gallium palmitate, gallium stearate, gallium myristate, gallium hydroxide, or a combination thereof.

[0146] The type of the above sulfur precursor is not particularly limited and can be appropriately selected. The sulfur precursor is an organic solvent dispersion or reaction product of sulfur, for example, sulfur-oleylamine (S-oleylamine), sulfur-dodecylamine (S-dodecylamine), sulfur-octadecene (S-ODE), trioctylphosphine-sulfide (S-TOP), tributylphosphine-sulfide (S-TBP), triphenylphosphine-sulfide (S-TPP), sulfur-trioctylamine (S-TOA), trimethylsilylalkyl sulfide, bis(trimethylsilyl) sulfide, mercaptopropyl silane, ammonium sulfide, sodium sulfide, thiol compounds having 1 to 30 carbon atoms (for example, α-toluenethiol, octanethiol, dodecanethiol, octadecenthiol, etc.), isothiocyanate compounds (for example, cyclohexylisothiocyanate cyclohexyl isothiocyanate), alkylenethiocarbonate (e.g., ethylene trithiocarbonate), allyl mercaptan, thiourea compound (e.g., thiourea, dialkylthiourea, phenylthiourea), or combinations thereof.

[0147] The X-type ligand of the above step (a) is a ligand that is bonded to the surface of the quantum dot via a negatively charged functional group selected from the group consisting of a carboxylate group, a phosphonate group, and a thiolate group, and may be a compound derived from a fatty acid having 5 to 30 carbon atoms. The X-type ligand may be derived from a saturated or unsaturated fatty acid such as, for example, octanoic acid, decanoic acid, dodecanoic acid, myristic acid, palmitic acid, stearic acid, oleic acid, etc., and may preferably be a compound derived from oleic acid.

[0148] The above oleic acid-derived compound is not particularly limited and may be appropriately selected. The oleic acid-derived compound may include zinc carboxylate, zinc phosphonate, zinc oleate, or a combination thereof.

[0149] The first surface modification of step (a) may be performed by introducing an X-type ligand into a quantum dot including silver, indium, gallium, and sulfur and reacting the quantum dot at 25 to 100°C for 30 minutes to 5 hours to modify the surface of the quantum dot, but is not limited thereto.

[0150] The secondary surface modification of step (b) may be performed by adding a compound represented by chemical formula 1 to the first surface-modified quantum dot and reacting it at 25 to 100°C for 30 minutes to 5 hours to modify the surface of the quantum dot, but is not limited thereto.

[0151] AIGS-based quantum dots are typically synthesized in the presence of a compound containing an amine group, a thiol group, a phosphine group, or a phosphine oxide group. Therefore, the AIGS-based quantum dots are surface-bound to the ligand compound via the unshared electron pair of a functional group selected from the group consisting of an amine group, a thiol group, a phosphine group, and a phosphine oxide group, thereby fabricating the surface of the quantum dots in an L-type configuration.

[0152] The L-type ligand binds to the surface of the quantum dot through a coordination bond via an unshared electron pair, whereas the X-type ligand binds to the surface of the quantum dot through a weak electrical interaction. The compound represented by Chemical Formula 1 used for the secondary surface modification is a type of X-type ligand containing a carboxylate group, and if the surface modification reaction is performed directly on the quantum dot having the L-type ligand, the yield of the surface substitution reaction is reduced. Therefore, by first modifying the surface of the AIGS-based quantum dot with the X-type ligand for the first time (step a) and then performing the secondary surface modification reaction using the compound represented by Chemical Formula 1 (step b), the yield of the quantum dot surface substitution reaction can be significantly increased.

[0153] In one embodiment of the present invention, the secondary surface modification of step (b) may be performed in the presence of a metal salt, preferably in the presence of a metal chloride, and more preferably in the presence of zinc chloride (ZnCl2).

[0154] The above-mentioned secondary surface-modified quantum dots can be obtained through centrifugation, and the obtained quantum dots can be dispersed in a photopolymerizable compound to prepare a solvent-free quantum dot ink composition.

[0155] < Curing film, color filter and display device >

[0156] The present invention provides a cured film comprising a cured product of the quantum dot ink composition. The cured product can be manufactured by including the steps of forming a pattern by applying the quantum dot ink composition described above onto a substrate using an inkjet spraying method; and the step of curing the pattern.

[0157] The substrate is not limited, and for example, a substrate having a flat surface such as a glass substrate, a silicon substrate, a polycarbonate substrate, a polyester substrate, an aromatic polyamide substrate, a polyamide-imide substrate, a polyimide substrate, an Al substrate, or a GaAs substrate can be used. The substrate can be pretreated by a chemical treatment using a chemical such as a silane coupling agent, a plasma treatment, an ion plating treatment, a sputtering treatment, a gas phase reaction treatment, or a vacuum deposition treatment. In addition, the substrate may have a barrier matrix formed thereon.

[0158] The present invention also provides a color filter comprising the cured film. The color filter may include a pixel layer formed by applying the quantum dot ink composition described above on a substrate in a predetermined pattern and then curing it. The composition and manufacturing method of the color filter are well known in the art, and thus a detailed description thereof will be omitted.

[0159] In addition, the present invention provides a display device including the color filter. The display device may include, but is not limited to, a liquid crystal display (LCD), an electroluminescent display (EL), a plasma display (PDP), a field emission display (FED), an organic light emitting diode (OLED), and the like. The display device of the present invention may further include a blue light source together with the color filter, and may include a configuration known in the art, if necessary.

[0160] Hereinafter, the present invention will be described in more detail through examples. However, the following examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention to the examples.

[0161] <Example>

[0162] Synthesis Example 1: Synthesis of AIGS quantum dots

[0163] Silver acetate was dissolved in oleylamine to prepare a 0.06 M silver precursor-containing solution (hereinafter referred to as “silver precursor”), sulfur was dispersed in oleylamine to prepare a 1 M sulfur precursor-containing solution (hereinafter referred to as “sulfur precursor”), and indium chloride (indium(III) chloride) was dissolved in ethanol to prepare a 0.2 M indium precursor-containing solution (hereinafter referred to as “indium precursor”).

[0164] Gallium acetylacetonate, octadecene (ODE), and 1-dodecanethiol were added to a 100 mL reaction flask and heated at 120°C under vacuum for 10 minutes. The flask was cooled to room temperature, the gas inside the flask was replaced with nitrogen, and the silver precursor, the sulfur precursor, and the indium precursor were added. The flask temperature was raised to 210°C and reacted for less than 60 minutes. The flask temperature was lowered to 180°C, trioctylphosphine (TOP) was added, and then cooled to room temperature. Hexane and ethanol were added to the obtained mixture to promote precipitation. The obtained first semiconductor nanocrystals (quantum dot cores) were recovered using centrifugation and redispersed in toluene. At this time, the molar ratio of the indium precursor, gallium precursor, and sulfur precursor used was 1:2.3:4.8.

[0165] Gallium chloride was dissolved in toluene to prepare a 4.5 M gallium precursor-containing solution (hereinafter referred to as “gallium precursor”).

[0166] Dimethylthiourea (DMTU), oleylamine, and dodecanethiol were placed in a flask and vacuumed at 120°C for 10 minutes. After replacing the inside of the reaction flask with N2, the flask was heated to 240°C, and the first semiconductor nanocrystals prepared above, gallium precursor, and silver precursor were added. The reactor was then heated to 320°C and reacted for approximately 10 minutes. The temperature of the reaction solution was raised to 180°C, trioctylphosphine was added, and then cooled to room temperature. The nanoparticles produced by adding hexane and ethanol were precipitated, and the obtained AIGS quantum dots were recovered by centrifugation and redispersed in toluene. At this time, the molar ratio of the gallium precursor, silver precursor, and sulfur precursor used was 1:0.5:1.

[0167] Synthesis Example 2: Synthesis of zinc oleate

[0168] A 2L flask was charged with 250 mmol of zinc acetate, 500 mmol of oleic acid, and 500 mL of trioctylamine, and a string bar was inserted and vacuum treatment was performed. The time required to reach 120°C was set to 30 minutes and maintained for 40 minutes. After switching to N2 blow mode, the temperature was increased to 280°C and maintained for 90 minutes. After the reaction was completed, the mantle was removed and cooled with air blow to obtain zinc oleate.

[0169] Synthesis Example 3: Synthesis of Ligand Compound A-1

[0170] Step 1

[0171] In a cooling water bath, 0.3 mol (64.9 g) of mono(2-acryloyloxyethyl) succinate, 1.5 mol (291 g) of tetraethylene glycol, 0.03 mol (3.7 g) of 4-(dimethylamino)-pyridine, and 150 g of dichloromethane were added and stirred. Then, 300 ml of 1.0 M 1,3-dicyclohexyl carbodiimide was slowly added, and the mixture was stirred at room temperature under a nitrogen atmosphere for about 1 hour. The reactant was filtered, extracted, and neutralized using a 10% HCl aqueous solution, a 1 M NaHCO3 aqueous solution, and distilled water. After neutralization, residual moisture was removed using magnesium sulfate (MgSO4) and concentrated using a vacuum evaporator.

[0172] Step 2

[0173] In a flask, 0.24 mol (72.5 g) of the product of Step 1, 0.24 mol (23.9 g) of succinic anhydride, 0.024 mol (2.93 g) of 4-(dimethylamino)-pyridine, and 220 g of 1,2-dichloroethane were placed and dispersed under a nitrogen atmosphere. A condenser was connected, heated to 65°C, and stirred for more than 1 hour. The reactant was extracted and neutralized using a 10% aqueous hydrogen chloride solution and distilled water. After neutralization, the remaining moisture was removed using MgSO4, concentrated using a vacuum evaporator, and dried in a vacuum oven to obtain a compound represented by the following chemical formula 3 (A-1; molecular weight: 492.47 g / mol).

[0174] [Chemical Formula 3]

[0175]

[0176] Synthesis Example 4: Synthesis of Ligand Compound a-1

[0177] Thioglycolic acid (0.271 mol), poly(ethylene glycol)methyl ether 550 (Mn 550) (0.276 mol), and p-toluene sulfonic acid monohydrate (0.027 mol) were mixed in 350 ml of cyclohexane and reacted at 80°C for 18 hours in a nitrogen environment.

[0178] After the reaction was completed, cyclohexane was removed and dissolved in chloroform. Neutralization was performed with an aqueous sodium bicarbonate (NaHCO3) solution, and the remaining solvent was removed using MgSO4 to obtain a compound (a-1; PEG-550T) represented by the following chemical formula 4.

[0179] [Chemical Formula 4]

[0180]

[0181] Synthesis Example 5: Synthesis of Ligand Compound a-2

[0182] Step 1

[0183] 20 g (0.05 mol) of MPEG-400 (polyoxyethylene monomethyl ether, Green Chemical Co.) and 5.1 g (0.05 mol) of triethylamine were dissolved in 350 ml of dichloromethane, and 9.5 g (0.05 mol) of p-toluenesulfonyl chloride was slowly added dropwise at 0°C, and the mixture was stirred and reacted at room temperature for 12 hours. The reactant was extracted with distilled water, and the remaining moisture in the organic layer was removed using anhydrous magnesium sulfate, and concentrated using a vacuum evaporator.

[0184] Step 2

[0185] 27 g (0.05 mol) of the product of Step 1 above was dissolved in 200 ml of water, 16.3 g (0.25 mol) of sodium azide was added in a nitrogen atmosphere, and the mixture was stirred at 80°C for 18 hours to react. After completion of the reaction, extraction was performed using dichloromethane, and the remaining moisture in the organic layer was removed using anhydrous magnesium sulfate, followed by concentration using a vacuum evaporator.

[0186] Step 3

[0187] 20.4 g (0.05 mol) of the product of Step 2 and 13.9 g (0.053 mol) of triphenylphosphine were placed in a flask and stirred at 50°C for 18 hours to allow the reaction to proceed. After completion of the reaction, 100 ml of water was added and stirred for 30 minutes. The solid formed during the reaction was filtered, and the filtrate was concentrated using a vacuum evaporator to obtain compound (a-2) represented by the following chemical formula 5.

[0188] [Chemical Formula 5]

[0189]

[0190] Synthesis Example 6: Synthesis of Ligand Compound a-3

[0191] A compound (a-3) represented by the following chemical formula 6 was obtained in the same manner as in Synthesis Example 5, except that MPEG-400 in Synthesis Example 5 was changed to MPEG-550 (Green Chemical Co.).

[0192] [Chemical Formula 6]

[0193]

[0194] Synthesis Example 7: Synthesis of ligand compound a-4

[0195] 2-Phenoxyethanol (20 g, 0.14 mol) and succinic anhydride (14.5 g, 0.14 mol) were dissolved in 350 ml of dichloroethane, and 4-(dimethylamino)pyridine (1.8 g, 0.014 mol) was added and stirred under a nitrogen atmosphere. A condenser was connected to the flask inlet, and the mixture was refluxed at 65°C for 3 hours to allow the reaction. After completion of the reaction, extraction and neutralization were performed using a 10% HCl aqueous solution and distilled water. After neutralization, the remaining moisture was removed using anhydrous magnesium sulfate, and the mixture was concentrated using a vacuum evaporator to obtain a compound (a-4) represented by the following chemical formula 7.

[0196] [Chemical Formula 7]

[0197]

[0198] Synthesis Example 8: Synthesis of Ligand Compound a-5

[0199] After dissolving 67.2 g (0.33 mol) of propylene glycol and 30 g (0.33 mol) of thioglycolic acid in 350 ml of toluene, 6.2 g (0.033 mol) of p-toluenesulfonic acid was added and stirred at 115°C for 24 hours to react. After completion of the reaction, extraction and neutralization were performed using a 1 M sodium bicarbonate (NaHCO3) aqueous solution and distilled water. After neutralization, residual moisture was removed using anhydrous magnesium sulfate, and the mixture was concentrated using a vacuum evaporator to obtain a compound (a-5) represented by the following chemical formula 8.

[0200] [Chemical Formula 8]

[0201]

[0202] Example 1: Preparation of quantum dot ink composition

[0203] 1) Zinc oleate treatment

[0204] The AIGS quantum dots obtained in Synthesis Example 1 were dispersed in cyclohexyl acetate at a 10 wt% concentration, then zinc oleate (0.43 M) was added and stirred at room temperature for 3 hours. After completion of the reaction, ethanol was added and centrifugation was performed to recover the quantum dots treated with zinc oleate. After recovering the quantum dots, they were dried in a vacuum oven at room temperature for 2 hours and dispersed in cyclohexyl acetate at a 10 wt% concentration.

[0205] 2) Surface modification of quantum dots

[0206] 0.68 g of a ZnCl2 solution (dispersed at 10 wt% in ethanol) was added to 10 g of the quantum dot dispersion (dispersed at 10 wt% in cyclohexyl acetate) treated with zinc oleate, and the mixture was stirred at room temperature for 10 minutes. Then, 3.66 g of the dispersion of the ligand compound A-1 according to Synthesis Example 3 (dispersed at 10 wt% in cyclohexyl acetate) was added, and the mixture was stirred at room temperature for 3 hours. After completion of the reaction, cyclohexane was added, and chemical precipitation was performed using a centrifuge. The precipitated quantum dots were separated, and the supernatant was discarded. The separated quantum dots were dried in a vacuum oven for 2 hours to obtain surface-modified quantum dots.

[0207] 3) Preparation of quantum dot ink composition

[0208] A dispersion of the above surface-modified quantum dots (dispersed at 40 wt% in 1,6-hexanediol diacrylate) and a TiO2 dispersion (dispersed at 50 wt% in 1,6-hexanediol diacrylate) were prepared so that the D90 particle size did not exceed 300 nm.

[0209] A quantum dot ink composition was prepared by mixing 75 g of quantum dot dispersion, 10 g of TiO2 dispersion, 1.5 g of TPO-L, 0.5 g of polymerization inhibitor (MEHQ), and 13 g of additional 1,6-hexndiol diacrylate.

[0210] Comparative Example 1: Preparation of quantum dot ink composition

[0211] 1) Zinc oleate treatment

[0212] A quantum dot dispersion treated with zinc oleate was obtained in the same manner as in 1) of Example 1.

[0213] 2) Surface modification of quantum dots

[0214] 0.169 g of ZnCl2 solution (10 wt% dispersed in ethanol) was added to 10 g of the quantum dot dispersion (10 wt% dispersed in cyclohexyl acetate) treated with the above zinc oleate, and the mixture was stirred at room temperature for 10 minutes. Then, 1.83 g of the dispersion of ligand compound a-1 according to Synthetic Example 4 (10 wt% dispersed in cyclohexyl acetate) was added, and the mixture was stirred at room temperature for 1 hour and 30 minutes. After completion of the reaction, 2 g of a dispersion of mono-2-(acryloyloxy)ethyl succinate (MAES) (10 wt% dispersed in cyclohexyl acetate) was added, and the mixture was stirred at room temperature for 1 hour and 30 minutes. After completion of the reaction, cyclohexane was added, and chemical precipitation was performed using a centrifuge. The precipitated quantum dots were separated, the supernatant was discarded, and the separated quantum dots were dried in a vacuum oven for 2 hours to obtain surface-modified quantum dots.

[0215] 3) Preparation of quantum dot ink composition

[0216] A quantum dot ink composition was prepared in the same manner as in 3) of Example 1, except that the quantum dot dispersion obtained in 2) of Comparative Example 1 (dispersed at 40 wt% in 1,6-hexanediol diacrylate) was used.

[0217] Comparative Example 2: Preparation of Quantum Dot Ink Composition

[0218] 1) Zinc oleate treatment

[0219] A quantum dot dispersion treated with zinc oleate was obtained in the same manner as in 1) of Example 1.

[0220] 2) Surface modification of quantum dots

[0221] Surface-modified quantum dots were obtained in the same manner as in 2) of Example 1, except that the dispersion of ligand compound A-1 according to Synthesis Example 3 was changed to a mono-2-(acryloyloxy)ethyl succinate dispersion (dispersed at 10 wt% in cyclohexyl acetate).

[0222] 3) Preparation of quantum dot ink composition

[0223] A quantum dot ink composition was prepared in the same manner as in 3) of Example 1, except that the quantum dot dispersion obtained in 2) of Comparative Example 2 (dispersed at 40 wt% in 1,6-hexanediol diacrylate) was used as the quantum dot dispersion.

[0224] Comparative Example 3: Preparation of Quantum Dot Ink Composition

[0225] 1) Zinc oleate treatment

[0226] A quantum dot dispersion treated with zinc oleate was obtained in the same manner as in 1) of Example 1.

[0227] 2) Surface modification of quantum dots

[0228] Surface-modified quantum dots were obtained in the same manner as in 2) of Example 1, except that the dispersion of ligand compound A-1 according to Synthesis Example 3 was changed to a dispersion of ligand compound a-4 according to Synthesis Example 7 (dispersed at 10 wt% in cyclohexyl acetate).

[0229] 3) Preparation of quantum dot ink composition

[0230] A quantum dot ink composition was prepared in the same manner as in 3) of Example 1, except that the quantum dot dispersion obtained in 2) of Comparative Example 3 (dispersed at 40 wt% in 1,6-hexanediol diacrylate) was used as the quantum dot dispersion.

[0231] Comparative Example 4: Preparation of Quantum Dot Ink Composition

[0232] 1) Surface modification of quantum dots

[0233] 15 g of a dispersion of ligand compound a-2 according to Synthesis Example 5 (10 wt% dispersed in ethanol) was added to 10 g of a dispersion of AIGS quantum dots obtained in Synthesis Example 1 (10 wt% dispersed in cyclohexyl acetate), and the mixture was stirred at room temperature for 3 hours. After completion of the reaction, cyclohexane was added and chemical precipitation was performed using a centrifuge. The precipitated quantum dots were separated, the supernatant was discarded, and the separated quantum dots were dried in a vacuum oven for 2 hours to obtain surface-modified quantum dots.

[0234] 2) Preparation of quantum dot ink composition

[0235] A quantum dot ink composition was prepared in the same manner as in 3) of Example 1, except that the quantum dot dispersion obtained in 1) of Comparative Example 4 (dispersed at 40 wt% in 1,6-hexanediol diacrylate) was used as the quantum dot dispersion.

[0236] Comparative Example 5: Preparation of Quantum Dot Ink Composition

[0237] 1) Surface modification of quantum dots

[0238] Surface-modified quantum dots were obtained in the same manner as 1) of Comparative Example 4, except that the dispersion of ligand compound a-2 according to Synthesis Example 5 was changed to a dispersion of ligand compound a-3 according to Synthesis Example 6 (dispersed at 10 wt% in cyclohexyl acetate).

[0239] 2) Preparation of quantum dot ink composition

[0240] A quantum dot ink composition was prepared in the same manner as in 3) of Example 1, except that the quantum dot dispersion obtained in 1) of Comparative Example 5 (dispersed at 40 wt% in 1,6-hexanediol diacrylate) was used as the quantum dot dispersion.

[0241] Comparative Example 6: Preparation of quantum dot ink composition

[0242] 1) Surface modification of quantum dots

[0243] 2 g of the dispersion of the ligand compound a-5 according to Synthesis Example 8 (dispersed at 10 wt% in cyclohexyl acetate) was added to 10 g of the dispersion of the AIGS quantum dots obtained in Synthesis Example 1 (dispersed at 10 wt% in cyclohexyl acetate), and the mixture was stirred at 80°C for 1 hour and 30 minutes. After completion of the reaction, ethanol was added, and the quantum dots were recovered using a centrifuge, and the recovered quantum dots were dispersed at 10 wt% in cyclohexyl acetate. Next, 15 g of the dispersion of the ligand compound a-3 according to Synthesis Example 6 (dispersed at 10 wt% in cyclohexyl acetate) was added, and the mixture was stirred at 80°C for 1 hour and 30 minutes. After completion of the reaction, cyclohexane was added, and chemical precipitation was performed using a centrifuge. The precipitated quantum dots were separated, the supernatant was discarded, and the separated quantum dots were dried in a vacuum oven for 2 hours to obtain surface-modified quantum dots.

[0244] 2) Preparation of quantum dot ink composition

[0245] A quantum dot ink composition was prepared in the same manner as in 3) of Example 1, except that the quantum dot dispersion obtained in 1) of Comparative Example 6 (dispersed at 40 wt% in 1,6-hexanediol diacrylate) was used as the quantum dot dispersion.

[0246] Comparative Example 7: Preparation of quantum dot ink composition

[0247] 1) Zinc oleate treatment

[0248] A quantum dot dispersion treated with zinc oleate was obtained in the same manner as in 1) of Example 1.

[0249] 2) Surface modification of quantum dots

[0250] Surface-modified quantum dots were obtained in the same manner as in 2) of Example 1, except that the dispersion of ligand compound A-1 according to Synthesis Example 3 was changed to a dispersion of a compound represented by the following chemical formula 9 (molecular weight: 232.2 g / mol) (dispersed at 10 wt% in cyclohexyl acetate).

[0251] [Chemical Formula 9]

[0252]

[0253] 3) Preparation of quantum dot ink composition

[0254] A quantum dot ink composition was prepared in the same manner as in 3) of Example 1, except that the quantum dot dispersion obtained in 2) of Comparative Example 7 (dispersed at 40 wt% in 1,6-hexanediol diacrylate) was used as the quantum dot dispersion.

[0255] The presence or absence of zinc-oleate treatment and addition of ZnCl2 of the quantum dots included in the quantum dot ink compositions of Example 1 and Comparative Examples 1 to 7, and the types of the first ligand and second ligand substituted on the surface of the quantum dots are summarized and shown in Table 1 below.

[0256]

[0257]

[0258] To select a ligand series suitable for AIGS quantum dot ink compositions, surface modification of quantum dots was attempted by applying thiol-based, acid-based, and amine-based ligand compounds. It was confirmed that, except for amine-based ligands, acid-based and thiol-based ligands required a change in the ligand type on the quantum dot surface from L-type to X-type for ligand exchange to occur.

[0259] As summarized in Table 1 above, in Example 1, Comparative Examples 1 to 3, and 7, the ligand exchange reaction was performed after zinc-oleate treatment, and the reaction was performed with ZnCl2 added to improve ligand binding force and reaction efficiency. In contrast, the ligand compounds used in Comparative Examples 4 to 6 were amine compounds, and since they had the same type of ligand structure as the surface of AIGS quantum dots, the zinc-oleate treatment process was omitted and surface modification was performed.

[0260] <Experimental Example>

[0261] 1. Manufacturing of cured film

[0262] Each of the quantum dot ink compositions according to Example 1 and Comparative Examples 1 to 7 was applied onto a glass substrate using a spin coater (Opticoat MS-A150, Mikasa), and exposed to 4000 mJ (83°C, 4 s) using a 395 nm UV exposure device to form a coating film having a thickness of 7 μm. The formed coating film was post-baked in a drying oven at 180°C and in a nitrogen atmosphere for 30 minutes to produce a cured film.

[0263] 2. Evaluation of light absorption rate and light conversion rate of cured film

[0264] A 2 cm x 2 cm single-film specimen of the cured film manufactured above was prepared. The specimen was loaded into an integrating sphere device (QE-2100, Otsuka Electronics Co., Ltd.) to measure the light absorption rate and light conversion rate, and the results are shown in Table 2 below.

[0265] The photoconversion rate (Green / blue) was calculated by loading the above-mentioned sample into an integrating sphere device, applying 450 nm blue light, absorbing all green light emitted upward in all directions, measuring the integration value, and calculating the increase in the peak converted to green relative to the decrease in the blue light absorption peak.

[0266]

[0267]

[0268] Referring to Table 2, it can be confirmed that Example 1, which includes quantum dots whose surface is modified with ligand compound A-1 (corresponding to the compound represented by Chemical Formula 1), has excellent light absorption and light conversion rates, and in particular, the light conversion rate is remarkably excellent at 31.7%.

[0269] In contrast, it can be confirmed that Comparative Examples 1 to 7 have significantly lower light absorption rates and / or light conversion rates compared to Example 1. In the case of Comparative Example 1, which includes quantum dots whose surfaces are modified with a thiol-based ligand compound, and Comparative Example 2, which includes quantum dots whose surfaces are modified with an acid-based ligand compound, the light absorption rates were somewhat good, but the light conversion rates tended to decrease. In particular, in the case of Comparative Examples 4 and 5, which include quantum dots whose surfaces are modified with an amine-based ligand compound, it can be confirmed that the light conversion rates were significantly reduced.

[0270] Considering the above results, when manufacturing AIGS-based quantum dots as an ink composition, it can be seen that an acid-based or thiol-based ligand compound substituted on the surface of the quantum dot has an advantage in improving the light conversion rate compared to an amine-based ligand compound, and among the acid-based ligand compounds, it can be seen that a compound represented by chemical formula 1 containing a polyalkylene glycol structure can exhibit the best effect.

[0271] The reason why the photoconversion rate is relatively high when acid or thiol ligand compounds are used compared to when amine ligand compounds are used is thought to be related to the addition of zinc oleate and zinc chloride (ZnCl2). Zinc oleate is thought to change the surface of AIGS-based quantum dots from L-type to X-type, creating an environment in which the ligand compounds can bind more strongly to the surface of the quantum dots, and together with zinc chloride, it is thought to play a role in passivating the surface of the quantum dots, thereby increasing the photoconversion rate.

[0272] 3. Initial viscosity evaluation of quantum dot ink composition

[0273] The initial viscosity of the quantum dot ink composition according to Example 1 was measured at room temperature (25°C) at 100 rpm for 2 minutes using a viscometer (RheoStress MARS-40, HAAKE Co., Ltd.). The results are shown in Table 3 below. For reference, the optical absorption rate, optical conversion rate, emission wavelength, half-maximum width, and film thickness of Example 1 described in Table 3 are the same as those described in Table 2 above.

[0274]

[0275]

[0276] Referring to Table 3, it can be confirmed that the quantum dot ink composition according to Example 1 exhibits excellent light absorption rate and light conversion rate, while also having a viscosity of 30 cP or less, and thus exhibits excellent physical properties applicable to the inkjet process.

Claims

1. A quantum dot ink composition comprising a quantum dot having a ligand layer on a surface and a photopolymerizable monomer, The above quantum dots contain silver, indium, gallium and sulfur, A quantum dot ink composition, wherein the ligand layer comprises a compound represented by the following chemical formula 1. [Chemical Formula 1] (In the above chemical formula 1, R 1 and R 2 are each independently a hydrogen atom or a methyl group, L 1 , L 2 and L 3 are each independently a hydrocarbon group having 1 to 20 carbon atoms, n is an integer from 1 to 20.) 2. In claim 1, The compound represented by the above chemical formula 1 has a weight average molecular weight (M w ) is 100 to 2000, quantum dot ink composition.

3. In claim 1, A quantum dot ink composition, wherein the content of the quantum dots is 1 to 50 wt% based on the total weight of the quantum dot ink composition.

4. In claim 1, A quantum dot ink composition, wherein the ligand layer comprises a compound represented by the following chemical formula 2. [Chemical Formula 2] (In the above chemical formula 2, R 3 and R 4 are each independently a hydrogen atom or a methyl group, o is an integer from 1 to 20.) 5. In claim 1, A quantum dot ink composition further comprising at least one selected from the group consisting of photoinitiators and scattering particles.

6. In claim 5, A quantum dot ink composition, wherein the photoinitiator comprises at least one selected from the group consisting of a phosphine oxide compound, an acetophenone compound, a benzophenone compound, a triazine compound, a biimidazole compound, an oxime compound, and a thioxanthone compound.

7. In claim 5, The above scattering particles are Al2O3, SiO2, ZnO, ZrO2, CaCO3, BaSO4, A quantum dot ink composition comprising at least one selected from the group consisting of BaTiO3, TiO2, Ta2O5, Ti3O5, ITO, IZO, ATO, ZnO-Al, Nb2O3, SnO, and MgO.

8. In claim 1, The viscosity of the quantum dot ink composition is 30 cP or less, A quantum dot ink composition, wherein a cured product of the quantum dot ink composition exhibits a light conversion rate of 29% or more for a blue light source at a thickness of 7 μm. 9.(a) A step of first surface modification of a quantum dot containing indium, gallium and sulfur with an X-type ligand; (b) a step of secondarily surface-modifying the first surface-modified quantum dot with a compound represented by chemical formula 1; and (c) A method for producing a quantum dot ink composition, comprising the step of dispersing the second surface-modified quantum dots in a photopolymerizable compound. [Chemical Formula 1] (In the above chemical formula 1, R 1 and R 2 are each independently a hydrogen atom or a methyl group, L 1 , L 2 and L 3 are each independently a hydrocarbon group having 1 to 20 carbon atoms, n is an integer from 1 to 20.) 10. A cured film comprising a cured product of a quantum dot ink composition according to any one of claims 1 to 8.

11. A color filter comprising a cured film according to claim 10.

12. A display device comprising a color filter according to claim 11.

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