Quantum dot optical sheet, and backlight unit and display device comprising the same

Abstract

This invention discloses a quantum dot optical sheet, as well as a backlight unit and a display device including the same. The quantum dot optical sheet exhibits excellent performance in both thermal stability and blocking properties, eliminating the need for expensive traditional blocking films, and can be effectively applied to the manufacture of backlight units and display devices, thereby providing high-quality display devices while reducing manufacturing costs.

Description

Technical Field

[0001] The present invention relates to a quantum dot optical sheet and a backlight unit and display device including the same. Prior Technology

[0002] Quantum dots (QDs), also known as semiconductor nanocrystals, can emit various colors by producing light with different wavelengths depending on the particle size. They also have the advantages of better color purity and photostability compared to typical light-emitting materials, and are therefore attracting attention as the next generation of light-emitting elements.

[0003] In particular, as a new trend in the display field, quantum dots can be applied to various displays, electronic devices, televisions, and LEDs. Quantum dots, represented by CdSe and InP, have achieved rapid improvements in luminous efficiency (quantum yield), and various methods for synthesizing quantum dots with luminous efficiency approaching 100% have been introduced into the technology. Therefore, televisions including quantum dot sheets have been commercialized in the technology.

[0004] Because quantum dots are susceptible to external factors (such as oxygen, humidity, and heat), and suffer from brightness degradation and significant changes in color coordinates when exposed to the external environment for extended periods, it has become necessary to use barrier films to protect them. However, barrier films with very high levels of barrier properties are relatively expensive, increasing the manufacturing cost of quantum dot sheets.

[0005] To reduce the manufacturing cost of quantum dot optics while compensating for the fragility of quantum dots to the external environment, it has been proposed to incorporate quantum dots into substrates containing polymer materials. However, such quantum dot optics do not easily satisfy both thermal stability and high-level barrier properties.

[0006] Therefore, there is a need to develop a novel quantum dot optical sheet that can solve the problem of high cost of traditional barrier films while satisfying both thermal stability and barrier properties. Summary of the Invention

[0007] [[] [Technical Issues] [] ]

[0008] One objective of this invention is to provide a quantum dot optical sheet that, while replacing high-cost traditional blocking films, exhibits excellent properties in both thermal stability and blocking characteristics.

[0009] Another object of the present invention is to provide a quantum dot optical sheet that does not suffer from brightness degradation and significant changes in color coordinates even when exposed to the external environment for a long time.

[0010] A further object of the present invention is to provide a backlight unit including a quantum dot optical sheet and a display device.

[0011] However, it should be understood that the present invention is not limited to the above objectives, and the above and other objectives will become apparent to those skilled in the art from the following description.

[0012] [[] [Technical Solution] [] ]

[0013] According to one aspect of the present invention, a quantum dot optical sheet includes: a first substrate; a first barrier layer formed on the first substrate; a second substrate disposed opposite to the first substrate; a second barrier layer formed on the second substrate; and a light conversion layer inserted between the first barrier layer and the second barrier layer, wherein each of the first barrier layer and the second barrier layer includes a cured product of a composition for the barrier layer, the composition for the barrier layer including (methyl)allyl monomers, monomers having at least two thiol groups at their ends, metal oxide nanoparticles, and a first photoinitiator, and wherein the light conversion layer includes a cured product of a composition for the light conversion layer, the composition for the light conversion layer including quantum dots, bisphenol monomers, cyclizable monomers, and a second photoinitiator.

[0014] In quantum dot optical sheets, (methyl)allyl monomers may include at least one of a group selected from triallyl isocyanurate, 1,3-diallyl-5-glycidyl isocyanurate, diallylpropyl isocyanurate, and trimethylallyl isocyanurate.

[0015] In quantum dot optical sheets, monomers having at least two thiol groups at their ends may include at least one of the groups selected from pentaerythritol tetra(2-mercaptoacetate), pentaerythritol tetra(3-mercaptopropionate), 1,2-ethylenedithiol, pentaerythritol tetra(mercaptopropionate), pentaerythritol tetra(thioglycolate), trimethylolpropane tri(2-mercaptoacetate), and trimethylolpropane tri(3-mercaptopropionate).

[0016] In quantum dot optical sheets, metal oxide nanoparticles may include at least one of the groups selected from titanium dioxide, aluminum oxide, chromium trioxide, zinc oxide, copper oxide, magnesium oxide, zirconium dioxide, molybdenum trioxide, vanadium pentoxide, niobium pentoxide, and tantalum pentoxide.

[0017] In quantum dot optical films, the quantum dots can be cadmium-free quantum dots.

[0018] In a quantum dot optical sheet, the quantum dots may have a ligand layer on their surface, and the ligand layer may include at least one of a group selected from carboxylic acid compounds, thiols, phosphine compounds, phosphine oxides, and amine compounds.

[0019] In quantum dot optical sheets, cyclizable monomers may include at least one of a group selected from alkyl 2-[(allyloxy)methyl](meth)acrylate, hydroxyalkyl 2-[(allyloxy)methyl](meth)acrylate, haloalkyl 2-[(allyloxy)methyl](meth)acrylate, cycloalkyl 2-[(allyloxy)methyl](meth)acrylate, aryl 2-[(allyloxy)methyl](meth)acrylate, alkoxyalkyl 2-[(allyloxy)methyl](meth)acrylate, alkoxycycloalkyl 2-[(allyloxy)methyl](meth)acrylate, and oxecycloalkyl 2-[(allyloxy)methyl](meth)acrylate.

[0020] In quantum dot optical sheets, the composition of the light conversion layer may further include at least one of a group selected from difunctional (meth)acrylate monomers, trifunctional (meth)acrylate monomers, and tetrafunctional or higher (meth)acrylate monomers.

[0021] In quantum dot optical sheets, after being exposed to light with a wavelength of 450 nanometers for 616 hours, the quantum dot optical sheets can have a brightness retention rate of 95% or higher (ΔLm); x-axis chromatic coordinate change (ΔCx) of -0.005 ≤ ΔCx ≤ 0.005; and y-axis chromatic coordinate change (ΔCy) of -0.005 ≤ ΔCy ≤ 0.005.

[0022] In quantum dot optical sheets, after being exposed to 60°C and 95% humidity for 616 hours, the quantum dot optical sheets can maintain a brightness retention rate of 90% or higher (ΔLm); x-axis chromatic coordinate change (ΔCx) of -0.010 ≤ ΔCx ≤ 0.010; and y-axis chromatic coordinate change (ΔCy) of -0.010 ≤ ΔCy ≤ 0.010.

[0023] In quantum dot optical sheets, after being exposed to 60°C for 616 hours, the quantum dot optical sheets can maintain a brightness retention rate (ΔLm) of 90% or higher; an x-axis chromatic coordinate change (ΔCx) of -0.015 ≤ ΔCx ≤ 0.015; and a y-axis chromatic coordinate change (ΔCy) of -0.015 ≤ ΔCy ≤ 0.015.

[0024] According to another aspect of the invention, a backlight unit comprising a quantum dot optical sheet is provided.

[0025] According to another aspect of the present invention, a display device including a backlight unit is provided.

[0026] [[] [Beneficial Effects] [] ]

[0027] The quantum dot optical sheet according to the present invention comprises a blocking layer containing metal oxide nanoparticles and a light conversion layer containing quantum dots and a polymer matrix with enhanced thermal stability, thereby achieving excellent properties in both thermal stability and blocking characteristics without using high-cost conventional blocking films.

[0028] Furthermore, the quantum dot optical sheet according to the present invention does not suffer from brightness degradation or significant changes in color coordinates even when exposed to the external environment for a long time.

[0029] Furthermore, the quantum dot optical sheet according to the present invention has excellent properties in both thermal stability and blocking characteristics without using high-cost conventional blocking films, and can therefore be effectively applied to the manufacture of backlight units and display devices, thereby providing high-quality display devices while reducing manufacturing costs. Simple Explanation of the Diagram

[0030] Figure 1 is a cross-sectional view of the stacked structure of the quantum dot optical sheet according to the present invention. Implementation

[0031] Unless otherwise defined herein, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Terms such as those defined in common dictionaries shall be interpreted as having the same meaning as they have in the relevant technical context, and shall not be interpreted in an idealized or exaggerated sense unless expressly defined herein.

[0032] Furthermore, as used herein, the terms "comprises", "comprising", "includes" and / or "including" specify the presence of the stated elements and / or steps, but do not exclude the presence or addition of at least one other element and / or step.

[0033] Furthermore, unless the context clearly indicates otherwise, the singular forms "a," "an," and "the" are intended to include the plural forms as well. For example, as used herein, "substrate" may refer to at least one of a first substrate and a second substrate, and "barrier layer" may refer to at least one of a first barrier layer and a second barrier layer.

[0034] Furthermore, spatially relative terms, such as "below," "lower surface," "below," "above," "upper surface," "above," etc., may be used herein for descriptive purposes to describe the relationship of an element to other elements shown in the diagrams. Spatially relative terms are intended to encompass different orientations of the apparatus in use, operation, and / or manufacture, in addition to those depicted in the diagrams. For example, if the sheet in the diagram is flipped, an element described as "below" or "below" other elements or features would be oriented as "above" or "above" other elements or features. Thus, the exemplary terms "below" or "below" can encompass both above and below orientations.

[0035] Furthermore, as used herein, the terms "monomer product" and "monomer" have the same meaning. In the context of this invention, a monomer is distinguished from oligomers and polymers, and is a compound having a weight average molecular weight of 1,000 or less.

[0036] Furthermore, as used herein, monomers may contain polymerizable functional groups, such as (meth)acrylate groups, and may be classified based on the number of polymerizable functional groups contained in a molecule as monofunctional (f=1), difunctional (f=2), trifunctional (f=3), and more than four functional groups (f≥4).

[0037] Furthermore, as used herein, "(meth)acrylate" refers to acrylate and methacrylate, "(meth)propenyl" refers to propenyl and methpropenyl, "(meth)acrylyl" refers to propenyl and methacrylyl, and "(meth)allyl" refers to allyl and methallyl.

[0038] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it should be understood that the drawings attached to this specification are intended to illustrate exemplary embodiments so that the technical concepts of the present invention can be fully understood in conjunction with the following description of the invention. Therefore, the present invention should not be construed as limited to what is shown in the drawings.

[0039] Figure 1 is a cross-sectional view of the stacked structure of the quantum dot optical sheet according to the present invention.

[0040] Referring to FIG1, the quantum dot optical sheet according to the present invention includes a first substrate 100-1; a first blocking layer 200-1 formed on the first substrate; a second substrate 100-2 configured to be opposite to the first substrate; a second blocking layer 200-2 formed on the second substrate; and a light conversion layer 300 inserted between the first blocking layer and the second blocking layer.

[0041] Preferably, the substrate comprises a light-transmitting resin with good light transmittance and may have, for example, 85% to 100% light transmittance at a wavelength of 550 nanometers.

[0042] The substrate can be formed from, for example, polyethylene terephthalate (PET), polyethylene naphthalate, acrylic resin, polystyrene, polycarbonate (PC), cyclic olefin polymers, etc. Preferably, the substrate is formed from polyethylene terephthalate (PET) for its excellent transparency, strength, and flexibility.

[0043] The substrate can be fabricated as a single layer or a multilayer structure with two or more layers, and can have a thickness of, for example, 10 micrometers to 200 micrometers, but is not limited thereto.

[0044] The barrier layer is used to protect the light conversion layer 300 containing quantum dots from the influence of the external environment, and can be formed to directly contact the light conversion layer 300.

[0045] The barrier layer includes a cured product of a composition for use in the barrier layer, the composition including (methyl)allyl monomers, monomers having at least two thiol groups at their ends, metal oxide nanoparticles, and a first photoinitiator.

[0046] (Methyl)allyl monomers may include at least one of a group selected from triallyl isocyanurate, 1,3-diallyl-5-glycidyl isocyanurate, diallylpropyl isocyanurate, and trimethylallyl isocyanurate, preferably triallyl isocyanurate.

[0047] (Methyl)allyl monomers may be present in an amount of 10% to 70% by weight, preferably 20% to 60% by weight, based on the total weight of the composition used for the barrier layer.

[0048] Monomers having at least two thiol groups at their ends may include at least one selected from pentaerythritol tetra(2-mercaptoacetate), pentaerythritol tetra(3-mercaptopropionate), 1,2-ethylenedithiol, pentaerythritol tetra(mercaptopropionate), pentaerythritol tetra(thioglycolate), trimethylolpropane tri(2-mercaptoacetate), and trimethylolpropane tri(3-mercaptopropionate), preferably pentaerythritol tetra(2-mercaptoacetate).

[0049] The monomer having at least two thiol groups at its end may be present in an amount of 15% to 85% by weight, preferably 30% to 70% by weight, based on the total weight of the composition used for the barrier layer.

[0050] The metal oxide nanoparticles may include at least one of the groups selected from titanium dioxide, aluminum oxide, chromium trioxide, zinc oxide, copper oxide, magnesium oxide, zirconium dioxide, molybdenum trioxide, vanadium pentoxide, niobium pentoxide and tantalum pentoxide, preferably aluminum oxide (Al2O3).

[0051] The metal oxide nanoparticles may be present in an amount of 0.1% to 20% by weight, preferably 1% to 15% by weight, based on the total weight of the composition used for the barrier layer.

[0052] The first photoinitiator can be any type of photoinitiator, as long as it can generate free radicals upon excitation by a light source such as ultraviolet (UV) light. First photoinitiators may include, for example, acetophenone compounds, benzophenone compounds, thioxanthone compounds, benzoin compounds, triazine compounds, or oxime compounds.

[0053] The primary photoinitiator may include, for example, ethyl (2,4,6-trimethylbenzoyl)phenylphosphonate, Irgacure 184, Irgacure 369, Irgacure 651, Irgacure 819, Irgacure 907, Irgacure TPO, TPO-L, benzoinalkylether, benzophenone, benzyl dimethyl ketal, hydroxycyclohexylphenylacetone, chloroacetophenone, 1,1-dichloroacetophenone, diethoxyacetophenone, hydroxyacetophenone, 2-chlorothiazolone, 2-ethylanthraquinone (2-ETAQ), 1-hydroxy-cyclohexyl-phenyl-one, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, methyl benzoyl carbamate. Photoinitiators, such as formate, are not necessarily limited to this. These photoinitiators can be used alone or as a mixture thereof.

[0054] The first photoinitiator may be present in an amount of 0.1% to 5% by weight, preferably 0.5% to 3% by weight, based on the total weight of the composition used for the blocking layer.

[0055] In the barrier layer, heat-resistant metal oxide nanoparticles are dispersed in a polymer matrix that enhances barrier properties, ensuring excellent performance in both thermal stability and barrier properties. This barrier layer can replace high-cost traditional barrier films that use conventional deposition techniques or special coatings (e.g., products of I-Components Co., Ltd., Dai Nippon Printing (DNP) Co., Ltd.).

[0056] The barrier layer can have any thickness, as long as it can protect the light conversion layer 300 from external environmental influences. For example, the barrier layer can have a thickness from 10 μm to 100 μm. Within this range, the barrier layer can ensure sufficient barrier properties without curling after curing, thereby preventing defects caused by curling.

[0057] The light conversion layer 300 is inserted between the first blocking layer 200-1 and the second blocking layer 200-2, and is in direct contact with at least one of the first blocking layer 200-1 and the second blocking layer 200-2.

[0058] The light conversion layer 300 includes a cured product of a composition for the light conversion layer, the composition including quantum dots, bisphenol monomers, cyclizable monomers and a second photoinitiator, wherein the quantum dots are dispersed within a polymer matrix formed by photocuring the monomers.

[0059] Quantum dots (QDs) are nanoscale semiconductor materials that can have different band gaps depending on their size and composition, and thus can emit light with different emission wavelengths.

[0060] These quantum dots can have a homogeneous monolayer structure, a multilayer structure (e.g., core-shell structure, gradient structure, etc.), or a mixture thereof. When the shell has a multilayer structure, each layer can contain different components, such as metal (metal-like) oxides.

[0061] Quantum dots (QDs) 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. When quantum dots are prepared in a core-shell structure, the core and shell can each be freely selected from the compositions exemplified below.

[0062] In one example, group II-VI compounds may be selected from groups consisting of: binary compounds consisting of groups selected from CdO, CdS, CdSe, CdTe, ZnO, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, MgSe, MgS, and mixtures thereof; and compounds selected from CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe ... Ternary compounds consisting of groups composed of nTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS and mixtures thereof; and quaternary compounds consisting of groups selected from CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe and mixtures thereof.

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

[0064] In another example, group IV-VI compounds may be selected from groups consisting of: binary compounds consisting of groups consisting of SnS, SnSe, SnTe, PbS, PbSe, PbTe and mixtures thereof; ternary compounds consisting of groups consisting of SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe and mixtures thereof; and quaternary compounds consisting of groups consisting of SnPbSSe, SnPbSeTe, SnPbSTe and mixtures thereof.

[0065] In another example, Group IV elements can be selected from groups composed of Si, Ge, and mixtures thereof. Group IV compounds can be binary compounds composed of groups selected from SiC, SiGe, and mixtures thereof.

[0066] The aforementioned binary, ternary, or quaternary compounds can exist in particles at a uniform concentration or at partially different concentrations. Quantum dots can also have a core / shell structure in which one quantum dot surrounds another. The interface between the core and shell can have a concentration gradient, where the concentration of elements in the shell gradually decreases towards its center.

[0067] Quantum dots can have any shape commonly used in the field of technology. For example, quantum dots can be nanoparticles, nanotubes, nanowires, nanofibers, or nanosheets with shapes such as spheres, rods, cones, disks, multi-arm shapes, and cubic shapes.

[0068] Furthermore, the size of quantum dots is not particularly limited and can be appropriately adjusted within typical ranges well known in the art. For example, quantum dots can have an average particle size (D50) of about 2 nanometers to about 10 nanometers. Thus, when the average particle size of quantum dots is adjusted to the range of about 2 nanometers to about 10 nanometers, the quantum dots can emit light of the desired color. For example, when the InP-containing quantum dot core / shell has a particle size of about 5 nanometers to about 6 nanometers, the quantum dots can emit light with a wavelength of about 520 nanometers to about 550 nanometers. On the other hand, when the InP-containing quantum dot core / shell has a particle size of about 7 nanometers to about 8 nanometers, the quantum dots can emit light with a wavelength of about 620 nanometers to about 640 nanometers. For example, cadmium-free (Cd) III-V group quantum dots (QDs) (e.g., InP, InGaP, InZnP, GaN, GaAs, or GaP) can be used as quantum dots that emit blue light.

[0069] Quantum dots can also have a full width at half maximum (FWHM) of about 40 nanometers or less in their emission wavelength spectrum. Within this range, color purity or color reproducibility may be improved. In addition, light emitted from quantum dots travels in all directions, thereby improving the viewing angle.

[0070] Based on the total weight of the components used in the light conversion layer, quantum dots may be present in amounts from 0.1 wt% to 30 wt%, preferably from 1 wt% to 20 wt%.

[0071] Quantum dots have a ligand layer on their surface, where ligands in the ligand layer are used to modify the surface of the quantum dots. Since the hydrophobic properties of the quantum dot surface hinder the dispersion of quantum dots in photopolymerizable monomers, the miscibility of quantum dots with respect to photopolymerizable monomers can be improved by surface modification of the quantum dots with appropriate ligands.

[0072] The ligand layer may include at least one group selected from carboxylic acid compounds, thiols, phosphine compounds, phosphine oxides, and amine compounds. Preferably, the ligand layer includes carboxylic acid compounds, phosphine compounds, phosphine oxides, and amine compounds.

[0073] Carboxylic acid compounds may include at least one group selected from formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, dodecanoic acid, hexadecanoic acid, octanoic acid, oleic acid and benzoic acid, preferably oleic acid.

[0074] Thiol compounds may include at least one group selected from methanethiol, ethanethiol, propanethiol, butanethiol, pentathiol, hexanethiol, octylthiol, dodecanethiol, hexadecethiol, octadecethiol, and benzylthiol.

[0075] Phosphine compounds may include at least one group selected from methylphosphine, ethylphosphine, propylphosphine, butylphosphine, pentylphosphine, octylphosphine, dioctylphosphine, tributylphosphine, and trioctylphosphine, preferably trioctylphosphine.

[0076] Phosphine oxide compounds may include at least one group selected from phosphine oxide, methyl phosphine oxide, ethyl phosphine oxide, propyl phosphine oxide, butyl phosphine oxide, pentyl phosphine oxide, tributyl phosphine oxide, octyl phosphine oxide, dioctyl phosphine oxide, and trioctyl phosphine oxide, preferably trioctyl phosphine oxide.

[0077] The amine compound may include at least one group selected from decylamine, tetradecylamine, dodecylamine, hexadecylamine, octadecylamine, oleylamine, octylamine and trioctylamine, preferably trioctylamine.

[0078] Bisphenol monomers may include, selected from, bis(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl) ether, bis(4-hydroxyphenyl) arsenide, bis(4-hydroxyphenyl) arsenide, bis(4-hydroxyphenyl) sulfide, bis(4-hydroxyphenyl) ketone, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z), 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2, At least one of the following groups: 2-bis(4-hydroxy-3,5-dichlorophenyl)propane, 2,2-bis(4-hydroxy-3-bromophenyl)propane, 2,2-bis(4-hydroxy-3-chlorophenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, and α,ω-bis[3-(o-hydroxyphenyl)propyl]polydimethylsiloxane.

[0079] Based on the total weight of the composition used in the light conversion layer, the bisphenol monomer may be present in an amount of 5% to 60% by weight, preferably 10% to 50% by weight.

[0080] Cyclomeric monomers refer to monomers that can form a ring structure during polymerization to obtain polymers with a ring structure. Cyclomeric monomers may include at least one group selected from alkyl 2-[(allyloxy)methyl](meth)acrylate, hydroxyalkyl 2-[(allyloxy)methyl](meth)acrylate, haloalkyl 2-[(allyloxy)methyl](meth)acrylate, cycloalkyl 2-[(allyloxy)methyl](meth)acrylate, aryl 2-[(allyloxy)methyl](meth)acrylate, alkoxyalkyl 2-[(allyloxy)methyl](meth)acrylate, alkoxycycloalkyl 2-[(allyloxy)methyl](meth)acrylate, and oxecycloalkyl 2-[(allyloxy)methyl](meth)acrylate, preferably alkyl 2-[(allyloxy)methyl](meth)acrylate.

[0081] Alkyl 2-[(allyloxy)methyl](meth)acrylate may include at least one group selected from methyl 2-[(allyloxy)methyl](meth)acrylate, ethyl 2-[(allyloxy)methyl](meth)acrylate, propyl 2-[(allyloxy)methyl](meth)acrylate, butyl 2-[(allyloxy)methyl](meth)acrylate, pentyl 2-[(allyloxy)methyl](meth)acrylate, hexyl 2-[(allyloxy)methyl](meth)acrylate, heptyl 2-[(allyloxy)methyl](meth)acrylate, octyl 2-[(allyloxy)methyl](meth)acrylate, ethylhexyl 2-[(allyloxy)methyl](meth)acrylate, nonyl 2-[(allyloxy)methyl](meth)acrylate, and decyl 2-[(allyloxy)methyl](meth)acrylate.

[0082] The hydroxyalkyl 2-[(allyloxy)methyl](meth)acrylate may include at least one group selected from hydroxymethyl 2-[(allyloxy)methyl](meth)acrylate, hydroxyethyl 2-[(allyloxy)methyl](meth)acrylate, hydroxypropyl 2-[(allyloxy)methyl](meth)acrylate, hydroxybutyl 2-[(allyloxy)methyl](meth)acrylate, hydroxypentyl 2-[(allyloxy)methyl](meth)acrylate, hydroxyhexyl 2-[(allyloxy)methyl](meth)acrylate, hydroxyheptyl 2-[(allyloxy)methyl](meth)acrylate, hydroxyoctyl 2-[(allyloxy)methyl](meth)acrylate, hydroxyethylhexyl 2-[(allyloxy)methyl](meth)acrylate, hydroxynonyl 2-[(allyloxy)methyl](meth)acrylate, and hydroxydecyl 2-[(allyloxy)methyl](meth)acrylate.

[0083] The haloalkyl 2-[(allyloxy)methyl](meth)acrylate may include at least one group selected from fluoroethyl 2-[(allyloxy)methyl](meth)acrylate, difluoroethyl 2-[(allyloxy)methyl](meth)acrylate, chloroethyl 2-[(allyloxy)methyl](meth)acrylate, dichloroethyl 2-[(allyloxy)methyl](meth)acrylate, bromoethyl 2-[(allyloxy)methyl](meth)acrylate, and dibromoethyl 2-[(allyloxy)methyl](meth)acrylate.

[0084] Cycloalkyl 2-[(allyloxy)methyl](meth)acrylate may include at least one group selected from cyclopentyl 2-[(allyloxy)methyl](meth)acrylate, cyclopentylmethyl 2-[(allyloxy)methyl](meth)acrylate, cyclohexyl 2-[(allyloxy)methyl](meth)acrylate, cyclohexylmethyl 2-[(allyloxy)methyl](meth)acrylate, tricyclodecyl 2-[(allyloxy)methyl](meth)acrylate, isobornyl 2-[(allyloxy)methyl](meth)acrylate, and dicyclopentyl 2-[(allyloxy)methyl](meth)acrylate.

[0085] aryl 2-[(allyloxy)methyl](meth)acrylate may include at least one group selected from phenyl 2-[(allyloxy)methyl](meth)acrylate, methylphenyl 2-[(allyloxy)methyl](meth)acrylate, dimethylphenyl 2-[(allyloxy)methyl](meth)acrylate, trimethylphenyl 2-[(allyloxy)methyl](meth)acrylate, butylphenyl 2-[(allyloxy)methyl](meth)acrylate, benzyl 2-[(allyloxy)methyl](meth)acrylate, diphenylmethyl 2-[(allyloxy)methyl](meth)acrylate, diphenylethyl 2-[(allyloxy)methyl](meth)acrylate, triphenylmethyl 2-[(allyloxy)methyl](meth)acrylate, naphthyl 2-[(allyloxy)methyl](meth)acrylate, and anthracene 2-[(allyloxy)methyl](meth)acrylate.

[0086] Alkoxyalkyl 2-[(allyloxy)methyl](meth)acrylate may include at least one group selected from methoxyethyl 2-[(allyloxy)methyl](meth)acrylate, methoxyethoxyethyl 2-[(allyloxy)methyl](meth)acrylate, methoxybutyl 2-[(allyloxy)methyl](meth)acrylate, ethoxyethyl 2-[(allyloxy)methyl](meth)acrylate, and ethoxyethoxyethyl 2-[(allyloxy)methyl](meth)acrylate.

[0087] Alkoxycycloalkyl 2-[(allyloxy)methyl](meth)acrylate may include at least one group selected from methoxycyclopentyl 2-[(allyloxy)methyl](meth)acrylate, ethoxycyclopentyl 2-[(allyloxy)methyl](meth)acrylate, methoxycyclohexyl 2-[(allyloxy)methyl](meth)acrylate, ethoxycyclohexyl 2-[(allyloxy)methyl](meth)acrylate, and dicyclopentenoxyethyl 2-[(allyloxy)methyl](meth)acrylate.

[0088] The oxetane alkyl 2-[(allyloxy)methyl](meth)acrylate may include at least one group selected from glycidyl 2-[(allyloxy)methyl](meth)acrylate, methyl glycidyl 2-[(allyloxy)methyl](meth)acrylate, ethyl glycidyl 2-[(allyloxy)methyl](meth)acrylate, 3,4-epoxycyclohexylmethyl 2-[(allyloxy)methyl](meth)acrylate, oxetanemethyl 2-[(allyloxy)methyl](meth)acrylate, tetrahydrofuranyl 2-[(allyloxy)methyl](meth)acrylate, tetrahydropyranyl 2-[(allyloxy)methyl](meth)acrylate, and dioxanyl 2-[(allyloxy)methyl](meth)acrylate.

[0089] Based on the total weight of the composition used in the light conversion layer, the cyclizable monomer may be present in an amount of 1% to 40% by weight, preferably 5% to 30% by weight.

[0090] The second photoinitiator can be any type of photoinitiator, as long as it can generate free radicals upon excitation by a light source such as ultraviolet (UV) light. Second photoinitiators may include, for example, acetophenone compounds, benzophenone compounds, thioxanone compounds, benzoin compounds, triazine compounds, or oxime compounds.

[0091] Secondary photoinitiators may include, for example, ethyl (2,4,6-trimethylbenzoyl)phenylphosphonate, Enkaco 184, Enkaco 369, Enkaco 651, Enkaco 819, Enkaco 907, Enkaco TPO, TPO-L, benzoyl alkyl ether, benzophenone, benzyl dimethyl ketal, hydroxycyclohexylphenylacetone, chloroacetophenone, 1,1-dichloroacetophenone, diethoxyacetophenone, hydroxyacetophenone, 2-chlorothiazolone, 2-ethylanthraquinone (2-ETAQ), 1-hydroxy-cyclohexyl-phenyl-one, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, methylbenzoylcarbamate, etc. These photoinitiators may be used alone or in mixtures thereof.

[0092] Based on the total weight of the composition used in the light conversion layer, the second photoinitiator may be present in an amount of 0.1% to 5% by weight, preferably 0.5% to 3% by weight.

[0093] In one embodiment, the composition for the light conversion layer may further include at least one group selected from difunctional (meth)acrylate monomers, trifunctional (meth)acrylate monomers, and tetrafunctional or higher (meth)acrylate monomers. Preferably, the composition for the light conversion layer may further include difunctional (meth)acrylate monomers, trifunctional (meth)acrylate monomers, and tetrafunctional or higher (meth)acrylate monomers.

[0094] By incorporating difunctional, trifunctional, and tetrafunctional (meth)acrylate monomers, the composition can form a denser three-dimensional network cross-linked structure due to the large number of functional groups in the molecule. This structure may enable improvements in the cross-linking density and glass transition temperature (Tg) of the matrix.

[0095] Examples of bifunctional (meth)acrylate monomers may include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyolefin glycol di(meth)acrylate, ethoxylated polypropylene glycol di(meth)acrylate, 2-hydroxy-3-acryloxypropyl methacrylate, 2-hydroxy-1,3-dimethylacryloxypropane, dioxanediol di(meth)acrylate, tricyclodecanediethanol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate. Esters, glycerol di(meth)acrylates, 1,6-hexanediol di(meth)acrylates, 1,9-nonanediol di(meth)acrylates, 1,10-decanediol di(meth)acrylates, neopentyl glycol di(meth)acrylates, 2-methyl-1,8-octanediol di(meth)acrylates, 1,9-nonanediol di(meth)acrylates, butyl ethyl propylene glycol di(meth)acrylates, and 3-methyl-1,5-pentanediol di(meth)acrylates, but not limited to these.

[0096] Examples of trifunctional (meth)acrylate monomers may include, but are not limited to, ethoxylated glycerol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, and pentaerythritol tri(meth)acrylate.

[0097] Examples of polyfunctional (meth)acrylate monomers may include tetrafunctional (meth)acrylate monomers, such as pentaerythritol tetra(meth)acrylate, di(trimethylolpropane)tetra(meth)acrylate, and ethoxylated pentaerythritol tetra(meth)acrylate; pentafunctional (meth)acrylate monomers, such as dipentaerythritol pentaacrylate, propionic acid-modified dipentaerythritol pentaacrylate, dipentaerythritol pentamethacrylate, propionic acid-modified dipentaerythritol pentamethacrylate, etc.; and hexafunctional (meth)acrylate monomers, such as dipentaerythritol hexaacrylate, caprolactone-modified dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate, caprolactone-modified dipentaerythritol hexamethacrylate, etc., but are not limited thereto.

[0098] When the composition used for the light conversion layer further includes at least one group selected from difunctional (meth)acrylate monomers, trifunctional (meth)acrylate monomers and tetrafunctional or higher (meth)acrylate monomers, these (meth)acrylate monomers may be present in an amount of 5% to 60% by weight, preferably 10% to 50% by weight, based on the total weight of the composition of the light conversion layer.

[0099] The light conversion layer 300 can have any thickness. Preferably, the light conversion layer 300 has a thickness of 10 micrometers to 100 micrometers. If the light conversion layer is too thick, oxygen or moisture can penetrate the optical sheet through the side edges and degrade the properties of the optical sheet, while also increasing manufacturing costs, thus limiting the application of the optical sheet in display devices. If the light conversion layer is too thin, the quantum dots cannot fully absorb the light emitted from the backlight unit, resulting in a deterioration in light conversion efficiency. Therefore, it is ideal for the light conversion layer 300 to meet the above-mentioned thickness range.

[0100] In one embodiment, the quantum dot optical sheet can have a brightness retention of 95% or higher (ΔLm) after being exposed to light at a wavelength of 450 nanometers for 616 hours; an x-axis chromaticity change (ΔCx) of -0.005 ≤ ΔCx ≤ 0.005; and a y-axis chromaticity change (ΔCy) of -0.005 ≤ ΔCy ≤ 0.005.

[0101] Preferably, the quantum dot optical sheet exhibits 100% or higher brightness retention (ΔLm) after being exposed to light at a wavelength of 450 nanometers for 616 hours; x-axis chromaticity coordinate change (ΔCx) of -0.001 ≤ ΔCx ≤ 0.001; and y-axis chromaticity coordinate change (ΔCy) of -0.002 ≤ ΔCy ≤ 0.002.

[0102] In one embodiment, the quantum dot optics, after being exposed to conditions of 60°C and 95% humidity for 616 hours, can have a brightness retention rate (ΔLm) of 90% or higher; an x-axis chromaticity coordinate change (ΔCx) of -0.015 ≤ ΔCx ≤ 0.015; and a y-axis chromaticity coordinate change (ΔCy) of -0.015 ≤ ΔCy ≤ 0.015.

[0103] Preferably, the quantum dot optics exhibit a brightness retention of 91% or higher (ΔLm) after being exposed to conditions of 60°C and 95% humidity for 616 hours; an x-axis chromaticity change (ΔCx) of -0.006 ≤ ΔCx ≤ 0.006; and a y-axis chromaticity change (ΔCy) of -0.011 ≤ ΔCy ≤ 0.011.

[0104] In one embodiment, the quantum dot optics, after being exposed to 60°C for 616 hours, can have a brightness retention rate (ΔLm) of 90% or higher; an x-axis chromaticity coordinate change (ΔCx) of -0.010 ≤ ΔCx ≤ 0.010; and a y-axis chromaticity coordinate change (ΔCy) of -0.010 ≤ ΔCy ≤ 0.010.

[0105] Preferably, the quantum dot optical sheet can have a brightness retention of 93% or higher (ΔLm) after being exposed to 60°C for 616 hours; an x-axis chromaticity change (ΔCx) of -0.007 ≤ ΔCx ≤ 0.007; and a y-axis chromaticity change (ΔCy) of -0.008 ≤ ΔCy ≤ 0.008.

[0106] Brightness retention rate (ΔLm) refers to the retention rate of the brightness (Lm2) of a quantum dot optical sheet at a certain point in time after exposure to light at a wavelength of 450 nanometers or conditions of 60°C and / or 95% humidity, relative to the initial brightness (Lm1) of the quantum dot optical sheet before exposure to light at a wavelength of 450 nanometers or conditions of 60°C and / or 95% humidity.

[0107] The luminance retention rate (ΔLm) can be calculated according to Equation 1.

[0108] [Equation 1]

[0109]

[0110] In equation 1,

[0111] Lm1 represents the initial brightness value of the quantum dot optical sheet, and

[0112] Lm2 represents the brightness value of a quantum dot optics measured at a certain point in time after exposure to light at a wavelength of 450 nanometers or to conditions of 60°C and / or 95% humidity.

[0113] Color coordinate variation (ΔCx, ΔCy) refers to the deviation between the initial color coordinates (Cx1, Cy1) measured before the quantum dot optical sheet is exposed to light at a wavelength of 450 nm or conditions of 60°C and / or 95% humidity, and the color coordinates (Cx2, Cy2) measured at a certain point in time after the quantum dot optical sheet is exposed to light at a wavelength of 450 nm or conditions of 60°C and / or 95% humidity.

[0114] The change in x-axis color coordinate (ΔCx) can be calculated according to Equation 2, and the change in y-axis color coordinate (ΔCy) can be calculated according to Equation 3.

[0115] [Equation 2]

[0116]

[0117] [Equation 3]

[0118]

[0119] In equations 2 and 3,

[0120] Cx1 and Cy1 represent the initial color coordinates of the quantum dot optical sheet, and

[0121] Cx2 and Cy2 represent the color coordinates of a quantum dot optics measured at a specific time point after exposure to light at a wavelength of 450 nanometers or to conditions of 60°C and / or 95% humidity.

[0122] The present invention provides a backlight unit comprising a quantum dot optical sheet.

[0123] The backlight unit (BLU) may include the following: a quantum dot optical sheet; a light source unit including a light source suitable for generating light; and a light guide plate suitable for guiding light. Here, the backlight unit may further include optical components and a reflective sheet.

[0124] The present invention also provides a display device including a backlight unit. The display device may include, but is not limited to, liquid crystal displays (LCDs), electroluminescent (EL) displays, plasma display panels (PDPs), field emission displays (FEDs), organic light emitting diode displays (OLEDs), etc. [[] [Forms of Invention] []]

[0125] The invention will now be described in more detail with reference to some examples. It should be understood that these examples are provided for illustrative purposes only and should not be construed as limiting the invention in any way.

[0126] [<] [Example] [>]

[0127] [Preparation Example] [1] [:Components used in the barrier layer] [A] [Preparation] [ ]

[0128] Composition A for the barrier layer was prepared by dispersing 40 g of triallyl isocyanurate with 5 g of alumina (Al2O3, specific surface area: 85 m2 / g to 115 m2 / g), followed by mixing with 1 g of cyproterone acetate TPO and 54 g of pentaerythritol tetra(2-mercaptoacetate).

[0129] [Preparation Example] [2] [:Components used in the barrier layer] [B] [Preparation] [ ]

[0130] Composition B for the barrier layer was prepared by dispersing 40 g of triallyl isocyanurate with 1 g of alumina (Al2O3, specific surface area: 85 m² / g to 115 m² / g), followed by mixing with 1 g of cyproterone acetate TPO and 58 g of pentaerythritol tetra(2-mercaptoacetate).

[0131] [Preparation Example] [3] [:Components used in the barrier layer] [C] [Preparation] [ ]

[0132] Composition C for the barrier layer was prepared by mixing 40 g of triallyl isocyanurate with 1 g of cypermethrin TPO and 59 g of pentaerythritol tetra(2-mercaptoacetate).

[0133] [Preparation Example] [4] [:ligand exchange()] [ligand-exchanged] [)of] [InP] [Preparation of quantum dot dispersions] [ ]

[0134] InP quantum dots, whose surfaces are coordinated with a mixed organic ligand of oleic acid, trioctylphosphine (TOP), trioctylphosphine oxide (TOPO), and trioctylamine, were dispersed and dissolved in isobornyl acrylate to obtain a 5 mL solution containing the dispersed quantum dots. Subsequently, 5 mL of di(3-mercaptopropionic acid) ethylene glycol was added to 5 mL of the quantum dot-containing solution, and the mixture was stirred at room temperature for 1 hour to prepare the quantum dot dispersion.

[0135] [Preparation Example] [5] [:Composition used in the light conversion layer] [1] [Preparation] [ ]

[0136] A photoreactive mixture was prepared by mixing 32 parts by weight of monomer A-1, 20 parts by weight of monomer A-2, 18 parts by weight of monomer B-1, 10 parts by weight of monomer B-2, 10 parts by weight of monomer B-3 and 1 part by weight of TPO as a photoinitiator, and then mixed with the quantum dot dispersion of Preparation Example 4 to have 9 parts by weight of quantum dots, thereby preparing composition 1 for the light conversion layer.

[0137] [Preparation Example] [6] [:Composition used in the light conversion layer] [2] [Preparation] [ ]

[0138] A photoreactive mixture was prepared by mixing 20 parts by weight of monomer A-1, 32 parts by weight of monomer A-3, 18 parts by weight of monomer B-1, 10 parts by weight of monomer B-2, 10 parts by weight of monomer B-3 and 1 part by weight of TPO as a photoinitiator, and then mixed with the quantum dot dispersion of Preparation Example 4 above to have 9 parts by weight of quantum dots, thereby preparing composition 2 for the light conversion layer.

[0139] The monomers used in Preparation Examples 5 and 6 are summarized in Table 1 below.

[0140] Table 1 project monomer Remark A-1 (Bisphenol monomers) Ethoxylated bisphenol A diacrylate f=2, Mw:512 g / mol Tg: 42°C A-2 (Cyclicable monomer) 2-((allyloxy)meth)methyl acrylate f=2, Mw:156 g / mol Tg: 84°C A-3 (Thiol monomers) Pentaerythritol tetra(3-mercaptopropionate) f=4, Mw:488 g / mol B-1 (Trifunctional acrylate monomer) Trimethylolpropane triacrylate f=3, Mw:296 g / mol Tg: 62°C B-2 (Multifunctional acrylate monomers) Dipentaerythritol pentaacrylate f=5, Mw:524 g / mol Tg: 68°C B-3 (Bifunctional acrylate monomer) 1,6-Hexanediol diacrylate f=2, Mw:226 g / mol Tg: 43°C

[0141] [Example] [1] Quantum dot optical film [1] [Preparation]

[0142] The composition A for the barrier layer prepared in Example 1 was coated onto a polyethylene terephthalate (PET, 100 micrometers thick) substrate using a laminator, followed by UV curing to form a 25-micrometer thick barrier layer.

[0143] Quantum dot optical sheet 1 was prepared by coating the composition 1 for the light conversion layer prepared in Preparation Example 5 to a thickness of 46 micrometers between the two barrier layers prepared above, and then irradiating it with UV light at a dose of 80 millijoules per square centimeter (mJ / cm2) for 4 seconds to form a light conversion layer.

[0144] [Example] [2] Quantum dot optical film [2] [Preparation] [ ]

[0145] The composition B for the barrier layer prepared in Example 2 was coated onto a polyethylene terephthalate (PET, 100 μm thick) substrate using a laminator, followed by UV curing to form a 25 μm thick barrier layer.

[0146] Quantum dot optical sheet 2 was prepared by coating the composition 1 for the light conversion layer prepared in Preparation Example 5 to a thickness of 46 micrometers between the two barrier layers prepared above, and then irradiating it with UV light at a dose of 80 millijoules / square centimeter for 4 seconds to form the light conversion layer.

[0147] [Comparative Example] [1] Quantum dot optical film [3] [Preparation] [ ]

[0148] Quantum dot optical sheet 3 was prepared by coating the composition 1 for the light conversion layer prepared in Preparation Example 5 to a thickness of 46 micrometers between two polyethylene terephthalate (PET, 100 micrometers thick) substrates, and then irradiating them with UV light at a dose of 80 millijoules / square centimeter for 4 seconds to form the light conversion layer.

[0149] [Comparative Example] [2] Quantum dot optical film [4] [Preparation] [ ]

[0150] The composition A for the barrier layer prepared in Example 1 was coated onto a polyethylene terephthalate (PET, 100 micrometers thick) substrate using a laminator, followed by UV curing to form a 25-micrometer thick barrier layer.

[0151] Quantum dot optical sheet 4 was prepared by coating the composition 2 for the light conversion layer prepared in Preparation Example 6 to a thickness of 46 micrometers between the two barrier layers prepared above, and then irradiating it with UV light at a dose of 80 millijoules / square centimeter for 4 seconds to form the light conversion layer.

[0152] [Comparative Example] [3] Quantum dot optical film [5] [Preparation] [ ]

[0153] The composition B for the barrier layer prepared in Example 2 was coated onto a polyethylene terephthalate (PET, 100 μm thick) substrate using a laminator, followed by UV curing to form a 25 μm thick barrier layer.

[0154] Quantum dot optical sheet 5 was prepared by coating the composition 2 for the light conversion layer prepared in Preparation Example 6 to a thickness of 46 micrometers between the two barrier layers prepared above, and then irradiating it with UV light at a dose of 80 millijoules / square centimeter for 4 seconds to form the light conversion layer.

[0155] [Comparative Example] [4] Quantum dot optical film [6] [Preparation] [ ]

[0156] The composition C for the barrier layer prepared in Example 3 was coated onto a polyethylene terephthalate (PET, 100 micrometers thick) substrate using a laminator, followed by UV curing to form a 25-micrometer thick barrier layer.

[0157] Quantum dot optical sheet 6 was prepared by coating the composition 1 for the light conversion layer prepared in Preparation Example 5 to a thickness of 46 micrometers between the two barrier layers prepared above, and then irradiating it with UV light at a dose of 80 millijoules / square centimeter for 4 seconds to form the light conversion layer.

[0158] [Comparative Example] [5] Quantum dot optical film [7] [Preparation] [ ]

[0159] The composition C for the barrier layer prepared in Example 3 was coated onto a polyethylene terephthalate (PET, 100 micrometers thick) substrate using a laminator, followed by UV curing to form a 25-micrometer thick barrier layer.

[0160] Quantum dot optical sheet 7 was prepared by coating the composition 2 for the light conversion layer prepared in Preparation Example 6 to a thickness of 46 micrometers between the two barrier layers prepared above, and then irradiating it with UV light at a dose of 80 millijoules / square centimeter for 4 seconds to form the light conversion layer.

[0161] [Example: Quantum dot optical film] [8] [Preparation] [ ]

[0162] Quantum dot optical sheet 8 was prepared by coating the composition 1 for the light conversion layer prepared in Preparation Example 5 to a thickness of 46 micrometers between two gas barrier films (IB-PET film, DNP, thickness 98 micrometers), and then irradiating it with UV light at a dose of 80 millijoules / square centimeter for 4 seconds to form a light conversion layer.

[0163] [<] [Experimental Example] [>]

[0164] [1.] [Evaluation of blocking properties under light exposure conditions] [ ]

[0165] Each of the quantum dot optical sheets prepared in the examples, comparative examples, and reference examples was exposed to blue light at a wavelength of 450 nm for 0 (initial), 15, 150, and 616 hours. The luminance (Lm) and chromaticity (Cx, Cy) at each exposure time were then measured using an integrating sphere (Neolight IS500, PIMACS). The luminance retention rate (ΔLm), x-axis chromaticity variation (ΔCx), and y-axis chromaticity variation (ΔCy) were calculated according to Equations 1 to 3, and the results are shown in Table 2.

[0166] Table 2 0 (Initial) 15 hours 150 hours 616 hours Example 1 ΔLm (%) 100 106 110 102 ΔCx 0.000 0.003 0.005 0.000 ΔCy 0.000 0.004 0.008 0.000 Example 2 ΔLm (%) 100 102 103 100 ΔCx 0.000 0.002 0.001 -0.001 ΔCy 0.000 0.001 0.000 -0.002 Comparative Example 1 ΔLm (%) 100 99 33 15 ΔCx 0.000 -0.001 -0.064 -0.090 ΔCy 0.000 -0.003 -0.106 -0.144 Comparative Example 2 ΔLm (%) 100 102 103 101 ΔCx 0.000 0.001 0.001 0.001 ΔCy 0.000 0.001 0.001 -0.001 Comparative Example 3 ΔLm (%) 100 101 103 81 ΔCx 0.000 0.000 0.001 -0.014 ΔCy 0.000 0.000 0.002 -0.031 Comparative Example 4 ΔLm (%) 100 102 103 84 ΔCx 0.000 0.001 0.001 -0.010 ΔCy 0.000 0.001 0.001 -0.024 Comparative Example 5 ΔLm (%) 100 102 102 78 ΔCx 0.000 0.001 0.001 -0.015 ΔCy 0.000 0.001 -0.001 -0.034 Reference Example ΔLm (%) 100 101 102 98 ΔCx 0.000 0.001 0.001 0.001 ΔCy 0.000 0.001 0.002 -0.002

[0167] Referring to Table 2, it can be seen that the quantum dot optical sheets of Examples 1 and 2 exhibit higher brightness and chromaticity changes within ±0.002 after 616 hours of exposure to blue light at a wavelength of 450 nm compared to their initial brightness. In other words, the quantum dot optical sheets of Examples 1 and 2 show similar characteristics to the quantum dot optical sheets of the reference examples prepared using typical gas barrier films, and exhibit excellent blocking properties upon light exposure. Conversely, the quantum dot optical sheets of Comparative Examples 1 to 5 show significant changes in brightness retention and / or chromaticity changes, indicating a significant deterioration in blocking properties upon light exposure.

[0168] [2.] [high temperature] [ / ] [Evaluation of barrier properties under high humidity conditions] [ ]

[0169] Each of the quantum dot optical sheets prepared in the examples, comparative examples, and reference examples was exposed to conditions of 60°C and 95% humidity for 0 (initial), 15, 150, and 616 hours. The luminance (Lm) and chromaticity (Cx, Cy) at each exposure time were then measured using an integrating sphere (Neolight IS500, PIMACS). The luminance retention rate (ΔLm), x-axis chromaticity variation (ΔCx), and y-axis chromaticity variation (ΔCy) were calculated according to Equations 1 to 3, and the results are shown in Table 3.

[0170] Table 3 0 (Initial) 15 hours 150 hours 616 hours Example 1 ΔLm (%) 100 104 104 102 ΔCx 0.000 0.002 0.003 -0.001 ΔCy 0.000 0.002 0.004 -0.001 Example 2 ΔLm (%) 100 97 95 93 ΔCx 0.000 -0.002 -0.005 -0.007 ΔCy 0.000 -0.005 -0.008 -0.008 Comparative Example 1 ΔLm (%) 100 95 98 97 ΔCx 0.000 -0.003 -0.002 -0.005 ΔCy 0.000 -0.006 -0.003 -0.005 Comparative Example 2 ΔLm (%) 100 98 90 87 ΔCx 0.000 -0.002 -0.006 -0.007 ΔCy 0.000 -0.005 -0.015 -0.018 Comparative Example 3 ΔLm (%) 100 90 85 84 ΔCx 0.000 -0.005 -0.008 -0.010 ΔCy 0.000 -0.013 -0.020 -0.024 Comparative Example 4 ΔLm (%) 100 95 92 91 ΔCx 0.000 -0.002 -0.005 -0.004 ΔCy 0.000 -0.007 -0.011 -0.011 Comparative Example 5 ΔLm (%) 100 91 89 89 ΔCx 0.000 -0.004 -0.005 -0.006 ΔCy 0.000 -0.011 -0.014 -0.014 Reference Example ΔLm (%) 100 101 102 98 ΔCx 0.000 0.001 0.001 0.001 ΔCy 0.000 0.001 0.002 -0.002

[0171] Referring to Table 3, it can be seen that the quantum dot optical sheets of Examples 1 and 2 exhibit a brightness retention rate of 93% or higher and a chromaticity change within ±0.008 after 616 hours of exposure to 60°C and 95% humidity. In other words, the quantum dot optical sheets of Examples 1 and 2 demonstrate similar properties to the quantum dot optical sheets of the reference examples prepared using typical gas barrier films, and exhibit excellent barrier properties under high temperature / high humidity conditions. Conversely, the quantum dot optical sheets of Comparative Examples 1 to 5 show significant changes in brightness retention rate and / or chromaticity change, indicating a significant deterioration in barrier properties under high temperature / high humidity conditions.

[0172] [3.] [Evaluation of Barrier Properties under High Temperature Conditions] [ ]

[0173] Each of the quantum dot optical sheets prepared in the examples, comparative examples, and reference examples was exposed to 60°C for 0 (initial), 15, 150, and 616 hours. The luminance (Lm) and chromaticity (Cx, Cy) at each exposure time were then measured using an integrating sphere (Neolight IS500, PIMACS). The luminance retention rate (ΔLm), x-axis chromaticity variation (ΔCx), and y-axis chromaticity variation (ΔCy) were calculated according to Equations 1 to 3, and the results are shown in Table 4.

[0174] Table 4 0 (Initial) 15 hours 150 hours 616 hours Example 1 ΔLm (%) 100 100 101 98 ΔCx 0.000 0.000 0.002 0.000 ΔCy 0.000 -0.002 0.000 -0.002 Example 2 ΔLm (%) 100 100 93 91 ΔCx 0.000 0.000 -0.006 -0.006 ΔCy 0.000 -0.002 -0.011 -0.011 Comparative Example 1 ΔLm (%) 100 92 88 83 ΔCx 0.000 -0.005 -0.008 -0.011 ΔCy 0.000 -0.010 -0.015 -0.020 Comparative Example 2 ΔLm (%) 100 99 91 84 ΔCx 0.000 0.000 -0.005 -0.007 ΔCy 0.000 -0.002 -0.014 -0.022 Comparative Example 3 ΔLm (%) 100 91 80 70 ΔCx 0.000 -0.004 -0.010 -0.017 ΔCy 0.000 -0.012 -0.028 -0.044 Comparative Example 4 ΔLm (%) 100 92 88 81 ΔCx 0.000 -0.004 -0.006 -0.010 ΔCy 0.000 -0.011 -0.015 -0.026 Comparative Example 5 ΔLm (%) 100 89 85 79 ΔCx 0.000 -0.006 -0.008 -0.011 ΔCy 0.000 -0.015 -0.022 -0.030 Reference Example ΔLm (%) 100 101 101 98 ΔCx 0.000 0.001 0.001 0.001 ΔCy 0.000 0.002 0.002 0.000

[0175] Referring to Table 4, it can be seen that the quantum dot optical sheets of Examples 1 and 2 exhibit a brightness retention rate of 91% or higher and a chromaticity change within ±0.011 after being exposed to 60°C for 616 hours. In other words, the quantum dot optical sheets of Examples 1 and 2 show similar characteristics to the quantum dot optical sheets of the reference examples prepared using typical gas barrier films, and exhibit excellent barrier properties under high-temperature conditions. Conversely, the quantum dot optical sheets of Comparative Examples 1 to 5 show significant changes in brightness retention rate and / or chromaticity change, indicating a significant deterioration in barrier properties under high-temperature conditions.

[0176] 100-1: First substrate / substrate 100-2: Second substrate / substrate 200-1: First barrier layer / barrier layer 200-2: Second barrier layer / barrier layer 300: Light conversion layer

Claims

1. A quantum dot optical sheet, comprising: First substrate; A first barrier layer is formed on the first substrate; The second substrate is disposed opposite to the first substrate; A second barrier layer is formed on the second substrate; And a light conversion layer, inserted between the first barrier layer and the second barrier layer, wherein each of the first barrier layer and the second barrier layer contains a cured product of a composition for the barrier layer, the composition for the barrier layer containing (methyl)allyl monomers, monomers having at least two thiol groups at their ends, metal oxide nanoparticles, and a first photoinitiator, and wherein the light conversion layer contains a cured product of a composition for the light conversion layer, the composition for the light conversion layer containing quantum dots, bisphenol monomers, cyclizable monomers, and a second photoinitiator.

2. The quantum dot optical sheet as claimed in claim 1, wherein the (methyl)allyl monomer comprises at least one group selected from triallyl isocyanurate, 1,3-diallyl-5-glycidyl isocyanurate, diallylpropyl isocyanurate, and trimethylallyl isocyanurate.

3. The quantum dot optical sheet as claimed in claim 1, wherein the monomer having at least two thiol groups at its ends comprises at least one group selected from pentaerythritol tetra(2-mercaptoacetate), pentaerythritol tetra(3-mercaptopropionate), 1,2-ethylenedithiol, pentaerythritol tetra(mercaptopropionate), pentaerythritol tetra(thioglycolate), trimethylolpropane tri(2-mercaptoacetate), and trimethylolpropane tri(3-mercaptopropionate).

4. The quantum dot optical sheet as claimed in claim 1, wherein the metal oxide nanoparticles comprise at least one group selected from titanium oxide, aluminum oxide, chromium trioxide, zinc oxide, copper oxide, magnesium oxide, zirconium dioxide, molybdenum trioxide, vanadium pentoxide, niobium pentoxide, and tantalum pentoxide.

5. The quantum dot optical sheet as claimed in claim 1, wherein the quantum dots are cadmium-free quantum dots.

6. The quantum dot optical sheet of claim 1, wherein the quantum dots have a ligand layer on their surface, the ligand layer comprising at least one group selected from carboxylic acid compounds, thiols, phosphine compounds, phosphine oxides, and amine compounds.

7. The quantum dot optical sheet as claimed in claim 1, wherein the cyclizable monomer comprises at least one group selected from alkyl 2-[(allyloxy)methyl](meth)acrylate, hydroxyalkyl 2-[(allyloxy)methyl](meth)acrylate, haloalkyl 2-[(allyloxy)methyl](meth)acrylate, cycloalkyl 2-[(allyloxy)methyl](meth)acrylate, aryl 2-[(allyloxy)methyl](meth)acrylate, alkoxyalkyl 2-[(allyloxy)methyl](meth)acrylate, alkoxycycloalkyl 2-[(allyloxy)methyl](meth)acrylate, and oxecycloalkyl 2-[(allyloxy)methyl](meth)acrylate.

8. The quantum dot optical sheet as claimed in claim 1, wherein the composition for the light conversion layer further comprises at least one group selected from difunctional (meth)acrylate monomers, trifunctional (meth)acrylate monomers, and tetrafunctional or higher (meth)acrylate monomers.

9. The quantum dot optical sheet as claimed in claim 1, wherein the quantum dot optical sheet has a brightness retention of 95% or higher (ΔLm) after being exposed to light at a wavelength of 450 nanometers for 616 hours; an x-axis chromaticity change (ΔCx) of -0.005 ≤ ΔCx ≤ 0.005; and a y-axis chromaticity change (ΔCy) of -0.005 ≤ ΔCy ≤ 0.

005.

10. The quantum dot optical sheet as claimed in claim 1, wherein the quantum dot optical sheet has a brightness retention of 90% or higher (ΔLm) after being exposed to 60°C and 95% humidity for 616 hours; an x-axis chromaticity change (ΔCx) of -0.010 ≤ ΔCx ≤ 0.010; and a y-axis chromaticity change (ΔCy) of -0.010 ≤ ΔCy ≤ 0.

010.

11. The quantum dot optics as claimed in claim 1, wherein the quantum dot optics has a luminance retention of 90% or higher (ΔLm) after being exposed to 60°C for 616 hours; an x-axis chromaticity variation (ΔCx) of -0.015 ≤ ΔCx ≤ 0.015; and a y-axis chromaticity variation (ΔCy) of -0.015 ≤ ΔCy ≤ 0.

015.

12. A backlight unit comprising a quantum dot optic sheet as described in any one of claims 1 to 11.

13. A display device comprising a backlight unit as described in claim 12.

Images