Backlight unit, down-conversion medium comprising backlight unit, and display device

Abstract

A backlight unit, a down-conversion medium including the backlight unit, and a display device including the down-conversion medium are provided. The backlight unit includes a light source configured to generate blue light; and an optical film configured to absorb a portion of the blue light generated from the light source to generate red light and green light, wherein the optical film includes a quantum dot array having a semimetallic element oxide embedded therein.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2021-0133317, filed on October 7, 2021, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a backlight unit comprising aerosolized quantum dots, a downconversion medium comprising the backlight unit, and a display device comprising the downconversion medium. Background Technology

[0004] Recently, it has been demonstrated that materials encapsulating perovskite nanocrystals with various polymers such as polystyrene and polymethyl methacrylate can be used as luminescent materials in commercial LED devices, and research on applying such materials to downconversion media (DCMs) is currently underway. However, in existing technologies, downconversion media must use color filters, which presents a challenge in improving luminous efficiency.

[0005] Furthermore, luminescent materials use insulating polymers as the matrix, which inherently suffer from susceptibility to thermal stress. In particular, long-term thermal stress can cause thermoplastic polymers such as polystyrene, polymethyl methacrylate, and cyclic olefin copolymers to soften, deform, or be destroyed. Summary of the Invention

[0006] The implementation scheme provides a backlight unit that can improve pattern processability and light efficiency.

[0007] Another implementation provides a down-conversion medium that includes a backlight unit.

[0008] Another embodiment provides a display device that includes a down-conversion medium.

[0009] Embodiments of the present invention provide a backlight unit comprising a light source configured to generate blue light, and an optical film configured to absorb a portion of the blue light generated from the light source to generate red and green light, wherein the optical film comprises a quantum dot array in which oxides of half-metal elements are embedded.

[0010] Semi-metallic elements may include boron, silicon, germanium, arsenic, antimony, tellurium, polonium, or combinations thereof.

[0011] The oxide of a semi-metallic element can be silicon dioxide.

[0012] Quantum dots can include group 2-6 quantum dots, group 3-5 quantum dots, group 4-6 quantum dots, group 4 quantum dots, group 1-3-6 quantum dots, or combinations thereof.

[0013] The quantum dots can be group 3-5 quantum dots.

[0014] The quantum dots can have a perovskite crystal structure.

[0015] The quantum dots can be metal halide-based quantum dots having a perovskite crystal structure.

[0016] The metal halide-based quantum dots having a perovskite crystal structure can be represented by Chemical Formula 1.

[0017]

Chemical Formula 1

[0018] ABX3

[0019] In Chemical Formula 1,

[0020] A is an organic cation or an inorganic cation,

[0021] B is a metal cation, and

[0022] X is a halide anion.

[0023] Chemical Formula 1 can be represented by CsPbX'3, where X' is CI, Br, and / or I.

[0024] The metal halide-based quantum dots having a perovskite crystal structure can be green quantum dots or red quantum dots.

[0025] The green quantum dots can be CsPbBr3and the red quantum dots can be CsPb(BrI)3.

[0026] The quantum dot array embedded with the half-metallic element oxide can be aerosolized.

[0027] The aerosolization can be performed under vacuum conditions.

[0028] The aerosol flow rate during the aerosolization can be about 0.1 L / min to about 10 L / min.

[0029] The light source configured to produce blue light can be a blue OLED, a blue LED, or a blue EL device.

[0030] Another embodiment provides a down-conversion medium comprising a backlight unit.

[0031] The down-conversion medium can be a filterless down-conversion medium.

[0032] Another embodiment provides a display device comprising a down-conversion medium.

[0033] Other embodiments of the invention comprise the following detailed description.

[0034] The backlight unit according to one embodiment can greatly improve the light efficiency of a down-conversion medium without a color filter, and thus ultimately improve the light efficiency of a display device including the down-conversion medium by completely blocking a blue light leakage phenomenon, and in addition, since a fine line width is achieved, pattern processing can be performed without a mask. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a schematic diagram showing a manufacturing process of a backlight unit according to an embodiment.

[0036] Figure 2 is a photomicrograph of a backlight unit in which green quantum dots (CsPbBr3) embedded with silicon dioxide are aerosolized and deposited on a blue OLED.

[0037] Figure 3 is a photomicrograph of a backlight unit in which red quantum dots (CsPb(BrI)3) embedded with silicon dioxide are aerosolized and deposited on a blue OLED.

[0038] Figure 4 is a photomicrograph of green quantum dots (CsPbBr3) aerosolized and deposited on a blue OLED.

[0039] Figure 5 is a photomicrograph of green quantum dots (CsPbBr3) embedded with aluminum oxide aerosolized and deposited on a blue OLED.

[0040] Figure 6 is a photomicrograph of green quantum dots (CsPbBr3) embedded with silicon dioxide aerosolized and deposited on a blue OLED.

[0041] Figure 7 is a photomicrograph of red quantum dots (CsPb(BrI)3) aerosolized and deposited on a blue OLED.

[0042] Figure 8 is a photomicrograph of red quantum dots (CsPb(BrI)3) embedded with aluminum oxide aerosolized and deposited on a blue OLED.

[0043] Figure 9 is a photomicrograph of red quantum dots (CsPb(BrI)3) embedded with silicon dioxide aerosolized and deposited on a blue OLED.

[0044] Figure 10 and Figure 11 is a graph each independently showing the light efficiency of a backlight unit according to Example 1, Comparative Example 1, and Comparative Example 2.

[0045] Figure 12 and Figure 13 is a graph showing luminance of a backlight unit according to Example 1, Comparative Example 1, and Comparative Example 2, respectively.

[0046] Figure 14 is a graph showing luminance (green) of a backlight unit according to Example 2.

[0047] Figure 15 is a graph showing luminance (green) of a backlight unit according to Example 1.

[0048] Figure 16 is a graph showing luminance (green) of a backlight unit according to Example 3. DETAILED DESCRIPTION

[0049] Hereinafter, embodiments of the present application will be described in detail. However, these embodiments are exemplary, the present application is not limited thereto, and the present application is defined by the scope of claims.

[0050] As used herein, when no specific definition is provided otherwise, "substituted" means that which is substituted with a substituent selected from the group consisting of halogen (F, Br, Cl, or I), hydroxyl, nitro, cyano, amino (NH2, NH(R 200 ) or N(R 201 )(R 202 ), wherein R 200 , R 201 and R 202 are the same or different and each independently C1 to C10 alkyl), amidino, hydrazino, hydrazono, carboxyl, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted alicyclic organic group, substituted or unsubstituted aryl, and substituted or unsubstituted heterocyclic group.

[0051] As used herein, when no specific definition is provided otherwise, "alkyl" means C1 to C20 alkyl, and specifically C1 to C15 alkyl, "cycloalkyl" means C3 to C20 cycloalkyl, and specifically C3 to C18 cycloalkyl, "alkoxy" means C1 to C20 alkoxy, and specifically C1 to C18 alkoxy, "aryl" means C6 to C20 aryl, and specifically C6 to C18 aryl, "alkenyl" means C2 to C20 alkenyl, and specifically C2 to C18 alkenyl, "alkylene" means C1 to C20 alkylene, and specifically C1 to C18 alkylene, and "arylene" means C6 to C20 arylene, and specifically C6 to C16 arylene.

[0052] As used herein, " (meth)acrylate " means "acrylate" and "methacrylate" and "(meth)acrylic acid" means "acrylic acid" and "methacrylic acid" when no specific definition is otherwise provided.

[0053] As used herein, "combination" means mixing or copolymerization when no specific definition is otherwise provided. Further, "copolymerization" means block copolymerization or random copolymerization, and "copolymer" means block copolymer or random copolymer.

[0054] In the chemical formulae of the present specification, hydrogen is bonded at a position where no chemical bond is formed, unless a specific definition is otherwise provided.

[0055] In the present specification, "*" indicates a point of connection of the same or different atoms or chemical formulae when no specific definition is otherwise provided.

[0056] Embodiments provide a backlight unit including a light source configured to generate blue light; and an optical film configured to absorb a portion of the blue light generated from the light source to generate red light and green light, wherein the optical film includes quantum dots in which a semi-metal element oxide is embedded.

[0057] A conventional deposition method can be currently employed to implement a large-area display, but there are problems such as process yield, mask warping, uniformity, etc., and in order to solve the problems, a method of inkjet printing is being discussed. A method of inkjet printing is currently employed to coat quantum dots on a blue OLED substrate, but there are problems such as nozzle clogging, non-uniform drying, difficulty in achieving bank height, increase in color conversion layer thickness, light leakage phenomenon, etc.

[0058] Since these problems are caused by a color filter used in a down-conversion medium (DCM), the inventors of the present invention repeated a large number of experiments and trial and error to enable the down-conversion medium to be used without the color filter, and solved the problems by coating nanocrystals in which a semi-metal element oxide is embedded, such as quantum dots, on a light source configured to generate blue light, such as a blue OLED substrate.

[0059] Quantum dots in which an oxide is embedded have been previously attempted to be used, but there has been no attempt to embed a semi-metal element oxide in quantum dots.

[0060] For example, the semi-metal element can include boron, silicon, germanium, arsenic, antimony, tellurium, polonium, or a combination thereof. For example, the semi-metal element can be silicon.

[0061] For example, the semi-metal element oxide can be silicon dioxide.

[0062] When the oxide embedded in the quantum dot is not a semimetal oxide but a metal oxide, the luminance of the finally manufactured backlight unit is lower than that of the semimetal oxide, and thus the effect of improving the light efficiency is weak.

[0063] For example, the quantum dot can include a group 2-6 quantum dot such as CdSe, CdS, CdTe, ZnSe, ZnS, or ZnTe, a group 3-5 quantum dot such as InP or InAs, a group 4-6 quantum dot such as PbS, PbSe, PbTe, a group 4 quantum dot such as Ge or Si, a group 1-3-6 quantum dot such as Cu 1-X In X S 1-y Se y (0 < x and y < 1), or a combination thereof, but is not necessarily limited thereto.

[0064] For example, the quantum dot can have a core-shell structure, in which the core can be formed of a group 2-6 quantum dot, a group 3-5 quantum dot, a group 4-6 quantum dot, a group 4 quantum dot, a group 1 quantum dot, a group 1-3-6 quantum dot, or a combination thereof, and the shell can be a single-layer shell, a double-layer shell, or a triple-layer shell.

[0065] Recently, due to a great increase in the degree of attention to the environment worldwide, and the strengthening of regulations on toxic substances, an environmentally friendly cadmium-free quantum dot (InP / ZnS, InP / ZeSe / ZnS, etc.) can be used instead of a quantum dot having a cadmium-based core, and for example, when the environmentally friendly cadmium-free quantum dot has a core-shell structure, a group 3-5 quantum dot can be used as the core, but is not necessarily limited thereto.

[0066] For example, the quantum dot can have a perovskite crystal structure.

[0067] For example, the quantum dot can be a metal halide-based quantum dot having a perovskite crystal structure. In this case, the quantum dot having a perovskite crystal structure can control a band gap by a metal halide element. The band gap energy of the quantum dot can be about 1 eV to about 5 eV.

[0068] For example, the metal halide-based quantum dot having a perovskite crystal structure can be represented by Chemical Formula 1, but is not necessarily limited thereto.

[0069]

Chemical Formula 1

[0070] ABX3

[0071] In Chemical Formula 1,

[0072] A is an organic cation or an inorganic cation,

[0073] B is a metal cation, and

[0074] X is a halide anion.

[0075] For example, Chemical Formula 1 can be represented by CsPbX'3, where X' is Cl, Br, and / or I.

[0076] For example, the metal halide-based quantum dot having a perovskite crystal structure can be a green quantum dot having an average particle diameter of 1 nm to 8 nm or a red quantum dot having an average particle diameter of 9 nm to 15 nm. In this case, the green quantum dot can be represented by CsPbBr3, and the red quantum dot can be represented by CsPb(BrI)3.

[0077] For example, the metal halide-based quantum dot having a perovskite crystal structure can have a size of about 1 nm to about 900 nm. When the metal halide-based quantum dot having a perovskite crystal structure has a size greater than about 900 nm, there can be a fundamental problem in that excitons can not reach light emission but can be dissociated into free charges and then disappear due to thermal ionization and delocalization of the carriers within the large nanocrystal.

[0078] For example, the quantum dot in which the oxide of the semimetallic element is embedded can be aerosolized. In other words, the quantum dot in which the oxide of the semimetallic element is embedded can be aerosolized and coated on a light source configured to generate blue light. In this context, it can have the effects of shortening the process time, reducing the thickness of the color conversion layer, improving the light efficiency, etc. compared to when the quantum dot that is not aerosolized is coated. In addition, when the quantum dot in which the oxide of the semimetallic element is embedded is aerosolized and coated on a blue OLED substrate, a blue light leakage phenomenon can be completely blocked at a thickness of about 7 μm. In addition, when the quantum dot in which the oxide of the semimetallic element is embedded is aerosolized and coated, the blue light leakage phenomenon can be completely blocked at a thinner thickness, for example, about 3 μm, and in addition, the light efficiency can be improved by about 40% or higher compared to when the oxide of the semimetallic element is coated without being embedded.

[0079] For example, aerosolization can be performed under vacuum conditions.

[0080] In an example embodiment, the quantum dot in which the oxide of the semimetallic element is embedded can be prepared by a method of mixing a precursor material of the quantum dot and a powder of the oxide of the semimetallic element in a solvent, growing nanocrystals on the surface of the powder of the oxide of the semimetallic element, and grinding them. In another example embodiment, a pre-synthesized quantum dot is mixed with a powder of the oxide of the semimetallic element in a solvent, the solvent is evaporated to allow nanocrystals to be adsorbed or bonded to the surface of the powder of the oxide of the semimetallic element, and they are ground.

[0081] In this paper, the precursor material of quantum dots or the half-metal oxide powder mixed with quantum dots can have a larger size than the quantum dots. For example, the half-metal oxide powder can have a size greater than or equal to about 300 nm and less than or equal to about 2000 nm. On the other hand, when quantum dots are mixed with half-metal oxide powder, the quantum dots can be mixed in an amount from about 0.5 parts by weight to about 20 parts by weight based on about 100 parts by weight of half-metal oxide powder.

[0082] Aerosol deposition equipment can be used to perform a coating process that involves aerosolizing quantum dots containing oxides of semi-metallic elements.

[0083] like Figure 1 As shown, an aerosol deposition apparatus may include an aerosol chamber (not shown), a deposition vacuum chamber, a carrier gas supply device, a vacuum pump (not shown), and a nozzle. The aerosol chamber may contain quantum dot and semi-metallic element oxide powders and is configured as a light source to generate blue light; for example, a blue OLED substrate may be disposed in the deposition chamber. The carrier gas supply device supplies carrier gas to the aerosol chamber, and the vacuum pump maintains a vacuum in the deposition chamber. The nozzle may be positioned spaced apart from the substrate in the deposition chamber and connected to the aerosol chamber via a connecting pipe. Alternatively, the aerosol chamber may be equipped with a vibrator, enabling the nozzle to spray composite powder in a uniform aerosol form.

[0084] The aerosol deposition process contains quantum dot and half-metal oxide powder in an aerosol chamber. When a carrier gas is injected into the aerosol chamber through a carrier gas supply device, and when the blue OLED substrate is placed in the deposition chamber, due to the pressure difference between the deposition chamber and the aerosol chamber in a vacuum state, the quantum dot and half-metal oxide powder can be sprayed onto the blue OLED substrate in the form of an aerosol through a nozzle, thus forming a film composed of quantum dots embedded in the blue OLED substrate by half-metal oxide.

[0085] In the implementation scheme, nitrogen (N2) can be used as the carrier gas for the aerosol deposition process.

[0086] Helium (He) is generally used as a carrier gas for an aerosol deposition process. However, since helium has a small molecular weight, when helium gas is used as a carrier gas, quantum dots and semimetal element oxide powders collide with a substrate and other powders at a relatively high speed in the aerosol deposition process. As such, when the quantum dots and semimetal element oxide powders collide with a substrate or other powders at a relatively high speed through the helium gas and thus are subjected to a high impact force, the helium gas forms a discharge plasma, and this plasma can cause serious damage to the quantum dots and semimetal element oxide powders, particularly the quantum dots. In an actual aerosol deposition process, when helium gas is used as a carrier gas to spray a CsPbBr3-SiO2 composite powder onto a substrate, strong light emission is observed in a local area, and light emitted from the thin film formed by the aerosol deposition process has a blue-shifted wavelength relative to light generated from the composite powder itself, resulting in a decrease in the intensity of brightness.

[0087] However, when nitrogen (N2) is used as a carrier gas for an aerosol deposition process as in the present application, nitrogen can not form a discharge plasma, but solves the problem of damaging quantum dots and semimetal element oxide powders caused by using helium as a carrier gas.

[0088] Since the aerosol deposition process is performed in the form of oxide powder particles of about 1 μm in size sprayed at a high speed, various factors such as the type of carrier gas, the shape of particles, the flow rate conditions of the carrier gas, the design of a nozzle, etc. can cause deterioration, but since the quantum dots applied in one embodiment have a very small size (about 1 nm to about 15 nm), the kinetic energy is not high enough to damage the quantum dots, and thus does not cause deterioration, but a high-speed spraying method can be used to form a fairly dense film without pinholes, defects, etc., and helps to greatly reduce the thickness of the film.

[0089] On the other hand, the aerosol gas flow rate of aerosolized quantum dots in which semimetal element oxides are embedded according to an example embodiment of the present application can be controlled to be about 0.1 L / min to about 10 L / min, for example, about 0.1 L / min to about 1.0 L / min, for example, about 0.1 L / min to about 0.5 L / min, or for example, about 0.2 L / min to about 0.4 L / min. When the aerosol flow rate is controlled as above, the amount of impact applied to the quantum dots and semimetal element oxide powders can be sufficiently reduced, so that the intensity of brightness is not reduced, and in addition, the mechanical properties or optical properties of the thin film are not deteriorated. In particular, when the aerosol gas flow rate is controlled as above, the light emitting properties among the optical properties can be greatly improved. In addition, when the aerosol gas flow rate is adjusted as above during aerosolization, a very fine line width can be achieved, so that pattern processing can be performed without a mask.

[0090] The quantum dot in which the semimetal element oxide is embedded can have a structure in which the quantum dots are uniformly dispersed in a semimetal element oxide matrix, and can have a thickness of about 1 µm to about 50 µm.

[0091] For example, the light source configured to generate blue light can be a blue OLED, a blue LED, a blue EL device, etc., but is not necessarily limited thereto. For example, the light source configured to generate blue light can be a direct light source unit including a diffusion plate and a blue OLED disposed below the diffusion plate, or a side-in light source unit including a light guide plate and a blue OLED disposed at a side surface of the light guide plate.

[0092] The optical film is disposed above the light source configured to generate blue light, and can absorb a portion of the blue light and then convert it into red light and green light.

[0093] For example, the optical film can include a first light conversion layer and a second light conversion layer.

[0094] The first light conversion layer can absorb blue light from the light source and then convert it into red light. In an embodiment, the first light conversion layer can have a structure in which red quantum dots are dispersed in a first semimetal element oxide matrix. The first semimetal element oxide matrix can be formed of silicon dioxide. The red quantum dots can be metal halide-based quantum dots having a perovskite crystal structure.

[0095] The second light conversion layer is formed on the first light conversion layer and can absorb blue light from the light source and then convert it into green light. In an embodiment, the second light conversion layer can have a structure in which green quantum dots are dispersed in a second semimetal element oxide matrix. The second semimetal element oxide matrix can also be formed of silicon dioxide. The green quantum dots can be metal halide-based quantum dots having a perovskite crystal structure.

[0096] In an embodiment, the optical film 120 can be formed by sequentially forming the first light conversion layer 122 and the second light conversion layer 123 on the substrate 121 by an aerosol deposition method.

[0097] The first light conversion layer can be formed on the light source by preparing a first composite powder of red quantum dots and a first semimetal element oxide, and then controlling an aerosol gas flow rate thereof in an aerosol deposition method using nitrogen as a carrier gas.

[0098] The second light conversion layer can be formed on the light source by preparing a second composite powder of green quantum dots and a second semimetal element oxide, and then controlling an aerosol gas flow rate thereof in an aerosol deposition method using nitrogen as a carrier gas.

[0099] Since the optical film applied to the backlight unit according to the present application has a structure including quantum dots, particularly metal halide-based quantum dots having a perovskite crystal structure, dispersed in a semi-metal element oxide matrix, excellent long-term stability against external heat, moisture, and stress can be obtained, and since the optical film is formed by controlling the aerosol gas flow rate, not only fine pattern processing can be performed without a mask, but also excellent mechanical and optical properties can be obtained.

[0100] Another embodiment provides a down-conversion medium comprising a backlight unit.

[0101] The down-conversion medium can be a filterless down-conversion medium, i.e., a down-conversion medium that does not include a color filter.

[0102] Another embodiment provides a display device comprising a down-conversion medium.

[0103] Hereinafter, the present content will be explained in more detail with reference to examples, but these examples should not be interpreted as limiting the scope of the present application in any sense.

[0104] <Manufacturing a Backlight Unit>

[0105] Example 1

[0106] A nearly perfect vacuum was generated in the chamber using a mechanical rotary pump, and a cadmium-free perovskite quantum dot (PeQD) film was formed at room temperature (25℃) and 10 -1TOPO-Zn CsPbBr3 (green) and TOPO-Zn CsPb(BrI)3 (red) quantum dots as light conversion layer materials were mixed in n-hexane at a concentration of 64 mg per 100 ml, respectively, after which the silica powder was sieved through a fine sieve (ASTM mesh No. 170). The green and red materials prepared were placed in different aerosol chambers, respectively. An ultrasonic nebulizer (1.8 MHz) and N2carrier gas injected at a rate of 1 L / min were used to generate aerosolized PeQD solution droplets, starting the deposition of clean PeQDs (green or red). For systems comprising a mixture of PeQDs and semi-metal oxide of silica, both constituent elements were allowed to converge from each aerosol chamber into one nozzle for subsequent co-deposition. To control the feed rate of PeQDs and silica, the mass flow rate controller was adjusted to control the flow rate of aerosol gas at 0.3 L / min by using N2carrier gas, and the PeQD aerosol generated by the ultrasound was made to pass rapidly through an orifice nozzle (1 mm in diameter) due to the pressure difference between the aerosol and the deposition chamber under the flow of carrier gas. This aerosol was rapidly sprayed onto a BOLED substrate at a distance of 5 mm from the nozzle. Subsequently, the substrate holder attached to the BOLED substrate was automatically moved along the XY plane at a scan speed of 5 mm / s. As a result, a PeQD layer or a PeQD-silica composite layer was densely deposited on the BOLED substrate. The film thickness of the layer was varied by adjusting the concentration of PeQDs and the number of scans. To block blue light, the light conversion layer was deposited at a PeQD (green and red) concentration of 64 mg / 100 ml and 3 to 4 scans.

[0107] Example 2

[0108] Cadmium-free perovskite quantum dots (PeQD) films were deposited in the same manner as in Example 1, except that the flow rate of aerosol gas was changed from 0.3 L / min to 0.1 L / min.

[0109] Example 3

[0110] Cadmium-free perovskite quantum dots (PeQD) films were deposited in the same manner as in Example 1, except that the flow rate of aerosol gas was changed from 0.3 L / min to 0.5 L / min.

[0111] Comparative Example 1

[0112] Cadmium-free perovskite quantum dots (PeQD) films were deposited in the same manner as in Example 1, except that no silica powder was used.

[0113] Comparative Example 2

[0114] A cadmium-free perovskite quantum dot (PeQD) film was deposited in the same manner as in Example 1, except that alumina (a-Al2O3) was used instead of the silica powder.

[0115] <Assessment>

[0116] Referring to Figure 2 and Figure 3 , green quantum dots and red quantum dots were both deposited on a BOLED substrate.

[0117] Referring to Figures 4 to 6 , green quantum dots, green quantum dots embedded with alumina, and green quantum dots embedded with silica were well deposited on a BOLED substrate (glass). Figure 4 a photograph of Comparative Example 1 is shown, Figure 5 a photograph of Comparative Example 2 is shown, and Figure 6 a photograph of Example 1 is shown.

[0118] Referring to Figures 7 to 9 , red quantum dots, red quantum dots embedded with alumina, and red quantum dots embedded with silica were well deposited on a BOLED substrate (glass). Figure 4 a photograph of Comparative Example 1 is shown, Figure 5 a photograph of Comparative Example 2 is shown, and Figure 6 a photograph of Example 1 is shown.

[0119] Figure 10 is a graph showing green light efficiency of a backlight unit according to Example 1 and Comparative Examples 1, 2, and Figure 11 is a graph showing red light efficiency of a backlight unit according to Example 1 and Comparative Examples 1, 2. Thus, the backlight unit according to Example 1 and Comparative Examples 1, 2 exhibited the same light efficiency, but the backlight unit according to Example 1 exhibited superior wavelength compatibility compared to the backlight units according to Comparative Examples 1 and 2.

[0120] Figure 12 is a graph showing green brightness of a backlight unit according to Example 1 and Comparative Examples 1, 2, and Figure 13 is a graph showing red brightness of a backlight unit according to Example 1 and Comparative Examples 1, 2. Thus, the backlight unit according to Example 1 has superior brightness compared to the backlight units according to Comparative Examples 1 and 2.

[0121] Figure 14 is a graph showing brightness (green) of a backlight unit according to Example 2, Figure 15 is a graph showing brightness (green) of a backlight unit of Example 1, and Figure 16is a graph showing luminance (green color) of the backlight unit of Example 3, which shows that the closer the flow rate of the aerosol gas is to 0.3 L / min, the better the light emitting characteristics, and the flow rate of the aerosol gas can be controlled to improve the luminance of the backlight unit.

[0122] While the application has been described in connection with what is presently considered to be the most practical example embodiments, it is to be understood that the application is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Therefore, the aforementioned embodiments should be understood as illustrative only and not limiting of the application in any way.

Claims

1. A backlight unit comprising A light source configured to produce blue light; and An optical film configured to absorb a portion of the blue light generated from a light source to produce red and green light. The optical film contains a quantum dot array in which oxides of half-metal elements are embedded. The quantum dot array, in which half-metal oxides are embedded, is aerosolized.

2. The backlight unit according to claim 1, wherein the semi-metallic element includes boron, silicon, germanium, arsenic, antimony, tellurium, polonium, or a combination thereof.

3. The backlight unit according to claim 2, wherein the semi-metallic element oxide is silicon dioxide.

4. The backlight unit according to claim 1, wherein the quantum dots include group 2-6 quantum dots, group 3-5 quantum dots, group 4-6 quantum dots, group 4 quantum dots, group 1-3-6 quantum dots, or combinations thereof.

5. The backlight unit according to claim 1, wherein the quantum dots have a perovskite crystal structure.

6. The backlight unit according to claim 5, wherein the quantum dot is a metal halide-based quantum dot having a perovskite crystal structure.

7. The backlight unit according to claim 6, wherein the metal halide-based quantum dot having a perovskite crystal structure is represented by chemical formula 1: 【Chemical Formula 1】 ABX3 in, In chemical formula 1, A can be an organic cation or an inorganic cation. B is a metal cation, and X is a halide anion.

8. The backlight unit according to claim 7, wherein chemical formula 1 is represented by CsPbX'3, wherein X' is Cl, Br and / or I.

9. The backlight unit according to claim 7, wherein the metal halide-based quantum dots having a perovskite crystal structure are green quantum dots or red quantum dots.

10. The backlight unit according to claim 9, wherein the green quantum dot is CsPbBr3 and the red quantum dot is CsPb(BrI)3.

11. The backlight unit according to claim 1, wherein aerosolization is performed under vacuum conditions.

12. The backlight unit according to claim 1, wherein the aerosol flow rate during aerosolization is from 0.1 L / min to 10 L / min.

13. The backlight unit according to claim 1, wherein the light source configured to generate blue light is a blue OLED, a blue LED, or a blue EL device.

14. A downconversion medium comprising a backlight unit according to claim 1.

15. The downconversion medium according to claim 14, wherein the downconversion medium is a filterless downconversion medium.

16. A display device comprising the down-conversion medium according to claim 14.

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