Quantum dot patterning method, optical element manufacturing method, backlight unit manufacturing method, and image display device manufacturing method

Abstract

To provide a patterning method of a quantum dot which can stably perform the target pattern formation of a quantum dot without being subjected to restriction due to an ink jet method and can suppress the degradation in the quantum dot.SOLUTION: A patterning method of a quantum dot comprises: a step of obtaining a resin layer by applying a mixture containing a quantum dot and a curable resin onto a substrate; a step of discharging a curing agent by an ink jet method onto the resin layer in a pattern shape; a curing processing step of curing a portion to which the curing agent is discharged in the resin layer; and a step of removing an uncured portion in the resin layer with a solvent.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for patterning quantum dots, a method for manufacturing an optical element, a method for manufacturing a backlight unit, and a method for manufacturing an image display device. [Background technology]

[0002] Semiconductor crystal particles with nano-sized particle diameters are called quantum dots, and the energy levels of the semiconductor crystal particles become discrete because the excitons generated by light absorption are confined in nano-sized regions, and the band gap changes depending on the particle diameter. Due to these effects, the fluorescent emission of quantum dots is brighter and more efficient than that of general phosphors, and the emission distribution is sharper.

[0003] In addition, quantum dots have the characteristic that the band gap changes depending on the particle size, making it possible to control the emission wavelength, and they are expected to be used as wavelength conversion materials in solid-state lighting and displays. For example, by using quantum dots as a wavelength conversion material in a display, a wider color gamut and lower power consumption can be achieved compared to conventional phosphor materials.

[0004] As a mounting method in which quantum dots are used as a wavelength conversion material, a method has been proposed in which quantum dots are dispersed in a resin material, and the resin material containing the quantum dots is laminated with a transparent film to incorporate it into a backlight unit as a wavelength conversion film (Patent Document 1).

[0005] It has also been proposed that quantum dots can be used as a color filter material, allowing the quantum dots to absorb the monochromatic blue light from a backlight unit and emit red or green light, thereby functioning as a color filter and wavelength conversion material, thereby making it suitable for use in image elements with high efficiency and excellent color reproducibility (Patent Document 2).

[0006] There is also a method of combining a phosphor layer containing quantum dots and a blue LED element in an LED chip used for displays and solid-state lighting (Patent Document 3).

[0007] It has also been proposed to use quantum dots as a wavelength conversion material in micro LED displays, in which tiny LED elements are formed on a substrate and used as a backlight unit for the display (Patent Document 4). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2013-544018 [Patent Document 2] JP 2017-21322 A [Patent Document 3] Special Publication No. 2002-510866 [Patent Document 4] Special Publication No. 2020-516015 [Patent Document 5] International Publication No. WO2018-225782 [Patent Document 6] Patent Publication No. 2021-12383 Summary of the Invention [Problem to be solved by the invention]

[0009] To use quantum dots as color filters, it is necessary to form patterns of two or three colors out of red, green, and blue on a substrate. For example, when an ultraviolet LED is used as the light source, quantum dots that absorb the ultraviolet light of the light source and emit red, blue, and green light, respectively, are patterned on the substrate to form subpixels, resulting in a backlight unit with three RGB colors. On the other hand, when a blue LED is used as the light source, quantum dots that absorb the blue light of the light source and emit red and green light, respectively, are patterned on the substrate, and the blue parts are made to transmit the blue light of the light source as is, resulting in a backlight unit with three RGB colors.

[0010] Methods for forming a pattern of quantum dots include, for example, photolithography using a photoresist and an inkjet method (Patent Documents 5 and 6).

[0011] In photolithography patterning, a pattern is formed through multiple steps such as baking, exposure, development, etc. During this process, quantum dots are deteriorated due to the effects of heat and light, which causes a problem of reduced luminous efficiency.

[0012] Inkjet patterning is expected to be a useful method for forming quantum dot color filters because it forms patterns by ejecting quantum dot ink, which is made of a resin solution containing quantum dots, directly from a nozzle onto a substrate, and therefore requires fewer processes and can minimize deterioration of the quantum dots due to heat, light, etc. In addition, inkjet patterning is excellent in terms of the efficiency of raw material use and therefore cost, because the raw material is ejected only in the necessary areas.

[0013] However, since inkjet ejects ink from a thin nozzle, the nozzle diameter must be small to form fine patterns of 100 μm or less, which is required for applications such as micro LEDs, and there are significant limitations on the ink characteristics to ensure stable ejection and pattern reproducibility. For example, there are the ink viscosity, ink evaporation rate, concentration of quantum dots contained in the ink, and aggregation and sedimentation of quantum dots in the resin solution. If these are not within the appropriate range for the device, problems such as clogging of the nozzle and ink supply line may occur, and continuous ejection may cause changes and variations in the ejection characteristics, which may cause uneven characteristics between pixels. In particular, with piezo-type inkjet devices, ejection is difficult if the ink viscosity is 100 mPa·s or more, and low-viscosity ink is essential for stable pattern formation. Inks containing resin or particles generally have a viscosity of 100 mPa·s or more, making them difficult to eject with inkjet devices. There are also problems such as poor patterning due to the wettability of the ink with the substrate, and uneven thickness of the pattern due to the coffee ring effect.

[0014] Due to these problems, the options for solvents, resin materials, quantum dot concentrations, etc., are significantly limited in inkjet patterning, and there is a problem in that it is not possible to form the desired quantum dot pattern.

[0015] The present invention has been made to solve the above problems, and aims to provide a quantum dot patterning method that can stably form the desired quantum dot pattern without being subject to the limitations caused by the inkjet method and that can also suppress deterioration of the quantum dots, as well as a method for manufacturing an optical element, a method for manufacturing a backlight unit, and a method for manufacturing an image display device that include such a quantum dot patterning method. [Means for solving the problem]

[0016] In order to solve the above problems, the present invention provides a method for patterning quantum dots, comprising the steps of: Applying a mixture containing quantum dots and a curable resin onto a substrate to obtain a resin layer; discharging a curing agent onto the resin layer in a pattern by an inkjet method; a hardening process for hardening a portion of the resin layer onto which the hardener is dispensed; removing uncured portions of the resin layer with a solvent; The present invention provides a method for patterning quantum dots, comprising:

[0017] The quantum dot patterning method of the present invention can stably form a quantum dot pattern without being subject to limitations imposed by the inkjet method, such as limitations on the ink solution in the inkjet process, and can also suppress deterioration of the quantum dots.

[0018] The curable resin may be a photocurable resin.

[0019] Photocurable resins are preferred because the reaction is easy to control.

[0020] For example, the photocurable resin may be at least one selected from the group consisting of epoxy resins, silicone resins, imide resins, acrylic resins, and vinyl resins.

[0021] The photocurable resin to be used is not particularly limited, but for example, the above-mentioned resins can be used.

[0022] Alternatively, the curable resin may be a thermosetting resin.

[0023] Thermosetting resins are preferred because the reaction is easy to control.

[0024] For example, the thermosetting resin may be at least one selected from the group consisting of epoxy resins, silicone resins, urethane resins, acrylic resins, phenolic resins, melamine resins, and amino resins.

[0025] The thermosetting resin to be used is not particularly limited, but for example, the above-mentioned thermosetting resins can be used.

[0026] The present invention also provides a method for producing an optical element, characterized in that a pattern of quantum dots is formed on a substrate by the quantum dot patterning method of the present invention, thereby obtaining a wavelength converting material having a function as a color filter.

[0027] According to such a method for manufacturing an optical element, it is possible to stably manufacture an optical element that includes quantum dots that are patterned into a desired pattern and in which degradation is suppressed.

[0028] The present invention also provides a method for producing an optical element by the method for producing an optical element of the present invention, Assembling a backlight unit incorporating a light source and the optical element; The present invention provides a method for manufacturing a backlight unit, comprising the steps of:

[0029] According to such a method for manufacturing a backlight unit, it is possible to stably manufacture a backlight unit that includes quantum dots that are patterned into a desired pattern and that are suppressed from deteriorating.

[0030] The light source can be an LED array substrate having a number of micro LED pixels.

[0031] The light source used is not particularly limited, but for example, an LED array substrate having a plurality of micro LED pixels can be used.

[0032] In addition, the present invention provides a method for manufacturing a backlight unit by the method for manufacturing a backlight unit of the present invention, A step of manufacturing an image display device incorporating the backlight unit; The present invention provides a method for producing an image display device, comprising the steps of:

[0033] According to such a method for manufacturing an image display device, it is possible to stably manufacture an image display device having a backlight unit including quantum dots that are patterned into a desired pattern and whose degradation is suppressed. Effect of the Invention

[0034] As described above, the quantum dot patterning method of the present invention makes it possible to stably form a quantum dot pattern without being subject to the limitations of the inkjet method, and also makes it possible to suppress deterioration of the quantum dots.

[0035] Furthermore, the method for producing an optical element of the present invention makes it possible to stably produce an optical element containing quantum dots patterned into a desired pattern while suppressing deterioration.

[0036] Furthermore, the method for producing a backlight unit of the present invention makes it possible to stably produce a backlight unit containing quantum dots patterned into a desired pattern while suppressing deterioration.

[0037] Furthermore, the method for manufacturing an image display device of the present invention makes it possible to stably manufacture an image display device including quantum dots patterned into a desired pattern while suppressing deterioration. [Brief description of the drawings]

[0038] [Figure 1] FIG. 1 is a schematic flow diagram showing an example of a quantum dot patterning method of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] As described above, the patterning of quantum dots using the inkjet method has many limitations due to the inkjet method, such as the use of quantum dot ink.

[0040] The present inventors have conducted extensive research to solve these problems. As a result, they have come to the conclusion that a patterning method in which a mixture of quantum dots and a curable resin is applied onto a substrate, a curing agent is ejected in a pattern by an inkjet method, and then the portion of the resin layer onto which the curing agent is ejected is cured by a curing reaction, and the unreacted portion is removed to form a quantum dot pattern can be formed without being subject to limitations due to the inkjet method, such as limitations of the ink solution, and further deterioration of the quantum dots can be suppressed, thereby completing the present invention.

[0041] That is, the present invention is a method for patterning quantum dots, comprising the steps of: Applying a mixture containing quantum dots and a curable resin onto a substrate to obtain a resin layer; discharging a curing agent onto the resin layer in a pattern by an inkjet method; a hardening process for hardening a portion of the resin layer onto which the hardener is dispensed; removing uncured portions of the resin layer with a solvent; The present invention relates to a method for patterning quantum dots, comprising the steps of:

[0042] The present invention also provides a method for producing an optical element, comprising forming a pattern of quantum dots on a substrate by the quantum dot patterning method of the present invention, to obtain a wavelength converting material having a function as a color filter.

[0043] Furthermore, the present invention provides a method for producing an optical element by the method for producing an optical element of the present invention, Assembling a backlight unit incorporating a light source and the optical element; The method for producing a backlight unit includes the steps of:

[0044] The present invention also relates to a method for manufacturing a backlight unit, comprising the steps of: A step of manufacturing an image display device incorporating the backlight unit; The present invention relates to a method for producing an image display device, comprising the steps of:

[0045] The present invention will be described in detail below, but the present invention is not limited thereto.

[0046] [Quantum dot patterning method] First, an example of the quantum dot patterning method of the present invention will be described with reference to Fig. 1. However, Fig. 1 is a schematic diagram for the purpose of explanation, and the dimensions, patterns, etc. are not limited to those shown in Fig. 1.

[0047] First, as shown in FIG. 1(a), a substrate 1 on which quantum dots are to be patterned is prepared.

[0048] The substrate 1 can be appropriately selected depending on the purpose. Examples include a silicon wafer, a glass substrate, a resin plate, a resin film, etc. The substrate 1 may be subjected to a surface treatment to improve the adhesion of the pattern.

[0049] On the other hand, a mixture containing quantum dots and a curable resin is prepared by mixing the quantum dots with a curable resin. The quantum dots may be dispersed in the curable resin. In this process, for example, the quantum dots dispersed in a solvent are added to and mixed with the curable resin, so that the quantum dots can be dispersed in the curable resin. In addition, the quantum dots can be dispersed in the curable resin by adding the quantum dots in powder form obtained by removing the solvent to the curable resin and kneading them. Alternatively, there is a method in which the monomers or oligomers that are components of the curable resin are polymerized in the presence of the quantum dots. Although several examples have been given, the method of dispersing the quantum dots in the curable resin is not particularly limited and can be appropriately selected according to the purpose.

[0050] In the present invention, the composition and manufacturing method of the quantum dots used are not particularly limited, and quantum dots can be selected according to the purpose. The quantum dots may have only a core or a core-shell structure, and the particle size can be appropriately selected according to the desired wavelength range.

[0051] Examples of the composition of the quantum dots include II-IV group semiconductors, III-V group semiconductors, II-VI group semiconductors, I-III-VI group semiconductors, II-IV-V group semiconductors, IV group semiconductors, and perovskite type semiconductors.

[0052] Specific examples include CdSe, CdS, CdTe, InP, InAs, InSb, AlP, AlAs, AlSb, ZnSe, ZnS, ZnTe, Zn3P2, GaP, GaAs, GaSb, CuInSe2, CuInS2, CuInTe2, CuGaSe2, CuGaS2, CuGaTe2, CuAlSe2, CuAlS2, CuAlTe2, AgInSe2, AgInS2, AgInTe, AgGaSe2, AgGaS2, AgGaTe2, PbSe, PbS, PbTe, GaN, AlN, AlGaN, Si, Ge, graphene, CsPbCl3, CsPbBr3, CsPbI3, and CH3NH3PbCl3, as well as mixed crystals thereof and those to which dopants are added.

[0053] Furthermore, the quantum dot surface may have a coating layer made of organic molecules, inorganic molecules or polymers, and the structure is not limited and can be appropriately selected.

[0054] Examples of the inorganic coating layer include silicon oxide, zinc oxide, aluminum oxide, zirconium oxide, titanium oxide, and cerium oxide.

[0055] Examples of the polymer coating layer include polysilsesquioxane, poly(methyl methacrylate), polyacrylonitrile, polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone.

[0056] Furthermore, the quantum dots may be spherical, cubic, or rod-shaped, and the shape of the quantum dots is not limited and can be freely selected.

[0057] The average particle size of the quantum dots is desirably 20 nm or less, because with an average particle size of 20 nm or less, the quantum size effect can be sufficiently obtained, high luminous efficiency can be realized, and the band gap can be sufficiently controlled by the particle size.

[0058] The particle diameter of the quantum dots can be calculated from the average value of the maximum diameter in a specific direction, i.e., the Feret diameter, of 20 or more particles measured by a particle image obtained by a transmission electron microscope (TEM). Of course, the method for measuring the average particle diameter is not limited to this, and other methods can be used for measurement.

[0059] The curable resin is not particularly limited and can be appropriately selected according to the purpose such as the pattern size, curing speed, and resin properties after curing. The resin material may be a monomer or oligomer, and may contain a crosslinking agent. The resin material may be one type or may contain two or more types.

[0060] As the curable resin, a thermosetting resin or a photocurable resin is preferable because the reaction is easily controlled. Examples of the photocurable resin include an epoxy resin, a silicone resin, an imide resin, an acrylic resin, and a vinyl resin. Examples of the thermosetting resin include an epoxy resin, a silicone resin, a urethane resin, an acrylic resin, a phenol resin, a melamine resin, an amino resin, and an amide resin.

[0061] The concentration of the quantum dots and the solid content in the mixture containing the quantum dots and the curable resin can be appropriately selected. If necessary, a solvent or a dispersant may be added.

[0062] The solvent is not particularly limited as long as it is compatible with the quantum dots and the resin material.

[0063] As the solvent, for example, toluene, hexane, ethyl acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, etc. can be used.

[0064] The viscosity of the mixture containing the quantum dots and the curable resin is not particularly limited, and can be appropriately selected depending on the purpose, such as the resin material and solid content concentration.

[0065] The mixture containing the quantum dots and the curable resin may further contain a scatterer, which scatters the excitation light and increases the probability of the quantum dots in the color filter absorbing the excitation light, thereby improving the excitation light conversion efficiency.

[0066] The scattering material can be selected from inorganic particles, organic particles, etc., depending on the purpose, and it is desirable to adjust the particle size and amount added to optimize the light extraction efficiency based on the wavelength of the light source or emission wavelength used and the structure of the wavelength conversion material. Examples of inorganic particles include silica, zirconia, alumina, barium titanate, and barium sulfate, while examples of organic particles include PMMA, polystyrene, and polycarbonate.

[0067] In addition, the mixture containing the quantum dots and the curable resin may further contain a sensitizer, and the type and amount of the sensitizer can be appropriately selected according to the resin material and the pattern shape. For example, photosensitizers include anthracene derivatives, anthraquinone derivatives, and benzophenone derivatives.

[0068] Next, a mixture containing quantum dots and a curable resin is applied onto the substrate 1 to obtain a resin layer 2, as shown in FIG. 1(b).

[0069] The mixture containing quantum dots and a curable resin can be applied onto the substrate 1 using, for example, a spray coater, a spin coater, a bar coater, or a doctor blade method, and the resin layer 2 can be formed by such application.

[0070] The thickness of the resin layer 2 is not particularly limited and can be appropriately selected depending on the application. Since a thinner resin layer 2 leads to a thinner device, the resin layer thickness is preferably 50 μm or less, and more preferably 20 μm or less.

[0071] Next, a hardener is ejected onto the resin layer 2 in a pattern by an inkjet method.

[0072] The curing agent can be discharged, for example, as a solution, in which case a solution of the curing agent is prepared and then discharged (applied) in a pattern onto the resin layer 2 on the substrate 1 by an inkjet device. The solvent used to prepare the solution of the curing agent is not particularly limited as long as it can dissolve the curing agent.

[0073] The hardener solution may be applied to each pattern portion one drop at a time, or may be applied multiple times.

[0074] The curing agent can be appropriately selected according to the type of curable resin. The curing agents are mainly radical curing agents, cationic curing agents, and anionic curing agents, and it is desirable to use a curing agent suitable for the curing conditions of the curable resin.

[0075] Examples of radical curing agents include benzophenone derivatives, acetophenone derivatives, benzoin ether derivatives, thioxanthone derivatives, azo compounds, peroxides, etc. Examples of cationic curing agents include sulfonium salts, iodonium salts, etc. Examples of anionic curing agents include alkali metals, alkyl lithiums, etc.

[0076] The hardener solution discharged in a pattern can partially permeate into the resin layer 2. As a result, as shown in Fig. 1(c), portions 21 of the resin layer 2 into which the hardener is discharged are formed in a pattern. Reference numeral 22 indicates portions into which the hardener is not discharged.

[0077] After the curing agent is discharged, the portion 21 of the resin layer 2 onto which the curing agent has been discharged is cured. If the resin is a photocurable resin, it is irradiated with UV light, and if the resin is a thermosetting resin, it is heated together with the substrate 1, so that only the portion 21 of the resin layer 2 onto which the curing agent has been discharged can be cured. If the resin is a thermosetting resin, it is also possible to thermally diffuse the curing agent into the portion 21 of the resin layer 2 during heating. It is preferable to adjust the curing conditions according to the resin material and the pattern shape.

[0078] On the other hand, the portion 22 onto which the curing agent has not been ejected is included in the resin layer 2 as an uncured portion.

[0079] After the curing process, the uncured portions of the resin layer 2 are removed with a solvent, thereby forming a pattern 23 of the cured resin layer containing quantum dots on the substrate 1, as shown in FIG.

[0080] The method for removing the uncured portion with a solvent can be appropriately selected depending on the resin characteristics and the pattern shape, for example, removal by spraying or immersing the substrate 1 in a solvent.

[0081] According to the patterning method of the present invention, it is possible to stably form a quantum dot pattern by the inkjet method without limitations due to the inkjet method such as the resin material and the quantum dot concentration. Furthermore, according to the patterning method of the present invention, the effects of heat and light on the quantum dots are smaller than those of the patterning method by photolithography, so that the deterioration of the quantum dots can be suppressed. Therefore, according to the patterning method of the present invention, it is possible to stably form the desired quantum dot pattern while suppressing the deterioration of the quantum dots.

[0082] [Method of manufacturing optical elements] The method for producing an optical element of the present invention is characterized in that a pattern of quantum dots is formed on a substrate by the quantum dot patterning method of the present invention, thereby obtaining a wavelength converting material that functions as a color filter.

[0083] According to the manufacturing method of the optical element of the present invention, the quantum dot patterning method of the present invention can stably form a quantum dot pattern and can also suppress deterioration of the quantum dots, so that a quantum dot color filter (wavelength conversion material) having a desired quantum dot pattern and suppressing deterioration of the quantum dots can be stably obtained.

[0084] The optical element manufactured by the present invention includes a wavelength converting material having a function as a color filter, but may further include other components. In the manufacturing method of the optical element of the present invention, the steps other than forming a pattern of quantum dots on a substrate by the quantum dot patterning method of the present invention to obtain a wavelength converting material having a function as a color filter are not particularly limited and can be appropriately selected according to the purpose.

[0085] [Backlight unit manufacturing method] The method for producing a backlight unit of the present invention is characterized by comprising the steps of producing an optical element by the method for producing an optical element of the present invention, and assembling a backlight unit incorporating a light source and the optical element.

[0086] According to the backlight unit manufacturing method of the present invention, since it includes a step of manufacturing an optical element by the optical element manufacturing method of the present invention, it is possible to stably manufacture a backlight unit containing quantum dots that are patterned into a desired pattern and have reduced deterioration.

[0087] The light source is not particularly limited, but for example, an LED array substrate having a plurality of micro LED pixels can be used.

[0088] The backlight unit produced by the present invention may further include components other than the optical elements and the light source depending on the purpose.

[0089] [Manufacturing method of image display device] The method for manufacturing an image display device of the present invention is characterized by comprising the steps of: manufacturing a backlight unit by the method for manufacturing a backlight unit of the present invention; and manufacturing an image display device incorporating the backlight unit.

[0090] According to the manufacturing method of the image display device of the present invention, a step of manufacturing a backlight unit by the manufacturing method of the backlight unit of the present invention is included, so that it is possible to stably manufacture an image display device having a backlight unit with quantum dots that are patterned into a desired pattern and have reduced degradation. EXAMPLES

[0091] The present invention will be specifically described below using examples and comparative examples, but the present invention is not limited to these.

[0092] In the following examples and comparative examples, InP / ZnSe / ZnS core-shell quantum dots were used as the quantum dot material. The fluorescence emission characteristics of the quantum dots (quantum dot-containing polymers) obtained by surface treatment were evaluated using a quantum efficiency measurement system (QE-2100) manufactured by Otsuka Electronics Co., Ltd., and the emission wavelength, fluorescence emission half-width, and fluorescence emission efficiency (internal quantum efficiency) of the quantum dots at an excitation wavelength of 450 nm were measured.

[0093] (Quantum dot core synthesis process) 0.23g (0.9mmol) of palmitic acid, 0.088g (0.3mmol) of indium acetate, and 10mL of 1-octadecene were added to the flask, and the mixture was heated and stirred at 100℃ under reduced pressure to dissolve the raw materials and degassed for 1 hour. After that, nitrogen was purged into the flask, and 0.75mL (0.15mmol) of a solution prepared by mixing tristrimethylsilylphosphine with trioctylphosphine to adjust the concentration to 0.2M was added, and the temperature was raised to 300℃. It was confirmed that the solution turned from yellow to red and that core particles were formed.

[0094] (Quantum dot shell layer synthesis process) Next, 2.85g (4.5mmol) of zinc stearate and 15mL of 1-octadecene were added to another flask, and the mixture was heated and stirred at 100°C under reduced pressure. While dissolving, a 0.3M zinc stearate octadecene solution was degassed for 1hr to prepare a solution. 3.0mL (0.9mmol) was added to the reaction solution after the core synthesis and cooled to 200°C. Next, 0.474g (6mmol) of selenium and 4mL of trioctylphosphine were added to another flask, and the mixture was heated to 150°C and dissolved to prepare a 1.5M selenium trioctylphosphine solution. The reaction solution after the core synthesis step, which had been cooled to 200°C, was heated to 320°C over 30 minutes, and the selenium trioctylphosphine solution was added in 0.1mL increments to a total of 0.6mL (0.9mmol), and the mixture was held at 320°C for 10 minutes, after which it was cooled to room temperature. 0.44 g (2.2 mmol) of zinc acetate was added and dissolved by heating and stirring at 100°C under reduced pressure. The flask was purged again with nitrogen and heated to 230°C, and 0.98 mL (4 mmol) of 1-dodecanethiol was added and held for 1 hour. The resulting solution was cooled to room temperature to produce a solution containing core-shell quantum dots consisting of InP / ZnSe / ZnS.

[0095] The emission wavelength, fluorescence emission half-width, and fluorescence emission efficiency (internal quantum efficiency) of this quantum dot were measured, and the emission wavelength was 533 nm, the half-width was 40 nm, and the internal quantum efficiency was 79%.

[0096] Example 1 The quantum dots synthesized by the above procedure and methacrylic modified silicone oil X-32-3817-3 (Shin-Etsu Chemical Co., Ltd.) as a photocurable resin were added and mixed so that the quantum dots were 30 parts by mass per 100 parts by mass of silicone oil. The viscosity of this mixture was measured with a rotational viscometer (Brookfield DV-I) and was 2166 mPa s at 25°C.

[0097] This mixture was applied onto a glass substrate using a spin coater (ACT-220AII, manufactured by Active Co., Ltd.) so that the resin layer was 10 μm thick. After application, the substrate was heated to 120° C. on a hot plate to remove excess solvent.

[0098] A photocuring agent was prepared by diluting Irgacure 1173 (IGM resins BV) 10 times with a propylene glycol monomethyl ether acetate solvent. This photocuring agent was ejected onto the resin layer in a pattern with a pitch of 200 μm using an inkjet device (Microjet LaboJet-600Bio, Inc.).

[0099] After dispensing the photocuring agent onto the substrate, the substrate was exposed to light in a nitrogen atmosphere at a wavelength of 365 nm and an output of 500 mW / cm. 2 The resin layer was irradiated with light of 1000 W to cure the portion of the resin layer where the curing agent had been discharged. Thereafter, the substrate was immersed in toluene and subjected to ultrasonic cleaning to remove the uncured portion of the resin layer.

[0100] When the quantum dot pattern remaining on the substrate (the pattern of the resin layer containing quantum dots) was measured using a laser microscope (Olympus Corporation, OLS-4100), it was confirmed that a dot pattern with an average thickness of 5 μm and a pattern size of 50 μm had been formed.

[0101] Example 2 The quantum dots synthesized by the above procedure and bisphenol A type epoxy resin EPICLON850 (DIC Corporation) as a thermosetting resin were added and mixed so that the quantum dots were 30 parts by mass per 100 parts by mass of epoxy resin. The viscosity of this mixture was measured with a rotational viscometer and was 1124 mPa s at 25°C.

[0102] This mixture was applied onto a glass substrate using a spin coater so that the resin layer was 10 μm thick. After application, the substrate was heated to 120° C. on a hot plate to remove excess solvent.

[0103] A polyamide amine curing agent EPICLONB-065 (DIC Corporation) was diluted 10 times with a propylene glycol monoethyl ether solvent to prepare a heat curing agent. This heat curing agent was ejected onto the resin layer in a pattern with a pitch of 200 μm using an inkjet device.

[0104] The substrate after the thermal curing agent was discharged was heated on a hot plate at 150° C. for 60 minutes to cure the portion of the resin layer where the curing agent was discharged. The substrate was then immersed in toluene and ultrasonically cleaned to remove the uncured portion of the resin layer.

[0105] When the quantum dot pattern remaining on the substrate was measured using a laser microscope, it was confirmed that a dot pattern with an average thickness of 6 μm and a pattern size of 60 μm had been formed.

[0106] Comparative Example 1 The quantum dots synthesized by the above procedure and methacryl-modified silicone oil X-32-3817-3 were added so that the quantum dots were 30 parts by mass per 100 parts by mass of silicone oil, and Irgacure 1173 (IGM resins BV) was further added so that the Irgacure 1173 was 2 parts by mass per 100 parts by mass of silicone oil, and mixed. The viscosity of this mixture was measured with a rotational viscometer and was 955 mPa s at 25°C.

[0107] This mixture was discharged directly onto a substrate using an inkjet device, but the nozzle became clogged midway through the process, making it impossible to continue the process.

[0108] Comparative Example 2 The quantum dots synthesized by the above procedure and methacryl-modified silicone oil X-32-3817-3 were added so that the quantum dots were 30 parts by mass per 100 parts by mass of silicone oil, and Irgacure 1173 (IGM resins BV) was further added so that the Irgacure 1173 was 2 parts by mass per 100 parts by mass of silicone oil, and mixed. Furthermore, propylene glycol monomethyl ether acetate was added to this mixture to dilute it 20 times. The viscosity of this mixture was measured with a rotational viscometer and was 106 mPa s at 25 °C.

[0109] This mixture was directly discharged onto the substrate at a pitch of 200 μm using an inkjet device. After discharging, the substrate was heated to 150° C. on a hot plate to remove the solvent.

[0110] Next, the substrate was irradiated with light at a wavelength of 365 nm and an output of 500 mW / cm in a nitrogen atmosphere. 2 The substrate was then immersed in toluene and ultrasonically cleaned to remove the uncured portions.

[0111] When the quantum dot pattern remaining on the substrate was measured by a laser microscope, it was confirmed that a dot pattern was formed having a concave shape with an average thickness of 5 μm on the periphery and 1 μm on the center, and the pattern size varied from 50 to 80 μm. In other words, in Comparative Example 2, the desired quantum dot pattern could not be stably formed.

[0112] As described above, by processing the substrate with the patterning method of the present invention, which includes a step of applying a mixture containing quantum dots and a curable resin onto the substrate to obtain a resin layer, a step of discharging a curing agent onto the resin layer in a patterned form by an inkjet method, a curing process step of curing the portion of the resin layer onto which the curing agent has been discharged, and a step of removing the uncured portion of the resin layer with a solvent, a pattern of quantum dots can be formed stably regardless of the quantum dot concentration or the resin material. Furthermore, the patterning method of the present invention has a smaller effect of heat and light on the quantum dots than the patterning method using photolithography, so that the deterioration of the quantum dots can be suppressed. In addition, by repeatedly forming quantum dot patterns that emit green, red, and blue light using the above patterning method, a quantum dot pattern of RGB can be obtained.

[0113] The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included in the technical scope of the present invention. [Explanation of symbols]

[0114] 1...substrate, 2...resin layer, 21...portion onto which hardener is ejected, 22...portion onto which hardener is not ejected, 23...pattern of cured resin layer.

Claims

1. A method for patterning quantum dots, comprising the steps of: Applying a mixture containing quantum dots and a curable resin onto a substrate to obtain a resin layer; discharging a curing agent onto the resin layer in a pattern by an inkjet method; a hardening process for hardening a portion of the resin layer onto which the hardener is dispensed; removing uncured portions of the resin layer with a solvent; 13. A method for patterning quantum dots, comprising:

2. 2. The method for patterning quantum dots according to claim 1, wherein the curable resin is a photocurable resin.

3. 3. The method for patterning quantum dots according to claim 2, wherein the photocurable resin is at least one selected from the group consisting of epoxy resin, silicone resin, imide resin, acrylic resin, and vinyl resin.

4. 2. The method for patterning quantum dots according to claim 1, wherein the hardening resin is a thermosetting resin.

5. 5. The quantum dot patterning method according to claim 4, wherein the thermosetting resin is at least one selected from the group consisting of epoxy resin, silicone resin, urethane resin, acrylic resin, phenol resin, melamine resin, and amino resin.

6. A method for manufacturing an optical element, comprising forming a pattern of quantum dots on a substrate by the method for patterning quantum dots according to any one of claims 1 to 5, to obtain a wavelength conversion material having a function as a color filter.

7. A step of producing an optical element by the method of producing an optical element according to claim 6; Assembling a backlight unit incorporating a light source and the optical element; A method for manufacturing a backlight unit comprising the steps of:

8. The method for manufacturing a backlight unit according to claim 7, wherein an LED array substrate having a plurality of micro LED pixels is used as the light source.

9. A step of manufacturing a backlight unit by the method for manufacturing a backlight unit according to claim 7 or 8; A step of manufacturing an image display device incorporating the backlight unit; A method for manufacturing an image display device, comprising:

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