Quantum dot manufacturing method

Abstract

A method for manufacturing quantum dots according to an embodiment of the present invention includes the steps of preparing a first solution including at least one first cation precursor and a second solution including at least one first anion precursor, mixing the first solution and the second solution at 20°C to 130°C to prepare a first mixture, heating the first mixture to a high temperature of 300°C within one minute, and cooling the heated first mixture to below 100°C within one minute to form a core, wherein the first cation precursor includes an indium oxocluster.

Description

Technical Field

[0001] This specification relates to a method for manufacturing quantum dots and the quantum dots manufactured thereby. More specifically, it relates to a method for manufacturing quantum dots that can obtain quantum dots with a shortened reaction time, easy mass production, high quantum efficiency, and improved optical and thermal stability.

Background Art

[0002] A quantum dot is a semiconductor material having a nano-sized crystal structure, which has high color purity, excellent optical and thermal stability compared to organic substances, and ease of bandgap adjustment. Due to its small size, such a quantum dot has a large surface area per unit volume and exhibits a quantum confinement effect, so it has physicochemical properties different from those of the semiconductor material itself. A quantum dot absorbs light from an excitation source to enter an energy-excited state, and emits energy corresponding to the energy bandgap of the quantum dot. The energy bandgap of a quantum dot can be adjusted by adjusting the size and composition of the nanocrystal, and it has high-color-purity light-emitting characteristics, so various application developments have been made for display elements, energy elements, or bioluminescent elements, etc.

[0003] When applying quantum dots to an element, efficiency decreases due to corrosion and oxidation of the quantum dots by high frequency, heat, moisture, etc. Therefore, conventionally mentioned quantum dots are mainly utilized in a core-shell structure in which a shell is coated on the surface of a core. When coating a shell on the surface of the core in this way, it is possible to improve the phenomenon that the quantum dots are corroded by heat and moisture, and it has the advantage of acting as an energy barrier for restraining charges formed by adding light and enhancing optical durability.

[0004] Generally, methods for fabricating core-shell quantum dots utilize a method in which a core is first synthesized by injecting an anion precursor solution into a high-temperature cation precursor solution at high temperatures, and then a shell is secondarily formed by injecting a solution constituting the shell components. In this process, core-shell or multi-shell quantum dots can be fabricated depending on the number of times the shell component solutions are added.

[0005] However, the quantum dot manufacturing method described above has the disadvantage of being complex and requiring a long synthesis time, as it involves preparing each precursor solution and synthesizing multiple solutions in a stepwise manner. In addition, while the emission wavelength of core-shell quantum dots can generally be controlled by adjusting the size of the core particles, controlling the emission wavelength is difficult because the reaction rate at which the core is synthesized is very fast. Furthermore, if a lattice mismatch occurs between the core and shell during the process of forming the core-shell structure through multiple steps, it can lead to problems with the thermal stability and quantum efficiency of the quantum dot. [Overview of the project] [Problems that the invention aims to solve]

[0006] Therefore, the present invention aims to provide a method for manufacturing quantum dots that can be easily mass-produced in a short amount of time.

[0007] Furthermore, the present invention aims to provide a method for manufacturing quantum dots that can achieve high quantum efficiency by having a narrow full width at half maximum.

[0008] Furthermore, the present invention aims to provide a method for manufacturing quantum dots that exhibit excellent photostability and thermal stability.

[0009] Furthermore, the present invention aims to provide a method for manufacturing quantum dots that allows for easy control of the reaction and diverse adjustment of the emission wavelength.

[0010] The problems addressed by the present invention are not limited to those mentioned above, and other problems not mentioned can be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0011] To solve the aforementioned problems, a method for producing quantum dots according to one embodiment of the present invention includes the steps of: preparing a first solution containing at least one first cation precursor and a second solution containing at least one first anion precursor; mixing the first solution and the second solution at 20°C to 130°C to produce a first mixture; raising the temperature of the first mixture to 300°C within 1 minute; and cooling the heated first mixture to 100°C or below within 1 minute to form a core, wherein the first cation precursor contains an indium oxocluster.

[0012] Specific details of other embodiments are included in the detailed description and drawings. [Effects of the Invention]

[0013] According to the manufacturing method of the present invention, quantum dots can be obtained that have a narrow full width at half maximum, thereby achieving high quantum efficiency.

[0014] According to the manufacturing method of the present invention, since synthesis technology involving high-temperature heat treatment is utilized, quantum dots with excellent photostability and thermal stability can be obtained.

[0015] According to the manufacturing method of the present invention, the core is used without centrifugation, the reaction time is short, and it may be possible to mass-produce in a short time using a small-scale continuous production method.

[0016] According to the manufacturing method of the present invention, the reaction can be easily controlled and the emission wavelength can be adjusted in various ways, which has the effect of minimizing the defect rate.

[0017] The effects of the present invention are not limited to those exemplified above, and a wide variety of other effects are included within the present invention. [Brief explanation of the drawing]

[0018] [Figure 1] This is a flowchart illustrating the core formation process in one embodiment of the quantum dot manufacturing method according to the present invention. [Figure 2] This is a flowchart illustrating the shell formation process in one embodiment of the quantum dot manufacturing method of the present invention. [Figure 3] This is a schematic diagram illustrating a method for manufacturing quantum dots according to one embodiment of the present invention. [Figure 4] This is a schematic diagram illustrating a method for manufacturing quantum dots according to one embodiment of the present invention. [Modes for carrying out the invention]

[0019] The advantages and features of the present invention, and the methods for achieving them, will become clearer with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but is embodied in a variety of different forms, and these embodiments are provided merely to complete the disclosure of the present invention and to fully inform a person with ordinary skill in the art to which the present invention belongs, and the present invention is defined only by the scope of the claims.

[0020] The shapes, areas, ratios, angles, numbers, etc. disclosed in the drawings illustrating embodiments of the present invention are illustrative; therefore, the present invention is not limited to those illustrated. Throughout the specification, the same reference numerals refer to the same components. Furthermore, when describing the present invention, if it is determined that a specific description of related prior art would unnecessarily obscure the gist of the invention, such detailed description will be omitted. Where "includes," "has," "is made," etc., as mentioned in the present invention, other parts may be added unless "only" is used. When a component is expressed singly, it includes cases where it includes multiple components unless otherwise explicitly stated.

[0021] When interpreting the constituent elements, they shall be interpreted as including a margin of error, even if not explicitly stated otherwise.

[0022] When it comes to the description of positional relationships, for example, when the positional relationship between two parts is described such as "on ~", "above ~", "below ~", "next to ~", etc., as long as "immediately" or "directly" is not used, one or more other parts may be located between the two parts.

[0023] An element or layer referred to as "on" another element or layer includes both cases where another layer or element is immediately above the other element or there are other layers or elements intervening in the middle.

[0024] Also, although the first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are merely used to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical idea of the present invention.

[0025] Throughout the specification, the same reference numerals refer to the same components.

[0026] The area and thickness of each configuration shown in the drawings are shown for the convenience of explanation, and the present invention is not necessarily limited to the area and thickness of the shown configuration.

[0027] The respective features of the various embodiments of the present invention can be partially or wholly combined or combined with each other, enabling various technical linkages and drives, and each embodiment may be implemented independently of each other or may be implemented together in an associated relationship.

[0028] Hereinafter, the present invention will be described with reference to the drawings.

[0029] FIG. 1 is a flowchart schematically showing a core formation process in a method for manufacturing quantum dots according to an embodiment of the present invention.

[0030] Referring to Figure 1, a method for producing quantum dots according to one embodiment of the present invention includes the steps of: preparing a first solution containing at least one first cation precursor and a second solution containing at least one first anion precursor (S110); mixing the first solution and the second solution at 20°C to 130°C to produce a first mixture (S120); raising the temperature of the first mixture to 300°C within 1 minute (S130); and cooling the heated first mixture to 100°C or below within 1 minute to form a core (S140), wherein the first cation precursor includes an indium oxocluster.

[0031] The method for manufacturing quantum dots according to the present invention will be described in detail step by step below.

[0032] First, a first solution containing at least one first cation precursor and a second solution containing at least one first anion precursor are prepared (S110).

[0033] In this case, at least one of the first solution and the second solution may contain two or more precursors. For example, the first solution may contain two cationic precursors, and the second solution may also contain two anionic precursors, but is not limited to this.

[0034] The first cation precursor includes an indium oxocluster. A cluster structure refers to a structure in which three or more atoms of the same or similar element are bonded together as a single mass, and active metal oxides such as indium oxoclusters (In-Oxo) can be synthesized by reacting an active metal precursor with a carboxylic acid. Specifically, indium oxoclusters (In-Oxo) can be formed by the reaction of an active metal precursor such as indium(III) acetate with a carboxylate such as oleic acid.

[0035] The first solution may contain one or more first cation precursors, which may further include cadmium (Cd), mercury (Hg), magnesium (Mg), aluminum (Al), manganese (Mn), copper (Cu), gallium (Ga), tin (Sn), barium (Ba), iron (Fe), or strontium (Sr).

[0036] Specifically, the first cation precursor may be further selected from, but is not limited to, oxides, peroxides, sulfates, halides, oleates, perchlorates, carboxylates, acetates, phosphates, acetylacetonates, cyanides, carbonates, or nitrates of cadmium (Cd), mercury (Hg), magnesium (Mg), aluminum (Al), manganese (Mn), copper (Cu), gallium (Ga), tin (Sn), barium (Ba), iron (Fe), or strontium (Sr).

[0037] Furthermore, the first cation precursor may further contain a zinc oxocluster (Zn Oxo). Similar to indium oxoclusters (In-Oxo), active metal oxides such as zinc oxoclusters (Zn-Oxo) can be synthesized by reacting an active metal precursor with a carboxylic acid. Specifically, zinc oxoclusters (Zn-Oxo) can be formed by the reaction of an active metal precursor such as zinc acetate with a carboxylate such as oleic acid.

[0038] The first anion precursor may be a compound containing sulfur (S), selenium (Se), phosphorus (P), tellurium (Te), arsenic (As), nitrogen (N), or antimony (Sb).

[0039] For example, the first anion precursor is sulfur, trialkylphosphine sulfide, trialkenylphosphine sulfide, alkylamino sulfide, alkenylamino sulfide, alkylthiol, selenium, trialkylphosphine selenide, trialkenylphosphine selenide, alkylamino selenide, alkenylamino selenide, trialkylphosphine telluride, trialkenylphosphine telluride, alkylamino telluride, alkenylamino telluride, alkylphosphine A selection of the following may be made, but is not limited to: phosphine, tris(trialkylsilyl)phosphine, tris(dialkylsilyl)phosphine, tris(dialkylaminophosphine), arsenic oxide, arsenic chloride, arsenic sulfate, arsenic bromide, arsenic iodide, nitric oxide, nitric acid, and ammonium nitrate.More specifically, the first anion precursor may include tris(trimethylsilyl)phosphine (TMSP).

[0040] The step of preparing the first solution may include a step of mixing the first cation precursor and the unsaturated fatty acid and then raising the temperature in order to form a more suitable first cation precursor. The first cation precursor thus produced can maintain a more stably dispersed form containing long-chain unsaturated fatty acid ligands. For example, the unsaturated fatty acid may be selected from myristic acid, oleic acid, stearic acid, lauric acid, and palmitic acid, and while oleic acid is preferred, it is not limited thereto, considering the dispersion stability, size distribution, and luminescence properties of the quantum dots.

[0041] The step of preparing the first solution includes the step of producing an indium oxocluster (In-Oxo). Specifically, the step of producing an indium oxocluster (In-Oxo) may include mixing indium(III) acetate and oleic acid, raising the mixed solution to 200°C under vacuum and then converting to atmospheric pressure, and thereafter adding octadecene (ODE) and synthesizing at 260°C to 300°C for 1 hour or more. As a result, the first solution will contain, but will not be limited to, an indium oxocluster.

[0042] Furthermore, the step of preparing the first solution may further include the step of producing zinc oxoclusters (Zn-Oxo). Specifically, the step of producing zinc oxoclusters (Zn-Oxo) may include the steps of mixing zinc acetate dihydrate and oleic acid, then raising the temperature to 190°C under vacuum, and then, after converting to atmospheric pressure, adding octadecene (ODE) and synthesizing at 300°C to 315°C for 1 hour or more, thereby the first solution may further contain zinc oxoclusters.

[0043] The composition ratio of indium oxoclusters to zinc oxoclusters in the first solution can be appropriately adjusted considering the emission wavelength of the final quantum dot. For example, the molar ratio of indium oxoclusters to zinc oxoclusters may be 1:1 to 1:0.4. More specifically, the molar ratio of indium oxoclusters to zinc oxoclusters may be 1.2:1.2 to 1.8:0.8, based on the case where the anion precursor, for example phosphorus (p), is 1, but is not limited to this.

[0044] The step of preparing the second solution may include a step of mixing the anion precursor and the trialkylphosphine and then raising the temperature in order to form a more suitable first anion precursor. The anion precursor thus produced contains a long-chain trialkylphosphine ligand and has even better dispersion stability. For example, the trialkylphosphine may be selected from trihexylphosphine, trioctylphosphine, and tridecylphosphine, and while trioctylphosphine is preferred when considering dispersion stability, etc., it is not limited thereto.

[0045] Next, the first solution and the second solution are mixed at 20°C to 130°C to produce the first mixture (S120).

[0046] Specifically, the first solution containing the first cation precursor and the second solution containing the first anion precursor can be mixed at a relatively low temperature of 20°C to 130°C, and more preferably at 80°C to 120°C. By mixing the first and second solutions at a relatively low temperature, the chemical reaction between the cation precursor and the anion precursor can be suppressed.

[0047] The solvent can be used to mix the first cation precursor in the first solution with the first anion precursor in the second solution. Any non-reactive solvent is acceptable and can be selected as appropriate. Specifically, the solvent may be, but is not limited to, primary alkylamines having 6 to 22 carbon atoms such as hexadecylamine, secondary alkylamines having 6 to 22 carbon atoms such as dioctylamine, tertiary alkylamines having 6 to 40 carbon atoms such as trioctylamine, nitrogen-containing heterocyclic compounds such as pyridine, aliphatic hydrocarbons having 6 to 40 carbon atoms such as hexadecane, octadecane, octadecene, and squalane (alkanes, alkenes, alkynes, etc.), aromatic hydrocarbons having 6 to 30 carbon atoms such as phenyldodecane, phenyltetradecane, and phenylhexadecane, phosphines substituted with alkyl groups having 6 to 22 carbon atoms such as trioctylphosphine, phosphine oxides substituted with alkyl groups having 6 to 22 carbon atoms such as trioctylphosphine oxide, phenyl ethers, benzyl ethers, aromatic ethers having 12 to 22 carbon atoms, and combinations thereof. Preferably, the solvent may be an aliphatic hydrocarbon having 6 to 40 carbon atoms, such as octadecene or squalane.

[0048] As another example, the solvent may be added in advance during the first solution preparation step and / or the second solution preparation step. Specifically, for example, after mixing indium acetate and oleic acid in the step of preparing the first solution, the solvent may be added after raising the temperature to 200°C.

[0049] Next, the first mixture is rapidly heated to 300°C to 350°C at a rate of 3°C / second to 10°C / second within 1 minute (S130).

[0050] In step S130, the first mixture is rapidly heated to 300°C to 350°C or higher within 120 seconds, preferably within 60 seconds. In this case, the synthesis time can be significantly reduced, which has the advantage of facilitating mass production. Furthermore, quantum dots or cores produced by rapid heating offer the advantages of a uniform particle size distribution, a narrow full width at half maximum, and excellent quantum efficiency.

[0051] As another example, in step S130, rapid heating can be completed in a range of 15 to 80 seconds, preferably 30 to 60 seconds. This range offers excellent advantages in both productivity and quantum dot quality.

[0052] In step S130, the heating rate may be 3°C / sec to 10°C / sec, preferably 3°C / sec to 8°C / sec. In this case, the synthesis time is greatly reduced, the size of the obtained quantum dots becomes uniform, and high quantum efficiency can be achieved.

[0053] More specifically, for example, in step S130, the first mixture at 80°C to 120°C can be rapidly heated to 300°C within 120 seconds, preferably within 60 seconds.

[0054] Rapid heating can be achieved using a rapid heating device. For example, the first mixture can be heated quickly using radiant heat generated from a lamp. In this case, a halogen lamp, a tungsten-halogen lamp, or a xenon arc lamp can be used to rapidly heat the first mixture.

[0055] The first mixture can be heated to 300°C or higher, preferably 300°C to 350°C. If the heated temperature is below 300°C, quantum dots cannot be synthesized stably, the reaction time may become very long, and the particle size distribution may increase. If the temperature exceeds 350°C, the purity of the quantum dots may decrease due to reactions with trace amounts of oxygen and moisture present in the reactor or other side reactions.

[0056] Next, although not shown in the schematic flowchart in Figure 1, the first mixture is heat-treated at 300°C or higher for 1 to 10 seconds while maintaining the elevated temperature to produce quantum dots.

[0057] When the first mixture is rapidly heated to the reaction temperature, the first cation precursor and first anion precursor in the solution react quickly, growing and producing a quantum dot core with a uniform morphology. In particular, the indium oxoclusters contained in the first solution further uniformly distribute the core, allowing it to have a PV (Peak to Valley) value of 0.6 or less, thus providing the quantum dot with excellent optical durability.

[0058] The heat treatment, like the rapid heating process, is carried out by radiant heat generated from the lamp of the rapid heating device. The heat treatment can be performed at 300°C or higher for 1 to 10 seconds. Within this range, the quantum dot synthesis time is significantly reduced, and quantum dots with a small size distribution and excellent optical efficiency can be obtained. If the heat treatment time is extended, the particle size increases due to aggregation between particles, the size distribution increases, and the full width at half maximum may increase.

[0059] In one embodiment of the present invention, a method for producing quantum dots is used, wherein at least one of the first solution and the second solution contains two or more precursors, and the first solution can contain indium oxoclusters and zinc oxoclusters, thereby forming quantum dots containing at least three or more elements such as indium (In), zinc (Zn), and phosphorus (P).

[0060] Next, although not shown in Figure 1, the heated first mixture can be mixed with trioctylphosphine (TOP) and then maintained at 300°C or higher for 10 seconds or more for a further heat treatment step. This is to improve the surface reactivity of the synthesized core and is not an essential step, but it enhances reactivity so that the subsequent shell synthesis process can proceed smoothly.

[0061] Next, the heated first mixture is cooled to 100°C or below within 1 minute to form a core (S140). That is, the process further includes a step of rapidly cooling the product after heat treatment. Rapid cooling can be carried out by removing the heat source and cooling to room temperature, and may be carried out by air cooling or water cooling if necessary. Specifically, the first mixture, which has been rapidly heated to 300°C or above, can be immediately moved to a cooling tank containing cooling water and rapidly cooled to 100°C or below within 1 minute.

[0062] The first mixture containing the core produced via the S140 step, by containing indium oxoclusters, can be used as the core solution itself in subsequent quantum dot shell formation steps without further purification steps such as centrifugation after cooling to room temperature. The elimination of separate purification steps such as centrifugation simplifies the process, reduces raw materials, shortens process time, and offers advantages in terms of quantum dot productivity.

[0063] Furthermore, although not shown in Figure 1, the size of the core produced by step S140 can be adjusted by further adding a first cation precursor and a first anion precursor to the core produced by step S140. Specifically, the process may further include the steps of: producing a first submixture by further adding a first subsolution containing a first cation precursor and a second subsolution containing a first anion precursor to the core previously produced by step S140 at room temperature; rapidly heating the first submixture to 300°C to 350°C within 1 minute; heat-treating the heated first submixture for 10 seconds to 5 minutes; and cooling the heat-treated first submixture to 100°C or below within 1 minute.

[0064] In this case, the steps of producing the first submixture, rapidly heating the first submixture, and cooling the first submixture can be carried out in substantially the same manner as steps S120, S130, and S140, respectively, and therefore redundant explanations will be omitted.

[0065] The first sub-solution and the second sub-solution may be, but are not limited to, the same as the first solution and the second solution provided in step S110. For example, the first sub-solution and the second sub-solution may contain the first cation precursor and the first anion precursor contained in the first solution and the second solution, respectively, but the amounts contained may differ.

[0066] On the other hand, the heated first submixture is heat-treated for 10 seconds to 5 minutes so that the pre-formed core can grow further. Unlike the initial step of forming the core through steps S110 to S140, sufficient heat treatment time is required for further particle aggregation to occur on the surface of the pre-formed core and for core formation to occur.

[0067] The size and wavelength of the core produced through such additional processes can be changed. Furthermore, the steps of producing the first submixture, rapidly heating the first submixture, heat-treating the first submixture, and cooling the first submixture can be repeated. The size and wavelength of the core produced through repeated processes can be appropriately adjusted.

[0068] Figure 2 is a flowchart illustrating the shell formation process in one embodiment of the quantum dot manufacturing method according to the present invention. Figure 2 illustrates the process of forming a shell on a quantum dot core manufactured by the quantum dot manufacturing method according to the embodiment shown in Figure 1.

[0069] Referring to Figure 2, a method for producing quantum dots according to one embodiment of the present invention includes the steps of: preparing a third solution containing at least one second cation precursor and a fourth solution containing at least one second anion precursor (S210); mixing the third solution and the fourth solution with a core solution at 20°C to 100°C to produce a second mixture (S220); rapidly heating the second mixture to 350°C to 370°C within 1 minute (S230); and cooling the heated second mixture to 100°C or below within 1 minute to form a shell on the surface of the core (S240).

[0070] The method for manufacturing quantum dots according to the present invention will be described in detail step by step below.

[0071] First, a third solution containing at least one secondary cation precursor and a fourth solution containing at least one secondary anion precursor are prepared (S210).

[0072] In this case, at least one of the third solution and the fourth solution may contain two or more precursors. For example, the third solution may contain two cationic precursors, and the fourth solution may also contain two anionic precursors, but is not limited to this.

[0073] The second cation precursor may include zinc (Zn), cadmium (Cd), mercury (Hg), indium (In), magnesium (Mg), aluminum (Al), manganese (Mn), copper (Cu), gallium (Ga), tin (Sn), barium (Ba), iron (Fe), or strontium (Sr).

[0074] Specifically, the secondary cation precursor may be selected from, but is not limited to, oxides, peroxides, sulfates, halides, oleates, perchlorates, carboxylates, acetates, phosphates, acetylacetonates, cyanides, carbonates, or nitrates of zinc (Zn), cadmium (Cd), mercury (Hg), indium (In), magnesium (Mg), aluminum (Al), manganese (Mn), copper (Cu), gallium (Ga), tin (Sn), barium (Ba), iron (Fe), or strontium (Sr). More specifically, the secondary cation precursor may include zinc oleate (Zn-OA).

[0075] The second anion precursor may include sulfur (S), selenium (Se), phosphorus (P), tellurium (Te), arsenic (As), nitrogen (N), or antimony (Sb).

[0076] For example, the second anion precursors include sulfur, trialkylphosphine sulfide, trialkenylphosphine sulfide, alkylamino sulfide, alkenylamino sulfide, alkylthiol, selenium, trialkylphosphine selenide, trialkenylphosphine selenide, alkylamino selenide, alkenylamino selenide, trialkylphosphine telluride, trialkenylphosphine telluride, alkylamino telluride, alkenylamino telluride, and alkylphosphine. A selection of the following may be made, but is not limited to: phosphine, tris(trialkylsilyl)phosphine, tris(dialkylsilyl)phosphine, tris(dialkylaminophosphine), arsenic oxide, arsenic chloride, arsenic sulfate, arsenic bromide, arsenic iodide, nitric oxide, nitric acid, and ammonium nitrate.More specifically, the second anion precursor may include trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP).

[0077] The step of preparing the third solution may include a step of mixing the second cation precursor and the unsaturated fatty acid and then raising the temperature in order to form a more suitable second cation precursor. The second cation precursor thus produced can maintain a more stably dispersed form containing long-chain unsaturated fatty acid ligands. For example, the unsaturated fatty acid may be selected from myristic acid, oleic acid, stearic acid, lauric acid, and palmitic acid, and while oleic acid is preferred, it is not limited thereto, considering the dispersion stability, size distribution, and luminescence properties of the quantum dots.

[0078] The step of preparing the third solution includes the step of producing zinc oleate (Zn-OA). Specifically, the step of producing zinc oleate (Zn-OA) may include mixing zinc acetate dihydrate and oleic acid, then raising the temperature to 190°C under vacuum, and, after stirring, adding trioctylamine (TOA), raising the temperature to 260°C, and then cooling. Thus, the third solution will contain, but will not be limited to, zinc oleate (Zn-OA).

[0079] The composition ratio of zinc (Zn) to oleic acid in the third solution can be appropriately adjusted considering the emission wavelength of the final quantum dot. For example, the molar ratio of zinc to oleic acid may be 1:1.3 to 1:1.7, preferably 1:1.5, but is not limited thereto.

[0080] The step of preparing the fourth solution may include a step of mixing the anion precursor and the trialkylphosphine and then raising the temperature in order to form a more suitable anion precursor. The anion precursor thus produced contains a long-chain trialkylphosphine ligand and has even better dispersion stability. For example, the trialkylphosphine may be selected from trihexylphosphine, trioctylphosphine, and tridecylphosphine, and while trioctylphosphine is preferred when considering dispersion stability, etc., it is not limited to this.

[0081] Specifically, the step of preparing the fourth solution is carried out by mixing selenium, sulfur, and trioctylphosphine, and then raising the temperature to 100°C to 150°C, thereby the fourth solution containing, but not limited to, trioctylphosphine sulfide and trioctylphosphine selenide.

[0082] The composition ratio of sulfur (S) to selenium (Se) in the fourth solution can be appropriately adjusted considering the emission wavelength of the final quantum dot. For example, the molar ratio of sulfur to selenium may be 1:1 to 1:2.5, preferably 1:1.4 to 1:2.0, but is not limited thereto.

[0083] Next, the process includes the step of mixing the third solution and the fourth solution with the core at 20°C to 100°C to produce a second mixture (S220).

[0084] Specifically, the third solution containing the second cation precursor and the fourth solution containing the second anion precursor can be mixed at a relatively low temperature of 20°C to 100°C, and more preferably at 80°C to 100°C. By mixing the third solution, the fourth solution, and the previously synthesized core solution at a relatively low temperature, the chemical reaction between the cation precursor and the anion precursor can be suppressed.

[0085] The solvent can be used to mix the second cation precursor of the third solution and the second anion precursor of the fourth solution. Any non-reactive solvent is acceptable and can be selected as appropriate. Specifically, the solvent may be, but is not limited to, primary alkylamines having 6 to 22 carbon atoms such as hexadecylamine, secondary alkylamines having 6 to 22 carbon atoms such as dioctylamine, tertiary alkylamines having 6 to 40 carbon atoms such as trioctylamine, nitrogen-containing heterocyclic compounds such as pyridine, aliphatic hydrocarbons having 6 to 40 carbon atoms such as hexadecane, octadecane, octadecene, and squalane (alkanes, alkenes, alkynes, etc.), aromatic hydrocarbons having 6 to 30 carbon atoms such as phenyldodecane, phenyltetradecane, and phenylhexadecane, phosphines substituted with alkyl groups having 6 to 22 carbon atoms such as trioctylphosphine, phosphine oxides substituted with alkyl groups having 6 to 22 carbon atoms such as trioctylphosphine oxide, phenyl ethers, benzyl ethers, aromatic ethers having 12 to 22 carbon atoms, and combinations thereof. Preferably, the solvent may be an aliphatic hydrocarbon having 6 to 40 carbon atoms, such as octadecene or squalane.

[0086] As another example, the solvent may be added in advance during the third solution preparation step and / or the fourth solution preparation step. Specifically, for example, after mixing zinc acetate and oleic acid in the step of preparing the third solution, the solvent may be added after raising the temperature to 190°C.

[0087] Next, the second mixture is rapidly heated to 350°C to 400°C within 1 minute (S230).

[0088] In step S230, the second mixture is rapidly heated to 350°C to 400°C or 350°C to 370°C within 120 seconds, preferably within 60 seconds. In this case, the synthesis time can be significantly reduced, which has the advantage of facilitating mass production. Furthermore, quantum dots produced by rapid heating offer the advantages of a uniform particle size distribution, a narrow full width at half maximum, and excellent quantum efficiency.

[0089] As another example, in the S230 step, rapid heating can be completed within a range of 15 to 80 seconds, preferably 30 to 60 seconds. This range offers significant advantages in both productivity and quantum dot quality.

[0090] More specifically, for example, in step S230, the second mixture from 20°C to 100°C can be rapidly heated to 350°C to 370°C within 60 seconds.

[0091] Rapid heating can be achieved using a rapid heating device. For example, the second mixture can be heated quickly using radiant heat generated from a lamp. In this case, a halogen lamp, a tungsten-halogen lamp, or a xenon arc lamp can be used to rapidly heat the second mixture.

[0092] The second mixture can be heated to 350°C or higher, preferably 350°C to 370°C. If the heated temperature is below 350°C, quantum dots cannot be synthesized stably, the reaction time may become very long, and the particle size distribution may increase. If the temperature exceeds 370°C, the purity of the quantum dots may decrease due to reactions with trace amounts of oxygen and moisture present in the reactor or other side reactions.

[0093] Next, although not shown in the schematic flowchart in Figure 2, the second mixture is heat-treated at 350°C to 400°C for 30 seconds to 5 minutes while maintaining the elevated temperature to produce quantum dots.

[0094] When the second mixture is rapidly heated to the reaction temperature, the second cation precursor and second anion precursor in the solution react quickly, growing to produce a quantum dot containing a shell in an alloy form. Such an alloy-form quantum dot has the advantage of excellent optical durability because it lacks shell boundaries, has a uniform shell distribution, and minimizes lattice mismatch.

[0095] The heat treatment, like the rapid heating process, is carried out using radiant heat generated from the lamp of a rapid heating device. The heat treatment can be performed at 350°C to 370°C for 30 seconds to 5 minutes. Within this range, the quantum dot synthesis time is significantly reduced, and quantum dots with a small size distribution and excellent optical efficiency can be obtained. If the heat treatment time is extended, the particle size increases due to aggregation between particles, the size distribution increases, and the full width at half maximum may increase.

[0096] In one embodiment of the invention, the method for producing quantum dots involves at least one of the third and fourth solutions containing two or more precursors, thereby forming quantum dots containing a shell composed of at least three or more elements. For example, quantum dots produced by the method according to one embodiment of the invention have a single shell shape composed of three or more elements, such as Zn-Se-S.

[0097] Next, the heated second mixture is cooled to 100°C or below within 1 minute to form a shell on the surface of the core (S240). That is, the process further includes a step of rapidly cooling the product after the heat treatment. Rapid cooling can be carried out by removing the heat source and cooling to room temperature, and may be carried out by air cooling or water cooling if necessary. Specifically, the second mixture, which has been rapidly heated to 350°C to 370°C, can be immediately moved to a cooling tank containing cooling water after the heat treatment step and rapidly cooled to 100°C or below within 1 minute.

[0098] The product, cooled to room temperature, can be washed and purified to obtain quantum dots of the desired purity. Washing and purification may include a step of adding a nonsolvent to the result to separate the quantum dots. The nonsolvent is a polar solvent that is miscible with the organic solvent used in the reaction but cannot disperse the quantum dots, and may, but is not limited to, acetone, ethanol, butanol, isopropanol, ethanediol, water, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), diethyl ether, or formaldehyde. Purification may also include a step of separating the quantum dots by methods such as centrifugation, precipitation, chromatography, or distillation. The quantum dots can also be redispersed in a solvent after purification.

[0099] In one embodiment of the present invention, a method for producing quantum dots utilizes indium oxoclusters and zinc oxoclusters as first cation precursors in the first solution. The first solution containing the first cation precursor and the second solution containing the first anion precursor are mixed at a low temperature to produce the first mixture. This mixture is then rapidly heated and heat-treated to cause a rapid reaction in a short time, thereby forming quantum dots with a uniform core.

[0100] Unlike conventional methods for producing cores with a uniform distribution, which involve injecting an anion precursor solution into a cation precursor solution at a temperature of 100°C or higher and then reacting them at 200°C to 280°C for a certain period of time, the quantum dot manufacturing method according to one embodiment of the present invention allows for the production of quantum dots by mixing the cation precursor and anion precursor at a low temperature, rapidly heating to 300°C or higher, and then rapidly cooling. This method has the advantage of shortening reaction time and cooling time, making mass production easier.

[0101] Furthermore, while conventional methods for manufacturing quantum dots using high-temperature injection can produce quantum dots containing three or more elemental components through a single reaction, they have the problem that the energy cost consumed to heat the reaction solution to temperatures above 300°C increases sharply as the synthesis scale increases. However, the quantum dot manufacturing method according to one embodiment of the present invention provides the advantage of being able to mass-produce quantum dots with a relatively small amount of heat treatment by rapidly heating and heat-treating the precursor solution using radiant heat generated from a lamp.

[0102] Furthermore, unlike conventional methods for manufacturing quantum dots having a core-shell structure, which require the formation of the core and then a purification process such as centrifugation to obtain the core, the method for manufacturing quantum dots according to one embodiment of the present invention simplifies the process and minimizes wastewater by using the manufactured core solution directly without centrifugation, resulting in cost savings and reduced process time, and thus offering advantages in terms of quantum dot productivity.

[0103] Furthermore, quantum dots produced by the quantum dot manufacturing method according to one embodiment of the present invention have a narrower full width at half maximum (FWHM) compared to conventional quantum dots having a core-shell structure. When the cation precursor contains indium oxoclusters and zinc oxoclusters, a uniform core can be produced by rapidly heating and rapidly cooling the first mixture, thereby reducing lattice fatigue and narrowing the FWHM. Not only that, but even in the process of forming a shell on the surface of the core, a uniform alloy shell can be obtained by mixing the cation precursor and anion precursor at a low temperature and then proceeding with the rapid heating and rapid cooling process, thereby narrowing the FWHM. In particular, by adjusting the ratio of zinc (Zn) to oleic acid (OA) to 1:1.5 during the shell formation process, the FWHM can be further narrowed. As a result, quantum dots produced by the quantum dot manufacturing method according to one embodiment of the present invention can have high quantum efficiency.

[0104] Furthermore, quantum dots produced by the quantum dot manufacturing method according to one embodiment of the present invention can have their optical and thermal stability ensured by carrying out a heat treatment process at a high temperature of 350°C or higher.

[0105] Furthermore, conventionally, since the wavelength of the core determines the wavelength of the final quantum dot, if the wavelengths do not match, the core must be synthesized from scratch, which increases costs and raises the defect rate. In contrast, the quantum dot manufacturing method according to one embodiment of the present invention allows for wavelength control not only by adjusting the ratio of indium oxoclusters (In-Oxo) and zinc oxoclusters (Zn-Oxo) in the core, but also by adjusting the ratio of zinc (Zn) and oleic acid (OA) in the shell, or the ratio of trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP). In other words, quantum dots in various wavelength bands can be synthesized with a single core, and conversely, quantum dots in the same wavelength band can be synthesized even if cores with various wavelengths are used. As a result, even if the wavelength formed in the core does not match, the wavelength can be controlled during the shell formation process, minimizing the defect rate, potentially reducing costs, shortening process time, and offering significant advantages in terms of productivity.

[0106] Example 1-1: Core synthesis of red fluorescence quantum dots Figure 3 is a schematic diagram illustrating a method for manufacturing quantum dots according to one embodiment of the present invention. An embodiment of the present invention will be described with reference to Figure 3.

[0107] First, 63 g (216.0 mmol) of indium(III) acetate and 183 g (648.0 mmol) of oleic acid were mixed in a 2 L container, heated to 200°C under vacuum, then converted to atmospheric pressure, and octadecene (ODE) was added. The mixture was then synthesized at 260°C to 300°C for more than one hour to produce the first cation precursor of the indium oxocluster.

[0108] 200 g (57.6 mmol) of the prepared indium oxocluster solution was placed in a 1 L quartz container, and 48 g (38.4 mmol) of TMSP (20 wt% in TOP) was added at 130°C to prepare the first mixture. At this time, the molar ratio of indium (In) to phosphorus (P) in the first mixture was 1.5:1.

[0109] Next, the first mixture, which consisted of a first cation precursor and a first anion precursor, was rapidly heated to 300°C by increasing the temperature by approximately 200°C per minute using radiant heat. After that, the heat-treated first mixture was rapidly cooled to below 100°C within one minute to form a quantum dot core.

[0110] Examples 1-2: Core synthesis of red fluorescence quantum dots The method for producing quantum dots according to Example 1-2 involved adding 100 g (28.8 mmol) of indium oxocluster solution and 36 g (28.8 mmol) of TMSP (20 wt% in TOP) to a solution containing the quantum dot core produced in Example 1-1. The mixture was then rapidly heated to 300°C by increasing the temperature by approximately 200°C per minute using radiant heat, and the heat-treated mixture was rapidly cooled to below 100°C within one minute to form the quantum dot core.

[0111] Examples 1-3: Core synthesis of red fluorescence quantum dots The method for producing quantum dots according to Examples 1-3 involved adding 100 g (28.8 mmol) of indium oxocluster solution and 36 g (28.8 mmol) of TMSP (20 wt% in TOP) to a solution containing the quantum dot core produced in Example 1-2. The mixture was then rapidly heated to 300°C by increasing the temperature by approximately 200°C per minute using radiant heat, and the reaction was maintained at the same temperature for 1 minute. Subsequently, the heat-treated mixture was rapidly cooled to below 100°C within 1 minute to form the quantum dot core.

[0112] Examples 1-4: Core synthesis of red fluorescence quantum dots The method for producing quantum dots according to Examples 1-4 involved adding 100 g (28.8 mmol) of indium oxocluster solution and 36 g (28.8 mmol) of TMSP (20 wt% in TOP) to a solution containing the quantum dot core produced in Example 1-3. The mixture was then rapidly heated to 300°C by increasing the temperature by approximately 200°C per minute using radiant heat, and the reaction was maintained at the same temperature for 1 minute. Subsequently, the heat-treated mixture was rapidly cooled to below 100°C within 1 minute to form the quantum dot core.

[0113] Examples 1-5: Core synthesis of red fluorescence quantum dots The method for producing quantum dots in Examples 1-5 involved adding 50 g (14.4 mmol) of indium oxocluster solution and 18 g (14.4 mmol) of TMSP (20 wt% in TOP) to a solution containing the quantum dot core produced in Example 1-4. The mixture was then rapidly heated to 300°C by increasing the temperature by approximately 200°C per minute using radiant heat, and the reaction was maintained at the same temperature for 1 minute. Subsequently, the heat-treated mixture was rapidly cooled to below 100°C within 1 minute to form the quantum dot core.

[0114] Examples 1-6: Core synthesis of red fluorescence quantum dots The method for producing quantum dots according to Examples 1-6 involved adding 50 g (14.4 mmol) of indium oxocluster solution and 18 g (14.4 mmol) of TMSP (20 wt% in TOP) to a solution containing the quantum dot core produced in Example 1-5. The mixture was then rapidly heated to 300°C by increasing the temperature by approximately 200°C per minute using radiant heat, and the reaction was carried out for 1 minute while maintaining the same temperature. The heat-treated mixture was rapidly cooled to below 100°C within 1 minute to form the quantum dot core.

[0115] Example 2-1: Core synthesis of green fluorescence quantum dots First, 63 g (216.0 mmol) of indium(III) acetate and 183 g (648.0 mmol) of oleic acid were mixed in a 2 L container, heated to 200°C under vacuum, then converted to atmospheric pressure, and octadecene (ODE) was added. The mixture was then synthesized at 260°C to 300°C for more than one hour to produce the first cation precursor of the indium oxocluster.

[0116] Next, 47 g (216.0 mmol) of zinc acetate dihydrate and 122 g (432.0 mmol) of oleic acid were mixed in a 1 L container, heated to 190°C under vacuum, then converted to atmospheric pressure, and octadecene (ODE) was added. The mixture was then synthesized at 300°C to 315°C for more than one hour to produce the first cation precursor of zinc oxocluster.

[0117] 180 g (51.8 mmol) of manufactured indium oxocluster solution and 43 g (23.0 mmol) of zinc oxocluster solution were mixed in a 1 L quartz container, heated to 100°C under an N2 atmosphere, and 36 g (28.8 mmol) of TMSP (20 wt% in TOP) was added to produce the first mixture. At this time, the molar ratio of indium (In):zinc (Zn):phosphorus (P) in the first mixture was 1.8:0.8:1.

[0118] Next, the first mixture, which consisted of the first cation precursor and the first anion precursor, was rapidly heated to 300°C by increasing the temperature by approximately 200°C per minute using radiant heat. The reaction was then carried out for 0 to 10 seconds while maintaining the same temperature. Subsequently, the heat-treated first mixture was rapidly cooled to below 100°C within 1 minute to produce the core solution.

[0119] Example 2-2: Core synthesis of green fluorescence quantum dots The method for producing quantum dots according to Example 2-2 differs from the method for producing quantum dots according to Example 2-1 only in the synthesis ratio of indium oxoclusters and zinc oxoclusters; the other components are substantially the same, so redundant explanations will be omitted.

[0120] The method for producing quantum dots according to Example 2-2 involves mixing an indium oxocluster solution and a zinc oxocluster solution in a 1 L quartz container so that the molar ratio of indium (In):zinc (Zn):phosphorus (P) is 1.8:1.2:1, heating to 100°C under an N2 atmosphere, and adding TMSP (20 wt% in TOP) to produce the first mixture.

[0121] Examples 2-3: Core synthesis of green fluorescence quantum dots The quantum dot manufacturing method according to Example 2-3 differs from the quantum dot manufacturing method according to Example 2-1 only in the synthesis ratio of indium oxoclusters and zinc oxoclusters; the other components are substantially the same, so redundant explanations will be omitted.

[0122] The method for producing quantum dots according to Example 2-3 involves mixing an indium oxocluster solution and a zinc oxocluster solution in a 1 L quartz container so that the molar ratio of indium (In):zinc (Zn):phosphorus (P) is 1.5:0.8:1, heating to 100°C under an N2 atmosphere, and adding TMSP (20 wt% in TOP) to produce the first mixture.

[0123] Examples 2-4: Core synthesis of green fluorescence quantum dots The quantum dot manufacturing method according to Example 2-4 differs from the quantum dot manufacturing method according to Example 2-1 only in the synthesis ratio of indium oxoclusters and zinc oxoclusters; the other components are substantially the same, so redundant explanations will be omitted.

[0124] The method for producing quantum dots according to Example 2-4 involves mixing an indium oxocluster solution and a zinc oxocluster solution in a 1 L quartz container so that the molar ratio of indium (In):zinc (Zn):phosphorus (P) is 1.2:0.8:1, heating to 100°C under an N2 atmosphere, and adding TMSP (20 wt% in TOP) to produce the first mixture.

[0125] Examples 2-5: Core synthesis of green fluorescence quantum dots The quantum dot manufacturing method according to Example 2-5 differs from the quantum dot manufacturing method according to Example 2-1 only in the synthesis ratio of indium oxoclusters and zinc oxoclusters; the other components are substantially the same, so redundant explanations will be omitted.

[0126] The method for producing quantum dots according to Example 2-5 involves mixing an indium oxocluster solution and a zinc oxocluster solution in a 1 L quartz container so that the molar ratio of indium (In):zinc (Zn):phosphorus (P) is 1.2:1.2:1, heating to 100°C under an N2 atmosphere, and adding TMSP (20 wt% in TOP) to produce the first mixture.

[0127] Comparative Example 1: Core synthesis using a conventional method The method for producing quantum dots according to Comparative Example 1 is a conventional method, and the only differences from the method for producing quantum dots according to Example 2-1 are that it uses an indium oleate (In-OA) solution and zinc oleate (Zn-OA) instead of an indium oxocluster solution and a zinc oxocluster solution as the first cation precursor, and the synthesis ratio. The other components are substantially the same, so redundant explanations will be omitted.

[0128] The method for producing quantum dots in Comparative Example 1 involved mixing an indium oleate solution and a zinc oleate solution in a 1 L quartz container so that the molar ratio of indium (In):zinc (Zn):phosphorus (P) was 1.5:0.8:1, heating the mixture to 100°C under an N2 atmosphere, and adding TMSP (20 wt% in TOP) to produce the first mixture.

[0129] Experimental Example 1 - Performance Evaluation The wavelength (Core λ) and PV (Peak to Valley) values ​​of cores manufactured by the manufacturing methods of Examples 1-1 to 2-5 and Comparative Example 1 were measured. The specific results are shown in Tables 1 and 2 below. Table 1 shows the measured values ​​for the cores of red fluorescent quantum dots manufactured in Examples 1-1 to 1-6, and Table 2 shows the measured values ​​for the cores of green fluorescent quantum dots manufactured in Examples 2-1 to 2-5 and Comparative Example 1.

[0130] [Table 1] First, the cores of the red fluorescent quantum dots produced by the manufacturing methods of Examples 1-1 to 1-6 utilize indium oxocluster as the cation precursor and TMSP as the anion precursor. Referring to Table 1, it can be confirmed that the cores produced by the manufacturing methods of Examples 1-1 to 1-6 have a uniform core distribution, and therefore all have excellent P / V (Peak to Valley) values ​​of 0.6 or less. Furthermore, by adjusting the molar ratio of indium (In):phosphorus (P) and the amount of precursor added, the core wavelength (Core λ) can be adjusted to different values. That is, it can be confirmed that the wavelength can be adjusted by the ratio of indium oxocluster to TMSP, the amount of precursor added, the number of times the precursor is added, etc. Thus, the quantum dots produced by the manufacturing methods of Examples 1-1 to 1-6 can have their wavelength easily adjusted, ensuring quality stability and exhibiting excellent reproducibility.

[0131] [Table 2] The cores produced by the manufacturing methods of Examples 2-1 to 2-5 were obtained by mixing a cation precursor containing indium oxoclusters and zinc oxoclusters with an anion precursor at a low temperature, rapidly heating to 300°C or higher within 1 minute, and then rapidly cooling. Referring to Table 2, the cores produced by the manufacturing methods of Examples 2-1 to 2-5 have a uniform core distribution, and therefore all have good P / V (Peak to Valley) values ​​of 0.6 or less. In particular, the core produced by the manufacturing method of Comparative Example 1, which was prepared by a conventional method, had a P / V value of 0.71 despite having the same indium (In):zinc (Zn):phosphorus (P) ratio as Example 2-3, confirming that Examples 2-1 to 2-5 of the present invention, which use indium oxocluster solution and zinc oxocluster solution, are superior. Furthermore, by adjusting the ratios of indium (In), zinc (Zn), and phosphorus (P) to different values, the core wavelength (Core λ) will have different values. In other words, it can be confirmed that the wavelength can be adjusted by changing the amount and molar ratio of the oxocluster precursor. As a result, the quantum dots produced by the manufacturing methods of Examples 2-1 to 2-5 can have their wavelength easily adjusted, ensuring quality stability and exhibiting excellent reproducibility.

[0132] Example 3: Shell synthesis on the core surface of a green fluorescence quantum dot Figure 4 is a schematic diagram illustrating a method for manufacturing quantum dots according to one embodiment of the present invention. An embodiment of the present invention will be described with reference to Figure 4.

[0133] First, 2063 g (9396.0 mmol) of zinc acetate dihydrate and 3981 g (14094.0 mmol) of oleic acid were mixed in a 20 L container, heated to 190°C under vacuum and stirred, then 3608 g of trioctylamine (TOA) was added, the temperature was raised to 260°C, and the mixture was cooled to produce the secondary cation precursor of zinc oleate (Zn-OA). At this time, the molar ratio of zinc (Zn) to oleic acid (OA) in zinc oleate (Zn-OA) was 1:1.5.

[0134] Next, 948 g (12000.0 mmol) of selenium (Se) powder and 5485 g (6.6 L) of trioctylphosphine (TOP) were mixed in a 10 L container, heated to 250°C under vacuum in an N2 atmosphere, stirred until completely dissolved, and then cooled to produce the second anion precursor of trioctylphosphine selenide (Se-TOP).

[0135] Next, 769.68 g (24000.0 mmol) of sulfur (S) powder and 10637 g (12.8 L) of trioctylphosphine (TOP) were mixed in a 30 L container, heated to 150°C under vacuum in an N2 atmosphere, stirred until completely dissolved, and then cooled to produce the second anion precursor of trioctylphosphine sulfide (S-TOP).

[0136] To 35 g of the core solution of Example 2-2, in which the ratio of indium (In):zinc (Zn):phosphorus (P) is 1.8:1.2:1, 273 g of zinc oleate (Zn-OA) (313.2 mmol of Zn) with a zinc (Zn):oleic acid (OA) ratio of 1:1.5 and 4 g of trioctylphosphine (TOP) were mixed in a 1 L quartz container and stirred. Then, 21 g (39.1 mmol) of previously prepared trioctylphosphine selenide (Se-TOP) and 27 g (56.7 mmol) of trioctylphosphine sulfide (S-TOP) were added at room temperature (20°C to 24°C) to produce the second mixture.

[0137] Next, the core solution from Example 2-2, a second mixture containing a second cation precursor and a second anion precursor, was rapidly heated to 370°C by increasing the temperature by 200°C per minute using radiant heat. The temperature was then maintained between 350°C and 370°C for 30 seconds to 5 minutes. Subsequently, the heat-treated second mixture was rapidly cooled to below 100°C within 1 minute to obtain quantum dots on the surface of the InZnP core with ZnSeS shells formed on them.

[0138] Comparative Example 2-1: Shell synthesis on the core surface of a green fluorescence quantum dot. The quantum dot manufacturing method according to Comparative Example 2-1 differs from the quantum dot manufacturing method according to Example 3 only in the synthesis ratio of zinc (Zn) and oleic acid (OA), and the other components are substantially the same, so a redundant explanation will be omitted.

[0139] In Comparative Example 2-1, 2063 g (9396.0 mmol) of zinc acetate dihydrate and 5308 g (18792.0 mmol) of oleic acid were mixed in a 20 L container, heated to 190°C under vacuum and stirred, then 3608 g of trioctylamine (TOA) was added, the temperature was raised to 260°C, and the mixture was cooled to produce the secondary cation precursor of zinc oleate (Zn-OA). At this time, the molar ratio of zinc (Zn) to oleic acid (OA) in zinc oleate (Zn-OA) was 1:2.

[0140] Comparative Example 2-2: Shell synthesis on the core surface of a green fluorescence quantum dot. The quantum dot manufacturing method according to Comparative Example 2-2 differs from the quantum dot manufacturing method according to Example 3 only in the synthesis ratio of zinc (Zn) and oleic acid (OA), and the other components are substantially the same, so a redundant explanation will be omitted.

[0141] In Comparative Example 2-2, zinc acetate dihydrate and oleic acid were mixed in a 20L container so that the molar ratio of zinc (Zn) to oleic acid (OA) in zinc oleate (Zn-OA) was 1:1. The mixture was heated to 190°C under vacuum and stirred, then 3608g of trioctylamine (TOA) was added, the temperature was raised to 260°C, and the mixture was cooled to produce the secondary cation precursor of zinc oleate (Zn-OA).

[0142] Comparative Example 2-3: Shell synthesis on the core surface of green fluorescence quantum dots The quantum dot manufacturing method according to Comparative Example 2-3 differs from the quantum dot manufacturing method according to Example 2-1 only in the heating rate of the second mixture; the other components are substantially the same, so redundant explanations will be omitted.

[0143] In Comparative Examples 2-3, the core solution and a second mixture containing a second cation precursor and a second anion precursor were slowly heated to 370°C by increasing the temperature by approximately 15°C per minute using conductive heat. The temperature was then maintained between 350°C and 370°C for 30 seconds to 5 minutes. Subsequently, the heat-treated second mixture was rapidly cooled to below 100°C within 1 minute to obtain quantum dots with shells formed on the core surface.

[0144] Experimental Example 2 - Performance Evaluation The maximum peak wavelength band (PL Max), full width at half maximum (FWHM), and quantum efficiency (QY) of quantum dots produced by the manufacturing methods of Example 3, Comparative Example 2-1, and Comparative Example 2-2 were measured. The specific results are shown in Table 3 below.

[0145] [Table 3] TIFF0007864963000003.tif47156 The quantum dots produced by the manufacturing methods of Example 3, Comparative Example 2-1, and Comparative Example 2-2 are identical in composition except for the molar ratio of zinc (Zn) to oleic acid (OA). Referring to Table 3, the quantum dots produced by the manufacturing method of Example 3, with a molar ratio of zinc (Zn) to oleic acid (OA) of 1:1.5, have a narrow full width at half maximum (FWHM) of 34 nm and a high quantum efficiency (QY) of 95%. In contrast, the quantum dots produced by the manufacturing method of Comparative Example 2-1, with a molar ratio of zinc (Zn) to oleic acid (OA) of 1:2, have a quantum efficiency (QY) of 96%, similar to Example 2-1, but a wider full width at half maximum (FWHM) of 37 nm. Furthermore, quantum dots produced by the manufacturing method of Comparative Example 2-2, where the molar ratio of zinc (Zn) to oleic acid (OA) is 1:1, have a full width at half maximum (FWHM) of 33 nm, similar to Example 2-1, but a low quantum efficiency (QY) of 84%. This confirms that a molar ratio of zinc (Zn) to oleic acid (OA) of zinc oleate (ZnOA), which is a secondary cation precursor necessary for forming a shell on the core surface, is preferably 1:1.5.

[0146] Furthermore, the quantum dots produced by the manufacturing methods of Example 3, Comparative Example 2-1, and Comparative Example 2-2 have different maximum peak wavelength bands (PL Max) by adjusting the molar ratio of zinc (Zn) and oleic acid (OA) to different values. In other words, it can be confirmed that the wavelength can be adjusted by changing the amount and molar ratio of the second cation precursor composed of zinc acetate and oleic acid. As a result, even if the core wavelength band is fixed by a single core, a variety of wavelengths can be synthesized by adjusting the ratio of zinc (Zn) and oleic acid (OA). That is, quantum dots with various wavelength bands can be synthesized with a single core, and conversely, quantum dots with the same wavelength band can be synthesized even if cores with various wavelength bands are used, thus minimizing the defect rate.

[0147] Experimental Example 3 - Performance Evaluation The maximum peak wavelength band (PL Max), full width at half maximum (FWHM), and quantum efficiency (QY) of quantum dots produced by the manufacturing methods of Example 3 and Comparative Examples 2-3 were measured. The specific results are shown in Table 4 below.

[0148] [Table 4] TIFF0007864963000004.tif28156 The quantum dots produced by the manufacturing methods of Example 3 and Comparative Examples 2-3 are identical in composition except for the heating rate of the second mixture. Specifically, Example 3 is a quantum dot reacted by rapidly heating the second mixture to 370°C by increasing the temperature by approximately 200°C per minute using radiant heat, while Comparative Examples 2-3 is a quantum dot reacted by slowly heating the second mixture to 370°C by increasing the temperature by approximately 15°C per minute using conductive heat. Referring to Table 4, the quantum dots rapidly heated at a heating rate of 200°C / min in Example 3 have a narrow full width at half maximum (FWHM) of 34 nm and a high quantum efficiency (QY) of 95%. In contrast, the quantum dots heated slowly at a heating rate of 15°C / min in Comparative Examples 2-3 not only have a wide full width at half maximum (FWHM) of 37 nm, but also a low quantum efficiency (QY) of 91%. This confirms that when the second mixture is rapidly heated using radiant heat, it is possible to obtain excellent quantum dots with a narrow FWHM and high quantum efficiency (QY). Furthermore, the quantum dots produced by the manufacturing methods of Example 3 and Comparative Examples 2-3 have different maximum peak wavelength bands (PL Max) depending on the heating rate of the second mixture. That is, it can be confirmed that the wavelength can also be adjusted by the heating rate of the second mixture. This means that even if the core wavelength band is fixed by a single core, a variety of wavelengths can be synthesized by adjusting the heating rate. In other words, the wavelength of quantum dots produced by the manufacturing method according to one embodiment of the present invention can be controlled not only by the content ratio of the precursor, but also by the heating rate, reaction rate, reaction time, etc.

[0149] Example 4-1: Shell synthesis on the core surface of a green fluorescence quantum dot The quantum dot manufacturing method according to Example 4-1 differs from the quantum dot manufacturing method according to Example 3 only in the core solution; the other components are substantially the same, so redundant explanations will be omitted.

[0150] In Example 4-1, 34.6 g of the core solution from Example 1-1, in which the ratio of indium (In):zinc (Zn):phosphorus (P) was 1.8:0.8:1, was mixed with 273 g (313.2 mmol) of zinc oleate (Zn-OA), in which the ratio of zinc (Zn):oleic acid (OA) was 1:1.5, and 4 g of trioctylphosphine (TOP) in a 1 L quartz container and stirred. Then, 21 g (39.1 mmol) of previously prepared trioctylphosphine selenide (Se-TOP) and 27 g (56.7 mmol) of trioctylphosphine sulfide (S-TOP) were added at room temperature (20°C to 24°C) to produce the second mixture.

[0151] Example 4-2: Shell synthesis on the core surface of a green fluorescence quantum dot The method for producing quantum dots according to Example 4-2 differs from the method for producing quantum dots according to Example 4-1 only in the synthesis ratio of trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP). Since the other components are substantially the same, redundant explanations will be omitted.

[0152] In the method for producing quantum dots according to Comparative Example 4-2, a second mixture was produced by adding trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP) so that the molar ratio of selenium (Se) to sulfur (S) was 1.0:1.96.

[0153] Example 4-3: Shell synthesis on the core surface of green fluorescence quantum dots The method for producing quantum dots according to Example 4-3 differs from the method for producing quantum dots according to Example 4-1 only in the synthesis ratio of trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP), and the other components are substantially the same, so redundant explanations will be omitted.

[0154] In the quantum dot manufacturing method according to Example 4-3, a second mixture was prepared by adding trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP) so that the molar ratio of selenium (Se) to sulfur (S) was 1.0:2.45.

[0155] Example 4-4: Shell synthesis on the core surface of green fluorescence quantum dots The method for producing quantum dots according to Example 4-4 differs from the method for producing quantum dots according to Example 4-1 only in the synthesis ratio of trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP), and the other components are substantially the same, so redundant explanations will be omitted.

[0156] In the quantum dot manufacturing method of Example 4-4, a second mixture was produced by adding trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP) so that the molar ratio of selenium (Se) to sulfur (S) was 1.5:1.45.

[0157] Experimental Example 4 - Performance Evaluation The maximum peak wavelength band (PL Max), full width at half maximum (FWHM), and quantum efficiency (QY) of quantum dots manufactured by the manufacturing methods of Examples 4-1 to 4-4 were measured. The specific results are shown in Table 5 below.

[0158] [Table 5] The quantum dots produced by the manufacturing methods of Examples 4-1 to 4-4 are identical in composition except for the molar ratio of trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP), which are anion precursors necessary for the cell formation process, added to the core surface. Referring to Table 5, the quantum dots produced by the manufacturing methods of Examples 4-1 to 4-4 have different maximum peak wavelength bands (PL Max) by adjusting the selenium (Se):sulfur (S) ratio in each case. That is, it can be confirmed that the wavelength can be adjusted by changing the amount and molar ratio of the second anion precursor composed of trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP). As a result, quantum dots produced by the manufacturing methods of Examples 4-1 to 4-4 can be synthesized at various wavelengths by adjusting the ratio of selenium (Se) to sulfur (S), even if the core wavelength band is fixed by a single core. That is, quantum dots at various wavelength bands can be synthesized with a single core, and conversely, quantum dots at the same wavelength band can be synthesized even if cores with various wavelength bands are used, thus minimizing the defect rate. A method for producing quantum dots according to one embodiment of the present invention can be described as follows.

[0159] A method for producing quantum dots according to one embodiment of the present invention includes the steps of: preparing a first solution containing at least one first cation precursor and a second solution containing at least one first anion precursor; mixing the first solution and the second solution at 20°C to 130°C to produce a first mixture; raising the temperature of the first mixture to 300°C to 350°C within 1 minute; and cooling the heated first mixture to 100°C or below within 1 minute to form a core, wherein the first cation precursor may include an indium oxocluster.

[0160] According to another feature of the present invention, the indium oxocluster can be produced by the steps of mixing indium acetate and oleic acid, raising the mixed solution to 200°C under vacuum and then converting to atmospheric pressure, and adding octadecene (ODE) and synthesizing at 260°C to 300°C for 1 hour or more.

[0161] According to another feature of the present invention, the first cation precursor may further comprise a zinc oxocluster.

[0162] According to another feature of the present invention, a zinc oxocluster can be produced by the steps of mixing zinc acetate and oleic acid, raising the mixed solution to 190°C under vacuum and then converting to atmospheric pressure, and adding octadecene (ODE) and synthesizing it at 300°C to 315°C for one hour or more.

[0163] According to yet another feature of the present invention, the step of producing the first mixture may further include the step of controlling the wavelength band of the quantum dot by adjusting the ratio of indium oxocluster and zinc oxocluster.

[0164] According to another feature of the present invention, the first cation precursor may further comprise one or more of cadmium (Cd), mercury (Hg), magnesium (Mg), aluminum (Al), manganese (Mn), copper (Cu), gallium (Ga), tin (Sn), barium (Ba), iron (Fe), and strontium (Sr).

[0165] Another feature of the present invention may further include a step of heat-treating the first mixture at 300°C or higher for 1 to 10 seconds between the step of rapidly heating the first mixture and the step of rapidly cooling the first mixture.

[0166] According to another feature of the present invention, the step of rapidly raising the temperature and the step of heat treatment can be carried out by radiant heat using a quartz container and a halogen lamp.

[0167] Another feature of the present invention may further include the step of mixing trioctylphosphine (TOP) with the heat-treated first mixture and further heat-treating it at 300°C or higher for 10 seconds or more to improve the surface reactivity of the core.

[0168] Another feature of the present invention further includes the steps of: preparing a first submixture by further adding a first subsolution containing a first cation precursor and a second subsolution containing a first anion precursor to a core solution at room temperature; raising the temperature of the first submixture to 300°C to 350°C within 1 minute; heat-treating the heated first submixture for 10 seconds to 5 minutes; and cooling the heat-treated first submixture to 100°C or below within 1 minute.

[0169] Another feature of the present invention may further include the steps of repeatedly performing the steps of producing a first submixture, rapidly heating the first submixture, heat-treating the first submixture, and cooling the first submixture.

[0170] Another feature of the present invention further includes the steps of: preparing a third solution containing at least one second cation precursor and a fourth solution containing at least one second anion precursor; mixing the third solution and the fourth solution with a core solution at 20°C to 100°C to produce a second mixture; rapidly heating the second mixture to 350°C to 400°C within 1 minute; and cooling the heated second mixture to 100°C or below within 1 minute to form a shell on the surface of the core.

[0171] According to another feature of the present invention, the third solution may contain zinc oleate (Zn-OA), and the fourth solution may contain trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP).

[0172] Another feature of the present invention may further include the step of controlling the wavelength band of the quantum dot by adjusting the molar ratio of zinc (Zn) to oleate (OA) in the third solution within the range of 1:1.3 to 1:1.7.

[0173] Another feature of the present invention may further include the step of controlling the wavelength band of the quantum dot by adjusting the ratio of trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP) in the fourth solution.

[0174] Another feature of the present invention may further include a step of heat-treating the second mixture at 350°C to 370°C for 30 seconds to 5 minutes between the step of rapidly heating the second mixture and the step of rapidly cooling the second mixture.

[0175] According to another feature of the present invention, the second cation precursor may include one or more of the following: zinc (Zn), cadmium (Cd), mercury (Hg), indium (In), magnesium (Mg), aluminum (Al), manganese (Mn), copper (Cu), gallium (Ga), tin (Sn), barium (Ba), iron (Fe), and strontium (Sr).

[0176] According to another feature of the present invention, the first anion precursor and the second anion precursor may contain one or more of sulfur (S), selenium (Se), phosphorus (P), tellurium (Te), arsenic (As), nitrogen (N), and antimony (Sb).

[0177] Although embodiments of the present invention have been described in more detail above with reference to the attached drawings, the present invention is not necessarily limited to these embodiments and can be modified and implemented in various ways within the scope of the technical concept of the present invention. Accordingly, the embodiments disclosed herein are for illustrative purposes only, not to limit the technical concept of the present invention, and the scope of the technical concept of the present invention is not limited by such embodiments. Therefore, the embodiments described above should be understood as illustrative and non-limiting in all respects. The scope of protection of the present invention should be interpreted by the following claims, and all technical concepts within an equivalent scope should be interpreted as being included in the scope of the rights of the present invention.

Claims

1. The steps include preparing a first solution containing at least one first cation precursor and a second solution containing at least one first anion precursor; A step of mixing the first solution and the second solution at 20°C to 130°C to produce a first mixture; A step of raising the temperature of the first mixture to 300°C to 350°C in less than one minute; and The step includes cooling the heated first mixture to 100°C or below within 1 minute to form a core, The first cation precursor comprises an indium oxocluster and a zinc oxocluster. The step of producing the first mixture involves adjusting the ratio of the indium oxocluster and the zinc oxocluster. A method for producing quantum dots, comprising the step of controlling the wavelength band of the quantum dots.

2. The aforementioned indium oxocluster is, A step of mixing indium acetate and oleic acid; The steps include: raising the mixed solution to 200°C under vacuum, and then converting to atmospheric pressure; and A method for producing quantum dots according to claim 1, comprising the step of adding octadecene (ODE) and synthesizing at 260°C to 300°C for one hour or more.

3. The aforementioned zinc oxocluster (Zn-Oxocluster) A step of mixing zinc acetate and oleic acid; The steps include: heating the mixed solution to 190°C under vacuum, and then converting to atmospheric pressure; and A method for producing quantum dots according to claim 1, comprising the step of adding octadecene (ODE) and synthesizing at 300°C to 315°C for one hour or more.

4. The first cation precursor is A method for producing quantum dots according to claim 1, further comprising one or more of cadmium (Cd), mercury (Hg), magnesium (Mg), aluminum (Al), manganese (Mn), copper (Cu), gallium (Ga), tin (Sn), barium (Ba), iron (Fe), and strontium (Sr).

5. A method for producing quantum dots according to claim 1, further comprising the step of heat-treating the first mixture at 300°C or higher for 1 to 10 seconds between the step of rapidly heating the first mixture and the step of rapidly cooling the first mixture.

6. The method for manufacturing quantum dots according to claim 5, wherein the step of rapidly raising the temperature and the step of heat treatment are carried out by radiant heat using a quartz container and a halogen lamp.

7. The method for producing quantum dots according to claim 5, further comprising the step of mixing trioctylphosphine (TOP) with the heat-treated first mixture and further heat-treating it at 300°C or higher for 10 seconds or more to improve the surface reactivity of the core.

8. A step of producing a first submixture by further adding a first subsolution containing the first cation precursor and a second subsolution containing the first anion precursor to the solution containing the core at room temperature; Step of raising the temperature of the first submixture to 300°C to 350°C within 1 minute; The steps of heat-treating the heated first submixture for 10 seconds to 5 minutes; and The method for producing quantum dots according to claim 1, further comprising the step of cooling the heat-treated first submixture to 100°C or below within 1 minute.

9. A method for producing quantum dots according to claim 8, further comprising the steps of repeatedly performing the steps of producing the first submixture, rapidly increasing the temperature of the first submixture, heat-treating the first submixture, and cooling the first submixture.

10. The steps include preparing a third solution containing at least one secondary cation precursor and a fourth solution containing at least one secondary anion precursor; A step of preparing a second mixture by mixing the third solution and the fourth solution with the solution containing the core at a temperature of 20°C to 100°C; The steps of rapidly heating the second mixture to 350°C to 400°C within one minute; and The method for producing a quantum dot according to claim 1, further comprising the step of cooling the heated second mixture to 100°C or below within 1 minute to form a shell on the surface of the core.

11. The third solution contains zinc oleate (Zn-OA), The method for producing quantum dots according to claim 10, wherein the fourth solution comprises trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP).

12. A method for producing a quantum dot according to claim 11, further comprising the step of controlling the wavelength band of the quantum dot by adjusting the molar ratio of zinc (Zn) to oleate (OA) in the third solution within 1:1.3 to 1:1.

7.

13. A method for producing a quantum dot according to claim 12, further comprising the step of controlling the wavelength band of the quantum dot by adjusting the ratio of trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP) in the fourth solution.

14. Between the step of rapidly heating the second mixture and the step of rapidly cooling the second mixture A method for producing quantum dots according to claim 10, further comprising the step of heat-treating the second mixture at 350°C to 370°C for 30 seconds to 5 minutes.

15. The second cation precursor is A method for producing quantum dots according to claim 10, comprising one or more of the following: zinc (Zn), cadmium (Cd), mercury (Hg), indium (In), magnesium (Mg), aluminum (Al), manganese (Mn), copper (Cu), gallium (Ga), tin (Sn), barium (Ba), iron (Fe), and strontium (Sr).

16. The first anion precursor and the second anion precursor are A method for producing quantum dots according to claim 10, comprising one or more of sulfur (S), selenium (Se), phosphorus (P), tellurium (Te), arsenic (As), nitrogen (N), and antimony (Sb).

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