How quantum dots are manufactured

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] The present specification relates to a method for manufacturing quantum dots and quantum dots manufactured thereby, and more particularly, to a method for manufacturing quantum dots that can provide quantum dots having high quantum efficiency and improved optical and thermal stability while shortening reaction time and facilitating mass production. [Background technology]

[0002] Quantum dots are semiconductor materials with nano-sized crystal structures, and have high color purity, excellent light stability and thermal stability compared to organic materials, and ease of band gap adjustment. Such quantum dots have a large surface area per unit volume due to their small size, and exhibit quantum confinement effects, so they have physicochemical properties different from those of semiconductor materials themselves. Quantum dots absorb light from an excitation source, become energy excited, and emit energy corresponding to the energy band gap of the quantum dots. Quantum dots can adjust the energy band gap by adjusting the size and composition of nanocrystals, and have luminescence properties with high color purity, so they are being developed for various applications such as display devices, energy devices, and bioluminescent devices.

[0003] When quantum dots are applied to devices, efficiency is reduced due to corrosion and oxidation of the quantum dots caused by high frequency, heat, moisture, etc., and therefore, conventional quantum dots generally have been used mainly in a core-shell structure in which a shell is coated on the surface of a core. Coating the surface of the core with a shell in this way has the advantage of improving the phenomenon of quantum dot corrosion caused by heat and moisture, and acting as an energy barrier that binds the charge formed by applying light, thereby improving optical durability.

[0004] In general, a method for manufacturing quantum dots having a core-shell structure is to first synthesize a core by injecting an anion precursor solution into a high-temperature cation precursor solution at high temperature, and then to secondarily form a shell by injecting a solution constituting the shell component. In this case, quantum dots having a core-shell or multi-shell structure can be manufactured depending on the number of times the solution constituting the shell component is added.

[0005] However, the above-mentioned method for manufacturing quantum dots has a drawback that the synthesis method is complicated and the synthesis time is increased because a series of processes is performed by preparing each precursor solution and synthesizing the multiple solutions in a stepwise manner. In addition, in general, the emission wavelength of quantum dots having a core-shell structure can be controlled by adjusting the particle size of the core, but it is difficult to control the emission wavelength because the reaction speed of synthesizing the core is very fast. In addition, if lattice mismatch occurs between the core and shell during the process of forming the core-shell structure through multiple steps, there is a problem that the thermal stability and quantum efficiency of the quantum dots are reduced. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an object of the present invention is to provide a method for producing quantum dots that can be easily mass-produced in a short period of time.

[0007] Another object of the present invention is to provide a method for manufacturing quantum dots that can realize high quantum efficiency by having a narrow half-width.

[0008] Another object of the present invention is to provide a method for producing quantum dots that have excellent photostability and thermal stability.

[0009] Another object of the present invention is to provide a method for producing quantum dots that allows easy reaction control and variably adjustable emission wavelengths.

[0010] The object of the present invention is not limited to the above-mentioned objects, and other objects not mentioned herein will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0011] In order to solve the above-mentioned problems, 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.

[0012] Further details of the embodiments are included in the detailed description and the drawings. Effect of the Invention

[0013] According to the manufacturing method of the present invention, it is possible to obtain quantum dots that have a narrow half-width and thus can realize high quantum efficiency.

[0014] According to the manufacturing method of the present invention, since a synthesis technique through high temperature heat treatment is used, quantum dots having excellent photostability and thermal stability can be obtained.

[0015] According to the manufacturing method of the present invention, the core is used without centrifugation, and the reaction time is short, so that mass production can be performed in a short time by 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 variably adjusted, so that the defective rate can be minimized.

[0017] The effects of the present invention are not limited to the above-mentioned examples, and various other effects are included within the scope of the present invention. [Brief description of the drawings]

[0018] [Figure 1] 2 is a flowchart illustrating a core forming process in a method for manufacturing quantum dots according to an embodiment of the present invention. [Diagram 2] 4 is a flowchart illustrating a shell formation process in a method for manufacturing quantum dots according to an embodiment of the present invention. [Diagram 3] 1 is a schematic diagram for explaining a method for producing quantum dots according to an embodiment of the present invention. [Figure 4] 1 is a schematic diagram for explaining a method for producing quantum dots according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The advantages and features of the present invention, and the methods for achieving them, will become clear from the detailed description of the embodiments of the present invention, taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and may be embodied in various different forms. The embodiments are provided solely to ensure that the disclosure of the present invention is complete, and to fully convey the scope of the invention to those skilled in the art to which the present invention pertains. The present invention is defined only by the scope of the claims.

[0020] The shapes, areas, ratios, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present invention are illustrative, and the present invention is not limited to the illustrated matters. The same reference symbols refer to the same components throughout the specification. In addition, when describing the present invention, if it is determined that a detailed description of related known technology may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. When "includes," "has," "is made," etc. are used in the present invention, other parts may be added since "only" is not used. When a component is expressed in the singular, it includes the plural unless otherwise explicitly stated.

[0021] When interpreting elements, they are interpreted as including a margin of error even if there is no other explicit description.

[0022] When describing a positional relationship, for example when describing the positional relationship of two parts using "on top of," "at the top of," "at the bottom of," "next to," etc., one or more other parts may be located between the two parts, so long as "immediately" or "directly" is not used.

[0023] When an element or layer is referred to as "on" another element or layer, this includes the case where the element or layer is directly on top of the other element, or has other layers or elements interposed therebetween.

[0024] In addition, although the terms "first", "second" and the like are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another. Therefore, the first component referred to below may be the second component within the technical concept of the present invention.

[0025] Like reference numbers refer to like elements throughout the specification.

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

[0027] The respective features of the various embodiments of the present invention may be partially or fully combined or combined with each other, and may be technically interlocked and driven in various ways, and each embodiment may be implemented independently of each other or may be implemented together in a related relationship.

[0028] In the following, the invention will be explained with reference to the drawings.

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

[0030] Referring to FIG. 1, 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 (S110), mixing the first solution and the second solution at 20° C. to 130° C. to prepare a first mixture (S120), heating the first mixture to 300° C. within one minute (S130), and cooling the heated first mixture to below 100° C. within one minute to form a core (S140), where the first cation precursor includes an indium oxo cluster (In-Oxocluster).

[0031] Each step of the method for producing quantum dots according to the present invention will be described in detail 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 cation precursors and the second solution may also contain two anion precursors, but is not limited thereto.

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

[0035] The first solution can include one or more first cation precursors, such that the first cation precursor can 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] In addition, the first cation precursor may further include a zinc oxocluster. As with the indium oxocluster (In-Oxo), an active metal oxide such as a zinc oxocluster (Zn-Oxo) may be synthesized by reacting an active metal precursor with a carboxylic acid. Specifically, the zinc oxocluster (Zn-Oxo) may be formed by reacting 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 may be 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, alkylthiol, selenium, trialkylphosphine selenide, trialkenylphosphine selenide, alkylamino selenide, alkenylamino selenide, trialkylphosphine telluride, trialkenylphosphine telluride, alkylamino telluride, alkenylamino telluride, alkylphosphine, alkylthiol, selenium, trialkylphosphine selenide, trialkenylphosphine selenide, alkylamino tellur ... The alkyl group may be selected from, but is not limited to, tris(trialkylsilyl)phosphine, tris(dialkylsilyl)phosphine, tris(dialkylsilyl)phosphine, tris(dialkylamino phosphine), arsenic oxide, arsenic chloride, arsenic sulfate, arsenic bromide, arsenic iodide, nitric oxide, nitric acid, and ammonium nitrate.More specifically, the first anion precursor can 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 heating the mixture to form a more suitable first cation precursor. The first cation precursor thus prepared may contain an unsaturated fatty acid ligand having a long chain length, and thus maintain a more stable dispersed form. For example, the unsaturated fatty acid may be selected from myristic acid, oleic acid, stearic acid, lauric acid, and palmitic acid, and it is preferable to use oleic acid in consideration of the dispersion stability, size distribution, and luminescence properties of the quantum dots, but is not limited thereto.

[0041] The step of preparing the first solution includes a step of preparing indium oxoclusters (In-Oxo). Specifically, the step of preparing indium oxoclusters (In-Oxo) may include a step of mixing indium acetate (Indium (III) acetate) and oleic acid, a step of heating the mixed solution to 200°C under vacuum and then converting to normal pressure, and a step of adding octadecene (ODE) and synthesizing at 260°C to 300°C for 1 hour or more. Thus, the first solution includes indium oxoclusters, but is not limited thereto.

[0042] Also, the step of preparing the first solution may further include a step of preparing zinc oxocluster (Zn-Oxo). Specifically, the step of preparing zinc oxocluster (Zn-Oxo) may include a step of mixing zinc acetate dihydrate and oleic acid, and then heating the mixture to 190°C under vacuum, and a step of converting the mixture to normal pressure, adding octadecene (ODE), and synthesizing the mixture at 300°C to 315°C for 1 hour or more, so that the first solution may further include zinc oxocluster.

[0043] The composition ratio of the indium oxoclusters and zinc oxoclusters in the first solution may be appropriately adjusted in consideration of the emission wavelength of the quantum dots finally formed. For example, the molar ratio of the indium oxoclusters and zinc oxoclusters may be 1:1 to 1:0.4. More specifically, the molar ratio of the indium oxoclusters and zinc oxoclusters may be 1.2:1.2 to 1.8:0.8 based on the anion precursor, for example, phosphorus (p), being 1, but is not limited thereto.

[0044] The step of preparing the second solution may include a step of mixing the anion precursor and trialkylphosphine and then heating the mixture to form a more suitable first anion precursor. The anion precursor thus prepared contains a trialkylphosphine ligand having a long chain length, and thus has better dispersion stability. For example, the trialkylphosphine may be selected from trihexylphosphine, trioctylphosphine, and tridecylphosphine, and it is preferable to use trioctylphosphine in consideration of dispersion stability, but is not limited thereto.

[0045] Next, the first solution and the second solution are mixed at 20° C. to 130° C. to prepare a 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., more preferably at 80° C. to 120° C. In this case, by mixing the first solution and the second solution at a relatively low temperature, a chemical reaction between the cation precursor and the anion precursor can be suppressed.

[0047] The solvent is not particularly limited as long as it is capable of mixing the first cation precursor in the first solution and the first anion precursor in the second solution and is a non-reactive solvent, and may be appropriately selected and used. Specifically, the solvent may be a primary alkylamine having 6 to 22 carbon atoms such as hexadecylamine, a secondary alkylamine having 6 to 22 carbon atoms such as dioctylamine, a tertiary alkylamine having 6 to 40 carbon atoms such as trioctylamine, a nitrogen-containing heterocyclic compound such as pyridine, an aliphatic hydrocarbon (alkane, alkene, alkyne, etc.) having 6 to 40 carbon atoms such as hexadecane, octadecane, octadecene, squalane, etc., an aromatic hydrocarbon having 6 to 30 carbon atoms such as phenyldodecane, phenyltetradecane, phenylhexadecane, etc., a phosphine substituted with an alkyl group having 6 to 22 carbon atoms such as trioctylphosphine, a phosphine oxide substituted with an alkyl group having 6 to 22 carbon atoms such as trioctylphosphine oxide, an aromatic ether having 12 to 22 carbon atoms such as phenyl ether, benzyl ether, etc., and a combination thereof, but is not limited thereto. 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 in the first solution preparation step and / or the second solution preparation step. Specifically, for example, in the step of preparing the first solution, indium acetate and oleic acid may be mixed, heated to 200° C., and then the solvent may be added.

[0049] Next, the first mixture is rapidly heated to 300° C. to 350° C. at a rate of 3° C. / sec to 10° C. / sec within one 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 shortened, and mass production is easy. In addition, the quantum dots or cores produced by rapid heating have the advantages of uniform particle size distribution, narrow half-width, and excellent quantum efficiency.

[0051] As another example, in step S130, the rapid temperature rise can be completed within a range of 15 to 80 seconds, preferably 30 to 60 seconds, which has 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 can be significantly shortened, the quantum dots obtained can have uniform sizes, 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] The rapid temperature rise can be achieved by using a rapid heating device. For example, the first mixture can be rapidly heated by utilizing radiant heat generated from a lamp. In this case, the first mixture can be rapidly heated by using a halogen lamp, a tungsten-halogen lamp, or a xenon arc lamp.

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

[0056] Next, although not shown in the schematic flow chart of FIG. 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 heated rapidly to reach the reaction temperature, the first cation precursor and the first anion precursor in the solution react quickly and grow to produce quantum dot cores with uniform morphology. In particular, the indium oxo clusters contained in the first solution distribute the cores more uniformly and enable the PV (Peak to Valley) value to be 0.6 or less, which is advantageous in terms of the optical durability of the quantum dots.

[0058] The heat treatment is also performed by radiant heat generated from a lamp of a rapid heating device, similar to the rapid temperature rise. The heat treatment can be performed at 300°C or higher for 1 to 10 seconds, and within this range, the quantum dot synthesis time can be significantly shortened, and quantum dots with a narrow size distribution and excellent optical efficiency can be obtained. If the heat treatment time is long, the particle size can increase due to aggregation between particles, and the size distribution can increase, resulting in an increase in the half-value width.

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

[0060] Next, although not shown in Fig. 1, the heated first mixture can be mixed with trioctylphosphine (TOP) and then maintained at 300°C or higher for 10 seconds or more to perform a further heat treatment process. This is for improving the surface reactivity of the synthesized core, and although it is not a necessary process, it is for increasing the reactivity so that the subsequent shell synthesis process can be carried out smoothly.

[0061] Next, the heated first mixture is cooled to 100°C or less within one minute to form a core (S140). That is, after the heat treatment, the process further includes a step of quenching the product. The quenching may be performed by removing the heat source and cooling to room temperature, and may be performed by air cooling or water cooling in some cases. Specifically, the first mixture, which has been heated at a high speed to 300°C or more, is immediately transferred to a cooling tank containing cooling water and rapidly cooled to 100°C or less within one minute.

[0062] The first mixture containing the cores produced through step S140 contains indium oxo clusters, and can be used in the subsequent quantum dot shell formation step as a core solution without a separate purification process such as centrifugation after cooling to room temperature. Since a separate purification process such as centrifugation is not required, the process can be simplified, raw materials can be saved, and the process time can be shortened, which is advantageous in terms of quantum dot productivity.

[0063] 1, the size of the core can be adjusted by further adding a first cation precursor and a first anion precursor to the core produced through step S140. Specifically, the method can further include the steps of: producing a first sub-mixture by further adding a first sub-solution containing a first cation precursor and a second sub-solution containing a first anion precursor at room temperature to the core previously produced through step S140; rapidly heating the first sub-mixture to 300°C to 350°C within 1 minute; heat-treating the heated first sub-mixture for 10 seconds to 5 minutes; and cooling the heat-treated first sub-mixture to 100°C or less within 1 minute.

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

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

[0066] Meanwhile, the heated first sub-mixture is heat-treated for 10 seconds to 5 minutes so that the pre-formed core can be further grown. Unlike the initial step of forming the core through steps S110 to S140, a sufficient heat treatment time is required so that the particles further aggregate on the surface of the pre-formed core to form the core.

[0067] The size and wavelength of the core manufactured through this additional process can be changed. In addition, the steps of manufacturing the first sub-mixture, rapidly heating the first sub-mixture, heat-treating the first sub-mixture, and cooling the first sub-mixture can be repeated. The size and wavelength of the core manufactured through the repeated implementation process can be appropriately adjusted.

[0068] 2 is a flow chart showing a process of forming a shell in the method for manufacturing quantum dots according to an embodiment of the present invention, which illustrates a process of forming a shell on the quantum dot core manufactured by the method for manufacturing quantum dots according to an embodiment of the present invention shown in FIG.

[0069] Referring to FIG. 2, a method for manufacturing quantum dots according to an 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 solution containing cores at 20°C to 100°C to prepare a second mixture (S220), rapidly heating the second mixture to 350°C to 370°C within one minute (S230), and cooling the heated second mixture to below 100°C within one minute to form a shell on the surface of the cores (S240).

[0070] Each step of the method for producing quantum dots according to the present invention will be described in detail below.

[0071] First, a third solution containing at least one second cation precursor and a fourth solution containing at least one second 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 cation precursors, and the fourth solution may also contain two anion precursors, but is not limited thereto.

[0073] The second cation precursor can 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 second 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 second cation precursor may include zinc oleate (Zn-OA).

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

[0076] For example, the second anion precursor may be 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, alkylthiol, selenium, trialkylphosphine selenide, trialkenylphosphine selenide, alkylamino selenide, alkenylamino selenide, trialkylphosphine telluride, trialkenylphosphine telluride, alkylamino telluride, alkenylamino telluride, alkylphosphine, alkylthiol, selenium, trialkylphosphine selenide, trialkenylphosphine selenide, alkylamino tellur ... The alkyl group may be selected from, but is not limited to, tris(trialkylsilyl)phosphine, tris(dialkylsilyl)phosphine, tris(dialkylsilyl)phosphine, tris(dialkylamino phosphine), arsenic oxide, arsenic chloride, arsenic sulfate, arsenic bromide, arsenic iodide, nitric oxide, nitric acid, and ammonium nitrate.More specifically, the second anion precursor can 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 heating the mixture to form a more suitable second cation precursor. The second cation precursor thus prepared may contain an unsaturated fatty acid ligand with a long chain length, and thus maintain a more stable dispersed form. For example, the unsaturated fatty acid may be selected from myristic acid, oleic acid, stearic acid, lauric acid, and palmitic acid, and it is preferable to use oleic acid in consideration of the dispersion stability, size distribution, and luminescence properties of the quantum dots, but is not limited thereto.

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

[0079] The composition ratio of zinc (Zn) and oleic acid in the third solution may be appropriately adjusted in consideration of the emission wavelength of the quantum dots finally formed. For example, the molar ratio of zinc and 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 trialkylphosphine and then heating the mixture to form a more suitable anion precursor. The anion precursor thus prepared contains a trialkylphosphine ligand having a long chain length, and thus has better dispersion stability. For example, the trialkylphosphine may be selected from trihexylphosphine, trioctylphosphine, and tridecylphosphine, and it is preferable to use trioctylphosphine in consideration of dispersion stability, but is not limited thereto.

[0081] Specifically, the step of preparing the fourth solution is performed by mixing selenium, sulfur, and trioctylphosphine, and then heating the mixture to 100°C to 150°C. Thus, the fourth solution includes, but is not limited to, trioctylphosphine sulfide and trioctylphosphine selenide.

[0082] The composition ratio of sulfur (S) and selenium (Se) in the fourth solution may be appropriately adjusted in consideration of the emission wavelength of the quantum dots finally formed. For example, the molar ratio of sulfur and 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 method includes a step of mixing the third solution and the fourth solution with the solution containing the cores at 20° C. to 100° C. to prepare 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., more preferably at 80° C. to 100° C. In this case, by mixing the third solution, the fourth solution, and the previously synthesized core solution at a relatively low temperature, a chemical reaction between the cation precursor and the anion precursor can be suppressed.

[0085] The solvent is not particularly limited as long as it is capable of mixing the second cation precursor of the third solution and the second anion precursor of the fourth solution and is a non-reactive solvent, and may be appropriately selected and used. Specifically, the solvent may be a primary alkylamine having 6 to 22 carbon atoms such as hexadecylamine, a secondary alkylamine having 6 to 22 carbon atoms such as dioctylamine, a tertiary alkylamine having 6 to 40 carbon atoms such as trioctylamine, a nitrogen-containing heterocyclic compound such as pyridine, an aliphatic hydrocarbon (alkane, alkene, alkyne, etc.) having 6 to 40 carbon atoms such as hexadecane, octadecane, octadecene, squalane, etc., an aromatic hydrocarbon having 6 to 30 carbon atoms such as phenyldodecane, phenyltetradecane, phenylhexadecane, etc., a phosphine substituted with an alkyl group having 6 to 22 carbon atoms such as trioctylphosphine, a phosphine oxide substituted with an alkyl group having 6 to 22 carbon atoms such as trioctylphosphine oxide, an aromatic ether having 12 to 22 carbon atoms such as phenyl ether, benzyl ether, etc., and a combination thereof, but is not limited thereto. 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 in the third solution preparation step and / or the fourth solution preparation step. Specifically, for example, in the step of preparing the third solution, zinc acetate and oleic acid may be mixed, heated to 190° C., and then the solvent may be added.

[0087] Next, the second mixture is rapidly heated to 350° C. to 400° C. within one 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 shortened, and mass production is easy. In addition, quantum dots manufactured by rapid heating have the advantages of uniform particle size distribution, narrow half-width, and excellent quantum efficiency.

[0089] As another example, in step S230, the rapid temperature rise can be completed within a range of 15 to 80 seconds, preferably 30 to 60 seconds, in which there are excellent advantages in both productivity and quality of quantum dots.

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

[0091] The rapid temperature rise can be achieved by using a rapid heating device. For example, the second mixture can be rapidly heated by utilizing radiant heat generated from a lamp. In this case, the second mixture can be rapidly heated by using a halogen lamp, a tungsten-halogen lamp, or a xenon arc lamp.

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

[0093] Next, although not shown in the schematic flow chart of FIG. 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 heated rapidly to reach the reaction temperature, the second cation precursor and the second anion precursor in the solution react quickly and grow to produce quantum dots including a shell having an alloy form. Such alloy-type quantum dots have the advantage of having excellent optical durability of quantum dots because the shell is uniformly distributed without shell boundaries and lattice constant mismatch is minimized.

[0095] The heat treatment is also performed by radiant heat generated from a lamp of a rapid heating device, similar to the rapid temperature rise. The heat treatment can be performed at 350°C to 370°C for 30 seconds to 5 minutes, and within this range, the quantum dot synthesis time can be significantly shortened and quantum dots with a narrow size distribution and excellent optical efficiency can be obtained. If the heat treatment time is long, the particle size can increase due to aggregation between particles, the size distribution can increase, and the half-value width can increase.

[0096] In the method for producing quantum dots according to an embodiment of the present invention, at least one of the third solution and the fourth solution contains two or more precursors, so that quantum dots having a shell composed of at least three elements are formed. For example, the quantum dots produced by the method for producing quantum dots according to an embodiment of the present 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 less within one minute to form a shell on the surface of the core (S240). That is, the method further includes a step of quenching the product after the heat treatment. The quenching may be performed by removing the heat source and cooling to room temperature, and may be performed by air cooling or water cooling in some cases. Specifically, the second mixture, which has been rapidly heated to 350°C to 370°C, can be transferred to a cooling tank filled with cooling water immediately after the heat treatment step and rapidly cooled to 100°C or less within one minute.

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

[0099] In one embodiment of the present invention, a method for producing quantum dots uses indium oxoclusters and zinc oxoclusters as first cation precursors in a first solution, and a first solution containing a first cation precursor and a second solution containing a first anion precursor are mixed at a low temperature to produce a first mixture, which is then rapidly heated and heat-treated to react quickly within a short period of time, thereby forming quantum dots having uniform cores.

[0100] Unlike a conventional manufacturing method in which an anion precursor solution is injected into a cation precursor solution at a temperature of 100°C or higher and then reacted at 200°C to 280°C for a certain period of time in order to manufacture cores with a uniform distribution, the manufacturing method of quantum dots according to an embodiment of the present invention can manufacture quantum dots by mixing a cation precursor and anion precursor at a low temperature, rapidly heating the mixture to 300°C or higher, and then rapidly cooling the mixture, thereby shortening the reaction time and cooling time and facilitating mass production.

[0101] In addition, the conventional method for manufacturing quantum dots using a high temperature injection method can manufacture quantum dots containing three or more elements through a single reaction, but has a problem that the energy cost consumed for heating the reaction solution to a high temperature of 300°C or more increases rapidly as the synthesis scale increases. However, the method for manufacturing quantum dots according to an embodiment of the present invention provides an advantage that quantum dots can be mass-produced 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] In addition, unlike the conventional method for manufacturing quantum dots having a core-shell structure, which requires a purification process such as centrifugation to obtain the core after forming the core, the method for manufacturing quantum dots according to an embodiment of the present invention uses the core solution prepared without centrifugation, thereby simplifying the process and minimizing waste liquid, thereby reducing costs and shortening the process time, which is advantageous in terms of quantum dot productivity.

[0103] In addition, the quantum dots manufactured by the method for manufacturing quantum dots according to an embodiment of the present invention have a narrower half-width than conventional quantum dots having a core-shell structure. When the cation precursor includes an indium oxocluster and a zinc oxocluster, the first mixture can be rapidly heated and rapidly cooled to manufacture a uniform core, thereby reducing lattice fatigue and narrowing the half-width. In addition, in the process of forming a shell on the surface of the core, the cation precursor and the anion precursor are mixed at a low temperature, and then the rapid heating and rapid cooling processes are carried out to form a uniform alloy shell, thereby narrowing the half-width. In particular, the half-width can be further narrowed by adjusting the ratio of zinc (Zn) and oleic acid (OA) to 1:1.5 in the shell formation process. As a result, the quantum dots manufactured by the method for manufacturing quantum dots according to an embodiment of the present invention can have high quantum efficiency.

[0104] In addition, the quantum dots manufactured by the method for manufacturing quantum dots according to an embodiment of the present invention can ensure optical stability and thermal stability by performing a heat treatment process at a high temperature of 350° C. or more.

[0105] In addition, in the past, the wavelength of the core determines the wavelength of the final quantum dot, so if the wavelength does not match, it must be synthesized from the core, which increases the cost and increases the defect rate. In contrast, the method for manufacturing quantum dots according to an embodiment of the present invention can control the wavelength by adjusting the ratio of indium oxocluster (In-Oxo) and zinc oxocluster (Zn-Oxo) in the core, and can also control the wavelength 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). That is, quantum dots of various wavelength bands can be synthesized from a single core, and conversely, quantum dots of the same wavelength band can be synthesized using cores of various wavelengths. As a result, even if the wavelength formed in the core does not match, the wavelength can be controlled during the shell formation process, so the defect rate can be minimized, costs can be reduced, and the process time can be shortened, which is very advantageous in terms of productivity.

[0106] Example 1-1: Synthesis of red fluorescent quantum dot cores 3 is a schematic diagram for explaining a method for producing quantum dots according to an embodiment of the present invention, an embodiment of the present invention will be explained with reference to FIG.

[0107] First, 63g (216.0mmol) of indium(III) acetate and 183g (648.0mmol) of oleic acid were mixed in a 2L container, heated to 200℃ under vacuum, and then converted to normal pressure. Octadecene (ODE) was added and synthesized at 260℃~300℃ for more than 1 hour to produce the first cation precursor of indium oxocluster.

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

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

[0110] Example 1-2: Synthesis of red fluorescent quantum dot cores In the method for producing quantum dots according to Example 1-2, 100 g (28.8 mmol) of an indium oxocluster solution and 36 g (28.8 mmol) of TMSP (20 wt% in TOP) were further added to the solution containing the quantum dot cores produced in Example 1-1, and the mixture was rapidly heated to 300°C by increasing the temperature by 200°C per minute using radiant heat, and the heat-treated mixture was rapidly cooled to below 100°C within one minute to form quantum dot cores.

[0111] Example 1-3: Synthesis of red fluorescent quantum dot cores In the method of manufacturing quantum dots according to Example 1-3, 100g (28.8mmol) of indium oxocluster solution and 36g (28.8mmol) of TMSP (20wt% in TOP) were further added to the solution containing quantum dot cores manufactured in Example 1-2, and the mixture was rapidly heated to 300°C by increasing the temperature by 200°C per minute using radiant heat, and reacted for 1 minute while maintaining the same temperature. Then, the heat-treated mixture was rapidly cooled to below 100°C within 1 minute to form quantum dot cores.

[0112] Example 1-4: Synthesis of red fluorescent quantum dot cores In the method of manufacturing quantum dots according to Example 1-4, 100g (28.8mmol) of indium oxocluster solution and 36g (28.8mmol) of TMSP (20wt% in TOP) were further added to the solution containing quantum dot cores manufactured in Example 1-3, and the mixture was rapidly heated to 300°C by increasing the temperature by 200°C per minute using radiant heat, and reacted for 1 minute while maintaining the same temperature. Then, the heat-treated mixture was rapidly cooled to below 100°C within 1 minute to form quantum dot cores.

[0113] Example 1-5: Synthesis of red fluorescent quantum dot cores In the method of manufacturing quantum dots according to Examples 1-5, 50g (14.4mmol) of indium oxocluster solution and 18g (14.4mmol) of TMSP (20wt% in TOP) were further added to the solution containing quantum dot cores manufactured in Examples 1-4, and the mixture was rapidly heated to 300°C by increasing the temperature by 200°C per minute using radiant heat, and then reacted for 1 minute while maintaining the same temperature. Then, the heat-treated mixture was rapidly cooled to below 100°C within 1 minute to form quantum dot cores.

[0114] Examples 1-6: Synthesis of red fluorescent quantum dot cores In the method of manufacturing quantum dots according to Examples 1-6, 50g (14.4mmol) of indium oxocluster solution and 18g (14.4mmol) of TMSP (20wt% in TOP) were further added to the solution containing quantum dot cores manufactured in Examples 1-5, and the mixture was rapidly heated to 300°C by increasing the temperature by 200°C per minute using radiant heat, and reacted for 1 minute while maintaining the same reaction temperature. The heat-treated mixture was rapidly cooled to below 100°C within 1 minute to form quantum dot cores.

[0115] Example 2-1: Synthesis of green fluorescent quantum dot cores First, 63g (216.0mmol) of indium(III) acetate and 183g (648.0mmol) of oleic acid were mixed in a 2L container, heated to 200℃ under vacuum, and then converted to normal pressure. Octadecene (ODE) was added and synthesized at 260℃~300℃ for more than 1 hour to produce the first cation precursor of indium oxocluster.

[0116] Next, 47g (216.0mmol) of zinc acetate dihydrate and 122g (432.0mmol) of oleic acid were mixed in a 1L container, heated to 190℃ under vacuum, and then converted to normal pressure. Octadecene (ODE) was added and synthesized at 300℃~315℃ for more than 1 hour to produce the first cation precursor of zinc oxo cluster.

[0117] The prepared indium oxocluster solution (180g, 51.8mmol) and zinc oxocluster solution (43g, 23.0mmol) were mixed in a 1L quartz container, heated to 100°C under a N2 atmosphere, and 36g (28.8mmol) of TMSP (20wt% in TOP) was added to prepare a 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 was a mixture of the first cation precursor and the first anion precursor, was rapidly heated to 300°C by increasing the temperature by 200°C per minute using radiant heat, and then reacted for 0 to 10 seconds while maintaining the same reaction temperature. Thereafter, the heat-treated first mixture was rapidly cooled to below 100°C within 1 minute to prepare a core solution.

[0119] Example 2-2: Synthesis of green fluorescent quantum dot cores The quantum dot manufacturing method of Example 2-2 differs from the quantum dot manufacturing method of Example 2-1 only in the synthesis ratio of indium oxoclusters and zinc oxoclusters, and other configurations are essentially the same, so duplicated explanations will be omitted.

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

[0121] Example 2-3: Synthesis of green fluorescent quantum dot cores The quantum dot manufacturing method of Example 2-3 differs from the quantum dot manufacturing method of Example 2-1 only in the synthesis ratio of indium oxoclusters and zinc oxoclusters, and other configurations are essentially the same, so duplicated explanations will be omitted.

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

[0123] Example 2-4: Synthesis of green fluorescent quantum dot cores The quantum dot manufacturing method of Example 2-4 differs from the quantum dot manufacturing method of Example 2-1 only in the synthesis ratio of indium oxoclusters and zinc oxoclusters, and other configurations are essentially the same, so duplicated explanations will be omitted.

[0124] In the method for producing quantum dots according to Examples 2-4, an indium oxocluster solution and a zinc oxocluster solution were mixed in a 1 L quartz container so that the molar ratio of indium (In):zinc (Zn):phosphorus (P) was 1.2:0.8:1, the temperature was raised to 100°C in a N2 atmosphere, and TMSP (20 wt% in TOP) was added to produce a first mixture.

[0125] Example 2-5: Synthesis of green fluorescent quantum dot cores The quantum dot manufacturing method of Example 2-5 differs from the quantum dot manufacturing method of Example 2-1 only in the synthesis ratio of indium oxoclusters and zinc oxoclusters, and other configurations are essentially the same, so duplicated explanations will be omitted.

[0126] In the method for producing quantum dots according to Examples 2-5, an indium oxocluster solution and a zinc oxocluster solution were mixed in a 1 L quartz container so that the molar ratio of indium (In):zinc (Zn):phosphorus (P) was 1.2:1.2:1, the temperature was raised to 100°C in a N2 atmosphere, and TMSP (20 wt% in TOP) was added to produce a first mixture.

[0127] Comparative Example 1: Core synthesis produced by conventional method The method for producing quantum dots according to Comparative Example 1 is a conventional method, and differs from the method for producing quantum dots according to Example 2-1 only in that an indium oleate (In-OA) solution and zinc oleate (Zn-OA) were used as the first cation precursors instead of an indium oxocluster solution and a zinc oxocluster (Zn-OA) solution, and in the synthesis ratio. Since the other configurations are substantially the same, a duplicated description will be omitted.

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

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

[0130] [Table 1] TIFF2025515263000002.tif55157First, the cores of the red fluorescent quantum dots manufactured by the manufacturing methods of Examples 1-1 to 1-6 use In Oxocluster as a cation precursor and TMSP as an anion precursor. At this time, referring to Table 1, it can be confirmed that the cores manufactured by the manufacturing methods of Examples 1-1 to 1-6 have uniform core distribution and therefore excellent P / V (Peak to Valley) values ​​of 0.6 or less. In addition, by adjusting the molar ratio of indium (In):phosphorus (P) and the amount of precursor input differently, the core wavelengths (Core λ) have different values. That is, it can be confirmed that the wavelength can be adjusted by the ratio of indium oxocluster and TMSP, the amount of precursor added, the number of times of precursor addition, etc. As a result, it is considered that the quantum dots manufactured by the manufacturing methods of Examples 1-1 to 1-6 can easily adjust the wavelength, can ensure quality stability, and have excellent reproducibility.

[0131] [Table 2] TIFF2025515263000003.tif55156The cores manufactured by the manufacturing methods of Examples 2-1 to 2-5 were prepared by mixing a cation precursor and an anion precursor containing an indium oxocluster and a zinc oxocluster at a low temperature, rapidly heating to 300°C or higher within 1 minute, and then rapidly cooling. Referring to Table 2, the cores manufactured by the manufacturing methods of Examples 2-1 to 2-5 have a uniform core distribution degree, and therefore the P / V (Peak to Valley) value is good, being 0.6 or less. In particular, the core manufactured by the manufacturing method of Comparative Example 1, which was prepared by a conventional method, has a P / V value of 0.71 despite having the same ratio of indium (In):zinc (Zn):phosphorus (P) as Example 2-3, and it can be confirmed that Examples 2-1 to 2-5 of the present invention, which use an indium oxocluster solution and a zinc oxocluster solution, are superior. In addition, by adjusting the ratio of indium (In):zinc (Zn):phosphorus (P) differently, the core wavelength (Core λ) has different values. That is, it can be confirmed that the wavelength can be adjusted by the input amount and molar ratio of the oxocluster precursor. Therefore, the quantum dots produced by the manufacturing methods of Examples 2-1 to 2-5 can be easily adjusted in wavelength, can ensure quality stability, and are considered to have excellent reproducibility.

[0132] Example 3: Shell synthesis on the surface of green fluorescent quantum dot cores 4 is a schematic diagram for explaining a method for producing quantum dots according to an embodiment of the present invention, an embodiment of the present invention will be explained with reference to FIG.

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

[0134] Next, 948 g (12,000.0 mmol) of selenium (Se) powder and 5,485 g (6.6 L) of trioctylphosphine (TOP) were mixed in a 10 L container, heated to 250°C under vacuum in a N2 atmosphere, stirred until completely dissolved, and then cooled to produce a second anion precursor of trioctylphosphine selenide (Se-TOP).

[0135] Next, 769.68 g (24,000.0 mmol) of sulfur (S) powder and 10,637 g (12.8 L) of trioctylphosphine (TOP) were mixed in a 30 L container, heated to 150°C under vacuum in a N2 atmosphere, stirred until completely dissolved, and then cooled to produce the second anion precursor of trioctylphosphine sulfide (S-TOP).

[0136] 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 (Zn-OA) (Zn:oleic acid (OA) is 1:1.5) (Zn" 313.2 mmol) and 4 g of trioctylphosphine (TOP) were mixed and stirred in a 1 L quartz container, and then 21 g (39.1 mmol) of trioctylphosphine selenide (Se-TOP) and 27 g (56.7 mmol) of trioctylphosphine sulfide (S-TOP) were added at room temperature of 20°C to 24°C to prepare a second mixture.

[0137] Next, the second mixture obtained by mixing the core solution, second cation precursor, and second anion precursor from Example 2-2 was rapidly heated to 370°C by increasing the temperature by 200°C every minute using radiant heat, and then reacted for 30 seconds to 5 minutes while maintaining the temperature at 350°C to 370°C. After that, the heat-treated second mixture was rapidly cooled to below 100°C within 1 minute to obtain quantum dots in which a ZnSeS shell was formed on the surface of the InZnP core.

[0138] Comparative Example 2-1: Shell synthesis on the surface of green fluorescent quantum dot core The quantum dot manufacturing method of Comparative Example 2-1 differs from the quantum dot manufacturing method of Example 3 only in the synthesis ratio of zinc (Zn) and oleic acid (OA), and other configurations are essentially the same, so duplicated explanations will be omitted.

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

[0140] Comparative Example 2-2: Shell synthesis on the surface of green fluorescent quantum dot core The quantum dot manufacturing method of Comparative Example 2-2 differs from the quantum dot manufacturing method of Example 3 only in the synthesis ratio of zinc (Zn) and oleic acid (OA), and other configurations are essentially the same, so duplicated explanations will be omitted.

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

[0142] Comparative Example 2-3: Shell synthesis on the surface of green fluorescent quantum dot core The quantum dot manufacturing method of Comparative Example 2-3 differs from the quantum dot manufacturing method of Example 2-1 only in the heating rate of the second mixture, and other configurations are essentially the same, so duplicated explanations will be omitted.

[0143] In Comparative Example 2-3, the second mixture, which was a mixture of the core solution, the second cation precursor, and the second anion precursor, was slowly heated to 370°C by increasing the temperature by 15°C every minute using conductive heat, and then reacted for 30 seconds to 5 minutes while maintaining the temperature at 350°C to 370°C. Thereafter, the heat-treated second mixture was rapidly cooled to below 100°C within 1 minute to obtain quantum dots with shells formed on the surfaces of the cores.

[0144] Experimental example 2 - Performance evaluation The maximum peak wavelength band (PL Max), full width at half maximum (FWHM) and quantum efficiency (QY) of the quantum dots manufactured 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] TIFF2025515263000004.tif47156 The quantum dots manufactured by the manufacturing methods of Example 3, Comparative Example 2-1, and Comparative Example 2-2 are identical in other configurations, with only the molar ratio of zinc (Zn) and oleic acid (OA) being different. Referring to Table 3, the quantum dots having a molar ratio of zinc (Zn) and oleic acid (OA) of 1:1.5 according to the manufacturing method of 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 having a molar ratio of zinc (Zn) and oleic acid (OA) of 1:2 according to the manufacturing method of Comparative Example 2-1 have a quantum efficiency (QY) of 96%, similar to that of Example 2-1, but a wide full width at half maximum (FWHM) of 37 nm. In addition, the quantum dots with a 1:1 molar ratio of zinc (Zn) and oleic acid (OA) according to the manufacturing method of Comparative Example 2-2 have a full width at half maximum (FWHM) of 33 nm, which is similar to that of Example 2-1, but a low quantum efficiency (QY) of 84%. This confirms that the molar ratio of zinc (Zn) and oleic acid (OA) in zinc oleate (ZnOA), which is the second cation precursor required in the process of forming a shell on the surface of the core, is preferably 1:1.5.

[0146] In addition, the quantum dots manufactured 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) differently. That is, it can be confirmed that the wavelength can be adjusted by the input amount and molar ratio of the second cation precursor composed of zinc acetate and oleic acid. Thus, even if the core wavelength band is fixed by a single core, various wavelengths can be synthesized by adjusting the ratio of zinc (Zn) and oleic acid (OA). That is, quantum dots of various wavelength bands can be synthesized by a single core, and conversely, quantum dots of the same wavelength band can be synthesized by using cores of various wavelength bands, so that the defective rate can be minimized.

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

[0148] [Table 4] TIFF2025515263000005.tif28156 The quantum dots manufactured by the manufacturing methods of Example 3 and Comparative Examples 2-3 are identical in other configurations, except for the heating rate of the second mixture. That is, Example 3 is a quantum dot reacted by rapidly heating the second mixture to 370°C by increasing the temperature by about 200°C per minute using radiant heat, and Comparative Examples 2-3 is a quantum dot reacted by slowly heating the second mixture to 370°C by increasing the temperature by about 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 slowly heated at a heating rate of 15° C. / min in Comparative Example 2-3 have a wide full width at half maximum (FWHM) of 37 nm and a low quantum efficiency (QY) of 91%. This confirms that when the second mixture is rapidly heated using radiant heat, excellent quantum dots with narrow full width at half maximum (FWHM) and high quantum efficiency (QY) can be obtained. In addition, the quantum dots manufactured by the manufacturing methods of Example 3 and Comparative Example 2-3 have different maximum peak wavelength bands (PL Max) by setting the heating rate of the second mixture differently. That is, it can be confirmed that the wavelength can be adjusted by the heating rate of the second mixture. Thus, even if the core wavelength band is fixed by a single core, various wavelengths can be synthesized by adjusting the heating rate. That is, the wavelength of the quantum dots manufactured by the manufacturing method according to an embodiment of the present invention can be controlled not only by the content ratio of the precursors but also by the heating rate, reaction rate, reaction time, etc.

[0149] Example 4-1: Shell synthesis on the surface of green fluorescent quantum dot cores The method for producing quantum dots according to Example 4-1 differs from the method for producing quantum dots according to Example 3 only in the core solution, and other configurations are substantially the same, so duplicated explanations will be omitted.

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

[0151] Example 4-2: Shell synthesis on the surface of green fluorescent quantum dot cores The quantum dot manufacturing method according to Example 4-2 differs from the quantum dot manufacturing method according to Example 4-1 only in the synthesis ratio of trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP), and other configurations are substantially the same, so duplicated 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):sulfur (S) was 1.0:1.96.

[0153] Example 4-3: Shell synthesis on the surface of green fluorescent quantum dot cores The quantum dot manufacturing method of Example 4-3 differs from the quantum dot manufacturing method of Example 4-1 only in the synthesis ratio of trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP), and other configurations are substantially the same, so duplicated explanations will be omitted.

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

[0155] Example 4-4: Shell synthesis on the surface of green fluorescent quantum dot cores The quantum dot manufacturing method of Example 4-4 differs from the quantum dot manufacturing method of Example 4-1 only in the synthesis ratio of trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP), and other configurations are substantially the same, so duplicated explanations will be omitted.

[0156] In the method for producing quantum dots according to 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):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 the 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] TIFF2025515263000006.tif67156 The quantum dots manufactured by the manufacturing methods of Examples 4-1 to 4-4 have the same configuration except for the molar ratio of trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP), which are anion precursors required in the cell formation process, added to the surface of the core. Referring to Table 5, the quantum dots manufactured by the manufacturing methods of Examples 4-1 to 4-4 have different maximum peak wavelength bands (PL Max) by adjusting the ratio of selenium (Se):sulfur (S) differently. That is, it can be confirmed that the wavelength can be adjusted by the input amount and molar ratio of the second anion precursor composed of trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP). Thus, even though the quantum dots according to the manufacturing methods of Examples 4-1 to 4-4 have a fixed core wavelength band due to a single core, various wavelengths can be synthesized by adjusting the ratio of selenium (Se) and sulfur (S). That is, quantum dots of various wavelength bands can be synthesized from a single core, and conversely, quantum dots of the same wavelength band can be synthesized using cores of various wavelength bands, so that the defect rate can be minimized. A method for manufacturing quantum dots according to an embodiment of the present invention can be described as follows.

[0159] 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 to 350°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 may include an indium oxocluster.

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

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

[0162] According to another aspect of the present invention, a zinc oxocluster can be prepared by mixing zinc acetate and oleic acid, heating the mixed solution to 190°C under vacuum and then converting the pressure to normal pressure, and adding octadecene (ODE) and synthesizing at 300°C to 315°C for at least 1 hour.

[0163] According to another feature of the present invention, the step of preparing the first mixture may further include a step of controlling the wavelength band of the quantum dots by adjusting the ratio of indium oxoclusters (In-Oxocluster) and zinc oxoclusters (Zn-Oxocluster).

[0164] According to another aspect of the present invention, the first cation precursor may further include 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] According to another feature of the present invention, the method 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 increasing the temperature of the first mixture and the step of rapidly cooling the first mixture.

[0166] According to another aspect of the present invention, the rapid temperature increase step and the heat treatment step may be performed by radiant heat using a quartz container and a halogen lamp.

[0167] According to another aspect of the present invention, the method may further include a step of mixing trioctylphosphine (TOP) with the heat-treated first mixture and further heat-treating the mixture at 300° C. or more for 10 seconds or more to improve the surface reactivity of the core.

[0168] According to another feature of the present invention, the method may further include the steps of preparing a first sub-mixture by further adding a first sub-solution containing a first cation precursor and a second sub-solution containing a first anion precursor to a solution containing a core at room temperature, heating the first sub-mixture to a high temperature of 300°C to 350°C within 1 minute, heat-treating the heated first sub-mixture for 10 seconds to 5 minutes, and cooling the heat-treated first sub-mixture to below 100°C within 1 minute.

[0169] According to another aspect of the present invention, the method may further include repeatedly carrying out the steps of preparing a first sub-mixture, rapidly increasing the temperature of the first sub-mixture, heat-treating the first sub-mixture, and cooling the first sub-mixture.

[0170] According to another aspect of the present invention, the method may further include 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 solution containing cores at 20°C to 100°C to prepare a second mixture, rapidly heating the second mixture to 350°C to 400°C within one minute, and cooling the heated second mixture to below 100°C within one minute to form a shell on a surface of the cores.

[0171] According to yet another aspect of the invention, the third solution can include zinc oleate (Zn-OA) and the fourth solution can include trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP).

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

[0173] According to another aspect of the present invention, the method may further include controlling the wavelength band of the quantum dots by adjusting the ratio of trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP) in the fourth solution.

[0174] According to another feature of the present invention, the method can 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 increasing the temperature of the second mixture and the step of rapidly cooling the second mixture.

[0175] According to another aspect of the present invention, the second cation precursor may include one or more 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), and strontium (Sr).

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

[0177] Although the embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not necessarily limited to these embodiments, and various modifications can be made within the scope of the technical idea of ​​the present invention. Therefore, the embodiments disclosed in the present invention are for illustration purposes, not for limiting the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by these embodiments. Therefore, it should be understood that the embodiments described above are illustrative and not restrictive in all respects. The scope of protection of the present invention should be interpreted according to the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

Claims

1. Providing 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 prepare a first mixture; heating the first mixture to a high temperature of 300°C to 350°C within 1 minute; and cooling the heated first mixture to below 100° C. within one minute to form a core; The first cation precursor comprises an indium oxocluster.

2. The indium oxocluster (In-Oxocluster) is Mixing indium acetate and oleic acid; The mixed solution is heated to 200° C. under vacuum and then transferred to normal pressure; and The method for producing quantum dots according to claim 1, which is produced by adding octadecene (ODE) and synthesizing at 260°C to 300°C for 1 hour or more.

3. The method of claim 1, wherein the first cation precursor further comprises a zinc oxocluster.

4. The zinc oxocluster is Mixing zinc acetate and oleic acid; The mixed solution is heated to 190° C. under vacuum and then converted to normal pressure; and The method for producing quantum dots according to claim 3, which is produced by adding octadecene (ODE) and synthesizing at 300°C to 315°C for 1 hour or more.

5. The step of preparing the first mixture includes adjusting the ratio of the indium oxocluster (In-Oxocluster) and the zinc oxocluster (Zn-Oxocluster), The method for producing quantum dots according to claim 3 , further comprising the step of controlling the wavelength band of the quantum dots.

6. The first cation precursor is The method of claim 3, further comprising at least one of cadmium (Cd), mercury (Hg), magnesium (Mg), aluminum (Al), manganese (Mn), copper (Cu), gallium (Ga), tin (Sn), barium (Ba), iron (Fe), and strontium (Sr).

7. Between the step of rapidly increasing the temperature of the first mixture and the step of rapidly cooling the first mixture, The 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.

8. The method for producing quantum dots according to claim 7 , wherein the rapid temperature increase step and the heat treatment step are performed by radiant heat using a quartz container and a halogen lamp.

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

10. adding a first sub-solution containing the first cation precursor and a second sub-solution containing the first anion precursor to the solution containing the cores at room temperature to prepare a first sub-mixture; heating the first sub-mixture to a high temperature of 300°C to 350°C within 1 minute; heat treating the heated first sub-mixture for 10 seconds to 5 minutes; and The method of claim 1 , further comprising the step of cooling the heat-treated first sub-mixture to below 100° C. within one minute.

11. The method for producing quantum dots according to claim 10, further comprising the steps of repeatedly performing the steps of preparing the first sub-mixture, rapidly increasing the temperature of the first sub-mixture, heat-treating the first sub-mixture, and cooling the first sub-mixture.

12. providing a third solution comprising at least one second cation precursor and a fourth solution comprising at least one second anion precursor; mixing the third solution and the fourth solution with the solution containing the cores at 20°C to 100°C to prepare a second mixture; Rapidly increasing the temperature of the second mixture to 350° C. to 400° C. within 1 minute; and The method of claim 1 , further comprising the step of cooling the heated second mixture to 100° C. or less within one minute to form a shell on the surface of the core.

13. the third solution comprises zinc oleate (Zn-OA); The method for producing quantum dots according to claim 12, wherein the fourth solution contains trioctylphosphine selenide (Se-TOP) and trioctylphosphine sulfide (S-TOP).

14. The method for producing quantum dots according to claim 13, further comprising the step of controlling the wavelength band of the quantum dots by adjusting the molar ratio of zinc (Zn) to oleate (OA) of the third solution within a range of 1:1.3 to 1:1.

7.

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

16. Between the step of rapidly increasing the temperature of the second mixture and the step of rapidly cooling the second mixture, The method for producing quantum dots according to claim 12, further comprising the step of heat-treating the second mixture at 350° C. to 370° C. for 30 seconds to 5 minutes.

17. The second cation precursor is 13. The method of claim 12, further comprising at least one 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), and strontium (Sr).

18. The first anion precursor and the second anion precursor are The method for producing quantum dots according to claim 12, comprising at least one of sulfur (S), selenium (Se), phosphorus (P), tellurium (Te), arsenic (As), nitrogen (N) and antimony (Sb).

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