KR102306678B1 - Quantum dot and the method for preparing the same - Google Patents

Abstract

The quantum dot of the present invention is a quantum dot having a core-shell structure having one or more stable layers, and the quantum dot has a conversion efficiency of 100% or more according to Formula 1 when the outermost lipid-soluble ligand is substituted with a water-soluble ligand.

Description

QUANTUM DOT AND THE METHOD FOR PREPARING THE SAME

The present invention relates to a quantum dot and a method for manufacturing the same.

Quantum dots are semiconductor nanoparticles and have a characteristic of emitting different light depending on the size of the particle due to the quantum isolation effect. Due to these characteristics, quantum dots are widely used not only in the optical device field but also in the bio field.

In order to increase the quantum efficiency of these quantum dots, many studies are being conducted, and in particular, the stability of the quantum dots has a great effect on the quantum efficiency. Therefore, there is a need for quantum dots with increased stability.

Prior art in this regard is disclosed in US Patent No. 6322901.

It is an object of the present invention to provide a quantum dot having excellent quantum efficiency and conversion efficiency and a method for manufacturing the same.

Another object of the present invention is to provide a quantum dot having excellent stability and a method for manufacturing the same.

All of the above and other objects of the present invention can be achieved by the present invention described below.

One aspect of the invention relates to quantum dots.

In one embodiment, the quantum dot is a quantum dot having a core-shell structure having one or more stable layers, and when the quantum dot replaces the outermost fat-soluble ligand with a water-soluble ligand, the conversion efficiency according to the following formula 1 is 100% More than that.

[Equation 1]

Conversion efficiency (%) = (Cw/Cf) x 100

(In Equation 1, Cw is the quantum efficiency of the quantum dot containing the water-soluble ligand in the outermost, Cf is the quantum efficiency of the quantum dot containing the fat-soluble ligand in the outermost).

In another embodiment, a first stabilizing layer between the core and the shell and a second stabilizing layer on the shell may be further included.

In another embodiment, the quantum dot may further include a ligand layer on the outermost side.

The shell and the stabilizing layer may include three or more components.

The first stable layer may include one or more components having a content difference of 15 mol% or less from the core, and may include one or more components having a content difference of 15 mol% or less from the shell.

The second stable layer may include one or more components having a content difference of 10 mol% or less from the shell.

In the second stable layer, a molar ratio of the group 12 element to the group 16 element may be 4:6 to 6:4.

The diameter of the core may be 1 nm to 6 nm.

The thickness of the shell may be 0.5 nm to 10 nm.

The thickness of the first stabilizing layer or the second stabilizing layer may be 0.3 nm to 2 nm.

The quantum dots may have an average diameter of 6 nm to 30 nm.

The quantum dot may have a quantum efficiency of 80% or more.

The quantum dots may have a stability index of 90% or more.

The half width of the quantum dots may be less than or equal to 40 nm.

The core, the shell, the first stable layer, or the second stable layer may include at least one of a Group 12-16 compound, a Group 13-15 compound, and a Group 14-16 compound.

The group 12-16 compound is cadmium sulfide (CdS), cadmium selenide (CdSe), cadmium thelenide (CdTe), zinc sulfide (ZnS), zinc selenide (ZnSe), zinc thelenide (ZnTe), mercury sulfide (HgS), Mercury Selenide (HgSe), Mercury Telenide (HgTe), Zinc Oxide (ZnO), Cadmium Oxide (CdO), Mercury Oxide (HgO), Cadmium Selenium Sulfide (CdSeS), Cadmium Selenium Telenide (CdSeTe) , Cadmium Sulfide Telenide (CdSTe), Cadmium Zinc Sulfide (CdZnS), Cadmium Zinc Selenide (CdZnSe), Cadmium Sulfide Selenide (CdSSe), Cadmium Zinc Telenide (CdZnTe), Cadmium Mercury Sulfide (CdHgS), Cadmium Mercury Cell Nide (CdHgSe), Cadmium Mercury Telenide (CdHgTe), Zinc Selenium Sulfide (ZnSeS), Zinc Selenium Telenide (ZnSeTe), Zinc Sulfide Telenide (ZnSTe), Mercury Selenium Sulfide (HgSeS), Mercury Selenium Telenide (HgSeTe) , Mercury Sulfide Telenide (HgSTe), Mercury Zinc Sulfide (HgZnS), Mercury Zinc Selenide (HgZnSe), Cadmium Zinc Oxide (CdZnO), Cadmium Mercury Oxide (CdHgO), Zinc Mercury Oxide (ZnHgO), Zinc Selenium Oxide ( ), Zinc Telenium Oxide (ZnTeO), Zinc Sulfide Oxide (ZnSO), Cadmium Selenium Oxide (CdSeO), Cadmium Telenium Oxide (CdTeO), Cadmium Sulfide Oxide (CdSO), Mercury Selenium Oxide (HgSeO), Mercury Telenium Oxide (HgTeO), Mercurysulfide Oxide (HgSO), Cadmium Zinc Selenium Sulfide (CdZnSeS), Cadmium Zinc Selenium Telenide (CdZnSeTe), Cadmium Zinc Sulfide Telenide (CdZnSTe), Cadmium Mercury Selenium Sulfide (CdHgSeS), (CdHgSeTe), Cadmium Mercury Sulfide Telenide (CdHgSTe), Mercury Zinc Selenium Sulfide (HgZnSeS), Mercury Zinc Selenium Telenide (HgZnSeTe), Mercury Zinc Sulfide Telenide (HgZnSTe), Cadmium Zinc Xelenium Oxide (CdZnSeO), Cadmium Zinc Telenium Oxide (CdZnTeO), Cadmium Zinc Sulfide Oxide (CdZnSO), Cadmium Mercury Selenium Oxide (CdHgSeO), Cadmium Mercury Telenium Oxide (CdHgTeO), Cadmium Mercury Sulfide Oxide (CdHgSO) Mercury selenium oxide (ZnHgSeO), zinc mercury terenium oxide (ZnHgTeO), and may include at least one of zinc mercury sulfide oxide (ZnHgSO).

The group 13-15 compound is gallium phosphorus (GaP), gallium arsenide (GaAs), gallium antimony (GaSb), gallium nitride (GaN), aluminum phosphorus (AlP), aluminum arsenide (AlAs), Aluminum antimony (AlSb), aluminum nitride (AlN), indium phosphorus (InP), indium arsenide (InAs), indium antimony (InSb), indium nitride (InN), gallium phosphorous arsenide (GaPAs) , Gallium phosphorus antimony (GaPSb), gallium phosphorus nitride (GaPN), gallium arsenide nitride (GaAsN), gallium antimony nitride (GaSbN), aluminum phosphorous arsenide (AlPAs), aluminum phosphorous anti Mono (AlPSb), aluminum phosphorus nitride (AlPN), aluminum arsenide nitride (AlAsN), aluminum antimony nitride (AlSbN), indium phosphorous arsenide (InPAs), indium phosphorus antimony (InPSb), Indium phosphorus nitride (InPN), indium arsenide nitride (InAsN), indium antimony nitride (InSbN), aluminum gallium phosphorus (AlGaP), aluminum gallium arsenide (AlGaAs), aluminum gallium antimony (AlGaSb) , aluminum gallium nitride (AlGaN), aluminum arsenide nitride (AlAsN), aluminum antimony nitride (AlSbN), indium gallium phosphorus (InGaP), indium gallium arsenide (InGaAs), indium gallium antimony (InGaSb) , indium gallium nitride (InGaN), indium arsenide nitride (InAsN), indium antimony nitride (InSbN), aluminum indium phosphorus (AlInP), aluminum indium arsenide (AlInAs), aluminum indium antimony (AlInSb) , aluminum indium nitride (AlInN), aluminum arsenide nitride (AlAsN), aluminum antimony nitride (AlSbN), aluminum phosphorus nitride (AlPN), gallium aluminum phosphorous arsenide (GaAlPAs), gallium aluminum phosphorus Antimony (GaAlPSb), gallium indium phosphorous arsenide (GaInPAs), Gallium indium aluminum arsenide (GaInAlAs), gallium aluminum phosphorus nitride (GaAlPN), lithium aluminum arsenide nitride (GaAlAsN), gallium aluminum antimony nitride (GaAlSbN), gallium indium phosphorus nitride (GaInPN), gallium Indium arsenide nitride (GaInAsN), gallium indium aluminum nitride (GaInAlN), gallium antimony phosphorus nitride (GaSbPN), gallium arsenide phosphorus nitride (GaAsPN), gallium arsenide antimony nitride (GaAsSbN) , gallium indium phosphorus antimony (GaInPSb), gallium indium phosphorus nitride (GaInPN), gallium indium antimony nitride (GaInSbN), gallium phosphorus antimony nitride (GaPSbN), indium aluminum phosphorous arsenide (InAlPAs) ), indium aluminum phosphorus nitride (InAlPN), indium phosphorus arsenide nitride (InPAsN), indium aluminum antimony nitride (InAlSbN), indium phosphorous antimony nitride (InPSbN), indium arsenide antimonite It may include at least one of lide (InAsSbN) and indium aluminum phosphorus antimony (InAlPSb).

The group 14-16 compound is tin oxide (SnO), tin sulfide (SnS), tin selenide (SnSe), tintelenide (SnTe), lead sulfide (PbS), lead selenide (PbSe), lead thelenide (PbTe), germanium oxide (GeO), germanium sulfide (GeS), germanium selenide (GeSe), germanium telenide (GeTe), tin selenium sulfide (SnSeS), tin selenium telenide (SnSeTe), tin Sulphide teleenide (SnSTe), lead selenium sulfide (PbSeS), lead selenium thelenide (PbSeTe), lead sulfide teleenide (PbSTe), tin lead sulfide (SnPbS), tin lead selenide (SnPbSe), tin lead thelenide ( SnPbTe), tin oxide sulfide (SnOS), tin oxide selenide (SnOSe), tin oxide thelenide (SnOTe), germanium oxide sulfide (GeOS), germanium oxide selenide (GeOSe), germanium oxide selenide (GeOTe) ), tin-lead sulfide-selenide (SnPbSSe), tin-lead-selenium-tellenide (SnPbSeTe), and tin-lead sulfide- selenide (SnPbSTe).

The ligand layer includes a fat-soluble ligand, and the fat-soluble ligand is tri-n-octylphosphine oxide, decylamine, didecylamine, tridecylamine. , tetradecylamine, pentadecylamine, hexadecylamine, octadecylamine, undecylamine, dioctadecylamine, N,N-dimethyldecyl Amine (N,N-dimethyldecylamine), N,N-dimethyldodecylamine (N,N-dimethyldodecylamine), N,N-dimethylhexadecylamine (N,N-dimethylhexadecylamine), N,N-dimethyltetradecylamine ( N,N-dimethyltetradecylamine), N,N-dimethyltridecylamine (N,N-dimethyltridecylamine), N,N-dimethylundecylamine (N,N-dimethylundecylamine), N-decylamine (N-decylamine), N -Methyloctadecylamine (N-methyloctadecylamine), didodecylamine (didodecylamine), tridodecylamine (tridodecylamine), cyclododecylamine (cyclododecylamine), N-methyldodecylamine (N-methyldodecylamine), trioctylamine ( trioctylamine, lauric acid, palmitic acid, oleic acid, stearic acid, myristicacid, elaidic acid, arachinic acid ( eicosanoic acid, heneicosanoic acid, tricosanoic acid, docosanoic acid, tetracosanoic acid, hexacosanoic aci d), heptacosanoic acid, octacosanoic acid, and cis-13-docosenoic acid.

The ligand layer includes a water-soluble ligand, and the water-soluble ligand includes silica, polyethylene glycol (PEG), mercaptopropionic acid (MPA), cysteamine, mercapto-acetic acid, and mercapto-undecanol. (mercapto-undecanol), 2-mercapto-ethanol, 1-thio-glycerol, deoxyribonucleic acid (DNA), mercapto acetic acid , mercapto undecanoic acid (mercapto-undecanoic acid), 1-mercapto-6-phenyl hexane (1-mercapto-6-phenyl-hexane), 1,16- dimercapto-hexadecane (1,16-dimecapto- hexadecane), 18-mercapto-octadecylamine (18-mercapto-octadecyl amine), tri-octyl phosphine, 6-mercapto-hexane (6-mercapto-hexane), 6-mercapto- Hexanoic acid (6-mercapto-hexanoic acid), 16-mercapto-hexadecanoic acid (16-mercapto-hexadecanoic acid), 18-mercapto-octadecylamine (18-mercapto-octadecyl amine), 6- Mercapto-hexyl amine or 8-hydroxy-octylthiol, 1-thio-glycerol, mercapto-acetic acid acid), mercapto-undecanoic acid, hydroxamate, a derivative of hydroxamic acid, and ethylene diamine.

The core, the shell, the first stabilizing layer and the second stabilizing layer may include cadmium (Cd).

The mole % of cadmium (Cd) or selenium (Se) may increase toward the center of the quantum dot.

In one embodiment, the core comprises at least one of cadmium (Cd) and selenium (Se), and the first stabilizing layer comprises at least one of cadmium (Cd), selenium (Se) and zinc (Zn), , wherein the shell includes at least one of cadmium (Cd), selenium (Se), zinc (Zn) and sulfur (S), and the second stable layer includes cadmium (Cd), zinc (Zn) and sulfur (S). may include one or more of

In another embodiment, the core comprises at least one of cadmium (Cd) and selenium (Se), and the first stabilizing layer comprises at least one of cadmium (Cd), selenium (Se), zinc (Zn) and sulfur (S). one or more, wherein the shell includes one or more of cadmium (Cd), selenium (Se), zinc (Zn) and sulfur (S), and the second stable layer includes cadmium (Cd), selenium (Se) , zinc (Zn) and sulfur (S).

In the first stable layer, a content difference between the core and cadmium (Cd) or selenium (Se) may be 15 mol% or less, and a content difference between the shell and zinc (Zn) may be 15 mol% or less.

In the second stable layer, a difference in content between the shell and sulfur (S) or zinc (Zn) may be 10 mol% or less.

The second stable layer may have a sulfur (S) content of 40 mol% to 50 mol%.

The shell may include one or more layers.

Another aspect of the present invention relates to a method for manufacturing quantum dots.

According to one embodiment, the quantum dot manufacturing method includes the steps of forming a core, forming a first stable layer, forming a shell, forming a second stable layer conversion efficiency according to the following formula 1 This may be a quantum dot manufacturing method for producing 100% or more quantum dots.

[Equation 1]

Conversion efficiency (%) = (Cw/Cf) x 100

(In Equation 1, Cw and Cf are the quantum efficiency (Cw) of the quantum dot containing the water-soluble ligand in the outermost portion when the outermost fat-soluble ligand is substituted with the water-soluble ligand, and the quantum dot containing the fat-soluble ligand in the outermost portion. Efficiency (Cf)).

The quantum dot manufacturing method may be one without a purification process after the core forming step, after the first stable layer forming step, and after the shell forming step.

The quantum dot manufacturing method includes the steps of forming the first stable layer, forming the shell, and forming the second stable layer, the product generated in the previous step in a reactor containing the reactants of each step. It may be a method of input.

The quantum dot manufacturing method may further include substituting a water-soluble ligand for the fat-soluble ligand of the quantum dot.

The quantum dot manufacturing method may be a manufacturing method for manufacturing a quantum dot having a stability index of 90% or more of the quantum dot.

The present invention has the effect of providing a quantum dot excellent in quantum efficiency, conversion efficiency and stability, and a method for manufacturing the same.

1 is a cross-sectional view of a quantum dot according to an embodiment of the present invention.
Figure 2 is a graph showing the change in relative quantum efficiency with time of the quantum dots containing the fat-soluble ligand of Example 1 and Comparative Example 1 of the present invention.
3 is a graph showing changes in relative quantum efficiency with time of quantum dots including water-soluble ligands of Example 1 and Comparative Example 1 of the present invention.

Hereinafter, specific embodiments of the present application will be described in more detail with reference to the accompanying drawings. However, the technology disclosed in the present application is not limited to the embodiments described herein and may be embodied in other forms.

However, the embodiments introduced herein are provided so that the disclosed content may be thorough and complete, and the spirit of the present application may be sufficiently conveyed to those skilled in the art. In the drawings, in order to clearly express the components of each device, the sizes such as width and thickness of the components are slightly enlarged. In addition, although only some of the components are illustrated for convenience of description, those skilled in the art will be able to easily grasp the remaining parts of the components.

In this specification, "upper" and "lower" are defined based on the drawings, and "upper" may be changed to "lower" and "lower" to "upper" depending on the viewpoint, and "on" Alternatively, what is referred to as “on” may include a case in which other structures are interposed in the middle as well as directly above. On the other hand, "directly on" or "directly on" means that other structures are not interposed therebetween.

In addition, those skilled in the art will be able to implement the idea of the present application in various other forms without departing from the technical spirit of the present application. And, in the plurality of drawings, the same reference numerals refer to elements that are substantially the same as each other.

In the present specification, "stability index" refers to an index indicating the degree of occurrence of defects or cracks on the surface or inside of the quantum dot for a certain period of time or longer. Specifically, the quantum dots containing the fat-soluble ligand and the quantum dots containing the water-soluble ligand can be measured in different ways. For example, for quantum dots containing a lipid-soluble ligand, the quantum dots are mixed with a solvent (nucleic acid: toluene = 1:1) and then precipitated by centrifugation. Purification is repeated three times by adding acetone to the precipitated quantum dots and centrifugation. After that, the final purified quantum dot powder is dissolved in a toluene solution at a concentration of 0.1 mg/ml, stored under a fluorescent lamp and at room temperature, the quantum efficiency is measured for 50 days, and the value calculated by the following Equation 2 means.

[Equation 2]

Stability index (%) = (50-day quantum efficiency)/(0-day quantum efficiency) × 100

(In Equation 2, the 0-day quantum efficiency means the quantum efficiency immediately after purification, and the 50-day quantum efficiency means the quantum efficiency after purification and storage at room temperature for 50 days in a toluene solution)

In addition, the quantum dots containing the water-soluble ligand were centrifuged three times with chloroform, purified by a method of removing the free ligand through a filter, and then the quantum dots were bathed in water at 95 ° C. for 2 hours, and then the following formula 3 It means the value calculated by

[Equation 3]

Stability index (%) = (quantum efficiency after 2 hours of bathing) / (quantum efficiency before bathing) × 100

As used herein, the term "core-shell structure" may refer to a conventional core-shell structure, and includes a structure in which the core or the shell is multi-layered, and "outermost" or "outermost layer" is the most means the outer layer.

As used herein, "component" means an element included in the core, the shell, the first stable layer and the second stable layer.

As used herein, the term “ligand layer” may refer to a layer formed by a space occupied by a ligand.

On the other hand, the meaning of the terms described in the present application should be understood as follows. Terms such as 'first' or 'second' are for distinguishing one component from other components, and the scope of rights should not be limited by these terms.

On the other hand, the expression in the singular described in the present application should be understood to include a plural expression unless the context clearly indicates otherwise, and terms such as 'comprise' or 'have' are used to describe features, numbers, steps, It is intended to designate the existence of an action, component, part, or combination thereof, but does not preclude the possibility of the existence or addition of one or more other features or numbers, steps, actions, components, parts, or combinations thereof. should be understood as

In addition, in performing the method or the manufacturing method, each process constituting the method may occur differently from the specified order unless a specific order is clearly described in context. That is, each process may occur in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

Hereinafter, the present invention will be described in detail.

quantum dots

Referring to FIG. 1, the quantum dot 100 of the present invention includes a core 10-shell 20 structure having one or more stable layers, and the quantum dot replaces the outermost fat-soluble ligand with a water-soluble ligand. The conversion efficiency according to the following formula 1 is 100% or more.

[Equation 1]

Conversion efficiency (%) = (Cw/Cf) x 100

(In Equation 1, Cw is the quantum efficiency of the quantum dot containing the water-soluble ligand in the outermost, Cf is the quantum efficiency of the quantum dot containing the fat-soluble ligand in the outermost).

For example, the quantum dot 100 may have a conversion efficiency of 100% or more, specifically 105% or more, more specifically 110% or more, according to Equation 1, when the outermost fat-soluble ligand is substituted with a water-soluble ligand. Within the above range, quantum dots have excellent quantum efficiency even in water-soluble solvents. Therefore, the quantum dot of the present invention has excellent quantum efficiency when it contains a lipid-soluble ligand and when it contains a water-soluble ligand, and the quantum efficiency does not decrease even if the ligand is substituted.

The diameter of the core 10 may be 1 nm to 6 nm, specifically 1.2 nm to 5 nm, and more specifically 2 nm to 5 nm. In the above range, two or more stable layers may be included, and the optical efficiency of quantum dots is excellent.

The thickness of the shell 20 may be 0.5 nm to 10 nm, specifically 0.5 nm to 8 nm, and more specifically 0.5 nm to 6 nm. In the above range, the stability of the quantum dot is increased. The shell may include two or more shells.

The quantum dot 100 of the present invention includes one or more stabilizing layers. The stabilizing layer may be formed between the layers and the layers of the core-shell structure or formed on the surface, and may increase the stability and reliability of the inside or the surface of the core-shell structure. Specifically, the stabilizing layer may be formed between the core and the shell and/or on the shell. The components of the stability layer can be applied to the core and the shell, and the content is appropriately adjusted to improve the bonding force between the layers, thereby increasing the stability and reliability of the core-shell structure.

Specifically, the quantum dot 100 may further include a first stabilizing layer 30 between the core 10 and the shell 20 and a second stabilizing layer 40 on the shell 20 . The quantum dot 100 may further include a ligand layer (ligand) 50 at the outermost portion.

The quantum dot 100 may further increase the stability or reliability of the quantum dot by including the first stable layer 30 and the second stable layer 40 .

The first stabilizing layer 30 is a layer that mediates the core 10 and the shell 20, and improves the bonding force between the core 10 and the shell 20, and core-shell internal defects or cracks ( crack) can be prevented, thereby increasing the stability or reliability of quantum dots.

For example, the first stable layer 30 includes one or more components having a content difference of 15 mol% or less, specifically 13 mol% or less, and more specifically 11 mol% or less, from the core 10, The shell 20 may include one or more components having a content difference of 15 mol% or less, specifically 13 mol% or less, and more specifically 11 mol% or less. In the above range, the stability of the core 10, the first stabilizing layer 30 and the shell 20 is increased.

In addition, the second stabilizing layer 40 is a layer that mediates the shell 20 and the ligand layer 50 , and improves the bonding force between the shell 20 and the ligand layer 50 , and core-shell surface defects. ) or by preventing the occurrence of cracks, it is possible to increase the stability or reliability of the quantum dots. In particular, the second stable layer may improve the binding force between the shell and the water-soluble ligand. In this case, the quantum dots have the advantage of further increasing stability when the ligand is substituted from oil-soluble to water-soluble.

For example, the second stable layer 40 may include one or more components having a content difference of 10 mol% or less, specifically 9 mol% or less, from the shell. In the above range, the stability of the shell 20, the second stable layer 40, and the ligand layer increases.

The molar ratio of the group 12 element to the group 16 element in the second stable layer 40 may be 4:6 to 6:4, specifically 5:5 to 6:4. Within the above range, quantum dots have the advantage of further increasing stability when the ligand is substituted from fat-soluble to water-soluble.

The thickness of the first stabilizing layer 30 or the second stabilizing layer 40 may be 0.3 nm to 2 nm, specifically 0.3 nm to 1.5 nm, and more specifically 0.3 nm to 1.0 nm. Within the above range, quantum dots have excellent stability and conversion efficiency.

The thickness ratio of the first stabilizing layer 30 and the second stabilizing layer 40 may be 0.5:1 to 2:1. In the above range, the quantum dots have excellent stability.

The quantum dots may have an average diameter of 6 nm to 30 nm, specifically 6 nm to 20 nm, and more specifically 6 nm to 12 nm. In the above range, the quantum dot may include two or more stable layers, and has the advantage of excellent optical properties.

The first stabilizing layer 30 or the second stabilizing layer 40 may have a shell-thickness ratio of 1:0.5 to 1:10, specifically 1:0.5 to 1:9. Within the above range, quantum dots are excellent in stability, quantum efficiency, conversion efficiency, and balance of optical properties.

The core, the shell, the first stable layer, or the second stable layer may include at least one of a Group 12-16 compound, a Group 13-15 compound, and a Group 14-16 compound.

The group 12-16 compound is cadmium sulfide (CdS), cadmium selenide (CdSe), cadmium thelenide (CdTe), zinc sulfide (ZnS), zinc selenide (ZnSe), zinc thelenide (ZnTe), mercury sulfide (HgS), Mercury Selenide (HgSe), Mercury Telenide (HgTe), Zinc Oxide (ZnO), Cadmium Oxide (CdO), Mercury Oxide (HgO), Cadmium Selenium Sulfide (CdSeS), Cadmium Selenium Telenide (CdSeTe) , Cadmium Sulfide Telenide (CdSTe), Cadmium Zinc Sulfide (CdZnS), Cadmium Zinc Selenide (CdZnSe), Cadmium Sulfide Selenide (CdSSe), Cadmium Zinc Telenide (CdZnTe), Cadmium Mercury Sulfide (CdHgS), Cadmium Mercury Cell Nide (CdHgSe), Cadmium Mercury Telenide (CdHgTe), Zinc Selenium Sulfide (ZnSeS), Zinc Selenium Telenide (ZnSeTe), Zinc Sulfide Telenide (ZnSTe), Mercury Selenium Sulfide (HgSeS), Mercury Selenium Telenide (HgSeTe) , Mercury Sulfide Telenide (HgSTe), Mercury Zinc Sulfide (HgZnS), Mercury Zinc Selenide (HgZnSe), Cadmium Zinc Oxide (CdZnO), Cadmium Mercury Oxide (CdHgO), Zinc Mercury Oxide (ZnHgO), Zinc Selenium Oxide ( ), Zinc Telenium Oxide (ZnTeO), Zinc Sulfide Oxide (ZnSO), Cadmium Selenium Oxide (CdSeO), Cadmium Telenium Oxide (CdTeO), Cadmium Sulfide Oxide (CdSO), Mercury Selenium Oxide (HgSeO), Mercury Telenium Oxide (HgTeO), Mercurysulfide Oxide (HgSO), Cadmium Zinc Selenium Sulfide (CdZnSeS), Cadmium Zinc Selenium Telenide (CdZnSeTe), Cadmium Zinc Sulfide Telenide (CdZnSTe), Cadmium Mercury Selenium Sulfide (CdHgSeS), (CdHgSeTe), Cadmium Mercury Sulfide Telenide (CdHgSTe), Mercury Zinc Selenium Sulfide (HgZnSeS), Mercury Zinc Selenium Telenide (HgZnSeTe), Mercury Zinc Sulfide Telenide (HgZnSTe), Cadmium Zinc Xelenium Oxide (CdZnSeO), Cadmium Zinc Telenium Oxide (CdZnTeO), Cadmium Zinc Sulfide Oxide (CdZnSO), Cadmium Mercury Selenium Oxide (CdHgSeO), Cadmium Mercury Telenium Oxide (CdHgTeO), Cadmium Mercury Sulfide Oxide (CdHgSO) Mercury selenium oxide (ZnHgSeO), zinc mercury terenium oxide (ZnHgTeO), and may include at least one of zinc mercury sulfide oxide (ZnHgSO).

The group 13-15 compound is gallium phosphorus (GaP), gallium arsenide (GaAs), gallium antimony (GaSb), gallium nitride (GaN), aluminum phosphorus (AlP), aluminum arsenide (AlAs), Aluminum antimony (AlSb), aluminum nitride (AlN), indium phosphorus (InP), indium arsenide (InAs), indium antimony (InSb), indium nitride (InN), gallium phosphorous arsenide (GaPAs) , Gallium phosphorus antimony (GaPSb), gallium phosphorus nitride (GaPN), gallium arsenide nitride (GaAsN), gallium antimony nitride (GaSbN), aluminum phosphorous arsenide (AlPAs), aluminum phosphorous anti Mono (AlPSb), aluminum phosphorus nitride (AlPN), aluminum arsenide nitride (AlAsN), aluminum antimony nitride (AlSbN), indium phosphorous arsenide (InPAs), indium phosphorus antimony (InPSb), Indium phosphorus nitride (InPN), indium arsenide nitride (InAsN), indium antimony nitride (InSbN), aluminum gallium phosphorus (AlGaP), aluminum gallium arsenide (AlGaAs), aluminum gallium antimony (AlGaSb) , aluminum gallium nitride (AlGaN), aluminum arsenide nitride (AlAsN), aluminum antimony nitride (AlSbN), indium gallium phosphorus (InGaP), indium gallium arsenide (InGaAs), indium gallium antimony (InGaSb) , indium gallium nitride (InGaN), indium arsenide nitride (InAsN), indium antimony nitride (InSbN), aluminum indium phosphorus (AlInP), aluminum indium arsenide (AlInAs), aluminum indium antimony (AlInSb) , aluminum indium nitride (AlInN), aluminum arsenide nitride (AlAsN), aluminum antimony nitride (AlSbN), aluminum phosphorus nitride (AlPN), gallium aluminum phosphorous arsenide (GaAlPAs), gallium aluminum phosphorus Antimony (GaAlPSb), gallium indium phosphorous arsenide (GaInPAs), Gallium indium aluminum arsenide (GaInAlAs), gallium aluminum phosphorus nitride (GaAlPN), lithium aluminum arsenide nitride (GaAlAsN), gallium aluminum antimony nitride (GaAlSbN), gallium indium phosphorus nitride (GaInPN), gallium Indium arsenide nitride (GaInAsN), gallium indium aluminum nitride (GaInAlN), gallium antimony phosphorus nitride (GaSbPN), gallium arsenide phosphorus nitride (GaAsPN), gallium arsenide antimony nitride (GaAsSbN) , gallium indium phosphorus antimony (GaInPSb), gallium indium phosphorus nitride (GaInPN), gallium indium antimony nitride (GaInSbN), gallium phosphorus antimony nitride (GaPSbN), indium aluminum phosphorous arsenide (InAlPAs) ), indium aluminum phosphorus nitride (InAlPN), indium phosphorus arsenide nitride (InPAsN), indium aluminum antimony nitride (InAlSbN), indium phosphorous antimony nitride (InPSbN), indium arsenide antimonite It may include at least one of lide (InAsSbN) and indium aluminum phosphorus antimony (InAlPSb).

The group 14-16 compound is tin oxide (SnO), tin sulfide (SnS), tin selenide (SnSe), tintelenide (SnTe), lead sulfide (PbS), lead selenide (PbSe), lead thelenide (PbTe), germanium oxide (GeO), germanium sulfide (GeS), germanium selenide (GeSe), germanium telenide (GeTe), tin selenium sulfide (SnSeS), tin selenium telenide (SnSeTe), tin Sulphide teleenide (SnSTe), lead selenium sulfide (PbSeS), lead selenium thelenide (PbSeTe), lead sulfide teleenide (PbSTe), tin lead sulfide (SnPbS), tin lead selenide (SnPbSe), tin lead thelenide ( SnPbTe), tin oxide sulfide (SnOS), tin oxide selenide (SnOSe), tin oxide thelenide (SnOTe), germanium oxide sulfide (GeOS), germanium oxide selenide (GeOSe), germanium oxide selenide (GeOTe) ), tin-lead sulfide-selenide (SnPbSSe), tin-lead-selenium-tellenide (SnPbSeTe), and tin-lead sulfide- selenide (SnPbSTe).

The core 10 , the shell 20 , the first stabilizing layer 30 or the second stabilizing layer 40 may include three or more components. For example, the shell 20, the first stabilizing layer 30, and the second stabilizing layer 40 may include three or more components, but is not limited thereto.

Specifically, the core 10 may include cadmium (Cd) and selenium (Se). The shell 20 , the first stabilizing layer 30 , or the second stabilizing layer 40 may include at least one of cadmium (Cd), selenium (Se), zinc (Zn), and sulfur (S).

The core, the shell, and the stabilizing layer may include cadmium (Cd).

Cadmium (Cd) or selenium (Se) content (mol%) may increase toward the center of the quantum dot.

In one embodiment, in the quantum dot, the core includes at least one of cadmium (Cd) and selenium (Se), and the first stable layer includes at least one of cadmium (Cd), selenium (Se) and zinc (Zn). Including, wherein the shell includes at least one of cadmium (Cd), selenium (Se), zinc (Zn) and sulfur (S), and the second stable layer includes cadmium (Cd), zinc (Zn) and sulfur (S) may include one or more of.

In another embodiment, the core comprises at least one of cadmium (Cd) and selenium (Se), and the first stabilizing layer comprises at least one of cadmium (Cd), selenium (Se), zinc (Zn) and sulfur (S). one or more, wherein the shell includes one or more of cadmium (Cd), selenium (Se), zinc (Zn) and sulfur (S), and the second stable layer includes cadmium (Cd), selenium (Se) , zinc (Zn) and sulfur (S).

In the first stable layer, the difference in content between the core and cadmium (Cd) or selenium (Se) is 15 mol% or less, specifically 13 mol% or less, more specifically 11 mol% or less, and the shell and zinc (Zn) ) may be 15 mol% or less, specifically 13 mol% or less, and more specifically 11 mol% or less. In addition, in the second stable layer, a difference in content between the shell and sulfur (S) or zinc (Zn) may be 10 mol% or less, specifically, 9 mol% or less.

The second stable layer may have a sulfur (S) content of 40 mol% to 50 mol%, specifically 40 mol% to 48 mol%, and more specifically 41 mol% to 46 mol%. Within the above range, quantum dots have excellent conversion efficiency.

In one embodiment, the quantum dot is, for example, the core 10 of the quantum dot 100 is cadmium (Cd) 50 to 60 mol%, specifically 53 to 57 mol%, selenium (Se) 40 to 50 mol%, specifically as 53 to 57 mol%. Within the above range, quantum dots have excellent quantum efficiency and optical properties at a wavelength of 500 nm to 560 nm.

In another embodiment, the quantum dot is, for example, the core 10 of the quantum dot 100 is cadmium (Cd) 75 to 85 mol%, specifically 78 to 82 mol%, selenium (Se) 15 to 25 mol%, specifically as 18 to 22 mol%. Within the above range, quantum dots have excellent quantum efficiency and optical properties at a wavelength of 560 nm to 630 nm.

In one embodiment, the first stable layer 30 is cadmium (Cd) 45 to 55 mol%, specifically 48 to 52 mol%, selenium (Se) 18 to 28 mol%, specifically 21 to 25 mol%, zinc ( Zn) 22 to 32 mol%, specifically 25 to 29 mol%. Within the above range, quantum dots have excellent conversion efficiency and optical properties at a wavelength of 500 nm to 560 nm.

In another embodiment, the first stable layer 30 is cadmium (Cd) 21 to 31 mol%, specifically 24 to 28 mol%, selenium (Se) 2 to 12 mol%, specifically 5 to 10 mol%, zinc ( Zn) 7 to 17 mol%, specifically 10 to 14 mol%, sulfur (S) 49 to 59 mol%, specifically 52 to 56 mol%. Within the above range, the quantum dots have excellent conversion efficiency and optical properties at a wavelength of 560 nm to 630 nm.

In one embodiment, the shell 20 is cadmium (Cd) 9 to 19 mol%, specifically 12 to 17 mol%, selenium (Se) 0.5 to 10 mol%, specifically 2 to 6 mol%, zinc (Zn) It may include 32 to 42 mol%, specifically 35 to 39 mol%, 39 to 49 mol% of sulfur (S), specifically 42 to 46 mol%. In the above range, the quantum dots have excellent conversion efficiency and optical properties at a wavelength of 500 nm to 560 nm.

In another embodiment, the shell 20 comprises 21 to 31 mole % cadmium (Cd), specifically 24 to 28 mole %, selenium (Se) 0.5 to 8 mole %, specifically 0.5 to 4 mole %, zinc (Zn) 11 to 21 mol%, specifically 14 to 19 mol%, 51 to 61 mol% of sulfur (S), specifically 53 to 58 mol%. In the above range, the quantum dots have excellent conversion efficiency and optical properties at a wavelength of 560 nm to 630 nm.

In one embodiment, the second stable layer 40 is cadmium (Cd) 7 to 17 mol%, specifically 10 to 14 mol%, zinc (Zn) 39 to 49 mol%, specifically 42 to 46 mol%, sulfur (S) 39 to 49 mol%, specifically 42 to 46 mol%. Within the above range, the quantum dots have excellent stability index, quantum efficiency, conversion efficiency, and optical properties at a wavelength of 500 nm to 560 nm.

In another embodiment, the second stabilizing layer 40 is cadmium (Cd) 26 to 36 mol%, specifically 29 to 33 mol%, selenium (Se) 0.1 to 5 mol%, specifically 0.1 to 3 mol%, zinc (Zn) 20 to 30 mol%, specifically 23 to 27 mol%, sulfur (S) 38 to 48 mol%, specifically 41 to 45 mol% may be included. Within the above range, the quantum dots have excellent stability index, quantum efficiency, conversion efficiency, and optical properties at a wavelength of 560 nm to 630 nm.

The quantum dot 100 may further include a ligand layer 50 on the outermost side. In FIG. 1 , the ligand layer 50 is illustrated in a form in which a ligand is coupled to the second stable layer, but the ligand layer 50 may refer to a layer formed by a space occupied by the ligand.

In one embodiment, the ligand layer 50 includes a fat-soluble ligand, and the fat-soluble ligand is tri-n-octylphosphine oxide, decylamine, didecylamine. ), tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, octadecylamine, undecylamine, dioctadecylamine ), N,N-dimethyldecylamine (N,N-dimethyldecylamine), N,N-dimethyldodecylamine (N,N-dimethyldodecylamine), N,N-dimethylhexadecylamine (N,N-dimethylhexadecylamine), N ,N-dimethyltetradecylamine (N,N-dimethyltetradecylamine), N,N-dimethyltridecylamine (N,N-dimethyltridecylamine), N,N-dimethylundecylamine (N,N-dimethylundecylamine), N-decyl Amine (N-decylamine), N-methyloctadecylamine (N-methyloctadecylamine), didodecylamine (didodecylamine), tridodecylamine (tridodecylamine), cyclododecylamine (cyclododecylamine), N-methyldodecylamine (N -methyldodecylamine, trioctylamine, lauric acid, palmiticacid, oleic acid, stearic acid, myristicacid, elaidic acid ( elaidic acid, eicosanoic acid, heneicosanoic acid, tricosanoic acid, docosanoic acid, tetracosanoic acid, hexacosanonic acid acosanoic acid), heptacosanoic acid, octacosanoic acid, and cis-13-docosenoic acid.

For example, quantum dots may include tri-n-octylphosphine as a fat-soluble ligand. When the quantum dot 100 contains a fat-soluble ligand, there is a stable effect in an organic solvent.

In another embodiment, the ligand layer 50 includes a water-soluble ligand, and the water-soluble ligand includes silica, polyethylene glycol (PEG), mercaptopropionic acid (MPA), cysteamine, and mercaptoacetic acid (mercapto-). acetic acid), mercapto-undecanol, 2-mercapto-ethanol, 1-thio-glycerol, deoxyribonucleic acid (DNA), Mercapto acetic acid, mercapto-undecanoic acid, 1-mercapto-6-phenyl-hexane, 1,16-dimercapto-hexa Decane (1,16-dimecapto-hexadecane), 18-mercapto-octadecyl amine (18-mercapto-octadecyl amine), tri-octyl phosphine, 6-mercapto-hexane (6-mercapto- hexane), 6-mercapto-hexanoic acid, 16-mercapto-hexadecanoic acid, 18-mercapto-octadecylamine (18- mercapto-octadecyl amine), 6-mercapto-hexyl amine or 8-hydroxy-octylthiol, 1-thio-glycerol , mercapto-acetic acid, mercapto-undecanoic acid, hydroxamate, a derivative of hydroxamic acid, and ethylene diamine. .

For example, quantum dots may include mercaptopropionic acid (MPA) as a water-soluble ligand. When the quantum dot 100 includes a water-soluble ligand, there is an advantage in dispersing the quantum dot in a water-soluble solvent.

The ligand layer 50 may have a thickness of 0.1 nm to 50 nm, specifically 0.1 nm to 20 nm, and more specifically 0.1 nm to 10 nm. Within the above range, quantum dots have advantages in that physical properties depending on the ligand are expressed, and dispersion power is excellent.

The quantum dot 100 may have a quantum efficiency of 80% or more, specifically 85% or more, and more specifically 90% or more. Within the above range, the quantum dots have excellent optical properties. The quantum dot of the present invention not only has high quantum efficiency immediately after synthesis, but also has a high stability index as described above, so that the quantum efficiency does not decrease even after a certain period of time after synthesis, so that the quantum efficiency can be maintained for a long time.

The quantum dots may have a stability index of 90% or more, specifically 95% or more, and more specifically 98% or more. Within the above range, quantum dots have excellent reliability and consistently excellent quantum efficiency.

The stability index is an index indicating the degree of occurrence of defects or cracks on the surface or inside of the quantum dots for more than a certain time, and the higher the stability index, the more stable the quantum dots without the occurrence of defects or cracks exist. When a defect or a crack occurs in a quantum dot, the quantum efficiency is rapidly reduced. Therefore, a quantum dot with a high stability index means not only excellent reliability but also consistently high quantum efficiency.

Here, the stability index can be measured by different methods for the quantum dots including the lipid-soluble ligand and the quantum dots including the water-soluble ligand.

For example, for quantum dots containing a fat-soluble ligand, after quantum dot synthesis, the quantum dots are mixed with a solvent (nucleic acid: toluene 1:1) and then precipitated by centrifugation. Purification is performed by adding acetone to the precipitated quantum dots and centrifuging. After repeating 3 times, the final purified quantum dot powder is dissolved in a toluene solution at a concentration of 0.1 mg/ml, stored under a fluorescent lamp and at room temperature, and quantum efficiency is measured for 50 days, which is a value calculated by Equation 2 below.

[Equation 2]

Stability index (%) = (50-day quantum efficiency)/(0-day quantum efficiency) × 100

In Equation 2, the 0-day quantum efficiency means the quantum efficiency immediately after purification, and the 50-day quantum efficiency means the quantum efficiency after purification and storage at room temperature for 50 days in a toluene solution.

In addition, the quantum dots containing the water-soluble ligand were centrifuged three times with chloroform, purified by a method of removing the free ligand through a filter, and then the quantum dots were bathed in water at 95 ° C. for 2 hours, and then the following formula 3 It means the value calculated by

[Equation 3]

Stability index (%) = (quantum efficiency after 2 hours of bathing) / (quantum efficiency before bathing) × 100

The half width of the quantum dots may be 40 nm or less, specifically 38 nm or less, and more specifically 35 nm or less. In the above range, quantum dots have an advantage in color realization.

quantum dots Manufacturing method

Another aspect of the present invention relates to a method for manufacturing quantum dots.

According to one embodiment, the quantum dot manufacturing method is converted by the following formula 1 comprising the step of forming a core, forming a first stable layer, forming a shell, forming a second stable layer The efficiency may be 100% or more, specifically 105% or more, and more specifically 110% or more.

[Equation 1]

Conversion efficiency (%) = (Cw/Cf) x 100

(In Equation 1, Cw and Cf are the quantum efficiency (Cw) of the quantum dot containing the water-soluble ligand in the outermost portion when the outermost fat-soluble ligand is substituted with the water-soluble ligand, and the quantum dot containing the fat-soluble ligand in the outermost portion. Efficiency (Cf)).

The water-soluble ligand is silica, polyethylene glycol (PEG), mercaptopropionic acid (MPA), cysteamine, mercapto-acetic acid, mercapto-undecanol, 2-mercapto. Ethanol (2-mercapto-ethanol), 1-thio-glycerol (1-thio glycerol), deoxyribonucleic acid (DNA), mercapto acetic acid, mercapto-undecanoic acid (mercapto-undecanoic) acid), 1-mercapto-6-phenyl hexane (1-mercapto-6-phenyl-hexane), 1,16-dimercapto-hexadecane (1,16-dimecapto-hexadecane), 18-mercapto-octadecyl 18-mercapto-octadecyl amine, tri-octyl phosphine, 6-mercapto-hexane, 6-mercapto-hexanoic acid ), 16-mercapto-hexadecanoic acid (16-mercapto-hexadecanoic acid), 18-mercapto-octadecylamine (18-mercapto-octadecyl amine), 6-mercapto-hexylamine (6-mercapto- hexyl amine) or 8-hydroxy-octylthiol, 1-thio-glycerol, mercapto-acetic acid, mercaptoundecanoic acid (mercapto- undecanoic acid), hydroxamate, a derivative of hydroxamic acid, and ethylene diamine. For example, the water-soluble ligand may include mercaptopropionic acid (MPA).

In the quantum dot manufacturing method, there may be no purification process after the core forming step, after the first stable layer forming step, and after the shell forming step.

In the quantum dot manufacturing method, the step of forming the first stable layer, the step of forming the shell, and the step of forming the second stable layer, the product generated in the previous step in a reaction tank containing the reactants of each step It may be a method of input.

Hereinafter, each step of the quantum dot manufacturing method will be described in detail.

The forming of the core may be a step of forming core-ligand particles by heating the first mixture including the core precursor, the ligand for the core and the buffer for 1 minute to 10 minutes, specifically, 1 minute to 5 minutes.

The core precursor may include a cation core precursor and an anion core precursor. The cation core precursor may include at least one of a group 12 element and a group 13 element, and the anion core precursor may include at least one of a group 15 element and a group 16 element.

For example, the cation core precursor includes at least one of zinc (Zn), cadmium (Cd) and indium (In), and the anion core precursor includes sulfur (S), selenium (Se), and tellurium (Te). and phosphorus (P). For example, the core precursor may include at least one of cadmium (Cd) and selenium (Se).

The heating may be 250°C to 350°C, specifically 270°C to 340°C, more specifically 300°C to 340°C. In the above range, the core yield increases, and the amount of unreacted precursor decreases.

The ligand for the core is octanethiol, decanethiol, dodecanethiol, lauric acid, palmitic acid, oleic acid, tri-n-octyl Phosphine oxide (tri-n-octylphosphine oxide), tri-n-octylphosphine (tri-n-octylphosphine), octylamine, decylamine, didecylamine, tridecylamine ( tridecylamine), tetradecylamine, pentadecylamine, hexadecylamine, octadecylamine, and dodecylamine. For example, the ligand for the core may use oleic acid or tri-n-octylphosphine.

The buffer is 1-octadecene (1-octadecene), 1-nonadecene (1-nonadecene), cis-2-methyl-7-octadecene (cis-2-methyl-7-octadecene), 1-heptadecene ( 1-heptadecene), 1-hexadecene (1-hexadecene), 1-pentadecene (1-pentadecene), 1-tetradecene (1-tetradecene), 1-tridecene (1-tridecene), 1-undecene ( 1-undecene), 1-dodecene, and 1-decene. For example, 1-octadecene can be used as a buffer.

The forming of the first stable layer includes heating the reactor including the first stable layer precursor and the ligand for the first stable layer for 1 minute to 20 minutes, specifically 5 minutes to 15 minutes, while the core-ligand prepared above The particles may be added to form the core-first stable layer-ligand particles.

The first stable layer precursor may include at least one of a group 12 element, a group 13 element, a group 15 element, and a group 16 element. Specifically, the first stable layer precursor may include at least one of zinc (Zn), cadmium (Cd), indium (In), sulfur (S), selenium (Se), tellurium (Te), and phosphorus (P). have. For example, the first stable layer precursor may include at least one of cadmium (Cd), selenium (Se), and sulfur (S).

The heating may be 250°C to 350°C, specifically, 270°C to 330°C, more specifically, 270°C to 310°C. In the above range, the yield of the first stable layer increases, and the amount of unreacted precursor decreases.

The ligand for the first stable layer is octanethiol, decanethiol, dodecanethiol, lauric acid, palmitic acid, oleic acid, tri-n -Octylphosphine oxide (tri-n-octylphosphine oxide), tri-n-octylphosphine (tri-n-octylphosphine), octylamine, decylamine, didecylamine, tridecyl It may include one or more of amine (tridecylamine), tetradecylamine (tetradecylamine), pentadecylamine (pentadecylamine), hexadecylamine (hexadecylamine), octadecylamine (octadecylamine), and dodecylamine (dodecylamine). For example, dodecanethiol may be used as the ligand for the first stable layer.

The step of forming the shell includes heating the reactor including the shell precursor and the ligand for the shell for 5 to 40 minutes, specifically 15 to 30 minutes, and adding the prepared core-first stable layer-ligand particles to , core-first stable layer-shell-ligand particles can be formed.

The shell precursor may include at least one of a group 12 element, a group 13 element, a group 15 element, and a group 16 element. Specifically, the shell precursor may include at least one of zinc (Zn), cadmium (Cd), indium (In), sulfur (S), selenium (Se), tellurium (Te), and phosphorus (P). For example, the shell precursor may include one or more of cadmium (Cd), selenium (Se), zinc (Zn), and sulfur (S).

The heating may be 250°C to 350°C, specifically, 270°C to 330°C, more specifically, 270°C to 310°C. In the above range, the yield of the shell increases, and the amount of unreacted precursor decreases.

The ligand for the shell is octanethiol, decanethiol, dodecanethiol, lauric acid, palmitic acid, oleic acid, tri-n-octylphos tri-n-octylphosphine oxide, tri-n-octylphosphine, octylamine, decylamine, didecylamine, tridecylamine ), tetradecylamine, pentadecylamine, hexadecylamine, octadecylamine, and dodecylamine. For example, the ligand for the shell may use tri-n-octylphosphine.

The forming of the second stable layer includes heating the reactor including the second stable layer precursor and the ligand for the second stable layer for 10 minutes to 60 minutes, specifically 20 minutes to 40 minutes, while the core-agent prepared above 1 stable layer-shell-ligand particles may be added to form core-first stable layer-shell-second stable layer-ligand particles.

The second stable layer precursor may include at least one of a group 12 element, a group 13 element, a group 15 element, and a group 16 element. Specifically, the second stable layer precursor may include at least one of zinc (Zn), cadmium (Cd), indium (In), sulfur (S), selenium (Se), tellurium (Te), and phosphorus (P). have. For example, the second stable layer precursor may include at least one of cadmium (Cd), selenium (Se), and sulfur (S).

The heating may be 250°C to 350°C, specifically, 270°C to 330°C, more specifically, 270°C to 310°C. In the above range, the yield of the second stable layer increases, and the amount of unreacted precursor decreases.

The ligand for the second stable layer is octanethiol, decanethiol, dodecanethiol, lauric acid, palmitic acid, oleic acid, tri-n -Octylphosphine oxide (tri-n-octylphosphine oxide), tri-n-octylphosphine (tri-n-octylphosphine), octylamine, decylamine, didecylamine, tridecyl It may include one or more of amine (tridecylamine), tetradecylamine (tetradecylamine), pentadecylamine (pentadecylamine), hexadecylamine (hexadecylamine), octadecylamine (octadecylamine), and dodecylamine (dodecylamine). For example, dodecanethiol may be used as the ligand for the second stable layer.

According to another embodiment, the quantum dot manufacturing method may further include substituting a water-soluble ligand for the fat-soluble ligand of the quantum dot.

In the step of substituting the oil-soluble ligand of the quantum dot with the water-soluble ligand, the prepared core-first stable layer-shell-second stable layer-ligand (oil-soluble) particles may be introduced into a reaction vessel containing a water-soluble ligand precursor.

The quantum dot manufacturing method may be a quantum dot manufacturing method for producing a quantum dot having a stability index of 90% or more, specifically 95% or more, and more specifically 98% or more of the quantum dot.

The stability index is substantially the same as described in the quantum dot, one aspect of the present invention.

The quantum dot manufacturing method may further include a purification step. The purification step may include precipitating the quantum dots in a non-polar solvent and centrifuging the quantum dots. The present invention is characterized in that only the final purification step is included after the formation of the quantum dot is completed, and the purification step is not included during the quantum dot synthesis. By applying the minimum purification step, the quantum dot synthesis yield is high, and there is an advantage in that the stability of the quantum dot can be prevented from being deteriorated.

Each step of the quantum dot manufacturing method may be performed in an inert gas atmosphere. The inert gas is not limited as long as it belongs to group 18. The inert gas may include, for example, one or more of argon, neon, helium, krypton, xenon, and radon.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is presented as a preferred example of the present invention and cannot be construed as limiting the present invention in any sense.

Content not described here will be omitted because it can be technically inferred sufficiently by a person skilled in the art.

Example

Example One

In a three-necked flask, 1 g of Zn(Ac), 0.441 g of CdO, 20 mL of Oleic Acid, and 75 mL of Octadecene were mixed, moisture was removed at 150 ° C for 1 hour under a nitrogen atmosphere, and the temperature was raised to 300 ° C. Then, TOP 1 ml and Se 0.045 g was injected and heated for 3 minutes to form a core.

After that, 0.5 ml of dodecanethiol is added and reacted for 10 minutes to form a first stable layer in the form of three or more alloys, and a solution containing 1 ml of TOP and 0.025 g of Se is added to the reaction port of the three-necked flask. was added to the reaction mixture for 20 minutes to form a shell.

After the shell is formed, 1g of Zn(Ac), 0.21g of CdO, Oleic Acid (10mL), and Octadecene (35mL) are reacted at 300℃ in another reaction port to prepare the second stable layer material, and 5ml of this is injected and reacted for 30 minutes, and 0.5 ml of dodecanethiol was injected and reacted for 20 minutes to finally form a second stable layer. A first stable layer-shell-second stable layer-ligand (oil-soluble) quantum dots were formed.

The stability index and quantum efficiency of the core-first stable layer-shell-second stable layer-ligand (oil-soluble) quantum dots were measured, and are shown in Table 1 below.

Thereafter, the prepared core-first stable layer-shell-second stable layer particles were added to a reaction tank containing mercaptopropionic acid (MPA), and reacted at 60° C. for 60 minutes to react with the core-first stable layer. -Shell-Second stable layer-Water-soluble ligand quantum dots were formed.

The stability index and quantum efficiency of the core-first stable layer-shell-second stable layer-water-soluble ligand quantum dots were measured, and the conversion efficiency was calculated and shown in Table 1 below.

The content of the core of the quantum dot is cadmium (Cd) 55 mol%, selenium 45 mol%, the content of the first stable layer is cadmium (Cd) 50 mol%, selenium 23 mol%, zinc 27 mol%, the shell The content of cadmium (Cd) is 14.5 mol%, selenium 4 mol%, zinc 37 mol%, sulfur 44.5 mol%, and the content of the second stable layer is cadmium (Cd) 12 mol%, zinc 44 mol%, sulfur 44 % by mole. The core had a particle diameter of 2.5 nm, and the thickness of each of the first stabilizing layer, the shell, and the second stabilizing layer was 0.45 nm, 2.9 nm, and 0.4 nm. The thickness of the water-soluble ligand layer was 0.4 nm.

The content (mol%) and thickness of each quantum dot layer is Time Of Flight- Medium Energy Ion Scattering Spectroscopy: MEIS-K120 SURFACE ANALYSIS SYSTEM (manufacturer: K-MAC), and quantum efficiency characteristics are QE-SERIES QUANTUM EFFICIENCY MEASUREMENT SYSTEM (manufacturer) Otsuka Electronics), the size was measured with a TEM of OXFORD Instruments.

Example 2

In a three-necked flask, 2 g of Zn(Ac), 0.2 g of CdO, 20 mL of Oleic Acid, and 75 mL of Octadecene were mixed, water was removed in a nitrogen atmosphere at 150 ° C. for 1 hour, and then the temperature was raised to 310 ° C., TOP 1 ml and Se 0.045 g, 0.5 ml of dodecanethiol was injected and heated for 10 minutes to form a core.

After that, TOP 1ml, S 0.2g were injected and reacted for 5 minutes to form a first stable layer in the form of three or more alloys, and a solution containing 0.5ml of dodecanethiol was put into the three-necked flask, The reaction was carried out for 20 minutes to form a shell.

After the shell is formed, 1 g of Zn(Ac), 0.21 g of CdO, 10 mL of Oleic Acid, and 35 mL of Octadecene are reacted at 300°C in another reaction zone to prepare a second stable layer material, 5 ml of which is injected for 30 minutes After reacting, 0.5 ml of dodecanethiol was injected and reacted for 20 minutes to finally form a second stable layer, purified with an ethanol and toluene mixture, dissolved in an organic solvent, and dispersed to disperse the core-first Stable layer-shell-second stable layer-ligand (oil-soluble) quantum dots were formed.

The stability index and quantum efficiency of the core-first stable layer-shell-second stable layer-ligand (oil-soluble) quantum dots were measured, and are shown in Table 1 below.

Thereafter, the prepared core-first stable layer-shell-second stable layer particles were added to a reaction tank containing mercaptopropionic acid (MPA), and reacted at 60° C. for 60 minutes to react with the core-first stable layer. -Shell-Second stable layer-Water-soluble ligand quantum dots were formed.

The stability index and quantum efficiency of the core-first stable layer-shell-second stable layer-water-soluble ligand quantum dots were measured, and the conversion efficiency was calculated and shown in Table 1 below.

The content (mol%) of the quantum dot core is cadmium (Cd) 80 mol%, selenium 20 mol%, and the content of the first stable layer is cadmium (Cd) 26.5 mol%, selenium (Se) 7.5 mol%, zinc (Zn) ) 12 mol%, sulfur (S) 54 mol%, and the shell content is cadmium (Cd) 26 mol%, selenium (Se) 2 mol%, zinc (Zn) 16.3 mol%, sulfur (S) 55.7 mol% , the content of the second stable layer is cadmium (Cd) 31 mol%, selenium (Se) 1 mol%, zinc (Zn) 25 mol%, sulfur (S) 43 mol%, the core has a particle size of 4 nm, The thickness of the first stabilizing layer, the shell and the second stabilizing layer was 0.5 nm, 0.75 nm, and 0.75 nm, respectively, and the thickness of the water-soluble ligand layer was 0.4 nm. The stability index, quantum efficiency and conversion efficiency were measured in the same manner as in Example 1 and are shown in Table 1 below.

comparative example One

Quantum dots were synthesized in the same manner as in Example 1, except that the first and second stable layers were not formed and the contents of the core and shell were adjusted as follows, and core-shell-ligand (oil-soluble) quantum dots And the stability index, quantum efficiency and conversion efficiency of the core-shell-water-soluble ligand quantum dots were measured, and are shown in Table 1 below.

The content of the core of the quantum dot is cadmium (Cd) 20 mol%, selenium 13 mol%, zinc 50 mol%, sulfur 17 mol%, and the content of the shell is selenium 5 mol%, zinc 41 mol%, sulfur 54 mol% It was. The core had a particle diameter of 5.8 nm, and the shell had a thickness of 2.4 nm. The thickness of the water-soluble ligand layer was 0.4 nm.

comparative example 2

Quantum dots were synthesized in the same manner as in Example 1 except that the first stable layer was not formed, and core-shell-second stable layer-ligand (oil-soluble) quantum dots and core-shell-second stable layer-water-soluble ligand The stability index, quantum efficiency and conversion efficiency of the quantum dots were measured, and are shown in Table 1 below.

The content of the core of the quantum dot is cadmium (Cd) 42 mol%, selenium 34 mol%, zinc 12 mol%, sulfur 12 mol%, and the content of the shell is cadmium (Cd) 13 mol%, selenium 7.5 mol%, 41 mol% of zinc and 38.5 mol% of sulfur, and the content of the second stable layer was 47 mol% of cadmium (Cd), 46 mol% of zinc, and 7 mol% of sulfur. The core had a particle diameter of 1.8 nm, and the thickness of the shell and the second stabilizing layer were 2.1 nm and 0.55 nm, respectively. The thickness of the water-soluble ligand layer was 0.4 nm.

comparative example 3

Quantum dots were synthesized in the same manner as in Example 2 except that the first stable layer was not formed, and core-first stable layer-shell-ligand (oil-soluble) quantum dots and core-first stable layer-shell-water-soluble ligand The stability index, quantum efficiency and conversion efficiency of the quantum dots were measured, and are shown in Table 1 below.

The content of the core of the quantum dot is cadmium (Cd) 62 mol%, selenium 38 mol%, the content of the shell is cadmium (Cd) 48 mol%, selenium 12 mol%, zinc 12 mol%, sulfur 28 mol%, The content of the second stable layer was 10 mol% of cadmium (Cd), 10 mol% of selenium, 33 mol% of zinc, and 47 mol% of sulfur. The core had a particle diameter of 2.3 nm, and the thickness of the shell and the second stabilizing layer was 2.5 nm and 0.5 nm, respectively. The thickness of the water-soluble ligand layer was 0.4 nm.

Example comparative example One 2 One 2 3 structure core ○ ○ ○ ○ ○ first stable layer ○ ○ × × × shell ○ ○ ○ ○ ○ second stable layer ○ ○ × ○ ○ quantum efficiency Lipid-soluble ligand (outermost) 90 90 60 80 70 Water-soluble ligand (outermost) 100 100 44 60 50 Conversion efficiency (%) 110 110 73 75 71 stability index Lipid-soluble ligand (outermost) 100 98 50 60 64 Water-soluble ligand (outermost) 100 100 20 62 60

As shown in Table 1, the quantum dots of the present invention including a first stable layer and a second stable layer in the core, the shell, as well as the quantum efficiency is excellent, the stability index and conversion efficiency is also excellent. On the other hand, it can be seen that in Comparative Examples 1 to 3, which do not include any one of the first and second stable layers, quantum efficiency, stability index, and conversion efficiency are significantly reduced.

Property evaluation method

(1) Analysis of components and contents of core, shell, stabilizing layer and ligand layer: Quantum efficiency was measured using QE-SERIES QUANTUM EFFICIENCY MEASUREMENT SYSTEM (Otsuka Electronics), and MEIS-K120 SURFACE ANALYSIS SYSTEM (TOF-MEIS:K- MAC) was analyzed for ligand composition ratio, and TEM was analyzed for SIZE.

(2) Quantum efficiency: QE-SERIES QUANTUM EFFICIENCY MEASUREMENT SYSTEM (Otsuka Electronics): Rate of the number of fluorescence photons to the number of absorbed photons was used to measure quantum efficiency.

(3) Conversion Efficiency: When the outermost lipid-soluble ligand is substituted with a water-soluble ligand, the conversion efficiency is calculated by the following formula (1).

[Equation 1]

Conversion efficiency (%) = (Cw/Cf) x 100

(In Equation 1, Cw is the quantum efficiency of the quantum dot containing the water-soluble ligand in the outermost, Cf is the quantum efficiency of the quantum dot containing the fat-soluble ligand in the outermost).

(4) Stability index

1) Quantum dots containing fat-soluble ligand: After synthesizing quantum dots, the quantum dots are mixed with a solvent (nucleic acid: toluene = 1:1) and then precipitated by centrifugation, purified by centrifugation by adding acetone to the precipitated quantum dots 3 times After repeating, the final purified quantum dot powder is dissolved in a toluene solution at a concentration of 0.1 mg/ml, stored under a fluorescent lamp and at room temperature, and quantum efficiency is measured for 50 days, calculated by the following formula 2, and is described in Table 1 did. The change in the relative quantum efficiency (based on the 0-day relative quantum efficiency of 100%) with time of the quantum dots containing the fat-soluble ligand of Example 1 and Comparative Example 1 is graphically shown in FIG. 2 .

[Equation 2]

Stability index (%) = (50-day quantum efficiency)/(0-day quantum efficiency) × 100

(In Equation 2, the 0-day quantum efficiency means the quantum efficiency immediately after purification, and the 50-day quantum efficiency means the quantum efficiency relative to the 0-day quantum efficiency after purification and storage at room temperature for 50 days in a toluene solution)

2) Quantum dots containing water-soluble ligand: After synthesizing quantum dots, centrifugation with chloroform three times, and purification by removing free ligands through a filter, and then bathing the quantum dots in water at 95 ° C. for 2 hours, followed by the following It was calculated by Equation 3, and is shown in Table 1 above. The change in quantum efficiency with time (based on 100% quantum efficiency before bathing) of the quantum dots including the water-soluble ligand of Example 1 and Comparative Example 1 is graphically illustrated in FIG. 3 .

[Equation 3]

Stability index (%) = (quantum efficiency after 2 hours of bathing) / (quantum efficiency before bathing) × 100

Claims (32)

It is a quantum dot comprising a core-shell structure,
The quantum dots include a first stable layer between the core and the shell, a second stable layer on the shell, and a ligand layer containing a lipid-soluble ligand at the outermost portion,
The core, the shell, the first stabilizing layer, and the second stabilizing layer each include a group 12-16 compound,
In the second stable layer, the molar ratio of the group 12 element and the group 16 element is 4: 6 to 6: 4,
When the quantum dot is substituted for the fat-soluble ligand with a water-soluble ligand, the quantum dot has a conversion efficiency of 100% or more by the following formula 1:
[Equation 1]
Conversion efficiency (%) = (Cw/Cf) x 100
(In Equation 1, Cw is the quantum efficiency of the quantum dot containing the water-soluble ligand in the outermost, Cf is the quantum efficiency of the quantum dot containing the fat-soluble ligand in the outermost).
delete delete The quantum dot according to claim 1, wherein each of the shell, the first stabilizing layer, and the second stabilizing layer comprises three or more components.
delete delete delete The quantum dot according to claim 1, wherein the core has a diameter of 1 nm to 6 nm.
The quantum dot according to claim 1, wherein the shell has a thickness of 0.5 nm to 10 nm.
The quantum dot according to claim 1, wherein the thickness of the first or second stabilizing layer is 0.3 nm to 2 nm.
The quantum dot of claim 1, wherein the quantum dot has an average diameter of 6 nm to 30 nm.
The quantum dot of claim 1, wherein the quantum dot has a quantum efficiency of 80% or more.
The quantum dot according to claim 1, wherein the quantum dot has a stability index of 90% or more of Formula 2:
[Equation 2]
Stability index (%) = (50-day quantum efficiency)/(0-day quantum efficiency) × 100
(In Equation 2, the 0-day quantum efficiency means the quantum efficiency immediately after purification, and the 50-day quantum efficiency means the quantum efficiency after purification and storage at room temperature for 50 days in a toluene solution).
The quantum dot according to claim 1, wherein the half width at half maximum of the quantum dot is 40 nm or less.
delete According to claim 1, wherein the Group 12-16 compound is cadmium sulfide (CdS), cadmium selenide (CdSe), cadmium thelenide (CdTe), zinc sulfide (ZnS), zinc selenide (ZnSe), zinc thelenide (ZnTe), Mercurysulfide (HgS), Mercury Selenide (HgSe), Mercury Telenide (HgTe), Zinc Oxide (ZnO), Cadmium Oxide (CdO), Mercury Oxide (HgO), Cadmium Selenium Sulfide (CdSeS), Cadmium Selenium Telenide (CdSeTe), Cadmium Sulfide Telenide (CdSTe), Cadmium Zinc Sulfide (CdZnS), Cadmium Zinc Selenide (CdZnSe), Cadmium Sulfide Selenide (CdSSe), Cadmium Zinc Telenide (CdZnTe), Cadmium Mercury Sulfide ( CdHgS), Cadmium Mercury Selenide (CdHgSe), Cadmium Mercury Selenide (CdHgTe), Zinc Selenium Sulfide (ZnSeS), Zinc Selenium Telenide (ZnSeTe), Zinc Sulfide Telenide (ZnSTe), Mercury Selenium Sulfide (HgSeS), Mercury Selenium Sulfide (HgSeS) Selenium Telenide (HgSeTe), Mercurysulfide Thelenide (HgSTe), Mercury Zinc Sulfide (HgZnS), Mercury Zinc Selenide (HgZnSe), Cadmium Zinc Oxide (CdZnO), Cadmium Mercury Oxide (CdHgO), Zinc Mercury Oxide (ZnHgO) , zinc selenium oxide (ZnSeO), zinc telen oxide (ZnTeO), zinc sulfide oxide (ZnSO), cadmium selenium oxide (CdSeO), cadmium selenium oxide (CdTeO), cadmium sulfide oxide (CdSO), mercury selenium oxide (HgSeO) ), Mercury Telenium Oxide (HgTeO), Mercury Sulfide Oxide (HgSO), Cadmium Zinc Selenium Sulfide (CdZnSeS), Cadmium Zinc Selenium Telenide (CdZnSeTe), Cadmium Zinc Sulfide Telenide (CdZnSTe), Cadmium Mercury Selenium Sulfide (CdHSgSeS) , Cadmium Mercury Selenium Telenide (CdHgSeTe), Cadmium Mercury Sulfide Telenide (CdHgSTe), Mercury Zinc Selenium Sulfide (HgZnSeS), Mercury Zinc Selenium Telenide (HgZnSeTe), Mercury Zinc Sulfide Telenide (HgZnSeTe) STe), Cadmium Zinc Selenium Oxide (CdZnSeO), Cadmium Zinc Telenium Oxide (CdZnTeO), Cadmium Zinc Sulfide Oxide (CdZnSO), Cadmium Mercury Selenium Oxide (CdHgSeO), Cadmium Mercury Telenium Oxide (CdHgTeO), Cadmium Mercury Sulfide Oxide (CdHgTeO) Quantum dots comprising at least one of CdHgSO), zinc mercury selenium oxide (ZnHgSeO), zinc mercury terenium oxide (ZnHgTeO), and zinc mercury sulfide oxide (ZnHgSO).
delete delete The method of claim 1, wherein the fat-soluble ligand is tri-n-octylphosphine oxide, decylamine, didecylamine, tridecylamine, tetradecylamine (tetradecylamine), pentadecylamine, hexadecylamine, octadecylamine, undecylamine, dioctadecylamine, N,N-dimethyldecylamine (N, N-dimethyldecylamine), N,N-dimethyldodecylamine (N,N-dimethyldodecylamine), N,N-dimethylhexadecylamine (N,N-dimethylhexadecylamine), N,N-dimethyltetradecylamine (N,N- dimethyltetradecylamine), N,N-dimethyltridecylamine (N,N-dimethyltridecylamine), N,N-dimethylundecylamine (N,N-dimethylundecylamine), N-decylamine (N-decylamine), N-methyloctadecyl Amine (N-methyloctadecylamine), didodecylamine (didodecylamine), tridodecylamine (tridodecylamine), cyclododecylamine (cyclododecylamine), N-methyldodecylamine (N-methyldodecylamine), trioctylamine (trioctylamine), lauric acid, palmitic acid, oleic acid, stearic acid, myristicacid, elaidic acid, eicosanoic acid, heneicosanoic acid, tricosanoic acid, docosanoic acid, tetracosanoic acid, hexacosanoic acid, heptacosanoic acid Quantum dots comprising at least one of tacosanoic acid, octacosanoic acid, and cis-13-docosenoic acid.
According to claim 1, wherein the water-soluble ligand is silica, PEG (polyethylene glycol), mercaptopropionic acid (MPA), cysteamine (cysteamine), mercaptoacetic acid (mercapto-acetic acid), mercapto-undecanol (mercapto-undecanol) ), 2-mercapto-ethanol, 1-thio-glycerol, deoxyribonucleic acid (DNA), mercapto acetic acid, mercapto unde Cano acid (mercapto-undecanoic acid), 1-mercapto-6-phenyl hexane (1-mercapto-6-phenyl-hexane), 1,16-dimercapto-hexadecane (1,16-dimecapto-hexadecane), 18 -mercapto-octadecylamine (18-mercapto-octadecyl amine), tri-octyl phosphine, 6-mercapto-hexane (6-mercapto-hexane), 6-mercapto-hexanoic acid ( 6-mercapto-hexanoic acid), 16-mercapto-hexadecanoic acid (16-mercapto-hexadecanoic acid), 18-mercapto-octadecyl amine (18-mercapto-octadecyl amine), 6-mercapto-hexyl 6-mercapto-hexyl amine or 8-hydroxy-octylthiol, 1-thio-glycerol, mercapto-acetic acid, mercap Quantum dots comprising at least one of mercapto-undecanoic acid, hydroxamate, a derivative of hydroxamic acid, and ethylene diamine.
The quantum dot of claim 1 , wherein the core, the shell, the first stabilizing layer and the second stabilizing layer include cadmium (Cd).
22. The method of claim 21,
The quantum dot is a quantum dot in which the mole % of cadmium (Cd) or selenium (Se) increases toward the center.
According to claim 1,
The core includes at least one of cadmium (Cd) and selenium (Se),
The first stabilizing layer includes at least one of cadmium (Cd), selenium (Se), and zinc (Zn),
The shell includes at least one of cadmium (Cd), selenium (Se), zinc (Zn) and sulfur (S),
The second stable layer is a quantum dot comprising at least one of cadmium (Cd), zinc (Zn) and sulfur (S).
According to claim 1,
The core includes at least one of cadmium (Cd) and selenium (Se),
The first stable layer includes at least one of cadmium (Cd), selenium (Se), zinc (Zn) and sulfur (S),
The shell includes at least one of cadmium (Cd), selenium (Se), zinc (Zn) and sulfur (S),
The second stable layer is quantum dots comprising at least one of cadmium (Cd), selenium (Se), zinc (Zn), and sulfur (S).
According to claim 1, wherein the first stabilizing layer,
The difference in the content of the core and cadmium (Cd) or selenium (Se) is 15 mol% or less,
A quantum dot having a content difference between the shell and zinc (Zn) of 15 mol% or less.
According to claim 1, wherein the second stabilizing layer,
A quantum dot having a content difference of 10 mol% or less between the shell and sulfur (S) or zinc (Zn).
According to claim 1, wherein the second stabilizing layer,
Quantum dots having a sulfur (S) content of 40 mol% to 50 mol%.
forming a core;
forming a first stabilizing layer;
forming a shell;
forming a second stabilizing layer;
A quantum dot manufacturing method for producing the quantum dot of claim 1, wherein the conversion efficiency is 100% or more by the following formula 1 comprising:
[Equation 1]
Conversion efficiency (%) = (Cw/Cf) x 100
(In Equation 1, Cw and Cf are the quantum efficiency (Cw) of the quantum dot containing the water-soluble ligand in the outermost portion when the outermost fat-soluble ligand is substituted with the water-soluble ligand, and the quantum dot containing the fat-soluble ligand in the outermost portion. Efficiency (Cf)).
The method of claim 28, wherein after the core forming step, after the forming the first stable layer, and after the forming the shell, there is no purification process.
29. The method of claim 28, wherein forming the first stabilizing layer, forming the shell, and forming the second stabilizing layer comprises:
A quantum dot manufacturing method in which the product generated in the previous step is added to a reaction tank containing the reactants of each step.
The method of claim 28, further comprising substituting a water-soluble ligand for the fat-soluble ligand of the quantum dot.
The method of claim 31, wherein the quantum dot has a stability index of 90% or more of the following formula 2:
[Equation 2]
Stability index (%) = (50-day quantum efficiency)/(0-day quantum efficiency) × 100
(In Equation 2, the 0-day quantum efficiency means the quantum efficiency immediately after purification, and the 50-day quantum efficiency means the quantum efficiency after purification and storage at room temperature for 50 days in a toluene solution).

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