KR20130046849A - Quantum dot having core-multishell structure and manufacturing method of the same - Google Patents

Abstract

PURPOSE: A quantum dot with a core-multishell structure and a manufacturing method thereof are provided to obtain a long electron transfer path by including a core composed of insulator particles. CONSTITUTION: A core is composed of insulator particles. A plurality of shells successively surround the core. The shell includes a semiconductor compound and a band gap which becomes larger according as a distance from the shell to the core increases. The thickness of the shell is 2 to 20 nm.

Description

Quantum dot having core-multishell structure and manufacturing method of the same

The present invention relates to a quantum dot of a core / multishell structure and a method of manufacturing the same, and more particularly, to include a core made of insulator particles, which has a larger size than a conventional quantum dot and has a longer electron migration path when irradiated with light. The present invention relates to a quantum dot and a method for manufacturing the same.

In general, the chemical and physical properties of solid crystals are independent of the size of the crystals. However, when the size of a solid crystal becomes a region of several nanometers, its size may be a variable that influences the chemical and physical properties of the crystal. Among these nano technologies, researches to form semiconductor nanocrystals (nanocystal, naanocluster) or quantum dots have been actively conducted worldwide. Quantum dots having a size of several nanometers exhibit a unique behavior called a quantum effect, and are known to be used in semiconductor structures, light emitting labels of molecules in vivo, etc. to create high efficiency light emitting devices.

As a study on quantum dots, gas phase research by laser vaporization was mainly performed. In this method, it is possible to make a cluster of 3-50 atoms, which makes it easy to observe the electronic structure. However, since the mass synthesis of quantum dots having a specific size is impossible, it is difficult to directly observe the structural properties of the quantum dots. . To compensate for this, a study on wet chemistry, which is a study of colloidal cluster chemistry through solution phase reaction, has begun. The solution phase reaction was through a capping ligand that prevents agglomeration between crystals and increases solubility. Synthesis of quantum dots through this capping method is largely due to organic capping and inorganic capping. Among these, organic capping is directly synthesized in a hot stabilizing ligand, and capping of CdSe quantum dots using trioctylphosphine oxide (TOPO), which was studied by Bawendi in 1993, is well known. Inorganic capping is achieved through a material having a larger band gap, which has the advantage of increasing luminous efficiency. This is because the inorganic capping enables quantum well formation and epitaxial growth, so that the surface of the quantum dot can be formed regularly. This can reduce surface defects and improve luminous efficiency.

Research on quantum dots of group 12 elements and group 16 element compounds having various compositions has shown that the properties of the crystals, i.e., band gaps, are changed by changing the semiconductor structure such as the size and surface of the semiconductor crystals in the nanometer range. Use the basic principle. Among the group 12 element-group 16 element compound quantum dots, quantum dots having a core / shell structure have been attracting much attention. Core / shell quantum dots have been developed to change the crystal surface to maintain or improve the chemical and physical properties of the quantum dots, such as luminescence in a variety of surroundings. The core / shell structure quantum dots are generally quantum dots in which a shell having a bandgap wider than the bandgap of the core is formed on the core surface, and the shell of the core surface has a shared band of energy lower than that of the core. It has a bandgap by a conduction band of higher energy than the conduction band of the core. Cadmium selenide (CdSe) / zinc sulfide (ZnS) as core / shell quantum dots [J. Phys. Chem. B, 1997, 101, 9463-9475], cadmium selenide (CdSe) / cadmium sulfide (CdS) [J. Am. Chem. Soc., 1997, 119, 7019-7029], cadmium selenide (CdSe) / zinc selenide (ZnSe) [Nano Letters, 2002, 2, 781-784], zinc selenide (ZnSe) / sulfide Zinc (ZnS) (Korean Patent Registration No. 10-0376403) and the like are known.

These various Group 12 element-group elemental compound quantum dots are generally limited in size to 2 to 10 nm, so that agglomeration easily occurs in a powder state, and it is difficult to disperse them again, and there is a problem of poor durability and flickering. There is a problem in that distance occurs. In order to solve this problem, research is being conducted to increase the size of the quantum dots by forming a shell with as many semiconductor compounds as possible on the core of the semiconductor compound, but there is a limit to increasing the size of the quantum dots only by increasing the number of shells. As the number of shells to be formed is added, the quantum dot manufacturing process is complicated and the productivity of the quantum dots is lowered.

SUMMARY OF THE INVENTION The present invention has been made to solve the conventional problems, and an object of the present invention is to provide a quantum dot of a novel structure having a huge size while maintaining the original crystal properties of the quantum dots.

Another object of the present invention is to provide a method for easily manufacturing the quantum dots.

The inventors of the present invention can produce a large particle sized quantum dot in the case of forming the core as an insulator particle in the quantum dot having a core / shell structure and forming the shell as a multishell, and the manufactured quantum dot is a core made of a semiconductor compound and It has the same quantum crystal properties as a conventional quantum dot including a shell made of a semiconductor compound, and at the same time improves physical properties due to an increase in particle size, high light emission efficiency due to an increase in electron transport path when irradiated with light, high light emission sharpness, and the like. It has been found that this can be expected and the present invention has been completed.

SUMMARY OF THE INVENTION In order to solve the object of the present invention, the present invention includes a core made of insulator particles and a plurality of shells sequentially surrounding the core, wherein the plurality of shells include a semiconductor compound, the larger the greater the distance from the core. It provides a quantum dot characterized by having a band gap. In this case, the plurality of shells are preferably formed on the surface of the core, the first shell comprising a semiconductor compound consisting of Group 12 elements and Group 16 elements; And a second shell formed on the surface of the first shell, the semiconductor compound including a group 12 element and a group 16 element, the second shell having a band gap larger than that of the first shell. A third shell formed on the surface of the second shell and including two different semiconductor compounds composed of Group 12 elements and Group 16 elements, the third shell having a band gap larger than that of the second shell; A fourth shell formed on the surface of the third shell and including two different semiconductor compounds formed of Group 12 elements and Group 16 elements, the fourth shell having a band gap larger than that of the third shell; A fifth shell formed on the surface of the fourth shell and including a semiconductor compound composed of Group 12 elements and Group 16 elements, and having a band gap larger than that of the fourth shell; And a sixth shell formed on the surface of the fifth shell, the semiconductor compound including a group 12 element and a group 16 element, and having a band gap larger than the band gap of the fifth shell.

In addition, to solve another object of the present invention, the present invention comprises the steps of (a) preparing a core made of insulator particles; (b) reacting a Group 12 element-containing compound and a Group 16 element-containing compound in a reaction medium to form a first shell including a semiconductor compound composed of Group 12 elements and Group 16 elements on the surface of the core; And (c) reacting the Group 12 element-containing compound and the Group 16 element-containing compound in a reaction medium, the semiconductor compound comprising a Group 12 element and a Group 16 element on the surface of the first shell, wherein the bandgap of the first shell It provides a method of producing a quantum dot comprising a; forming a second shell having a larger band gap. In addition, the method for producing a quantum dot according to the present invention preferably comprises (d) reacting a Group 12 element-containing compound and a Group 16 element-containing compound in a reaction medium, and using the Group 12 element and Group 16 element on the surface of the second shell. Forming a third shell comprising two different semiconductor compounds, each having a bandgap larger than the bandgap of the second shell; (e) reacting a Group 12 element-containing compound and a Group 16 element-containing compound in a reaction medium to include two different types of semiconductor compounds composed of Group 12 elements and Group 16 elements on the surface of the third shell; Forming a fourth shell having a bandgap larger than the bandgap of the shell; (f) reacting the Group 12 element-containing compound and the Group 16 element-containing compound in a reaction medium, wherein the surface of the fourth shell contains a semiconductor compound composed of Group 12 element and Group 16 element, and is less than the band gap of the fourth shell. Forming a fifth shell having a larger bandgap; And (g) reacting the Group 12 element-containing compound and the Group 16 element-containing compound in a reaction medium, the semiconductor compound comprising a Group 12 element and a Group 16 element on the surface of the fifth shell, wherein the band gap of the fifth shell The method may further include forming a sixth shell having a larger band gap.

Since the quantum dots according to the present invention include a core made of insulator particles and at least two shells that sequentially surround the quantum dots, the quantum dots can have a huge particle size compared to a quantum dot including a core made of a conventional semiconductor compound, thereby handling The improvement of the ease, stability of particle | grains, and dispersibility are anticipated. In addition, the quantum dot according to the present invention has a large particle size but retains the original crystalline characteristics of the quantum dot, the first shell has the characteristic that most of the photoluminescence characteristics are determined. In addition, in the quantum dot according to the present invention, since the first shell may provide a longer electron migration path when irradiating light than the core of the conventional quantum dot, high luminous efficiency, high luminous clarity, and the like are expected.

1 shows a bandgap according to the particle radius of various metal compounds or metalloids.
2 is a photograph taken with a transmission electron microscopy (TEM) of a quantum dot of the core / hexashell structure made of the insulator particles prepared in Example 6 of the present invention.
3 is a result of analyzing the quantum dot and the control quantum dot of the core / six-shell structure prepared in Example 5 of the present invention by an X-ray diffractometer (X-Ray Diffractometer, XRD).

Before describing the present invention specifically, the terms used in the present invention will be described first. Insulator in the present invention is an electrical insulation material having a small electrical conductivity and hardly passes a current, and includes a non-conductor, and is a relative concept of a conductor and a semiconductor which are commonly defined. In the present invention, the semiconductor compound refers to a semiconductor composed of two or more elemental compounds, and includes group 13-15 compound semiconductors such as gallium arsenide (GaAs), indium phosphorus (InP), and gallium phosphorus (GaP); Group 12-16 compound semiconductors such as cadmium sulfide (CdS) and zinc telluride (ZnTe); It is a concept containing a group 14-16 compound semiconductor, such as lead sulfide (PbS).

Hereinafter, the present invention will be described in detail. One aspect of the invention relates to a quantum dot of a core / multishell structure. The quantum dot of the present invention includes a core made of insulator particles and a plurality of shells sequentially surrounding the core. The plurality of shells contain a semiconductor compound, the greater the band gap of the shell toward the outermost shell relative to the core, that is, the outermost shell, resulting in the quantum mechanical wave function of electrons and holes generated inside the excited quantum dots Can be maintained better. 1 shows a bandgap according to the particle radius of various metal compounds or metalloids. The farther away from the core, the characteristics of the shell having a larger bandgap can be designed by adjusting the type of components constituting each shell and the thickness (or size) of each shell. Further, in the quantum dot according to the present invention, the plurality of shells preferably have a total thickness of 2 to 20 nm, more preferably 4 to 10 nm.

The quantum dot according to the present invention is characterized in that the core is made of insulator particles, wherein the insulator particles are not particularly limited as long as the insulator particles are made of a known material having insulation properties and predetermined heat resistance, and preferably, polymers, metal oxides, It consists of one or more selected from metal nitrides, metalloid oxides, and metalloid nitrides. Representative metal oxides having insulating properties include alumina, zirconia, and the like. Representative metalloids having insulating properties include silica, and silicon nitride and the like. The insulator particles constituting the core in the quantum dots of the present invention may be coated with polystyrene particles, amorphous silica particles, or polymer particles coated with mesoporous silica, for example, mesoporous silica, in consideration of commercial availability and compatibility with semiconductor compounds. It is preferable that it is a polystyrene particle. Commercial products of insulator particles used as cores include Polystyrene latex microsphere dispersion in water series (Stock number: 42711 (particle size 50 nm), 42712 (particle size 100 nm), 42713 (particle size) by Alfa Asear GmbH & Co.KG. 200nm)), Silicon (IV) oxide series (Stock number: 44781 (particle size 80nm), 44782 (particle size 10 ~ 20nm)), Silicon (IV) nitride series (Stock number: 44736 (particle size 30 ~ 70 nm), 45611 (particle size 15-30 nm), and the like. In addition, the size of the insulator particles constituting the core is not particularly limited, for example, may have a range of 5 nm to 1 μm, preferably 10 to 200 nm in terms of maintaining a nanoscale, and 10 to 100 It is more preferable that it is nm, and it is most preferable that it is 20-100 nm.

In the quantum dot according to an embodiment of the present invention, the plurality of shells are formed on the surface of the core, the first shell comprising a semiconductor compound consisting of Group 12 elements and Group 16 elements; And a second shell formed on the surface of the first shell, the semiconductor compound including a group 12 element and a group 16 element, and having a band gap larger than that of the first shell. Group 12 elements in the quantum dot according to an embodiment of the present invention is preferably zinc (Zn), cadmium (Cd), or mercury (Hg), group 16 elements are sulfur (S), selenium (Se), tellurium ( Te) or polonium (Po) is preferable. Further, in the quantum dot according to an embodiment of the present invention, the semiconductor compound composed of Group 12 elements and Group 16 elements of the first shell is preferably any one selected from CdSe or CdTe, and the Group 12 elements of the second shell The semiconductor compound composed of Group 16 elements is preferably selected from CdS or ZnS. In addition, in the quantum dot according to an embodiment of the present invention, the second shell may include both CdS and ZnS.

In the quantum dot according to another embodiment of the present invention, the plurality of shells are formed on the surface of the core, the first shell comprising a semiconductor compound consisting of Group 12 elements and Group 16 elements; A second shell formed on the surface of the first shell and including a semiconductor compound composed of Group 12 elements and Group 16 elements, the second shell having a band gap larger than that of the first shell; A third shell formed on the surface of the second shell and including two different semiconductor compounds formed of Group 12 elements and Group 16 elements, the third shell having a band gap larger than that of the second shell; A fourth shell formed on the surface of the third shell and including two different semiconductor compounds formed of Group 12 elements and Group 16 elements, the fourth shell having a band gap larger than that of the third shell; A fifth shell formed on the surface of the fourth shell and including a semiconductor compound composed of Group 12 elements and Group 16 elements, and having a band gap larger than that of the fourth shell; And a sixth shell formed on the surface of the fifth shell, the semiconductor compound including a group 12 element and a group 16 element, and having a band gap larger than that of the fifth shell. Group 12 elements in the quantum dot according to another embodiment of the present invention is preferably zinc (Zn), cadmium (Cd), or mercury (Hg), Group 16 elements are sulfur (S), selenium (Se), tellurium ( Te) or polonium (Po) is preferable. Further, in the quantum dot according to another embodiment of the present invention, the semiconductor compound composed of Group 12 elements and Group 16 elements of the first shell is preferably any one selected from CdSe or CdTe. In addition, the semiconductor compound composed of Group 12 elements and Group 16 elements of the second shell is preferably CdS. In addition, it is preferable that the two kinds of semiconductor compounds different from each other consisting of Group 12 elements and Group 16 elements of the third shell are semiconductor compounds composed of Cd and S and semiconductor compounds composed of Zn and S. At this time, the molar ratio of Cd to S in the semiconductor compound consisting of Cd and S of the third shell is preferably 1: 3 to 1: 9, more preferably 1: 5 to 1: 7, and about 1: 6. Is most preferred. When the molar ratio of Cd to S in the semiconductor compound consisting of Cd and S is 1: 6, this is represented as Cd6S. In addition, the molar ratio of Zn to S in the semiconductor compound consisting of Zn and S of the third shell is preferably 1: 3 to 1: 9, more preferably 1: 5 to 1: 7, and about 1: 6. Is most preferred. In the semiconductor compound consisting of Zn and S, when the molar ratio of Zn to S is 1: 6, this is expressed as Zn6S. In addition, when the third shell includes two semiconductor compounds different from each other, a semiconductor compound consisting of Cd and S and a semiconductor compound consisting of Zn and S, the semiconductor compound consisting of Cd and S versus a semiconductor consisting of Zn and S The molar ratio of the compound is preferably 2: 1 to 1: 2, most preferably about 1: 1. In addition, it is preferable that two different types of semiconductor compounds composed of Group 12 elements and Group 16 elements of the fourth shell are CdS and ZnS, wherein the molar ratio of CdS to ZnS is 1: 2 to 1: 6. More preferably from 1: 3 to 1: 5, most preferably from about 1: 4. In addition, the semiconductor compound composed of Group 12 elements and Group 16 elements of the fifth shell is preferably ZnS. In addition, the semiconductor compound composed of Group 12 elements and Group 16 elements of the sixth shell is preferably ZnS. In the quantum dot of the present invention, the semiconductor compound composed of Group 12 elements and Group 16 elements of the fifth shell is preferably the same as the semiconductor compound composed of Group 12 elements and Group 16 elements of the sixth shell, wherein the fifth shell and the sixth The shells are identical in composition and vary only in the thickness of the shells. In addition, even if the fifth shell and the sixth cell is composed of the same components, since the fifth shell and the sixth cell are generated by independent manufacturing steps, the fifth shell and the sixth cell are divided into separate shells in the quantum dots.

The total particle size of the quantum dots according to the present invention is mainly determined by the size of the core consisting of insulator particles, preferably about 12 to 220 nm, more preferably about 14 to 120 nm, most preferably about 24 ˜110 nm. Further, in the quantum dot according to the present invention, the first shell corresponds to the core of a conventional quantum dot, and the photoluminescent property according to the present invention is mainly determined by the first shell. Meanwhile, in the quantum dot according to the present invention, the first shell is sandwiched between the core and the second shell and provides a longer electron moving path than the electron moving path provided by the core of the conventional quantum dot. Characteristics such as efficiency (or quantum yield) and high luminescence clarity are expected.

Another aspect of the invention relates to a method of making a quantum dot of a core / multishell structure. Hereinafter, in the method of manufacturing a quantum dot according to the present invention, the same content as that of the quantum dot described above will be omitted. The method of manufacturing a quantum dot according to the present invention includes a core preparation step, a first shell forming step, and a second shell forming step sequentially, and preferably, a third shell forming step, a fourth shell forming step, and a fifth shell forming step. And, may further comprise a sixth shell forming step sequentially. Specifically, the method for manufacturing a quantum dot according to the present invention comprises the steps of (a) preparing a core made of insulator particles; (b) reacting a Group 12 element-containing compound and a Group 16 element-containing compound in a reaction medium to form a first shell including a semiconductor compound composed of Group 12 elements and Group 16 elements on the surface of the core; And (c) reacting the Group 12 element-containing compound and the Group 16 element-containing compound in a reaction medium, the semiconductor compound comprising a Group 12 element and a Group 16 element on the surface of the first shell, wherein the bandgap of the first shell And forming a second shell having a larger bandgap. In addition, the method for producing a quantum dot according to the present invention preferably comprises (d) reacting a Group 12 element-containing compound and a Group 16 element-containing compound in a reaction medium, and using the Group 12 element and Group 16 element on the surface of the second shell. Forming a third shell comprising two different semiconductor compounds, each having a bandgap larger than the bandgap of the second shell; (e) reacting a Group 12 element-containing compound and a Group 16 element-containing compound in a reaction medium to include two different types of semiconductor compounds composed of Group 12 elements and Group 16 elements on the surface of the third shell; Forming a fourth shell having a bandgap larger than the bandgap of the shell; (f) reacting the Group 12 element-containing compound and the Group 16 element-containing compound in a reaction medium, wherein the surface of the fourth shell contains a semiconductor compound composed of Group 12 element and Group 16 element, and is less than the band gap of the fourth shell. Forming a fifth shell having a larger bandgap; And (g) reacting the Group 12 element-containing compound and the Group 16 element-containing compound in a reaction medium, the semiconductor compound comprising a Group 12 element and a Group 16 element on the surface of the fifth shell, wherein the band gap of the fifth shell The method may further include forming a sixth shell having a larger band gap. In this case, the quantum dot obtained after the step (g) has a structure comprising a core, a first shell, a second shell, a third shell, a fourth shell, a fifth shell, a sixth shell, the first shell, The total thickness of the second shell, third shell, fourth shell, fifth shell and sixth shell is preferably 2-20 nm.

Group 12 element-containing compounds in the method for producing quantum dots according to the present invention is preferably cadmium oxide, zinc acetate, cadmium acetate, cadmium chloride, zinc chloride, zinc oxide, mercury chloride, mercury oxide, mercury acetate or a combination thereof The group 16 element-containing compound is preferably sulfur powder, selenium powder, tellurium powder, polonium powder, octanthiol or a combination thereof, and the group 16 element-containing compound is trioctylphosphine or tributylphosphine. Or a solution dissolved in trioctylamine or the like is more preferable.

In addition, in the method for preparing quantum dots according to the present invention, the reaction medium preferably includes a coordinating solvent, wherein the coordinating solvent can assist in controlling the growth of the shell by coordinating with the surface of the growing shell with a donor hole electron pair. If it exists, the kind is not restrict | limited greatly, For example, hexadecylamine, trioctylamine, oleylamine, trioctyl phosphine, trioctyl phosphine oxide, etc. are mentioned. In addition, in the method for preparing a quantum dot according to the present invention, the reaction medium preferably includes an unsaturated fatty acid, which forms a complex with a Group 12 element-containing compound to facilitate thermal decomposition of the Group 12 element upon heating. Examples of unsaturated fatty acids used in the method for preparing quantum dots according to the present invention are oleic acid, stearic acid, myristic acid, myristic acid, lauric acid, palmitic acid ), Elaidic acid, eicosanoic acid, heeicosanoic acid, tricosanoic acid, docosanoic acid, tetracosanoic acid , Hexacosanoic acid, heptacosanoic acid, octacosanoic acid or cis-13-docosenoic acid. In addition, in the quantum dot manufacturing method according to the present invention, the reaction medium may preferably further include an organic solvent capable of uniformly dispersing the quantum dots, and specific examples of the organic solvent include octadecene, octadecane, and the like.

In the quantum dot manufacturing method according to the present invention, the reaction temperature of each step is about 150 to 400 ° C, preferably 200 to 350 ° C. Specifically, the reaction temperature of the steps (b) to (e) is preferably about 200 ~ 350 ℃, the reaction temperature of the (f) and (g) step is preferably about 250 ~ 300 ℃. In addition, the reaction temperature of the step (f) and (g) is preferably about 200 ~ 300 ℃ when manufacturing green light emitting quantum dot.

In the method for preparing a quantum dot according to the present invention, the step (a) is preferably performed by adding a core composed of insulator particles to a reaction medium such as a coordinating solvent and uniformly dispersing the core in the reaction medium by mechanical stirring or sonication. Include.

In addition, in the method of manufacturing a quantum dot according to the present invention, the group 12 element-containing compound of step (b) is a cadmium-containing compound, and the group 16 element-containing compound is preferably a selenium-containing compound or tellurium-containing compound. Specifically, cadmium oxide or cadmium acetate is more preferably used as the cadmium-containing compound, and as selenium compound, it is more preferable to use a solution of selenium powder dissolved in trioctylphosphine, and tellurium compound is tellurium powder. It is more preferable to use what was dissolved in trioctylphosphine.

In the method for preparing a quantum dot according to the present invention, the group 12 element-containing compound of step (c) is a cadmium-containing compound or a zinc-containing compound, and the group 16 element-containing compound is preferably a sulfur-containing compound. Specifically, cadmium oxide or cadmium acetate is more preferably used as the cadmium-containing compound, zinc acetate or zinc oxide is more preferably used as the zinc-containing compound, and octanylol is used as the sulfur-containing compound. It is more preferable to use what was dissolved in or dissolved in trioctylphosphine.

In the method for preparing a quantum dot according to the present invention, the molar ratio of the Group 12 element-containing compound to the Group 16 element-containing compound of step (d) is preferably 1: 3 to 1: 9, more preferably 1: 5 to 1: 7. Preferred, most preferably about 1: 6. At this time, it is preferable that the group 12 element-containing compound of step (d) is a cadmium-containing compound and a zinc-containing compound, and the group 16 element-containing compound is a sulfur-containing compound. Specifically, cadmium oxide or cadmium acetate is more preferably used as the cadmium-containing compound, zinc acetate or zinc oxide is more preferably used as the zinc-containing compound, and octanethiol is used as the sulfur-containing compound in trioctylamine. It is more preferable to use the dissolved thing or the thing which melt | dissolved the sulfur powder in trioctylphosphine. In addition, the molar ratio of the cadmium-containing compound to the zinc-containing compound of step (d) is preferably 2: 1 to 1: 2, more preferably about 1: 1. The reaction product passed through step (d) includes a quantum dot having a core / first cell / second shell / third shell structure, wherein the reaction product is slowly cooled to room temperature and then acetone, methanol, butanol, or It is preferable to add two or more kinds in combination and wash the quantum dots by centrifugation and precipitation. The washed quantum dots are preferably used in step (e) after being dispersed in a specific concentration in toluene, hexene, hexane, benzene, chloroform or a dispersion solvent combining two or more thereof. In this case, the concentration of the quantum dots dispersed in the dispersion solvent may be represented by an absorbance value at a specific wavelength (for example, 490 nm, 620 nm, etc.), and the absorbance value of the quantum dots dispersed in the dispersion solvent is about 0.2 to 0.6. Preferably, it is adjusted to 0.4-0.5. In addition, the amount of the quantum dots dispersed in the dispersion solvent in step (e) is adjusted in consideration of the thickness of the fourth shell formed in step (e).

In the method of manufacturing a quantum dot according to the present invention, the group 12 element-containing compound of step (e) is a cadmium-containing compound and a zinc-containing compound, and the group 16 element-containing compound is preferably a sulfur-containing compound. Specifically, cadmium oxide or cadmium acetate is more preferably used as the cadmium-containing compound, zinc acetate or zinc oxide is more preferably used as the zinc-containing compound, and octanethiol is used as the sulfur-containing compound in trioctylamine. It is more preferable to use the dissolved thing or the thing which melt | dissolved the sulfur powder in trioctylphosphine. Further, the molar ratio of cadmium-containing compound to zinc-containing compound of step (e) is preferably 1: 2 to 1: 6, more preferably 1: 3 to 1: 6, most preferably about 1: 4. desirable. The reaction product passed through step (e) includes a quantum dot having a core / first cell / second shell / third shell / fourth shell structure, wherein the reaction product is slowly cooled to room temperature and then acetone, methanol, butanol It is preferable to add two or more kinds thereof in combination and to wash the quantum dots by centrifugation and precipitation. The washed quantum dots are preferably used in step (f) after being dispersed in toluene, hexene, hexane, benzene, chloroform or a dispersion solvent combining two or more thereof.

In the method for producing a quantum dot according to the present invention, it is preferable that the Group 12 element-containing compound of step (f) is a zinc-containing compound, and the Group 16 element-containing compound is a sulfur-containing compound. Specifically, zinc acetate or zinc oxide is more preferably used as the zinc-containing compound, and sulfur-containing compounds are those in which octanethiol is dissolved in trioctylamine or sulfur powder in trioctylphosphine. More preferred. In the quantum dot manufacturing method according to the present invention, the Group 12 element-containing compound of step (g) is preferably a zinc-containing compound, and the Group 16 element-containing compound is a sulfur-containing compound. Specifically, zinc acetate or zinc oxide is more preferably used as the zinc-containing compound, and sulfur-containing compounds are those in which octanethiol is dissolved in trioctylamine or sulfur powder in trioctylphosphine. More preferred. In addition, the steps (f) and (g) may preferably be performed from the same reaction raw material including the Group 12 element-containing compound and the Group 16 element-containing compound in the reaction medium, wherein the reaction raw material in step (f) A portion of the fifth shell is formed, and after the formation of the fifth shell is completed, the remaining raw material is used to form a sixth shell different from the fifth shell.

By the production method according to the present invention, the quantum dots are provided as a quantum dot solution (more precisely, a quantum dot sol) dispersed in toluene, hexene, hexane, benzene, chloroform or a dispersion solvent combining two or more thereof. A quantum dot light emitting device can be manufactured by coating a surface of the light emitting device to form a thin film. More specifically, the quantum dot LED may be manufactured by applying the thin film forming composition mixed with the quantum dot solution and the curing agent of the present invention to the surface of the light emitting diode, and curing at a temperature of about 120 to 150 ° C. for about 1 to 2 hours ( The curing temperature and curing time may vary depending on the nature of the curing agent). The quantum dot LEDs produced from the quantum dots of the present invention have excellent thermal stability and exhibit desirable properties such as high luminous efficiency, high luminous clarity and the like.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are intended to clearly illustrate the present invention and not to limit the scope of protection of the present invention.

1. Preparation of quantum dots

(1) Example 1: Preparation of red light emitting quantum dots of the core / double shell structure consisting of polystyrene nanoparticles

Example 1-1 Preparation of Cores Made of Polystyrene Nanoparticles

Polystyrene nanoparticles dispersed in water (particle size: 100 nm; supplier: Alfa Asear) were dried to obtain polystyrene nanoparticles in powder form. Thereafter, 1 g of polystyrene nanoparticles in powder form was added to 20 ml of trioctylamine, mixed vigorously with a stirrer and sonicated for about 20 minutes to prepare a core solution in which the polystyrene nanoparticles were uniformly dispersed.

Example 1-2 Synthesis of First Shell Consisting of CdSe

0.502 (0.4 mmol) cadmium oxide, 1.2 ml (3.7 mmol) oleic acid and 20 ml of trioctylamine were placed in a reactor equipped with a syringe, a condenser and a J type thermocouple. After the temperature was raised to 110 ° C., the temperature was raised to about 300 ° C. in a state filled with nitrogen gas, the mixture was stirred vigorously, and slowly cooled to room temperature to obtain a Cd precursor solution including a complex of cadmium and oleic acid.

The core solution prepared in Example 1-1 was placed in a separate reactor equipped with a syringe, a condenser and a thermometer (J Type thermocouple), and after adjusting the temperature of the reactor to about 220 ° C., the prepared Cd precursor solution was prepared. Was injected into the reactor at a rate of about 0.5 ml / min using a metering pump. 0.2 ml of a selenium / trioctylphosphine solution having a selenium concentration of 2 M (dissolved in selenium powder having a purity of 99.99% or more in trioctylphosphine having a purity of 90% or more; hereinafter referred to as a 2M TOPSe solution) Diluted (0.4 mmol on the basis of selenium) in 10 ml of trioctylamine was injected into the reactor at a rate of about 0.5 ml / min using a metering pump. After reacting for about 40 minutes at about 220 ℃ to form a first shell consisting of CdSe on the surface of the core.

Example 1-3 Synthesis of Second Shell Consisting of ZnS

1.1 g (6.0 mmol) of zinc acetate, 4 ml (12.4 mmol) of oleic acid, and 20 ml of trioctylamine were added to a separate reactor (with a syringe, a cooler, and a thermometer), and the temperature was raised to about 110 ° C. under reduced pressure near a vacuum. Thereafter, the mixture was heated to about 320 ° C. in a state filled with nitrogen gas, stirred, and cooled slowly to room temperature to obtain a Zn precursor solution including a complex of zinc and oleic acid. 20 ml of the Zn precursor solution thus obtained was injected into the reactor in which the first shell was formed at a rate of about 0.5 ml / min using a metering pump. Thereafter, 1050 µl (6.0 mmol) of n-octanethiol was dissolved in 6 ml of trioctylamine, and injected into the reactor at a rate of about 0.5 ml / min using a metering pump, and reacted at about 300 ° C. for about 80 minutes. A second shell made of ZnS was formed on the surface of one shell.

Thereafter, the reaction product was slowly cooled to room temperature, acetone and butanol were added, and the precipitate was washed by centrifugation to obtain red light emitting quantum dots having an insulator particle core / 2 double-shell structure.

(2) Example 2 Preparation of Red Light Emitting Quantum Dots of Core / Double Shell Structure Composed of Amorphous Silica Nanoparticles

Example 2-1 Preparation of Cores Comprising Amorphous Silica Nanoparticles

1 g of amorphous silica nanoparticles (particle size: 80 nm; supplier: Alfa Asear) was added to 20 ml of trioctylamine, mixed vigorously with a stirrer and sonicated for about 20 minutes to prepare a core solution in which amorphous silica nanoparticles were uniformly dispersed. It was.

Example 2-2: Synthesis of First Shell Consisting of CdSe

0.502 g (0.4 mmol) of cadmium oxide, 1.2 ml (3.7 mmol) of oleic acid and 20 ml of trioctylamine were placed in a reactor equipped with a syringe, a condenser and a thermometer (J Type thermocouple). After the temperature was raised to about 110 ° C., the temperature was raised to about 300 ° C. in a state filled with nitrogen gas, the mixture was stirred vigorously, and slowly cooled to room temperature to obtain a Cd precursor solution including a complex of cadmium and oleic acid.

The core solution prepared in Example 2-1 was placed in a separate reactor equipped with a syringe, a condenser and a thermometer (J Type thermocouple), and after adjusting the temperature of the reactor to about 220 ° C., the prepared Cd precursor solution was prepared. Was injected into the reactor at a rate of about 0.5 ml / min using a metering pump. 0.2 ml of a selenium / trioctylphosphine solution having a selenium concentration of 2 M (dissolved in selenium powder having a purity of 99.99% or more in trioctylphosphine having a purity of 90% or more; hereinafter referred to as a 2M TOPSe solution) Diluted (0.4 mmol on the basis of selenium) in 10 ml of trioctylamine was injected into the reactor at a rate of about 0.5 ml / min using a metering pump. After reacting for about 40 minutes at about 220 ℃ to form a first shell consisting of CdSe on the surface of the core.

Example 2-3 Synthesis of Second Shell Made of ZnS

1.1 g (6.0 mmol) of zinc acetate, 4 ml (12.4 mmol) of oleic acid, and 20 ml of trioctylamine were added to a separate reactor (with a syringe, a cooler, and a thermometer), and the temperature was raised to about 110 ° C. under reduced pressure near a vacuum. Thereafter, the mixture was heated to about 320 ° C. in a state filled with nitrogen gas, stirred, and cooled slowly to room temperature to obtain a Zn precursor solution including a complex of zinc and oleic acid. 20 ml of the Zn precursor solution thus obtained was injected into the reactor in which the first shell was formed at a rate of about 0.5 ml / min using a metering pump. Thereafter, 1050 µl (6.0 mmol) of n-octanethiol was dissolved in 6 ml of trioctylamine, and injected into the reactor at a rate of about 0.5 ml / min using a metering pump, and reacted at about 300 ° C. for about 80 minutes. A second shell made of ZnS was formed on the surface of one shell.

Thereafter, the reaction product was slowly cooled to room temperature, acetone and butanol were added, and the precipitate was washed by centrifugation to obtain red light emitting quantum dots having an insulator particle core / 2 double-shell structure.

(3) Example 3 Preparation of Red Light Emitting Quantum Dots of Core / 2 Double Shell Structures Consisting of Polystyrene Nanoparticles Coated with Mesoporous Silica

Example 3-1 Preparation of Cores Comprising Polystyrene Nanoparticles Coated with Mesoporous Silica

12 g of polystyrene latex having 9 wt% of polystyrene nanoparticles having a uniform particle size of about 80 nm was added to the flask reactor and stirred vigorously. Then, 4.5 g of water, 0.4 g of hexadecyltrimethylammonium bromide (CTBA), 5.5 g of ethanol, and 1 ml of ammonium hydroxide were added thereto, followed by vigorous stirring, followed by sonication for about 10 minutes. The contents were uniformly dispersed by sonication. Thereafter, the mixture was stirred vigorously at room temperature for 30 minutes, and 0.75 g of tetraethyl orthosilicate (TEOS) was slowly added dropwise and stirred vigorously at room temperature for 48 hours. The reaction product was then centrifuged to yield polystyrene nanoparticles coated with mesoporous silica. The obtained polystyrene nanoparticles coated with mesoporous silica were washed several times with ethanol and dried to obtain polystyrene nanoparticles coated with mesoporous silica in powder form. The size of the polystyrene nanoparticles coated with mesoporous silica was about 70 ~ 100nm. Then, 1 g of polystyrene nanoparticles coated with mesoporous silica obtained on the surface of trioctylamine were mixed vigorously with a stirrer and sonicated for about 20 minutes to uniformly disperse the polystyrene nanoparticles coated with mesoporous silica. The solution was prepared.

Example 3-2 Synthesis of First Shell Consisting of CdSe

0.502 g (0.4 mmol) of cadmium oxide, 1.2 ml (3.7 mmol) of oleic acid and 20 ml of trioctylamine were placed in a reactor equipped with a syringe, a condenser and a thermometer (J Type thermocouple). After the temperature was raised to about 110 ° C., the temperature was raised to about 300 ° C. in a state filled with nitrogen gas, the mixture was stirred vigorously, and slowly cooled to room temperature to obtain a Cd precursor solution including a complex of cadmium and oleic acid.

In a separate reactor equipped with a syringe, a condenser, and a thermometer (J Type thermocouple), the core solution prepared in Example 3-1 was added, and after adjusting the temperature of the reactor to about 220 ° C., the prepared Cd precursor solution was prepared. Was injected into the reactor at a rate of about 0.5 ml / min using a metering pump. 0.2 ml of a selenium / trioctylphosphine solution having a selenium concentration of 2 M (dissolved in selenium powder having a purity of 99.99% or more in trioctylphosphine having a purity of 90% or more; hereinafter referred to as a 2M TOPSe solution) Diluted (0.4 mmol on the basis of selenium) in 10 ml of trioctylamine was injected into the reactor at a rate of about 0.5 ml / min using a metering pump. After reacting for about 40 minutes at about 220 ℃ to form a first shell consisting of CdSe on the surface of the core.

Example 3-3: Synthesis of Second Shell Consisting of ZnS

1.1 g (6.0 mmol) of zinc acetate, 4 ml (12.4 mmol) of oleic acid, and 20 ml of trioctylamine were added to a separate reactor (with a syringe, a cooler, and a thermometer), and the temperature was raised to about 110 ° C. under reduced pressure near a vacuum. Thereafter, the mixture was heated to about 320 ° C. in a state filled with nitrogen gas, stirred, and cooled slowly to room temperature to obtain a Zn precursor solution including a complex of zinc and oleic acid. 20 ml of the Zn precursor solution thus obtained was injected into the reactor in which the first shell was formed at a rate of about 0.5 ml / min using a metering pump. Thereafter, 1050 µl (6.0 mmol) of n-octanethiol was dissolved in 6 ml of trioctylamine, and injected into the reactor at a rate of about 0.5 ml / min using a metering pump, and reacted at about 300 ° C. for about 80 minutes. A second shell made of ZnS was formed on the surface of one shell.

Thereafter, the reaction product was slowly cooled to room temperature, acetone and butanol were added, and the precipitate was washed by centrifugation to obtain red light emitting quantum dots having an insulator particle core / 2 double-shell structure.

(4) Example 4: Preparation of red light emitting quantum dots of core / hexashell structure made of polystyrene nanoparticles

Example 4-1 Preparation of Cores Made of Polystyrene Nanoparticles

Polystyrene nanoparticles dispersed in water (particle size: 100 nm; supplier: Alfa Asear) were dried to obtain polystyrene nanoparticles in powder form. Thereafter, 1 g of polystyrene nanoparticles in powder form was added to 20 ml of trioctylamine, mixed vigorously with a stirrer and sonicated for about 20 minutes to prepare a core solution in which the polystyrene nanoparticles were uniformly dispersed.

Example 4-2 Synthesis of First Shell Consisting of CdSe

0.103 g (0.8 mmol) of cadmium oxide, 1.2 mL (3.7 mmol) of oleic acid, and 20 mL of trioctylamine were placed in a reactor equipped with a syringe, a condenser, and a J type thermocouple. After the temperature was raised to about 110 ° C., the temperature was raised to about 300 ° C. in a state filled with nitrogen gas, the mixture was stirred vigorously, and slowly cooled to room temperature to obtain a Cd precursor solution including a complex of cadmium and oleic acid.

The core solution prepared in Example 4-1 was placed in a separate reactor equipped with a syringe, a condenser, and a thermometer (J Type thermocouple), and after adjusting the temperature of the reactor to about 220 ° C., the prepared Cd precursor solution was prepared. Was injected into the reactor at a rate of about 0.5 ml / min using a metering pump. 0.2 ml of a selenium / trioctylphosphine solution having a selenium concentration of 2 M (dissolved in selenium powder having a purity of 99.99% or more in trioctylphosphine having a purity of 90% or more; hereinafter referred to as a 2M TOPSe solution) Diluted (0.4 mmol on the basis of selenium) in 10 ml of trioctylamine was injected into the reactor at a rate of about 0.5 ml / min using a metering pump. After reacting for about 40 minutes at about 220 ℃ to form a first shell consisting of CdSe on the surface of the core. After the synthesis of the CdSe first shell is completed, about 0.4 mmol of cadmium is present in the reaction product in a complex with oleic acid.

Example 4-3: Synthesis of Second Shell Consisting of CdS

As soon as the synthesis of the first shell composed of CdSe of Example 4-2 was completed, 70 µl (0.4 mmol) of n-octanethiol was dissolved in 3 ml of trioctylamine at a rate of about 1 ml / min using a metering pump. The reaction product in Example 4-2 was added dropwise into the reactor. After reacting for about 17 minutes at 320 ℃ to form a second shell made of CdS on the surface of the first shell CdSe.

Example 4-4: Synthesis of Third Shell Consisting of Cd6S and Zn6S

Into a separate reactor (with syringe, cooler and thermometer), 0.11 g (0.6 mmol) zinc acetate, 0.08 g (0.6 mmol) cadmium oxide, 1.6 mL (5.0 mmol) oleic acid and 9 mL trioctylamine After the temperature was raised to about 110 ° C. under reduced pressure, the temperature was raised to about 320 ° C. under nitrogen gas, followed by stirring, followed by slow cooling to room temperature, thereby obtaining a clear solution including a complex of cadmium and oleic acid and a complex of zinc and oleic acid.

As soon as the synthesis of the second shell composed of CdS of Example 4-3 was finished, a clear solution containing the complex of cadmium and oleic acid and the complex of zinc and oleic acid was added to the reactor in the reaction product of Example 4-3. Injection was made at a rate of 1 ml / min. At the end of the injection, 1300 µl (7.5 mmol) of n-octanethiol was dissolved in 3 ml of trioctylamine and added dropwise into the reactor at a rate of about 1 ml / min using a metering pump. After reacting at 320 ° C. for about 16 minutes, the third shell made of Cd6S (molar ratio of Cd to S is 6) and Zn6S (mole ratio of Zn to S is 1: 6) on the surface of the second shell made of CdS Formed. The reaction product was then slowly cooled to room temperature, acetone and methanol were added, followed by precipitation and centrifugation to wash the quantum dots having a polystyrene nanoparticle core / 3-shell structure. At this time, the washed quantum dots are present in the form of ligand trioctylamine on the surface of the third shell. Trioctylamine acts as a dispersant to allow quantum dots to be evenly dispersed in the organic solvent. Thereafter, a quantum dot having a polystyrene nanoparticle core / 3 double-shell structure was dispersed in toluene to prepare a quantum dot solution having an absorbance of about 610 nm of 0.5, and 6 ml of this was prepared in advance. Absorbance values in quantum dot solutions indirectly indicate the concentration of quantum dots.

Example 4-5 Synthesis of Fourth Shell Consisting of CdS and ZnS

Into a separate reactor (with syringe, cooler and thermometer) add 0.45 g (2.5 mmol) zinc acetate, 0.08 g (0.6 mmol) cadmium oxide, 2.5 mL (7.8 mmol) oleic acid and 20 mL trioctylamine After the temperature was raised to about 110 ° C. under reduced pressure, the temperature was raised to about 320 ° C. under nitrogen gas, followed by stirring, followed by slow cooling to room temperature, thereby obtaining a clear solution including a complex of cadmium and oleic acid and a complex of zinc and oleic acid. Thereafter, the temperature of the solution in the reactor was adjusted to about 320 ° C., and 6 ml of a quantum dot solution having an absorbance of 0.5 at about 610 nm prepared in Example 4-4 was quickly injected, and immediately 560 μl of n-octanthiol (3.2 mmol) was obtained. ) Dissolved in 3 ml of trioctylamine was added dropwise into the reactor at a rate of about 1 ml / min using a metering pump. After reacting for about 48 minutes at 320 ℃ to form a fourth shell consisting of CdS and ZnS on the surface of the third shell consisting of Cd6S and Zn6S. At this time, the molar ratio of CdS to ZnS constituting the fourth shell is about 1: 4. The reaction product was then slowly cooled to room temperature, acetone and butanol were added, followed by precipitation and centrifugation to wash the quantum dots having a polystyrene nanoparticle core / 4 double-shell structure. Thereafter, the washed quantum dots were dispersed in toluene to prepare a toluene solution in which a quantum dot having a polystyrene nanoparticle core / 4 double-shell structure was dispersed.

Example 4-6 Synthesis of Fifth Shell Made of ZnS and Sixth Shell Made of ZnS

1.1 g (6.0 mmol) of zinc acetate, 4 ml (12.4 mmol) of oleic acid, and 20 ml of trioctylamine were added to a separate reactor (with a syringe, a cooler, and a thermometer), and the temperature was raised to about 110 ° C. under reduced pressure near a vacuum. After that, the mixture was heated to about 320 ° C. under nitrogen gas and stirred to obtain a clear solution containing a complex of zinc and oleic acid. Thereafter, 1050 µl (6 mmol) of n-octanethiol dissolved in 6 ml of trioctylamine was injected into the reactor, stirred, and cooled slowly to room temperature to obtain a mixed precursor solution including a zinc precursor and a sulfur precursor.

Into a separate reactor (with a syringe, a cooler, and a thermometer) was injected the toluene solution in which the quantum dots prepared in Example 4-5 were dispersed, and an amount corresponding to half the volume of the mixed precursor solution obtained above was injected. The reaction was carried out at 300 ° C. for 10 minutes to form a fifth shell made of ZnS on the surface of the fourth shell made of CdS and ZnS. After the formation of the fifth shell, the mixed precursor solution remaining in the reactor was injected and reacted at about 300 ° C. for 30 minutes to form a sixth shell made of ZnS on the surface of the fifth shell. After the sixth shell was formed, ultraviolet rays were irradiated to the reactor (transparent glass material) to confirm that the quantum dots having the polystyrene nanoparticle core / hexashell structure emit red light. The reaction product was then slowly cooled to room temperature, acetone and butanol were added, followed by precipitation and centrifugation to obtain quantum dots of the washed polystyrene nanoparticle core / hexashell structure.

(5) Example 5: Preparation of red light emitting quantum dots of core / hexashell structure composed of amorphous silica nanoparticles

Example 5-1 Preparation of Core Comprising Amorphous Silica Nanoparticles

1 g of amorphous silica nanoparticles (particle size: 80 nm; supplier: Alfa Asear) was added to 20 ml of trioctylamine, mixed vigorously with a stirrer and sonicated for about 20 minutes to prepare a core solution in which amorphous silica nanoparticles were uniformly dispersed. It was.

Example 5-2 Synthesis of First Shell Consisting of CdSe

0.103 g (0.8 mmol) of cadmium oxide, 1.2 mL (3.7 mmol) of oleic acid, and 20 mL of trioctylamine were placed in a reactor equipped with a syringe, a condenser, and a J type thermocouple. After the temperature was raised to about 110 ° C., the temperature was raised to about 300 ° C. in a state filled with nitrogen gas, the mixture was stirred vigorously, and slowly cooled to room temperature to obtain a Cd precursor solution including a complex of cadmium and oleic acid.

The core solution prepared in Example 5-1 was placed in a separate reactor equipped with a syringe, a condenser, and a thermometer (J Type thermocouple), and after adjusting the temperature of the reactor to about 220 ° C., the prepared Cd precursor solution was prepared. Was injected into the reactor at a rate of about 0.5 ml / min using a metering pump. 0.2 ml of a selenium / trioctylphosphine solution having a selenium concentration of 2 M (dissolved in selenium powder having a purity of 99.99% or more in trioctylphosphine having a purity of 90% or more; hereinafter referred to as a 2M TOPSe solution) Diluted (0.4 mmol on the basis of selenium) in 10 ml of trioctylamine was injected into the reactor at a rate of about 0.5 ml / min using a metering pump. After reacting for about 40 minutes at about 260 ℃ to form a first shell consisting of CdSe on the surface of the core. After the synthesis of the CdSe first shell is completed, about 0.4 mmol of cadmium is present in the reaction product in a complex with oleic acid.

Example 5-3: Synthesis of Second Shell Consisting of CdS

As soon as the synthesis of the first shell composed of CdSe of Example 5-2 was completed, 70 µl (0.4 mmol) of n-octanethiol was dissolved in 3 ml of trioctylamine at a rate of about 1 ml / min using a metering pump. The reaction product in Example 5-2 was added dropwise into the reactor. After reacting for about 17 minutes at 320 ℃ to form a second shell made of CdS on the surface of the first shell CdSe.

Example 5-4: Synthesis of Third Shell Consisting of Cd6S and Zn6S

Into a separate reactor (with syringe, cooler and thermometer), 0.11 g (0.6 mmol) zinc acetate, 0.08 g (0.6 mmol) cadmium oxide, 1.6 mL (5.0 mmol) oleic acid and 9 mL trioctylamine After the temperature was raised to about 110 ° C. under reduced pressure, the temperature was raised to about 320 ° C. under nitrogen gas, followed by stirring, followed by slow cooling to room temperature, thereby obtaining a clear solution including a complex of cadmium and oleic acid and a complex of zinc and oleic acid.

As soon as the synthesis of the second shell consisting of CdS of Example 5-3 was completed, a clear solution containing the complex of cadmium and oleic acid and the complex of zinc and oleic acid was added to the reactor in the reaction product of Example 5-3. Injection was made at a rate of 1 ml / min. At the end of the injection, 1300 µl (7.5 mmol) of n-octanethiol was dissolved in 3 ml of trioctylamine and added dropwise into the reactor at a rate of about 1 ml / min using a metering pump. After reacting at 320 ° C. for about 16 minutes, the third shell made of Cd6S (molar ratio of Cd to S is 6) and Zn6S (mole ratio of Zn to S is 1: 6) on the surface of the second shell made of CdS Formed. The reaction product was then slowly cooled to room temperature, acetone and methanol were added, followed by precipitation and centrifugation to wash the quantum dots with the amorphous silica nanoparticle core / 3-shell structure. At this time, the washed quantum dots are present in the form of ligand trioctylamine on the surface of the third shell. Trioctylamine acts as a dispersant to allow quantum dots to be evenly dispersed in the organic solvent. Thereafter, a quantum dot having an amorphous silica nanoparticle core / 3 double-shell structure was dispersed in toluene to prepare a quantum dot solution having an absorbance of about 610 nm of 0.5, and 6 ml of this was prepared in advance. Absorbance values in quantum dot solutions indirectly indicate the concentration of quantum dots.

Example 5-5 Synthesis of Fourth Shell Consisting of CdS and ZnS

Into a separate reactor (with syringe, cooler and thermometer) add 0.45 g (2.5 mmol) zinc acetate, 0.08 g (0.6 mmol) cadmium oxide, 2.5 mL (7.8 mmol) oleic acid and 20 mL trioctylamine After the temperature was raised to about 110 ° C. under reduced pressure, the temperature was raised to about 320 ° C. under nitrogen gas, followed by stirring, followed by slow cooling to room temperature, thereby obtaining a clear solution including a complex of cadmium and oleic acid and a complex of zinc and oleic acid. Thereafter, the temperature of the solution in the reactor was adjusted to about 320 ° C., and 6 ml of a quantum dot solution having an absorbance of 0.5 at about 610 nm prepared in Example 5-4 was quickly injected, and 560 μl (3.2 mmol) of n-octanethiol was immediately obtained. ) Dissolved in 3 ml of trioctylamine was added dropwise into the reactor at a rate of about 1 ml / min using a metering pump. After reacting for about 48 minutes at 320 ℃ to form a fourth shell consisting of CdS and ZnS on the surface of the third shell consisting of Cd6S and Zn6S. At this time, the molar ratio of CdS to ZnS constituting the fourth shell is about 1: 4. The reaction product was then slowly cooled to room temperature, acetone and butanol were added, followed by precipitation and centrifugation to wash the quantum dots with amorphous silica nanoparticle core / 4 double-shell structure. Thereafter, the washed quantum dots were dispersed in toluene to prepare a toluene solution in which quantum dots having an amorphous silica nanoparticle core / 4 double-shell structure were dispersed.

Example 5-6 Synthesis of Fifth Shell Made of ZnS and Sixth Shell Made of ZnS

1.1 g (6.0 mmol) of zinc acetate, 4 ml (12.4 mmol) of oleic acid, and 20 ml of trioctylamine were added to a separate reactor (with a syringe, a cooler, and a thermometer), and the temperature was raised to about 110 ° C. under reduced pressure near a vacuum. After that, the mixture was heated to about 320 ° C. under nitrogen gas and stirred to obtain a clear solution containing a complex of zinc and oleic acid. Thereafter, 1050 µl (6 mmol) of n-octanethiol dissolved in 6 ml of trioctylamine was injected into the reactor, stirred, and cooled slowly to room temperature to obtain a mixed precursor solution including a zinc precursor and a sulfur precursor.

Into a separate reactor (with a syringe, a cooler and a thermometer) was injected the toluene solution in which the quantum dots prepared in Example 5-5 were dispersed, and an amount corresponding to half the volume of the mixed precursor solution obtained above was injected. The reaction was carried out at 300 ° C. for 10 minutes to form a fifth shell made of ZnS on the surface of the fourth shell made of CdS and ZnS. After the formation of the fifth shell, the mixed precursor solution remaining in the reactor was injected and reacted at about 300 ° C. for 30 minutes to form a sixth shell made of ZnS on the surface of the fifth shell. After the sixth shell was formed, it was confirmed that the quantum dot having the amorphous silica nanoparticle core / hexashell structure emits red light by irradiating ultraviolet rays to the reactor (transparent glass material). The reaction product was then slowly cooled to room temperature, acetone and butanol were added, followed by precipitation and centrifugation to obtain quantum dots of the washed amorphous silica nanoparticle core / hexashell structure.

(6) Example 6: Preparation of red light emitting quantum dots of core / hexashell structure consisting of polystyrene nanoparticles coated with mesoporous silica

Example 6-1 Preparation of Cores Comprising Polystyrene Nanoparticles Coated with Mesoporous Silica

12 g of polystyrene latex having 9 wt% of polystyrene nanoparticles having a uniform particle size of about 80 nm was added to the flask reactor and stirred vigorously. Then, 4.5 g of water, 0.4 g of hexadecyltrimethylammonium bromide (CTBA), 5.5 g of ethanol, and 1 ml of ammonium hydroxide were added thereto, followed by vigorous stirring, followed by sonication for about 10 minutes. The contents were uniformly dispersed by sonication. Thereafter, the mixture was stirred vigorously at room temperature for 30 minutes, and 0.75 g of tetraethyl orthosilicate (TEOS) was slowly added dropwise and stirred vigorously at room temperature for 48 hours. The reaction product was then centrifuged to yield polystyrene nanoparticles coated with mesoporous silica. The obtained polystyrene nanoparticles coated with mesoporous silica were washed several times with ethanol and dried to obtain polystyrene nanoparticles coated with mesoporous silica in powder form. The size of the polystyrene nanoparticles coated with mesoporous silica was about 70 ~ 100nm. Then, 1 g of polystyrene nanoparticles coated with mesoporous silica obtained on the surface of trioctylamine were mixed vigorously with a stirrer and sonicated for about 20 minutes to uniformly disperse the polystyrene nanoparticles coated with mesoporous silica. The solution was prepared.

Example 6-2 Synthesis of First Shell Consisting of CdSe

0.103 g (0.8 mmol) of cadmium oxide, 1.2 mL (3.7 mmol) of oleic acid, and 20 mL of trioctylamine were placed in a reactor equipped with a syringe, a condenser, and a J type thermocouple. After the temperature was raised to about 110 ° C., the temperature was raised to about 300 ° C. in a state filled with nitrogen gas, the mixture was stirred vigorously, and slowly cooled to room temperature to obtain a Cd precursor solution including a complex of cadmium and oleic acid.

In a separate reactor equipped with a syringe, a condenser, and a thermometer (J Type thermocouple), the core solution prepared in Example 6-1 was added, and after adjusting the temperature of the reactor to about 220 ° C., the prepared Cd precursor solution was prepared. Was injected into the reactor at a rate of about 0.5 ml / min using a metering pump. 0.2 ml of a selenium / trioctylphosphine solution having a selenium concentration of 2 M (dissolved in selenium powder having a purity of 99.99% or more in trioctylphosphine having a purity of 90% or more; hereinafter referred to as a 2M TOPSe solution) Diluted (0.4 mmol on the basis of selenium) in 10 ml of trioctylamine was injected into the reactor at a rate of about 0.5 ml / min using a metering pump. After reacting for about 40 minutes at about 240 ℃ to form a first shell consisting of CdSe on the surface of the core. After the synthesis of the CdSe first shell is completed, about 0.4 mmol of cadmium is present in the reaction product in a complex with oleic acid.

Example 6-3: Synthesis of Second Shell Consisting of CdS

As soon as the synthesis of the first shell composed of CdSe of Example 5-2 was completed, 70 µl (0.4 mmol) of n-octanethiol was dissolved in 3 ml of trioctylamine at a rate of about 1 ml / min using a metering pump. It was dripped in the reactor in which the reaction product of Example 6-2 exists. After reacting for about 17 minutes at 320 ℃ to form a second shell made of CdS on the surface of the first shell CdSe.

Example 6-4: Synthesis of Third Shell Consisting of Cd6S and Zn6S

Into a separate reactor (with syringe, cooler and thermometer), 0.11 g (0.6 mmol) zinc acetate, 0.08 g (0.6 mmol) cadmium oxide, 1.6 mL (5.0 mmol) oleic acid and 9 mL trioctylamine After the temperature was raised to about 110 ° C. under reduced pressure, the temperature was raised to about 320 ° C. under nitrogen gas, followed by stirring, followed by slow cooling to room temperature, thereby obtaining a clear solution including a complex of cadmium and oleic acid and a complex of zinc and oleic acid.

As soon as the synthesis of the second shell composed of CdS of Example 6-3 was completed, a clear solution containing the complex of cadmium and oleic acid and the complex of zinc and oleic acid was added to the reactor in which the reaction product of Example 6-3 was present. Injection was made at a rate of 1 ml / min. At the end of the injection, 1300 µl (7.5 mmol) of n-octanethiol was dissolved in 3 ml of trioctylamine and added dropwise into the reactor at a rate of about 1 ml / min using a metering pump. After reacting at 320 ° C. for about 16 minutes, the third shell made of Cd6S (molar ratio of Cd to S is 6) and Zn6S (mole ratio of Zn to S is 1: 6) on the surface of the second shell made of CdS Formed. The reaction product was then slowly cooled to room temperature, acetone and methanol were added, followed by precipitation and centrifugation to wash the quantum dots having a polystyrene nanoparticle core / 3fold shell structure coated with mesoporous silica. At this time, the washed quantum dots are present in the form of ligand trioctylamine on the surface of the third shell. Trioctylamine acts as a dispersant to allow quantum dots to be evenly dispersed in the organic solvent. Thereafter, a quantum dot having an amorphous silica nanoparticle core / 3 double-shell structure was dispersed in toluene to prepare a quantum dot solution having an absorbance of about 610 nm of 0.5, and 6 ml of this was prepared in advance. Absorbance values in quantum dot solutions indirectly indicate the concentration of quantum dots.

Example 6-5: Synthesis of Fourth Shell Consisting of CdS and ZnS

Into a separate reactor (with syringe, cooler and thermometer) add 0.45 g (2.5 mmol) zinc acetate, 0.08 g (0.6 mmol) cadmium oxide, 2.5 mL (7.8 mmol) oleic acid and 20 mL trioctylamine After the temperature was raised to about 110 ° C. under reduced pressure, the temperature was raised to about 320 ° C. under nitrogen gas, followed by stirring, followed by slow cooling to room temperature, thereby obtaining a clear solution including a complex of cadmium and oleic acid and a complex of zinc and oleic acid. Thereafter, the temperature of the solution in the reactor was adjusted to about 320 ° C., and 6 ml of the quantum dot solution having an absorbance of 0.5 at about 610 nm prepared in Example 6-4 was rapidly injected, and immediately 560 μl of n-octanthiol (3.2 mmol) was obtained. ) Dissolved in 3 ml of trioctylamine was added dropwise into the reactor at a rate of about 1 ml / min using a metering pump. After reacting for about 48 minutes at 320 ℃ to form a fourth shell consisting of CdS and ZnS on the surface of the third shell consisting of Cd6S and Zn6S. At this time, the molar ratio of CdS to ZnS constituting the fourth shell is about 1: 4. The reaction product was then slowly cooled to room temperature, acetone and butanol were added, followed by precipitation and centrifugation to wash the quantum dots having a polystyrene nanoparticle core / 4fold shell structure coated with mesoporous silica. Thereafter, the washed quantum dots were dispersed in toluene to prepare a toluene solution in which quantum dots having an amorphous silica nanoparticle core / 4 double-shell structure were dispersed.

Example 6-6 Synthesis of Fifth Shell Made of ZnS and Sixth Shell Made of ZnS

1.1 g (6.0 mmol) of zinc acetate, 4 ml (12.4 mmol) of oleic acid, and 20 ml of trioctylamine were added to a separate reactor (with a syringe, a cooler, and a thermometer), and the temperature was raised to about 110 ° C. under reduced pressure near a vacuum. After that, the mixture was heated to about 320 ° C. under nitrogen gas and stirred to obtain a clear solution containing a complex of zinc and oleic acid. Thereafter, 1050 µl (6 mmol) of n-octanethiol dissolved in 6 ml of trioctylamine was injected into the reactor, stirred, and cooled slowly to room temperature to obtain a mixed precursor solution including a zinc precursor and a sulfur precursor.

Into a separate reactor (with a syringe, a cooler and a thermometer) was injected the toluene solution in which the quantum dots prepared in Example 6-5 were dispersed, and an amount corresponding to half the volume of the mixed precursor solution obtained above was injected. The reaction was carried out at 300 ° C. for 10 minutes to form a fifth shell made of ZnS on the surface of the fourth shell made of CdS and ZnS. After the formation of the fifth shell, the mixed precursor solution remaining in the reactor was injected and reacted at about 300 ° C. for 30 minutes to form a sixth shell made of ZnS on the surface of the fifth shell. After forming the sixth shell, the reactor (made of transparent glass) was irradiated with ultraviolet light to confirm that the quantum dot having a polystyrene nanoparticle core / hexashell structure coated with mesoporous silica emits red light. The reaction product was then slowly cooled to room temperature, acetone and butanol were added, followed by precipitation and centrifugation to obtain quantum dots of a polystyrene nanoparticle core / hexashell structure coated with washed mesoporous silica.

(7) Example 7: Preparation of green light emitting quantum dots of core / hexashell structure composed of amorphous silica nanoparticles

Example 7-1 Preparation of Cores Comprising Amorphous Silica Nanoparticles

1 g of amorphous silica nanoparticles (particle size: 80 nm; supplier: Alfa Asear) was added to 20 ml of trioctylamine, mixed vigorously with a stirrer and sonicated for about 20 minutes to prepare a core solution in which amorphous silica nanoparticles were uniformly dispersed. It was.

Example 7-2 Synthesis of First Shell Consisting of CdSe

Into a reactor equipped with a syringe, a condenser, and a thermometer (J type thermocouple), 0.0515 g (0.4 mmol) of cadmium oxide, 0.7 ml of oleic acid, and 10 ml of octadecane were heated, and the temperature was raised to about 110 ° C under reduced pressure close to a vacuum. Thereafter, the mixture was heated to about 300 ° C. in a state filled with nitrogen gas, stirred vigorously, and cooled slowly to room temperature to obtain a Cd precursor solution including a complex of cadmium and oleic acid.

The core solution prepared in Example 7-1 was placed in a separate reactor equipped with a syringe, a condenser, and a thermometer (J Type thermocouple), and after adjusting the temperature of the reactor to about 220 ° C., the prepared Cd precursor solution was prepared. Was injected into the reactor at a rate of about 0.5 ml / min using a metering pump. Thereafter, 50 µl (0.1 mmol based on selenium) of TOPSe solution having a selenium concentration of 2 M was diluted in 10 ml of trioctylamine and injected into the reactor at a rate of about 0.5 ml / min using a metering pump. After reacting for about 5 minutes at about 320 ℃ to form a first shell consisting of CdSe on the surface of the core. After the synthesis of the CdSe first shell is completed, about 0.3 mmol of cadmium is present in the reaction product in a complex with oleic acid.

Example 7-3: Synthesis of Second Shell Consisting of CdS

As soon as the synthesis of the first shell composed of CdSe of Example 7-2 was completed, 0.0096 g (0.3 mmol) of sulfur powder was dissolved in 1 ml of trioctylphosphine at a rate of about 1 ml / min using a metering pump. It dripped in the reactor in which the reaction product of Example 7-2 exists. After reacting for about 9 minutes at 320 ℃ to form a second shell made of CdS on the surface of the first shell CdSe.

Example 7-4: Synthesis of Third Shell Consisting of Cd6S and Zn6S

In a separate reactor (with a syringe, cooler and thermometer), 0.0255 g (0.3 mmol) of zinc oxide, 0.04 g (0.3 mmol) of cadmium oxide, 0.8 ml of oleic acid and 5.5 ml of octadecane were placed under reduced pressure near vacuum. After the temperature was raised to 110 ° C., the temperature was raised to about 320 ° C. in a state filled with nitrogen gas, stirred, and cooled slowly to room temperature to obtain a clear solution including a complex of cadmium and oleic acid and a complex of zinc and oleic acid.

As soon as the synthesis of the second shell made of CdS of Example 7-3 was completed, a clear solution containing the complex of cadmium and oleic acid and the complex of zinc and oleic acid was added to the reactor in the reaction product of Example 7-3. Injection was made at a rate of 1 ml / min. At the end of the injection, 0.117 g (3.6 mmol) of sulfur powder was dissolved in 1 ml of trioctylphosphine and dropped into the reactor at a rate of about 1 ml / min using a metering pump. After reacting at 320 ° C. for about 14 minutes, the third shell made of Cd6S (molar ratio of Cd to S is 6) and Zn6S (mole ratio of Zn to S is 1: 6) on the surface of the second shell made of CdS Formed. The reaction product was then slowly cooled to room temperature, acetone and methanol were added, followed by precipitation and centrifugation to wash the quantum dots with the amorphous silica nanoparticle core / 3-shell structure. At this time, the washed quantum dot is present in the ligand form of trioctylphosphine or oleic acid on the surface of the third shell. Trioctylphosphine or oleic acid acts as a dispersant to allow quantum dots to be evenly dispersed in an organic solvent. Thereafter, a quantum dot having an amorphous silica nanoparticle core / 3 double-shell structure was dispersed in toluene to prepare a quantum dot solution having an absorbance of about 610 nm of 0.5, and 6 ml of this was prepared in advance. Absorbance values in quantum dot solutions indirectly indicate the concentration of quantum dots.

Example 7-5 Synthesis of Fourth Shell Consisting of CdS and ZnS

In a separate reactor (with syringe, cooler and thermometer), 0.1017 g (1.25 mmol) of zinc oxide, 0.04 g (0.3 mmol) of cadmium oxide, 3 ml of oleic acid, and 10 ml of octadecane were decompressed close to vacuum. After the temperature was raised to about 110 ° C., the temperature was raised to about 320 ° C. in a state filled with nitrogen gas, stirred, and cooled slowly to room temperature to obtain a clear solution including a complex of cadmium and oleic acid and a complex of zinc and oleic acid. Thereafter, the temperature of the solution in the reactor was adjusted to about 320 ° C., and 6 ml of a quantum dot solution having an absorbance of 0.5 at about 610 nm prepared in Example 7-4 was quickly injected, and immediately 0.05 g (1.56 mmol) of sulfur powder was added. What was dissolved in 1 ml of trioctylphosphine was dropped into the reactor at a rate of about 1 ml / min using a metering pump. After reacting for about 14 minutes at 320 ℃ to form a fourth shell consisting of CdS and ZnS on the surface of the third shell consisting of Cd6S and Zn6S. At this time, the molar ratio of CdS to ZnS constituting the fourth shell is about 1: 4. The reaction product was then slowly cooled to room temperature, acetone and butanol were added, followed by precipitation and centrifugation to wash the quantum dots with amorphous silica nanoparticle core / 4 double-shell structure. Thereafter, the washed quantum dots were dispersed in toluene to prepare a toluene solution in which quantum dots having an amorphous silica nanoparticle core / 4 double-shell structure were dispersed.

Example 7-6 Synthesis of Fifth Shell Made of ZnS and Sixth Shell Made of ZnS

Into a separate reactor (with syringe, cooler and thermometer), 0.2034 g (2.5 mmol) of zinc oxide, 7 ml of oleic acid and 12 ml of octadecane were heated to about 110 ° C. under reduced pressure close to vacuum, followed by nitrogen gas. It was heated to about 320 ℃ in the state filled with and stirred to obtain a clear solution containing a complex of zinc and oleic acid. Thereafter, 0.08 g (2.5 mmol) of sulfur powder dissolved in 2 ml of trioctylphosphine was injected into the reactor, stirred, and cooled slowly to room temperature to obtain a mixed precursor solution including a zinc precursor and a sulfur precursor.

Into a separate reactor (with a syringe, a cooler and a thermometer) was injected with the toluene solution in which the quantum dots prepared in Example 7-5 were dispersed, and an amount corresponding to half the volume of the mixed precursor solution obtained above was injected. The reaction was performed at 200 ° C. for 5 minutes to form a fifth shell made of ZnS on the surface of the fourth shell made of CdS and ZnS. After the formation of the fifth shell, the mixed precursor solution remaining in the reactor was injected and reacted at about 300 ° C. for 15 minutes to form a sixth shell made of ZnS on the surface of the fifth shell. After the sixth shell was formed, ultraviolet rays were irradiated to the reactor (transparent glass material) to confirm that the quantum dots having the amorphous silica nanoparticle core / hexashell structure emit green light. The reaction product was then slowly cooled to room temperature, acetone and butanol were added, followed by precipitation and centrifugation to obtain quantum dots of the washed amorphous silica nanoparticle core / hexashell structure.

2. Form and Crystal Characteristics of Quantum Dots

(1) Form of quantum dot

The cross-sectional structure of the quantum dots, the size of the core, the thickness of the shell, and the size of the quantum dots were measured by transmission electron microscopy (TEM). 2 is a photograph taken with a transmission electron microscopy (TEM) of a quantum dot of the core / hexashell structure made of the insulator particles prepared in Example 6 of the present invention. As shown in FIG. 2, the quantum dots of the core / hexashell structure made of the insulator particles prepared in Example 6 of the present invention had a total size of about 75-108 nm and a thickness of the hexashell was about 5-8 nm.

(2) Crystal Characteristics of Quantum Dots

Crystalline characteristics of the quantum dots were measured using a line diffractometer (X-Ray Diffractometer, XRD). At this time, as a control, a red light emitting quantum dot having a third shell consisting of CdSe core / CdS first shell / Cd6S and Zn6S / CdS and ZnS third shell / ZnS fourth shell / ZnS fifth shell structure (product name: H-100; Manufacturer: QD Solution, Korea). 3 is a result of analyzing the quantum dot and the control quantum dot of the core / six-shell structure prepared in Example 5 of the present invention by an X-ray diffractometer (X-Ray Diffractometer, XRD). As shown in FIG. 3, the quantum dots of the core / hexashell structure of the present invention showed the same crystal peaks as the quantum dots of the core / 5-shell structure made of CdSe, although the core was composed of insulator particles.

Although the present invention has been described through the above embodiments as described above, the present invention is not necessarily limited thereto, and various modifications can be made without departing from the scope and spirit of the present invention. In addition, many modifications may be made to adapt a particular situation and material to the teachings of the invention without departing from the essential scope thereof. Accordingly, the protection scope of the present invention should not be construed as being limited to the particular embodiments disclosed as the best mode contemplated for carrying out the invention but to cover all embodiments falling within the scope of the appended claims.

Claims (30)

A core made of insulator particles and a plurality of shells sequentially surrounding the core,
The plurality of shells comprises a semiconductor compound, characterized in that the further away from the core has a larger bandgap.
The quantum dot of claim 1, wherein the plurality of shells have a total thickness of 2 to 20 nm.
The quantum dot of claim 1, wherein the insulator particles are made of at least one selected from a polymer, a metal oxide, a metal nitride, a metalloid oxide, and a metalloid nitride.
The quantum dot of claim 3, wherein the insulator particles are polystyrene particles.
The quantum dot of claim 3, wherein the insulator particles are amorphous silica particles.
4. The quantum dot of claim 3, wherein the insulator particles are polymer particles coated with mesoporous silica.
The quantum dot of claim 3, wherein the insulator particles have a size of 10 nm to 100 nm.
The semiconductor device of claim 1, wherein the plurality of shells comprises: a first shell formed on a surface of the core and comprising a semiconductor compound composed of Group 12 elements and Group 16 elements; And a second shell formed on the surface of the first shell, the semiconductor compound including a group 12 element and a group 16 element, the second shell having a band gap larger than that of the first shell. Quantum dots.
The quantum dot of claim 8, wherein the semiconductor compound consisting of Group 12 elements and Group 16 elements of the first shell is any one selected from CdSe or CdTe.
The quantum dot of claim 8, wherein the semiconductor compound composed of Group 12 elements and Group 16 elements of the second shell is CdS or ZnS.
The semiconductor device of claim 1, wherein the plurality of shells comprises: a first shell formed on a surface of the core and comprising a semiconductor compound composed of Group 12 elements and Group 16 elements; A second shell formed on the surface of the first shell and including a semiconductor compound composed of Group 12 elements and Group 16 elements, the second shell having a band gap larger than that of the first shell; A third shell formed on the surface of the second shell and including two different semiconductor compounds formed of Group 12 elements and Group 16 elements, the third shell having a band gap larger than that of the second shell; A fourth shell formed on the surface of the third shell and including two different semiconductor compounds formed of Group 12 elements and Group 16 elements, the fourth shell having a band gap larger than that of the third shell; A fifth shell formed on the surface of the fourth shell and including a semiconductor compound composed of Group 12 elements and Group 16 elements, and having a band gap larger than that of the fourth shell; And a sixth shell formed on the surface of the fifth shell and including a semiconductor compound composed of a Group 12 element and a Group 16 element, the sixth shell having a band gap larger than that of the fifth shell. Quantum dots.
12. The quantum dot of claim 11, wherein the semiconductor compound consisting of Group 12 elements and Group 16 elements of the first shell is any one selected from CdSe or CdTe.
12. The quantum dot of claim 11, wherein the semiconductor compound composed of Group 12 elements and Group 16 elements of the second shell is CdS.
12. The method of claim 11, wherein the two kinds of semiconductor compounds different from each other consisting of Group 12 elements and Group 16 elements of the third shell are compounds consisting of Cd and S and compounds consisting of Zn and S,
In the semiconductor compound consisting of Cd and S, the molar ratio of Cd to S is 1: 3 to 1: 9,
The quantum dot is characterized in that the molar ratio of Zn to S in the semiconductor compound consisting of Zn and S is 1: 3 to 1: 9.
The quantum dot of claim 14, wherein the molar ratio of the semiconductor compound consisting of Cd and S to the semiconductor compound consisting of Zn and S is 2: 1 to 1: 2.
12. The semiconductor compound of claim 11, wherein the two different semiconductor compounds composed of Group 12 elements and Group 16 elements of the fourth shell are CdS and ZnS,
The molar ratio of CdS to ZnS is 1: 2 to 1: 6.
12. The quantum dot of claim 11, wherein the semiconductor compound composed of Group 12 elements and Group 16 elements of the fifth shell is ZnS.
The quantum dot of claim 1, wherein the semiconductor compound composed of Group 12 elements and Group 16 elements of the sixth shell is ZnS.
(a) preparing a core of insulator particles;
(b) reacting a Group 12 element-containing compound and a Group 16 element-containing compound in a reaction medium to form a first shell including a semiconductor compound composed of Group 12 elements and Group 16 elements on the surface of the core; And
(c) reacting a Group 12 element-containing compound and a Group 16 element-containing compound in a reaction medium, wherein the surface of the first shell contains a semiconductor compound composed of Group 12 elements and Group 16 elements, and is less than the bandgap of the first shell. Forming a second shell having a larger bandgap.
20. The method of claim 19,
(d) reacting the Group 12 element-containing compound and the Group 16 element-containing compound in a reaction medium, wherein the surface of the second shell contains two different kinds of semiconductor compounds composed of Group 12 elements and Group 16 elements; Forming a third shell having a bandgap larger than the bandgap of the shell;
(e) reacting a Group 12 element-containing compound and a Group 16 element-containing compound in a reaction medium to include two different types of semiconductor compounds composed of Group 12 elements and Group 16 elements on the surface of the third shell; Forming a fourth shell having a bandgap larger than the bandgap of the shell;
(f) reacting the Group 12 element-containing compound and the Group 16 element-containing compound in a reaction medium, wherein the surface of the fourth shell contains a semiconductor compound composed of Group 12 element and Group 16 element, and is less than the band gap of the fourth shell. Forming a fifth shell having a larger bandgap; And
(g) reacting the Group 12 element-containing compound and the Group 16 element-containing compound in a reaction medium, wherein the surface of the fifth shell contains a semiconductor compound composed of Group 12 element and Group 16 element, and is less than the band gap of the fifth shell. Forming a sixth shell having a larger band gap; Method of producing a quantum dot further comprising.
21. The method of claim 20, wherein the total thickness of the first shell, the second shell, the third shell, the fourth shell, the fifth shell, and the sixth shell is 2-20 nm.
22. The method according to any one of claims 19 to 21, wherein the insulator particles of step (a) comprise one or more selected from polymers, metal oxides, metal nitrides, metalloid oxides, and metalloid nitrides. Method of producing a quantum dot.
22. The method according to any one of claims 19 to 21, wherein the insulator particles of step (a) are any one of polystyrene particles, amorphous silica particles, or polymer particles coated with mesoporous silica. .
22. The method according to any one of claims 19 to 21, wherein the size of the insulator particles in step (a) is 10 to 100 nm.
22. The compound of any one of claims 19 to 21, wherein the Group 12 element-containing compound of step (b) is a cadmium-containing compound, and the Group 16 element-containing compound is a selenium-containing compound or tellurium-containing compound. Method for producing quantum dots.
22. The quantum dot according to any one of claims 19 to 21, wherein the Group 12 element-containing compound of step (c) is a cadmium-containing compound or a zinc-containing compound, and the Group 16 element-containing compound is a sulfur-containing compound. Manufacturing method.
22. The method according to any one of claims 19 to 21, wherein the molar ratio of the Group 12 element-containing compound to the Group 16 element-containing compound of step (d) is from 1: 3 to 1: 9. .
28. The method according to claim 27, wherein the group 12 element-containing compound of step (d) is a cadmium-containing compound and a zinc-containing compound, the group 16 element-containing compound is a sulfur-containing compound,
Wherein the molar ratio of cadmium-containing compound to zinc-containing compound is 2: 1 to 1: 2.
The compound of any one of claims 19 to 21, wherein the Group 12 element-containing compound of step (e) is a cadmium-containing compound and a zinc-containing compound, and the Group 16 element-containing compound is a sulfur-containing compound,
Wherein the molar ratio of cadmium containing compound to zinc containing compound is 1: 2 to 1: 6.
22. The compound of any one of claims 19 to 21, wherein the group 12 element-containing compound of step (f) and (g) is a zinc-containing compound, and the group 16 element-containing compound is a sulfur-containing compound. Method of producing a quantum dot.

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