KR20220081443A - Preparing method for nanocrystals, composition for preparing nanocrystals, and nanocrystals prepared by the same - Google Patents

Abstract

An object of the present invention is to provide a method for manufacturing a nanocrystal capable of finely controlling the wavelength of light emission.
The present invention can finely control the light emission wavelength by controlling the growth rate of the nanocrystals by attaching a crystal growth inhibitor, which is a cyclic compound, to the surface of the nanocrystals during the preparation of the nanocrystals.

Description

Method for producing nanocrystals, composition for producing nanocrystals, and nanocrystals prepared thereby

The present invention relates to a method for producing a nanocrystal, a composition for producing a nanocrystal, and a nanocrystal prepared thereby.

As shown in FIG. 1, the nanocrystal is a semiconductor crystal of several nanometers made of an inorganic semiconductor material. The core part, the shell part, and the organic solvent bonded to the surface of the shell part of the nanocrystal to increase solubility in organic solvents. It consists of a substance, a ligand.

In general, nanocrystal materials have a characteristic that an energy bandgap (Eg) between a valence band and a conduction band changes according to their size. In addition, nanocrystal materials have various material advantages, such as excellent absorption coefficient, high electron mobility, and the ability to control emission wavelength according to particle size control. In particular, nanocrystal materials are attracting attention as a next-generation display device material because of their excellent photostability because the light-emitting core is an inorganic material rather than an organic material.

Nanocrystals composed of semiconductor elements can be synthesized through various methods. Nanocrystals having a core/shell/ligand structure with excellent optical properties are generally synthesized through a wet chemical solution process. In particular, nanocrystals applied to the inkjet printing method are synthesized by hot-injection batch synthesis because the dispersion characteristics of the nanocrystals in organic solvents must be excellent due to the characteristics of the process. According to this method, the nanocrystal core and the shell are formed by injecting various precursors as reactants into the high-temperature metal compound solution. For the purpose of increasing solubility, a capping ligand having a high boiling point is used as a reaction solvent. Representative capping ligands used in high-temperature solution synthesis are oleylamine and trioctylphosphine oxide (TOPO). These ligands are finally bonded to the surface of the shell of the synthesized nanocrystal to protect the nanocrystal. and increase solubility in organic solvents. Therefore, by selecting an appropriate metal compound and precursor and controlling the reaction conditions (concentration, temperature, time), nanocrystals having various elements and structures can be prepared.

In the method for preparing CdSe, which is a representative nanocrystal material, by high-temperature solution synthesis, the crystal growth process of the nanocrystals is shown in FIG. 2 . In a high-temperature solution, metal compounds and precursors are decomposed to form very small nanocrystal nuclei, which are attached to the surface of larger nanocrystals and grow into large nanocrystals. When grown into large crystals, compared to small nanocrystals, the volume-to-surface area ratio of the crystals is lowered, resulting in a more energetically stable state. Conversely, because small crystals have a high volume to surface area ratio, they are decomposed into individual elements and attached to large crystals again, resulting in a more energetically stable state. Therefore, it can be seen that the size of the nanocrystals is determined by the reaction conditions in which the crystals are made in addition to the properties of the metal compounds and precursors participating in the reaction.

As an example, when InCl, ZnCl ₂ , and P4 (white phosphorus) compounds are reacted at a reaction temperature of 150° C. and a high temperature solution process condition for 30 minutes, InP/ZnS nanocrystals emitting green light are generated. However, InP/ZnS nanocrystals emitting red light are produced at a reaction temperature of 210°C and a high-temperature solution process for 1 hour. The sizes of the green and red InP/ZnS nanocrystals generated at this time were 3.31 ± 0.22 nm and 3.83 ± 0.22 nm, respectively, and the size difference was only 0.5 nm on average. Since the wavelength of the emitted light varies greatly and sensitively according to the size of the nanocrystals, the reaction conditions must be precisely controlled when synthesizing the nanocrystals in a high-temperature solution. In addition, in order to use nanocrystals as a material for a display device, it is necessary to finely control the emission wavelength of several nanometers to several tens of nanometers, but there are many difficulties with existing synthesis methods.

Korean Patent No. 10-1468985

It is an object of the present invention to provide a method for producing nanocrystals capable of finely controlling the wavelength of light emission.

In addition, it is an object of the present invention to provide a composition capable of producing nanocrystals capable of finely controlling the wavelength of light emission.

In addition, it is an object of the present invention to provide a nanocrystal prepared according to the method for manufacturing the nanocrystal.

According to a first aspect of the present invention, it comprises the steps of forming nanocrystals from the core precursor compound and the shell precursor compound, and combining the nanocrystals with the crystal growth inhibitor, wherein the crystal growth inhibitor is a compound of Formula 1 and Formula 1 A method for preparing nanocrystals, wherein the compound is at least one of the compounds of 2, is provided.

[Formula 1]

[Formula 2]

(In Formulas 1 and 2, X ₁ is at least one atom selected from the group consisting of O, S, Se and Te,

R ₁ and R ₂ are each independently hydrogen, a straight-chain or branched alkyl group having 1 to 10 carbon atoms, a straight-chain or branched alkenyl group having 2 to 12 carbon atoms, a straight-chain or branched alkynyl group having 2 to 20 carbon atoms, or an aryl group having 6 to 15 carbon atoms, and R ₁ and R ₂ are each independently -NR ₃ R ₄ , -OR ₃ , -CF ₃ , -CCl ₃ , -CN, -NO ₂ , -COR ₃ or -CONH ₂ may be substituted, wherein R ₃ and R ₄ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, or an aryl group having 6 to 15 carbon atoms; , R ₁ and R ₂ may not form a bond or form a bond and may be connected in a chain or ring form,

n is an integer from 2 to 18.)

According to a second aspect of the present invention, it comprises a core precursor compound, a shell precursor compound, and a crystal growth inhibitor, wherein the crystal growth inhibitor is at least one of the compound of Formula 1 and the compound of Formula 2, for producing nanocrystals A composition is provided.

According to a third aspect of the present invention, there is provided a nanocrystal prepared according to the above method.

According to the present invention, the nanocrystal growth rate can be controlled by introducing a cyclic compound containing an electron donor atom in a solution process for preparing nanocrystals. By controlling the growth rate of the nanocrystals in this way, it is possible to finely control the light emission wavelength of the nanocrystals.

1 shows the energy band gap according to the nanocrystal structure, the nanocrystal energy level, and the nanocrystal particle size.
FIG. 2 schematically shows the crystal growth process of nanocrystals in a method for manufacturing CdSe, which is a nanocrystal material, by a high-temperature solution synthesis method.
3 shows the exciton transition energy according to the nanocrystal particle size.
4 is a schematic diagram showing that the crown ether is coordinated with the nanocrystal surface to form a host-guest compound.
5 to 9 are graphs comparing the light emission wavelength of the nanocrystals prepared in Examples 1 to 5 and Comparative Examples.
10 is a graph showing the results of X-ray diffraction analysis (XRD) of the nanocrystals prepared in Examples 1 to 4;
11 shows the CIE color coordinate system.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiment of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

The present invention relates to a method for producing nanocrystals. Referring to FIG. 1 , a nanocrystal is a semiconductor crystal with a size of several nanometers made of an inorganic semiconductor material, and is bonded to a core part, a shell part, and the surface of the shell part of the nanocrystal to increase solubility in organic solvents. It is composed of an organic substance called a ligand.

Unlike bulk materials, nanocrystals exhibit unique electrical and optical properties because the energy band gap varies according to their size and shape. As shown in FIG. 3 , since the exciton transition energy varies according to the size of the nanocrystal, the energy band gap can be broadly adjusted to the ultraviolet, infrared, and visible ray regions only by controlling the size of the nanocrystal. In general, the visible light emission wavelength of the nanocrystal material is determined according to the size of the core and the shell. Therefore, in order to use a nanocrystalline material as a display device material that emits a visible light spectrum with high quantum efficiency and excellent color purity, the size of the core and the shell of the nanocrystalline material must be finely controlled.

The present invention provides a novel high-temperature solution synthesis system capable of controlling the size of nanocrystals. Hereinafter, the present invention will be described in detail.

The nanocrystal manufacturing method according to the present invention may include forming nanocrystals from a core precursor and a shell precursor, and combining the nanocrystals with a crystal growth inhibitor. Electron donor atoms such as O, S, Se, and Te, which have relatively strong coordination ability, exist in the crystal growth inhibitor molecule, and are bound to the surface of the nanocrystal during the nanocrystal formation process to form a nanocrystal metal ion and a host-guest compound. Forms stable coordination compounds.

The crystal growth inhibitory agent may be at least one of a compound of Formula 1 and a compound of Formula 2.

[Formula 1]

[Formula 2]

In Formulas 1 and 2, X ₁ may be one or more atoms selected from the group consisting of O, S, Se, and Te.

In addition, R ₁ and R ₂ are each independently hydrogen, a straight-chain or branched alkyl group having 1 to 10 carbon atoms, a straight-chain or branched alkenyl group having 2 to 12 carbon atoms, or a straight-chain or branched alkyl group having 2 to 20 carbon atoms. A nyl group, or an aryl group having 6 to 15 carbon atoms, R ₁ and R ₂ are each independently -NR ₃ R ₄ , -OR ₃ , -CF ₃ , -CCl ₃ , -CN, -NO ₂ , -COR ₃ Or -CONH ₂ may be substituted, wherein R ₃ and R ₄ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, or 6 to 15 carbon atoms It is an aryl group, and R ₁ and R ₂ may not form a bond or form a bond and may be connected in a chain or ring form, and n may be an integer of 2 to 18.

In the present invention, the alkyl group means a monovalent hydrocarbon, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, n-hexyl, n- octyl, n-decyl, and the like, but is not limited thereto.

an alkenyl group It refers to an unsaturated hydrocarbon having one or more carbon-carbon double bonds, and examples thereof include, but are not limited to, ethyleneyl, propenyl, butenyl, pentenyl, and the like.

The alkynyl group refers to an unsaturated hydrocarbon having one or more carbon-carbon triple bonds, and examples thereof include, but are not limited to, acetylenyl, propynyl, butynyl, and the like.

The aryl group includes both an aromatic group and a heteroaromatic group and partially reduced derivatives thereof. The aromatic group has a simple ring form or a fused ring form, and the heteroaromatic group refers to an aromatic group containing at least one oxygen, sulfur or nitrogen. The aryl group is, for example, phenyl, naphthyl, pyridinyl, furanyl, thiophenyl, indolyl, quinolinyl, imidazolyl Nyl (imidazolinyl), oxazolyl (oxazolyl), thiazolyl (thiazolyl), tetrahydronaphthyl (tetrahydronaphthyl), and the like may be mentioned, but is not limited thereto.

In the process of nanocrystal growth, the crystal growth inhibitor represented by Formula 1 or Formula 2 forms a nanocrystal and a host-guest compound or forms a coordination compound to surround the surface of the nanocrystal. This may delay the growth rate of the nanocrystals.

In the present invention, the crystal growth inhibitor may be, for example, a crown ether. Crown ether is a compound having a large ring-shaped polyethylene ether skeleton in which an oxyethylene group is formed in the form of -(OCH ₂ CH ₂ )n-, and is a crown-type compound in which an oxygen atom and an ethylene substituent are crossed. 4 is a schematic diagram showing that the crown ether is coordinated with the nanocrystal surface to form a host-guest compound. Referring to FIG. 4 , oxygen, which is an electron donor atom of the crown ether, forms a host-guest compound by providing electrons to metal ions, thereby delaying the growth rate of nanocrystals.

In this case, if the void space inside the crystal growth inhibitor is too large or small compared to the size of the nanocrystal, the crystal growth inhibitor and the host-guest compound of the nanocrystal may not be properly formed. Therefore, it is preferable to select a crystal growth inhibitor in consideration of the size of the nanocrystals.

The size of the nanocrystals in the present invention may vary depending on the addition amount of the crystal growth inhibitor compared to the core precursor compound and the shell precursor compound.

Specifically, the molar equivalent ratio of the core precursor compound and the crystal growth inhibitor added during nanocrystal production may be 1:0.1 to 1:4, preferably 1:1 to 1:4. If the molar equivalent ratio of the core precursor compound and the crystal growth inhibitor is less than 1:0.1, the amount of the crystal growth inhibitor compared to the core precursor compound is too small, so that the effect of retarding the growth of nanocrystals may be reduced. On the other hand, if the molar equivalent ratio of the core precursor compound and the crystal growth inhibitor exceeds 1:4, there is a risk that the nanocrystals may not grow properly due to excessive input of the crystal growth inhibitor.

In addition, the molar equivalent ratio of the shell precursor compound and the crystal growth inhibitor added during the preparation of the nanocrystals may be 1:0.1 to 1:4, preferably 1:0.1 to 1:1. If the molar equivalent ratio of the shell precursor compound and the crystal growth inhibitor is less than 1:0.1, the amount of the crystal growth inhibitor compared to the shell precursor compound is too small to reduce the effect of delaying the growth of nanocrystals. On the other hand, when the molar equivalent ratio of the shell precursor compound and the crystal growth inhibitor exceeds 1:4, there is a risk that the nanocrystals may not grow properly due to excessive input of the crystal growth inhibitor.

According to the present invention, the core precursor and the shell precursor may be semiconductor compound precursors made of metal and/or non-metal, for example, InCl ₃ , InBr ₃ , InI ₃ , ZnCl ₂ , ZnBr ₂ , ZnI ₂ It may be not limited

In the present invention, the core part and the shell part of the nanocrystal may be at least one selected from the group consisting of IB, IIB, IIIB, IVB, VB and VIB of the periodic table of elements, preferably IVB, IIB- It may be a compound of Group VIB, IVB-VIB, IIIB-VB, IB-IIIB-VIB.

Examples of group IVB precursors include Si, Ge, and SiC, examples of group IIB-VIB precursors include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, and the like, and examples of group IVB-VIB precursors include PbS , PbSe, PbTe, and the like. Also, examples of the group IIIB-VB precursor include AlP, AlAs, AlSb, InN. InP, InAs, GaN, GaP, GaAs, GaSb, InGaP, etc., and examples of the group IB-IIIB-VIB precursor include AgGaS ₂ , AgGaSe ₂ , AgGaTe ₂ , AgInS ₂ , AgInSe ₂ , AgInTe ₂ , CuInS ₂ , CuInSe ₂ , CuInTe ₂ , CuGaS ₂ , CuGaSe ₂ , CuGaTe ₂ , and the like.

On the other hand, pure nanocrystals without a ligand in the shell exhibit strong polar properties due to dangling bond atoms present on the crystal surface, and intermolecular dipole-dipole interaction between these nanocrystals and the ligand and coordination bonding. Therefore, if an electron donor atom with high electronegativity (N-atom electronegativity = 3.0, O-atom electronegativity = 3.5) exists inside the ligand, such as a nitrogen atom or an oxygen atom, nanocrystal-ligand A strong intermolecular dipole dipole interaction is formed between them. And if there is an atom with lone pair electrons of sp ³ hybrid orbital function with excellent coordination ability inside the ligand, the ligand forms a relatively strong coordination bond with the metal surface of the nanocrystal surface.

In the present invention, a capping ligand may be used as a reaction solvent. The capping ligand is bound to the surface of the finally formed nanocrystal shell to protect the nanocrystal and increase solubility in organic solvents. Examples of the capping ligand include, but are not limited to, oleylamine, trioctylphosphine oxide, and oleic acid.

According to the present invention, the crystal growth inhibitor can be finally removed after the nanocrystal growth is completed. The crystal growth inhibitor removal process may be performed by centrifuging the nanocrystals in a solution state and then vacuum drying, but is not limited thereto, and may be removed by a known method.

The present invention provides a composition for preparing nanocrystals comprising a core precursor compound, a shell precursor compound, and a crystal growth inhibitor, wherein the crystal growth inhibitor is at least one of the compound of Formula 1 and the compound of Formula 2 above. The composition may further include a capping ligand, and the metal compound, the semiconductor compound precursor, the crystal growth inhibitor, and the capping ligand have the above-described technical characteristics.

Example

Hereinafter, embodiments of the present invention will be described in detail. The following examples are only for understanding of the present invention, and do not limit the present invention.

1. Preparation of InP/ZnS nanocrystals

(1) Example 1

In a 50 mL Schlenk flask, 119 mg (0.45 mmol) of 18-crown-6 ether as a crystal growth inhibitor, Indium (III) bromide (InBr ₃ ) 160 mg (0.45) as a metal compound mmol), 300 mg (2.2 mmol) of zinc chloride (ZnCl ₂ ), and 5 ml of oleylamine as a metal precursor of the shell were added, and then the reaction mixture was stirred at 120° C. for 1 hour under an argon gas atmosphere. degassed. After heating the reaction mixture to 180° C., 0.45 mL (1.6 mmol) of prepared tris(diethylamine)phosphine was rapidly injected. The obtained solution was further stirred for 30 minutes, and after heating to 210°C, 2.282 g (11.27 mmol) of 1-dodecanethiol was slowly injected into the solution. The solution was maintained at 210° C. for 90 minutes and then naturally cooled to room temperature to obtain a light green-orange solid. A chloroform solvent was slowly added to the reaction flask until the light green-orange solid was completely dissolved. Ethanol was added to this solution to precipitate nanocrystals, and the solid was separated by centrifugation. The obtained InP/ZnS nanocrystals were purified several times with a solvent combination of chloroform/ethanol and vacuum dried.

(2) Example 2

InP/ZnS nanocrystals were prepared in the same manner as in Example 1, except that 476 mg (1.8 mmol) of 18-crown-6 ether was used as a crystal growth inhibitor.

(3) Example 3

InP/ZnS nanocrystals were prepared in the same manner as in Example 1, except that 476 mg (1.8 mmol) of 18-crown-6 ether was used as a crystal growth inhibitor and 450 mg (3.3 mmol) of zinc chloride was used as a precursor of the shell metal. did

(4) Example 4

InP/ZnS nanocrystals were prepared in the same manner as in Example 1, except that 476 mg (1.8 mmol) of 18-crown-6 ether was used as a crystal growth inhibitor and 600 mg (4.4 mmol) of zinc chloride was used as a precursor of the shell metal. did

(5) Example 5

InP/ZnS nanocrystals were prepared in the same manner as in Example 1, except that 396 mg (1.8 mmol) of 15-crown-5 ether was used as a crystal growth inhibitor.

(6) Comparative Example

InP/ZnS nanocrystals were prepared in the same manner as in Example 1, except that no crystal growth inhibitor was used.

2. Measurement of photoluminescence wavelength of InP/ZnS nanocrystals

InP/ZnS nanocrystals prepared in Examples 1 to 5 and Comparative Examples were dissolved in a small amount of chloroform to prepare a solution. The solution was placed in a quartz cell for measurement, and a photoluminescence spectrum was measured using a spectrophotometer (JASCO, FP-6500).

Table 1 below and FIGS. 5 to 9 are results of comparing the photoluminescence spectra of the InP/ZnS nanocrystals obtained when the crystal growth inhibitor was not used (Comparative Example) and when it was used (Examples 1 to 5).

compound with InBr ₃
crystal growth
inhibitory
molar equivalent ratio ZnCl ₂ and
crystal growth
inhibitory
molar equivalent ratio photoluminescence
peak
wavelength
(nm) wavelength
change ^*
(nm) InBr ₃
input
(mmol) ZnCl ₂
input
(mmol) crystal growth
inhibitor type input
(mmol) Example 1 0.45 2.2 18-crown-6
ether 0.45 1:1 1:0.20 547 21 Example 2 0.45 2.2 1.8 1:4 1:0.82 527 41 Example 3 0.45 3.3 1.8 1:4 1:0.55 543 25 Example 4 0.45 4.4 1.8 1:4 1:0.41 567 One Example 5 0.45 2.2 15-crown-5
ether 1.8 1:4 1:0.82 562 6 comparative example 0.45 2.2 - - - - 568 -

* The wavelength change indicates the degree of decrease in the photoluminescence peak wavelength of the nanocrystals prepared in Examples 1 to 5 compared to the photoluminescence peak wavelength of the nanocrystals prepared in Comparative Examples.

Referring to Table 1, it can be seen that when a crystal growth inhibitor was added during the preparation of nanocrystals as in Examples 1 to 5, the photoluminescence peak wavelength was reduced compared to Comparative Examples in which the crystal growth inhibitor was not added. This is a result of the crystal growth inhibitor wrapping the surface of the nanocrystal and inhibiting the growth of the nanocrystal.

When only the input amount of the crystal growth inhibitor was increased under the same conditions as in Examples 1 and 2, nanocrystal growth was relatively more inhibited, resulting in a low photoluminescence peak wavelength and a large wavelength change.

Comparing Examples 2 to 4, the greater the amount of ZnCl ₂ input compared to the crystal growth inhibitor, the less the wavelength change value, and it can be seen that the nanocrystal growth is controlled according to the relative input amount of the crystal growth inhibitor.

On the other hand, in Example 2 using 18-crown-6 ether, the wavelength change was measured to be 41 nm, and in Example 5 using 15-crown-5 ether, the wavelength change was measured to be 5 nm. From this, it can be seen that the InP/ZnS nanocrystals more effectively form a host-guest compound with 18-crown-6 ether, thereby inhibiting the growth of the nanocrystals.

3. X-ray diffraction analysis of InP/ZnS nanocrystals

The results of X-ray diffraction analysis (XRD) of the nanocrystals prepared in Examples 1 to 4 are shown in FIG. 10 . X-ray diffraction analysis (XRD) profiles were obtained using an X-ray diffractometer (Rigaku, Ultima IV) with a monochromatic Cu Kα radiation source.

The application potential of nanocrystal materials capable of finely tunable wavelength can be found in the electronic field, and in particular, it can be actively applied to the display industry in the future as a display device material. As can be seen from the CIE color coordinate system of FIG. 8 , for the display device, it is essential to adjust the red, green, and blue color coordinates (green coordinate change A→B in FIG. 8) and fine-tune the white balance depending on the product. In other words, since the display element material used for the display must have a color control function, the nanocrystal material with easy fine color adjustment can show excellent competitiveness as a display element material in the future.

Claims (8)

forming nanocrystals from the core part precursor compound and the shell part precursor compound; and
Comprising the step of combining the nanocrystals and the crystal growth inhibitor,
The crystal growth inhibitor is at least one compound of the compound of formula 1 and the compound of formula 2, nanocrystal production method.
[Formula 1]

[Formula 2]

(In Formulas 1 and 2, X ₁ is at least one atom selected from the group consisting of O, S, Se and Te,
R ₁ and R ₂ are each independently hydrogen, a straight-chain or branched alkyl group having 1 to 10 carbon atoms, a straight-chain or branched alkenyl group having 2 to 12 carbon atoms, a straight-chain or branched alkynyl group having 2 to 20 carbon atoms, or an aryl group having 6 to 15 carbon atoms, and R ₁ and R ₂ are each independently -NR ₃ R ₄ , -OR ₃ , -CF ₃ , -CCl ₃ , -CN, -NO ₂ , -COR ₃ or -CONH ₂ may be substituted, wherein R ₃ and R ₄ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, or an aryl group having 6 to 15 carbon atoms; , R ₁ and R ₂ may not form a bond or form a bond and may be connected in a chain or ring form,
n is an integer from 2 to 18.)
The method of claim 1,
Nanocrystals are to form a crystal growth inhibitor and a host-guest compound or to form a coordination compound, nanocrystal production method.
The method of claim 1,
The crystal growth inhibitor is a crown ether (crown ether), nanocrystal production method.
a core precursor compound, a shell precursor compound, and a crystal growth inhibitor;
The crystal growth inhibitor is at least one of the compound of Formula 1 and the compound of Formula 2, the composition for producing nanocrystals.
[Formula 1]

[Formula 2]

(In Formulas 1 and 2, X ₁ is at least one atom selected from the group consisting of O, S, Se and Te,
R ₁ and R ₂ are each independently hydrogen, a straight-chain or branched alkyl group having 1 to 10 carbon atoms, a straight-chain or branched alkenyl group having 2 to 12 carbon atoms, a straight-chain or branched alkynyl group having 2 to 20 carbon atoms, or an aryl group having 6 to 15 carbon atoms, and R ₁ and R ₂ are each independently -NR ₃ R ₄ , -OR ₃ , -CF ₃ , -CCl ₃ , -CN, -NO ₂ , -COR ₃ or -CONH ₂ may be substituted, wherein R ₃ and R ₄ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, or an aryl group having 6 to 15 carbon atoms; , R ₁ and R ₂ may not form a bond or form a bond and may be connected in a chain or ring form,
n is an integer from 2 to 18.)
5. The method of claim 4,
The molar equivalent ratio of the core precursor compound and the crystal growth inhibitor is 1:0.1 to 1:4, a composition for producing nanocrystals.
5. The method of claim 4,
The molar equivalent ratio of the shell precursor compound and the crystal growth inhibitor is 1:0.1 to 1:4, a composition for producing nanocrystals.
5. The method of claim 4,
The composition for preparing nanocrystals further comprises a capping ligand.
A nanocrystal prepared according to any one of claims 1 to 3.

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