KR102037047B1 - Method of synthesizing quantum dot using dual anion precursor - Google Patents

Abstract

A quantum dot synthesis method is disclosed. According to the quantum dot synthesis method, after preparing a reaction solution containing an indium precursor compound, a zinc precursor compound and a double precursor compound of phosphorus and sulfur, the reaction solution is heat-treated to synthesize nanocrystal particles composed of an In-P-Zn-S alloy. Can be. In this case, the zinc precursor compound comprises a diethylzinc (Et ₂ Zn) compound, and the dual precursor compound of phosphorus and sulfur contains an alkylthiophosphine compound.

Description

Quantum dot synthesis method using double anion precursor {METHOD OF SYNTHESIZING QUANTUM DOT USING DUAL ANION PRECURSOR}

The present invention relates to a method for synthesizing a quantum dot made of an In—P—Zn—S alloy using a hydrothermal synthesis process.

Quantum dots have received a lot of attention due to their size-dependent physical properties, for example, optical and electrical properties, and have recently been applied to many fields such as light emitting devices (LEDs), solar cells, and bio imaging.

Initially, much research has been focused on cadmium-based quantum dots such as CdSe / ZnS, and currently manufactured cadmium-based quantum dots have not only achieved the required level but also have some successful applications. However, due to the toxicity of cadmium, new quantum dots are required to replace cadmium-based quantum dots. Recently, much research has been focused on InP-based quantum dots such as InP / ZnS, InP / ZnSe, InP / GaP / ZnS.

Typical synthetic methods for the preparation of quantum dots are the addition of cation and anion precursors to a non-coordinating solvent containing a surfactant, which is then exposed to high temperatures to allow the cation to react with the anion.

In the case of InP-based quantum dots, many challenges still exist to achieve the quality required for InP-based quantum dots due to the covalent nature of InP and the limitation of the available anion precursors. Conventionally, TMS ₃ P (tris (trimethylsilyl) phosphine (P (SiMe ₃ ) ₃ ) has been widely used as an anion precursor for InP quantum dot synthesis, but TMS ₃ P is unstable and uses highly ignitable phosphorus (P) and Na / K alloys. There were many problems due to difficulties in the synthesis process, including.

It is an object of the present invention to provide a method for synthesizing In-P-Zn-S alloy nanocrystals using an alkylthiophosphine compound containing a PS bond as a double precursor compound of phosphorus (P) and sulfur (S). .

A method for synthesizing a quantum dot according to an embodiment of the present invention includes a first step of preparing a reaction solution including an indium precursor compound, a zinc precursor compound, and a double precursor compound of phosphorus and sulfur; And a second step of synthesizing the nanocrystalline particles made of the In—P—Zn—S alloy by heat treating the reaction solution. In this case, the zinc precursor compound may include a diethyl zinc (Et ₂ Zn) compound, and the double precursor compound of phosphorus and sulfur may include an alkylthiophosphine compound including a PS bond.

In one embodiment, the alkylthiophosphine compound may include a trisalkylthiophosphine compound of the formula (1).

[Formula 1]

P (S (CH ₂ ) _n CH ₃ ) ₃

In Formula 1, n may be an integer of 3 or more and 9 or less.

In one embodiment, the alkylthiophosphine compound may include a trishexylthio phosphine (Tris (hexylthio) phosphine) compound.

In one embodiment, the diethyl zinc (Et ₂ Zn) compound in the reaction solution may be attached to the trisalkylthiophosphine compound to form an activated complex.

In one embodiment, the trisalkylthiophosphine compound and the diethyl zinc (Et ₂ Zn) compound in the reaction solution may be mixed in a molar ratio of 1: 0.5 to 1: 2.

In one embodiment, the zinc precursor compound may further comprise a zinc halide. For example, the zinc halide may include one or more selected from the group consisting of zinc chloride (ZnCl ₂ ), zinc bromide (ZnBr ₂ ), and zinc iodide (ZnI ₂ ).

In an embodiment, the first step of preparing the reaction solution may include mixing an indium chloride and an oleylamine compound in an organic solvent to prepare a first solution; Preparing a second solution by mixing the trisalkylthiophosphine compound of Formula 1 and the diethylzinc (Et ₂ Zn) compound in an organic solvent; And adding the second solution to the first solution. In this case, in the preparing of the first solution, the indium chloride (InCl ₃ ) and the oleylamine (C ₁₈ H ₃₅ NH ₂ ) may be reacted to form a six-coordinated indium oleylamine complex compound.

In an embodiment, the method may further include a third step of forming a ZnS shell covering the nanocrystalline particles made of the alloy of In—P—Zn—S.

Conventionally, when synthesizing InP-based quantum dots, tristrimethylsilylphosphine (P (SiMe ₃ ) ₃ ) compound was mainly used as an anion precursor material, but the tristrimethylsilylphosphine (P (SiMe ₃ ) ₃ ) compound was damp. There was a problem that it was unstable and difficult to handle, such as having vulnerability to However, according to the present invention, in synthesizing nanocrystalline particles made of an alloy of In-P-Zn-S, an alkylthiophosphine compound such as trisalkylthiophosphine, which is stable, may be substituted for phosphorus (P) and sulfur (S). InP-based quantum dots can be easily synthesized by using the double anion precursor material.

1 is a flowchart illustrating a quantum dot synthesis method according to an embodiment of the present invention.
2 is a view for explaining the mechanism of the synthesis of InPZnS alloy quantum dots using THTP and Et ₂ Zn.
FIG. 3A shows P-NMR data of THTP (a), THTP-Et ₂ Zn complex (b) and THTP-Et ₂ Zn-InCl ₃ -OLA complex (C), FIG. 3B of THTP-Et ₂ Zn The FAB-Mass data of the complex is shown.
4A shows absorption and emission spectra of quantum dots synthesized according to Examples 1 to 4, FIG. 4B shows XRD patterns of quantum dots synthesized according to Examples 1 to 4, and FIG. 4C shows Examples 1 to 4 TEM images of quantum dots synthesized according to FIG.
5a shows absorption and emission spectra of quantum dots synthesized by changing the reaction time to 1h, 5h, 10h and 20h for the reaction solution of Example 2 having a molar ratio of THTP and Et ₂ Zn of 1: 1; FIG. 5B shows the XRD pattern for the synthesized quantum dots, and FIG. 5C shows the size for the synthesized quantum dots.
6A and 6B show emission spectra and XRD patterns of quantum dots synthesized using a reaction solution without zinc halide.
7a shows absorption and emission spectra of quantum dots synthesized by reacting the reaction solution of Example 5 in which ZnCl ₂ was replaced with ZnBr ₂ for 1h, 5h, 10h, and 20h, and FIG. 7b shows ZnCl ₂ as ZnI ₂ . The reaction solution of Example 6 was replaced with 1h, 5h, 10h, and 20h to show absorption and emission spectra of the synthesized quantum dots.
FIG. 8 shows absorption and emission spectra measured for quantum dots in which ZnS shells were formed on InPZnS alloy nanocrystals synthesized by reacting the reaction solutions of Examples 2, 5 and 6 for 20 h.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprises" or "having" are intended to indicate that there is a feature, step, operation, component, part, or combination thereof described on the specification, and one or more other features or steps. It is to be understood that the present invention does not exclude, in advance, the possibility of the presence or addition of any operation, component, part, or combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

1 is a flowchart illustrating a quantum dot synthesis method according to an embodiment of the present invention.

Referring to FIG. 1, a quantum dot synthesis method according to an embodiment of the present invention may include a first step (S110) of preparing a reaction solution including an indium precursor compound, a zinc precursor compound, and a double precursor compound of phosphorus and sulfur; Heat treating the reaction solution to synthesize nanocrystal particles made of an In—P—Zn—S alloy (S120).

In the first step (S110), the indium precursor compound may include indium chloride. In one embodiment, a complex of indium chloride (InCl ₃ ) and oleylamine (C ₁₈ H ₃₅ NH ₂ ) may be used as the indium precursor compound.

The zinc precursor compound may include a diethyl zinc (Et ₂ Zn) compound. On the other hand, the zinc precursor compound may further include a zinc halide together with the diethylzinc (Et ₂ Zn) compound. The zinc halide may include one or more selected from zinc chloride (ZnCl ₂ ), zinc bromide (ZnBr ₂ ), and zinc iodide (ZnI ₂ ).

The double precursor compound of phosphorus and sulfur may include an alkylthiophosphine compound containing a P-S bond. In one embodiment, the double precursor compound of phosphorus and sulfur may include a trisalkylthiophosphine compound of the formula (1). For example, the double precursor compound of phosphorus and sulfur may include a trishexylthio phosphine (Tris (hexylthio) phosphine) compound.

[Formula 1]

P (S (CH ₂ ) _n CH ₃ ) ₃

In Formula 1, n may be an integer of 3 or more and 9 or less. If n is less than 3, a problem that cannot control the reaction rate may occur, and if it exceeds 9, a problem may occur that the quantum dot synthesis reaction is too slow. For example, n may be an integer of 4 or more and 7 or less.

In one embodiment, the first step (S110) comprises the steps of mixing the indium chloride and the oleylamine compound in an organic solvent to prepare a first solution; Preparing a second solution by mixing the trisalkylthiophosphine compound of Formula 1 and the diethylzinc (Et ₂ Zn) compound in an organic solvent; And adding the second solution to the first solution.

In the preparing of the first solution, indium chloride (InCl ₃ ) and oleylamine (C ₁₈ H ₃₅ NH ₂ ) may be reacted to form a six-coordinated indium oleylamine complex compound. To this end, the indium chloride and the oleylamine compound may be added to an organic solvent and then heated to a temperature of about 100 to 120 ° C., and maintained at a vacuum for about 1 to 3 hours at the heating temperature. .

In an embodiment, in the first solution, the indium chloride and the oleylamine (C ₁₈ H ₃₅ NH ₂ ) may be mixed in a molar ratio of about 1: 3 or more and 1:80 or less. When the molar ratio of the indium chloride and the oleylamine (C ₁₈ H ₃₅ NH ₂ ) is less than 1: 3 or more than 1:80, a problem may occur in that quantum yield is lowered.

Meanwhile, in order to prepare the first solution, the zinc halide may be further added to the organic solvent and mixed with the indium chloride and the oleylamine compound. In one embodiment, in the first solution, the indium chloride and the zinc halide may be mixed in a molar ratio of about 1: 1 or more and 1:10 or less.

In preparing the second solution, the diethylzinc (Et ₂ Zn) compound may be attached to the trisalkylthiophosphine compound to form an activated complex. In the case of the trisalkylthiophosphine compound, there is a problem that the quantum dot synthesis reaction hardly occurs due to the stability of the PS bond. However, when the trisalkylthiophosphine compound is combined with a diethyl zinc (Et ₂ Zn) compound, which is a kind of Lewis acid, A quantum dot can be effectively synthesized by the (Et ₂ Zn) compound acting as an activating material.

In one embodiment, in the second solution, the trisalkylthiophosphine compound and the diethylzinc (Et ₂ Zn) compound may be mixed in a molar ratio of about 1: 0.5 or more and 1: 2 or less. When the molar ratio of the trisalkylthiophosphine compound and the diethyl zinc (Et ₂ Zn) compound is less than 1: 0.5 or greater than 1: 2, a problem may occur in that quantum yield is lowered.

During the second step, the reaction solution may be heat treated in such a manner that it is maintained for about 15 to 25 hours at a temperature of about 250 to 300 ℃. During such heat treatment, an indium oleylamine complex, an indium precursor material, and an activating complex produced by the combination of the diethylzinc (Et ₂ Zn) compound and the trisalkylthiophosphine compound react to form In-P-Zn-. Nanocrystalline particles made of an alloy of S can be synthesized.

On the other hand, quantum dot synthesis method according to an embodiment of the present invention after the second step (S120), a third step (S130) to form a ZnS shell covering the nano-crystal particles made of the alloy of In-P-Zn-S ) May be further included.

In order to form the ZnS shell, after addition of trioctylphosphine in which sulfur (S) particles are dissolved in the reaction solution in which nanocrystalline particles made of the alloy of In-P-Zn-S are synthesized, It may be maintained for about 15 to 25 hours at a temperature of about 250 to 300 ℃.

Conventionally, when synthesizing InP-based quantum dots, tristrimethylsilylphosphine (P (SiMe ₃ ) ₃ ) compound was mainly used as an anion precursor material, but the tristrimethylsilylphosphine (P (SiMe ₃ ) ₃ ) compound was damp. There was a problem that it was unstable and difficult to handle, such as having vulnerability to However, according to the present invention, in synthesizing nanocrystalline particles made of an alloy of In-P-Zn-S, an alkylthiophosphine compound such as trisalkylthiophosphine, which is stable, may be substituted for phosphorus (P) and sulfur (S). InP-based quantum dots can be easily synthesized by using the double anion precursor material.

Hereinafter, examples and experimental examples of the present invention will be described in detail. The following examples relate to some of the various embodiments of the present invention, and the scope of the present invention should not be construed as being limited to the following examples.

<Synthesis of trishexylthiophosphine (THTP)>

To a solution consisting of tetrahydrofuran (70 mL) solvent and 1-hexanethiol (9.3 mL, 65.5 mmol), N, N-dimethylaniline (DMA) (5.5 mL, 14.6 mmol) was added dropwise at 0 ° C. and then The final solution was stirred for 16 h while slowly increasing from 0 ° C. to room temperature. The mixture was then filtered to remove the solid phase generated during the reaction, and filtration was extracted using Et ₂ O and H ₂ O. The organic layer was separated, dried over Na ₂ SO ₄ and centrifuged. The residue was then column chromatographed with hexane-EtOAc (25: 1) as eluent to give THTP colorless liquid in 90% yield.

Synthesis of InPZnS Alloy Core

Example 1

InCl ₃ (53 mg, 0.24 mmol) and ZnCl ₂ (164 mg, 1.2 mmol) were housed in a 25 mL flask with OLA (C ₁₈ H ₃₅ NH ₂ ) (4 mL, 12 mmol) and 1 mL of ODE (octadecene, C _18). H ₃₆ ), which was heated to 110 ° C. and maintained under vacuum for 2 hours to prepare a first solution.

After degassing, a 1 mL ODE solution and Et ₂ Zn (0.25 mL) added with THTP (82.4 mg, 0.24 mmol) were loaded into a syringe in a glovebox to prepare a second solution. At this time, Et ₂ Zn was added so that the molar ratio of Et ₂ Zn to THTP was 0.75.

A second solution of the syringe was added to the first solution of the 25 mL flask at room temperature to prepare a reaction solution. The reaction solution was heated to 280 ° C. and maintained for a predetermined time to synthesize InPZnS alloy nanocrystals.

Example 2

The InPZnS the alloy nanocrystals were synthesized THTP and Et ₂ Zn 2-2 solution, a molar ratio of Et ₂ Zn to THTP to be 1 in the same manner as in Example 1 except that a mixture.

Example 3

The InPZnS the alloy nanocrystals were synthesized THTP and Et ₂ Zn 2-2 solution, a molar ratio of Et ₂ Zn to THTP to be 1.25 in the same manner as in Example 1 except that a mixture.

Example 4

The InPZnS the alloy nanocrystals were synthesized THTP and Et ₂ Zn 2-2 solution, a molar ratio of Et ₂ Zn to THTP to be 1.5 in the same manner as in Example 1 except that a mixture.

Example 5

The ZnCl ₂ was synthesized InPZnS alloy nanocrystals in the same manner as in Example 2 was replaced with ZnBr _2.

Example 6

InPZnS alloy nanocrystals were synthesized in the same manner as in Example 2, except that ZnCl ₂ was replaced with ZnI ₂ .

<Formation of ZnS Shell>

[Examples 7 to 12]

Sulfur (S) (0.36 g, 11 mmol) was added to a 10 mL vial sealed with a septum, and then degassed at room temperature for 10 minutes. After filling with nitrogen (N ₂ ), 5 mL of TOP (trioctylphosphine) was added, and then TOP-S was synthesized by dissolving S through sonication.

0.55 mL of the TOP-S (2.2 M) was added to the reaction solution of Examples 1 to 6 in which InPZnS alloy nanocrystals were synthesized, and the ZnS shell was formed on the surface of the InPZnS alloy nanocrystals by maintaining it at 280 ° C. for 20 hours. Formed.

Experimental Example

2 is a view for explaining the mechanism of the synthesis of InPZnS alloy quantum dots using THTP and Et ₂ Zn.

Referring to FIG. 2, InCl 3 and OLA form a six-coordinated indium oleylamine complex that functions as an indium precursor, and Et ₂ Zn is attached to THTP to form an activated complex, which reacts to synthesize InPZnS alloy quantum dots. It seems to be.

There have been efforts to use THTP as an anion precursor in the past, but most of these efforts have not been successful due to the stability of PS bonds present in THTP. In the present invention, quantum dots were successfully synthesized by applying diethylzinc (Et ₂ Zn), which is a type of Lewis acid, as an activating material.

FIG. 3A shows P-NMR data of THTP (a), THTP-Et ₂ Zn complex (b) and THTP-Et ₂ Zn-InCl ₃ -OLA complex (C), FIG. 3B of THTP-Et ₂ Zn The FAB-Mass data of the complex is shown. The data in FIGS. 3A and 3B were measured for samples of THTP and Et ₂ Zn mixed in ODE solvent. (A) of FIG. 3A is a result measured for Sample 1 to which THTP was added in an ODE solvent, and FIGS. 3A and 3B are for Sample 2 to which THTP and Et ₂ Zn were mixed in an ODE solvent. (C) of FIG. 3A is a result measured for Sample 3 in which THTP and Et ₂ Zn and InCl ₃ and OLA were mixed in an ODE solvent.

In (b) of FIG. 3A, a new peak at 86.01 ppm, which is not present in (a), was observed, and in FIG. 3B, a molecular ion peak (M +) of 504 was observed. Since the mass data show the same molecular mass, and the new peak at 86.01 ppm is a shift in the upfield direction that appears when the three coordinating phosphine is transformed into a fourth coordinating phosphine, THTP and Et ₂ Zn react with THTP from these data. It can be seen that a complex of -Et ₂ Zn is formed.

In addition, a new peak at 191.83 ppm, which is not present in (a) and (b), is observed in (c) of FIG. 3A, from which the InCl ₃ and OLA react to form a six-coordinated indium oleylamine complex. You can check it.

4A shows absorption and emission spectra of quantum dots synthesized according to Examples 1 to 4, FIG. 4B shows XRD patterns of quantum dots synthesized according to Examples 1 to 4, and FIG. 4C shows Examples 1 to 4 TEM images of quantum dots synthesized according to FIG. And Table 1 below shows the results of elemental analysis by ICP. 4A to 4C illustrate the results of quantum dots synthesized by reacting the reaction solutions for 20 h.

Molar ratio of THTP and Et ₂ Zn 1: 0.75 1: 1 1: 1.25 1: 1.5 Light emission peak wavelength (nm) 577 568 525 510 In / Zn ratio 30/70 (0.43) 23/76 (0.30) 20/80 (0.25) 15/85 (0.18)

Referring to (a) of FIG. 4A, band edge peaks around 570 nm are shown in absorption data (a) of quantum dots synthesized under molar ratios of THTP and Et ₂ Zn of 1: 0.75 and 1: 1. And appeared to shift blue as the amount of Et ₂ Zn increased. However, such absorption peaks were not observed in the absorption spectra of the quantum dots synthesized under conditions in which the molar ratios of THTP and Et ₂ Zn were 1: 1.25 and 1: 1.5.

Referring to FIG. 4A (b) and Table 1, as the ratio of Et ₂ Zn is increased, the emission wavelength of the synthesized quantum dots was found to be blue shifted, and the ratio of zinc in the quantum dots was increased. 4B, the diffraction pattern was shifted in the bulk ZnS direction as the molar ratio of Et ₂ Zn to THTP was increased.

The relationship between the In / Zn ratio and the emission wavelength can help to determine the quantum dot structure. Specifically, in the InPZnS alloy structure, since the ZnS has a wider bandgap than InP, the emission wavelength is blue shifted as the Zn ratio is increased, whereas in the InP / ZnS coreshell structure, the Zn ratio is increased due to the band arrangement of the core and the shell. The more the light emission wavelength is shifted red.

In the present invention, as shown in Figure 4a, 4b and Table 1, the emission wavelength is blue shifted as the ratio of Zn increases, it is determined that the quantum dots synthesized according to the present invention has an InPZnS alloy structure.

Referring to FIG. 4C, even when the molar ratio of THTP and Et ₂ Zn is changed, the synthesized quantum dots do not change significantly, and quantum dots having a size of about 4.5 nm are synthesized.

On the other hand, when the Et ₂ Zn / THTP molar ratios were 0.75 and 1, the quantum yields were 9.07% and 10.2%, respectively, whereas the Et ₂ Zn / THTP molar ratios were 1.25 and 1.5, respectively, 5.8% and 5.6. Proton yields of% are shown respectively. Therefore, in order to achieve high quantum yield, it is preferable to adjust the Et ₂ Zn / THTP molar ratio in the reaction solution to about 0.7 to 1.1.

5a shows absorption and emission spectra of quantum dots synthesized by changing the reaction time to 1h, 5h, 10h and 20h for the reaction solution of Example 2 having a molar ratio of THTP and Et ₂ Zn of 1: 1; FIG. 5B shows the XRD pattern for the synthesized quantum dots, and FIG. 5C shows the size for the synthesized quantum dots.

5A and 5B, as the reaction time increases, both the absorption and emission spectra of the synthesized quantum dots shift from a shorter wavelength range (578 nm to 550 nm in the emission spectrum and from 530 nm to 510 nm in the absorption spectrum). ). The XRD pattern was also shifted in the bulk ZnS direction. This means that the proportion of ZnS increased with increasing reaction time in the alloy structure.

On the other hand, the quantum yield (QY) was found to increase with increasing reaction time. Samples at reaction times of 1h, 5h, 10h and 20h showed quantum yields of 1%, 4.4%, 8.6% and 10.2%, respectively, after which no further changes were seen. Therefore, the reaction time for the reaction solution is preferably about 20 h or more.

Referring to FIG. 5C, the particle size was also slightly increased (from 3.71 nm to 4.51 nm) as the reaction time was increased up to about 10 h. However, when the reaction time was greater than 10 h, the particles were increased. It was found that the size hardly changed.

From these measurements, it is determined that the change in quantum yield between 10h and 20h reaction time is because the crystallinity of the quantum dots improves over the reaction time.

6A and 6B show emission spectra and XRD patterns of quantum dots synthesized using a reaction solution without zinc halide.

6A and 6B, when only Et ₂ Zn is introduced as a zinc precursor compound and no zinc halide is introduced into the reaction solution, the optical properties of the synthesized quantum dots may be deteriorated.

7a shows absorption and emission spectra of quantum dots synthesized by reacting the reaction solution of Example 5 in which ZnCl ₂ was replaced with ZnBr ₂ for 1h, 5h, 10h, and 20h, and FIG. 7b shows ZnCl ₂ as ZnI ₂ . The reaction solution of Example 6 was replaced with 1h, 5h, 10h, and 20h to show absorption and emission spectra of the synthesized quantum dots.

Referring to FIGS. 7A and 7B, even when ZnCl ₂ was replaced with ZnBr ₂ or ZnI ₂ , it was found that the peaks of the absorption and emission spectra shifted to shorter wavelength regions as the reaction time increased.

The emission wavelength was shorter when ZnI ₂ was applied than when ZnCl ₂ and ZnBr ₂ were applied, which may be due to the low reactivity of the ZnI ₂ -oleylamine complex. And when ZnI ₂ is applied than when ZnCl ₂ and ZnBr ₂ are applied, the quantum yield was found to be remarkably improved. Specifically, when ZnCl ₂ , ZnBr ₂ , ZnI ₂ were applied, the quantum yields were found to be 10.2%, 12.7%, and 24.2%, respectively. In addition, when ZnI ₂ was applied, the full width at half maximum (FWHM) of the emission spectrum was smaller than that of ZnCl ₂ and ZnBr ₂ . This is because the crystallinity of quantum dots is improved when ZnI ₂ is applied than when ZnCl ₂ and ZnBr ₂ are applied.

However, even if the zinc halide was changed, the size of the synthesized quantum dots was found to hardly change.

FIG. 8 shows absorption and emission spectra measured for quantum dots in which ZnS shells were formed on InPZnS alloy nanocrystals synthesized by reacting the reaction solutions of Examples 2, 5 and 6 for 20h, and 2 is a result of analyzing the emission spectrum of FIG.

QY (%) Photoluminescence (nm) FWHM (nm) ZnCl ₂ 21.3 556 73 ZnBr ₂ 30.5 558 69 ZnI ₂ 42 530 56

Referring to FIG. 7 and Table 2, when the ZnS shell was formed through the introduction of the TOP-S (trioctylphosphine-sulfur) complex, the emission wavelength was not changed, but the quantum yield and the FWHM were significantly improved.

On the other hand, as a result of synthesizing quantum dots using smaller alkylthiophosphine compounds such as tris (ethylthio) phosphine) as trisalkylthiophosphine compounds, the reaction rate could not be controlled and white precipitates formed. It became.

While the foregoing has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

none

Claims (10)

A first step of preparing a reaction solution comprising an indium precursor compound, a zinc precursor compound and a double precursor compound of phosphorus and sulfur; And
Comprising a second step of synthesizing the nano-crystal particles of the In-P-Zn-S alloy by heat-treating the reaction solution,
The zinc precursor compound includes a diethyl zinc (Et ₂ Zn) compound,
The double precursor compound of phosphorus and sulfur includes an alkylthiophosphine compound containing a PS bond,
The alkylthiophosphine compound is characterized in that it comprises a trisalkylthiophosphine compound of formula (1), quantum dot synthesis method:
[Formula 1]
P (S (CH ₂ ) _n CH ₃ ) ₃
In Formula 1, n is an integer of 3 or more and 9 or less.
delete The method of claim 1,
The alkylthiophosphine compound is characterized in that it comprises a trishexylthiophosphine (Tris (hexylthio) phosphine) compound, quantum dot synthesis method. The method of claim 1,
The diethyl zinc (Et ₂ Zn) compound in the reaction solution is attached to the trisalkylthiophosphine compound to form an activated complex, quantum dot synthesis method. The method of claim 4, wherein
In the reaction solution, the trisalkylthiophosphine compound and the diethyl zinc (Et ₂ Zn) compound is characterized in that the mixing ratio of 1: 0.5 or more and 1: 2 or less, quantum dot synthesis method. The method of claim 1,
The zinc precursor compound further comprises a zinc halide, quantum dot synthesis method. The method of claim 6,
The zinc halide comprises at least one selected from the group consisting of zinc chloride (ZnCl ₂ ), zinc bromide (ZnBr ₂ ) and zinc iodide (ZnI ₂ ). The method of claim 1,
The first step,
Mixing the indium chloride and oleylamine compound in an organic solvent to prepare a first solution;
Preparing a second solution by mixing the trisalkylthiophosphine compound of Formula 1 and the diethylzinc (Et ₂ Zn) compound in an organic solvent; And
And adding the second solution to the first solution. The method of claim 8,
In preparing the first solution, indium chloride (InCl ₃ ) of the indium chloride and oleylamine (C ₁₈ H ₃₅ NH ₂ ) of the oleylamine compound react to form a 6-coordinated indium oleylamine complex compound. Formed, characterized in that the quantum dot synthesis method. The method of claim 1,
And a third step of forming a ZnS shell covering the nanocrystalline particles made of the alloy of In-P-Zn-S.

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