KR101187663B1 - Sinthesizing Method for Indium Posphate Quantum Dot Core and Indium Posphate/Zinc Sulfide Core-Shell Quantum Dot - Google Patents

Abstract

The present invention relates to a method for synthesizing an indium phosphide quantum dot core and an indium phosphide / zinc sulfide quantum dot using a dropwise method.
The present invention is advantageous in synthesizing quantum dots having the same emission wavelength since the reaction can be carried out uniformly with respect to the reaction conditions using a large amount of precursors compared with the conventional synthesis method. Therefore, as a method for obtaining a simple reaction process and good efficiency in mass synthesis, the quantum dots produced by the method of the present invention can be utilized in various fields such as displays, solar cells, bio imaging, and the like.

Description

Synthesizing Method for Indium Posphate Quantum Dot Core and Indium Posphate / Zinc Sulfide Core-Shell Quantum Dot}

The present invention relates to a more efficient mass synthesis method of indium phosphide (InP) quantum dot cores and indium phosphide / zinc sulfide (InP / ZnS) quantum dots.

Quantum dots, semiconductor nanoparticles, are materials with unique electrical and optical properties due to quantum limitation effects. These characteristics of quantum dots can be utilized in various fields such as display, solar cell, bio-imaging, and so on, many studies are being conducted. As such, quantum dots are applied in many fields, and a high efficiency mass synthesis method is necessary to be commercialized.

In the early days of quantum dot research, research was focused on group II-VI, which is relatively well synthesized. However, in the case of II-VI quantum dots, there are environmental problems with heavy metals such as cadmium, selenium, tellurium, and so on, and thus, they are limited to various applications. Therefore, group III-V quantum dots, which are non-toxic, environmentally friendly quantum dots, are in the spotlight.

As a chemical quantum dot synthesis method, a colloidal method using a surfactant is used. This method is to generate quantum dots by stabilizing the quantum dot core formed in a high temperature organic solvent through a surfactant and adjusting its size. In order to generate quantum dots of uniform size, a "Hot-Injection" method is generally used in which a core is generated only at a high temperature for a short time.

The "Hot-Injection" method has been used as a method for synthesizing existing InP quantum dots. The general synthesis method used is as follows. As a precursor, indium acetate and tris (trimethylsilyl) phosphine are used, and as a surfactant, an acid-based substance is dissolved in a solvent to form a core through hot-injection. (See: Xiaogang Peng, Nano lett., 2002, 2, 1027-1030.)

The Hot-Injection method showed good results in laboratory size and small amount of quantum dot synthesis, but did not produce good results in mass synthesis where the amount of reactants increased. This is because the Hot-Injection method requires that the reactants are uniformly introduced into all parts in a very short time to form a core at the same time. In the case of mass synthesis, good results could not be obtained because it was difficult to form a uniform core at the same time. As an alternative, Peter Reiss's group presented several new ways to synthesize InP quantum dots. First, phosphine (PH ₃ ) was used instead of tris (trimethylsilyl) phosphine, a phosphine precursor that was generally used. InP quantum dots were formed by continuously supplying phosphine gas generated by reacting calcium phosphide with hydrochloric acid. (Refer to Peter Reiss, Chem. Mater., 2008, 20 (8), 2621-2623.) Next, the One-Pot synthesis method, which is mainly used in the synthesis of metal oxides In the same flask, both the precursor and the surfactant were put in a temperature to synthesize a quantum dot of the desired wavelength according to the reaction time. (Ref .: Peter Reiss, J. Am. Chem. Soc., 2008, 130 (35), 1158811589) However, phosphine precursors have a disadvantage in that they have a high risk of handling due to the use of toxicity and gas. Synthesis method has the disadvantage that the efficiency appears different for each wavelength band, there was a problem that is not efficient even in the mass synthesis. In the United States, AJ Nozik et al. Reacted with indium chloride and sodium oxalate to obtain indium oxalate. A method of preparing indium phosphide quantum dots by reacting was developed. This method has a meaning as a method of producing nanoparticles of indium phosphide by a chemical method, but has a disadvantage that the reaction temperature is a high temperature of 300 ℃ and it is impossible to obtain a uniform quantum dot. (Ref .: AJ Nozik, J. Phys. Chem. B, 1997, 101, 4904) The above manufacturing method was subsequently improved by DV Talapin in Germany. Indium chloride is reacted with trioctylphosphine in the presence of dodecylamine to form a metal complex of indium chloride with trioctylphosphine and then reacted with tris (trimethylsilyl) phosphine to prepare an indium phosphide quantum dot. Developed. This manufacturing method has the advantage of producing indium phosphide quantum dots more easily than the method of AJ Nozik, etc., but the finished indium phosphide quantum dots are similarly multi-dispersed in size and are also contaminated by indium oxide, a by-product. The disadvantage is that it loses value. (See: DV Talapin, Colloids and Surfaces A, 2002, 202, 145)

Representative examples of the indium phosphide synthesis by a chemical synthesis method according to the patent was prepared for U.S. Patent No. 4,220,488 arcs indium phosphide by the reaction of two-step process, by the high temperature pyrolysis of the first phosphine gas (PH ₃₎ as at 700 ℃ of Compound (P ₄ ) and hydrogen were obtained, which were then reacted with triethylindium at a high temperature of 500 ° C. to obtain the final indium phosphide. The above method requires a lot of energy because the reaction is carried out at an extremely high temperature, and furthermore, the phosphine gas (PH ₃ ), which is difficult to handle due to spontaneous ignition and explosiveness, needs to be used, which poses a risk of enlargement. Next, according to the domestic patent (Registration No. 10-0549402) of the Korea Research Institute of Chemical Technology, white chlorine and metal sodium were reacted with dimethylformamide or diethoxyethane as a reaction solvent to obtain Na ₃ P, which was then 4-ethylpyridine or There is a method of selectively preparing indium phosphide quantum dots by reacting with indium chloride dissolved in dimethylformamide. In this case, very dangerous precursors such as white phosphorus and sodium metal are used.

In the case of zinc sulfide shells, two methods are mainly used. First, in 2001, Horst Weller formed a zinc sulfide shell on indium chloride quantum dots using diethyl zinc and bis (trimethylsilyl) sulfide. (See Horst Weller, ChemPhys Chem, 2001, 5, 331-334.) Next, a zinc sulfide shell is formed by sequentially adding zinc acetate and 1-dodecanethiol over a reaction time. (Reference: KR 10-2008-0130499, Sang-Wook Kim, Chem. Mater. 2009, 21 (4), 573-575)

However, no effective mass synthesis has been reported for group III-V quantum dots. As a result, we continued research on non-toxic group III-V quantum dots that are easy to apply and use in other fields, and indium phosphide quantum dot core and indium phosphide / zinc sulfide (InP / ZnS) which are representative materials of group III-V quantum dots. The mass synthesis method of core / shell was studied.

An object of the present invention is to provide a method for synthesizing an indium phosphide (InP) quantum dot core and an indium phosphide / zinc sulfide (InP / ZnS) quantum dot, which is more efficient for mass synthesis than conventional techniques.

The present invention relates to a method for synthesizing a core of InP quantum dots using a dropwise method. More specifically, the present invention relates to a method of synthesizing an indium phosphide quantum dot core by dissolving an indium (In) precursor and a surfactant in an organic solvent and then adding a phosphorus (P) precursor.

The present invention also relates to a method of manufacturing InP / Zns quantum dots by stacking a ZnS shell to increase the quantum efficiency and the stability of the quantum dots in the synthesized quantum dot core.

The present invention is advantageous in synthesizing quantum dots having the same emission wavelength since the reaction can be performed uniformly over a large reaction condition as compared with the conventional synthesis method. Therefore, as a method for obtaining a simple reaction process and good efficiency in mass synthesis, the quantum dots produced by the method of the present invention can be utilized in various fields such as displays, solar cells, bio imaging, and the like.

1 is a schematic schematic diagram of an embodiment of synthesizing InP / ZnS quantum dots by a dropwise method.
2 is a transmission electron microscope (TEM) photograph of the InP quantum dot core synthesized in Example 5. FIG.
3 is a transmission electron microscope (TEM) image of InP / ZnS quantum dots synthesized in Example 7. FIG.
4 shows UV / Vis absorption spectra of InP quantum dot cores and InP / ZnS quantum dots synthesized in Examples 1 to 7. FIG.
5 is an X-ray diffraction analysis result of InP / ZnS quantum dots synthesized in Example 7.
6 is a UV / Vis absorbance spectrum of InP / ZnS quantum dots synthesized in Examples 7 to 17.
7 is a photoluminescence (PL) spectrum of InP / ZnS quantum dots synthesized in Examples 7 to 17. FIG.

The present invention relates to a method for synthesizing a core of InP quantum dots using a dropwise method. More specifically, the present invention relates to a method of synthesizing an indium phosphide quantum dot core by dissolving an indium (In) precursor and a surfactant in an organic solvent and then adding a phosphorus (P) precursor.

The organic solvent is not particularly limited as long as it is a substance capable of dissolving the indium precursor and the surfactant, but a heterocyclic compound including a C ₆ to C ₂₄ alkyl amine, alcohol, ketone ester, nitrogen or sulfur, alkanes, Alkenes, alkynes, trialkylphosphines or trialkyl phosphine oxides and the like. More preferably, C ₆ -C ₂₄ alkenes are preferable, and 1-octadecene is more preferable.

The indium precursor may be an indium precursor that is generally used in the art, but at least one selected from the group consisting of indium elements, nitrates, sulfates, carbonates, halides, acetates, oxides, and hydrates thereof. It is possible to use. More preferably indium acetate.

The surfactant may be a C ₆ ~ C ₂₄ alkanes or alkenes having a -COOH group, -POOH group, -SOOH group, -NH ₂ group at the terminal, for example, oleic acid, stearic acid (stearic) acid, palmitic acid, hexyl phosphonic acid, n-octyl phosphonic acid, tetratradecyl phosphonic acid, octadecyl phosphonic acid, octadecyl phosphonic acid acid), n-octylamine or hexadecyl amine. Preferably palmitic acid.

The phosphorus (P) precursor may be a phosphorus precursor generally used in the art, but may be one or more selected from the group consisting of phosphorus element, phosphine, phosphite and phosphine oxide. Preferably tris (trialkylsilyl) phosphine is preferred, and more preferably tris (trimethylsilyl) phosphine.

The input rate of the phosphorus precursor may be 0.5 ~ 2.5 ml / hr. If less than 0.5 ml / hr may have a problem that the first quantum dots produced by the deterioration due to the high temperature, the quantum efficiency is lowered, if it exceeds 2.5 ml / hr the reaction proceeds too fast to be stabilized by the surfactant There may be a problem that quantum dots are precipitated.

When the quantum dot core synthesis temperature is preferably adjusted to 200 ~ 220 ℃. If the above range is not satisfied, the core formation may be affected, thereby lowering the quantum efficiency.

The total amount of the phosphorus precursor is preferably adjusted to a molar ratio of indium in the indium precursor and phosphorus of the phosphorus precursor is 1: 0.1 to 10. By controlling the molar ratio, it is possible to synthesize indium phosphide quantum dot cores having various emission wavelengths.

In addition, a sulfur precursor and a zinc precursor may be further included in a solution in which the indium precursor and the surfactant are mixed. In particular, it is possible to control the emission wavelength of the indium phosphide quantum dot core by controlling the addition and the amount of the sulfur precursor.

It is possible to control the emission wavelength of the quantum dot through the mixing ratio of the indium precursor and the sulfur precursor. Specifically, the molar ratio of indium in the indium precursor and sulfur in the sulfur precursor may be 1: 0.1 to 3 when the initial indium phosphide quantum dot core is generated. When adjusted to a molar ratio of 1: 3, a quantum dot core having an emission wavelength of about 490 nm may be prepared, and when adjusted to 1: 0.1, a quantum dot core having an emission wavelength of about 630 nm may be prepared.

The sulfur precursor is not particularly limited to a compound containing sulfur, but may be C ₂ to C ₂₄ alkanes or alkenes having a —SH group at the terminal. More preferably 1-dodecanethiol.

The zinc (Zn) precursor may be a zinc precursor commonly used in the art, but selected from the group consisting of zinc elements, nitrates, sulfates, carbonates, halides, acetates, oxides and hydrates thereof. It is possible to use more than one species. More preferably zinc acetate.

The present invention also relates to an indium phosphide / zinc sulfide (InP / ZnS) quantum dot coated with a zinc sulfide (ZnS) shell on the indium phosphide quantum dot core. It is possible to apply various kinds of metal shells to the indium phosphide quantum dot core without particular limitation, but it is preferable to coat zinc sulfide shells in terms of improving stability of quantum dots and improving quantum efficiency.

The method of forming the indium phosphide / zinc sulfide core-shell quantum dots may include a method such as a method of additionally adding a sulfur precursor and a zinc precursor to the prepared solution of the indium phosphide quantum dot core. The sulfur precursor and the zinc precursor may be simultaneously added, or after the sulfur precursor is added, zinc precursors may be sequentially added or vice versa.

The sulfur precursor is not particularly limited to a compound containing sulfur, but may be C ₂ to C ₂₄ alkanes or alkenes having a —SH group at the terminal. More preferably 1-dodecanethiol.

The zinc (Zn) precursor may be a zinc precursor commonly used in the art, but selected from the group consisting of zinc elements, nitrates, sulfates, carbonates, halides, acetates, oxides and hydrates thereof. It is possible to use more than one species. More preferably zinc acetate.

The shell formation time is preferably 3 to 5 hours. If the reaction time is not enough, the quantum efficiency may be reduced, and if it is too long, the quantum efficiency may be reduced.

Hereinafter, the present invention will be described in more detail with reference to examples, but the following examples are merely to illustrate the present invention, but it should be understood that the present invention is not limited thereto.

Example  One. InP Quantum dots  Synthesis of Cores In  : P = 1: 0.2)

In 45 ml of 1-octadecene, 292 mg (indium 1 mmol) of indium acetate as an indium precursor, 768 mg of palmitic acid as a surfactant, 606 mg (sulfur 3 mmol) of 1-dodecanethiol as a sulfur precursor, 184 mg of zinc acetate as a zinc precursor (Zinc 1 mmol) was mixed. In the solution thus prepared, 50.8 mg (phosphorus 0.2 mmol) of tris (trimethylsilyl) phosphine as a phosphorus precursor was dissolved in 1-octadecene and dropped at a rate of 1.5 ml / hr to synthesize a quantum dot core. The precipitate was filtered off and dried to finally give an InP quantum dot core. A schematic diagram of the synthesis is shown in FIG. 1.

Example  2. InP Quantum dots  Synthesis of Cores In  : P = 1: 0.4)

Tris (trimethylsilyl) phosphine was synthesized in the same manner as in Example 1 except that a total of 100.2 mg (0.4 mmol) of phosphorus was dropped.

Example  3. InP Quantum dots  Synthesis of Cores In  : P = 1: 0.6)

Tris (trimethylsilyl) phosphine was synthesized in the same manner as in Example 1 except that a total of 150.3 mg (0.6 mmol) was dropped.

Example  4. InP Quantum dots  Synthesis of Cores In  : P = 1: 0.8)

Tris (trimethylsilyl) phosphine was synthesized in the same manner as in Example 1 except that a total of 200.5 mg (phosphorus 0.8 mmol) was dropped.

Example  5. InP Quantum dots  Synthesis of Cores In  : P = 1: 1)

Tris (trimethylsilyl) phosphine was synthesized in the same manner as in Example 1 except that 250.5 mg (1.0 mmol) of total phosphorus was dropped. The obtained quantum dot core was analyzed by transmission electron microscope (TEM) and the results are shown in FIG. 2.

Example  6. InP Of ZnS Quantum dots  synthesis

In 45 ml of 1-octadecene, 292 mg (indium 1 mmol) of indium acetate as an indium precursor, 768 mg of palmitic acid as a surfactant, 606 mg (sulfur 3 mmol) of 1-dodecanethiol as a sulfur precursor, 184 mg of zinc acetate as a zinc precursor (Zinc 1 mmol) was mixed. In the solution thus prepared, 250.5 mg (1.0 mmol) of tris (trimethylsilyl) phosphine as a phosphorus precursor was dissolved in 1-octadecene and dropped at a rate of 1.5 ml / hr to synthesize a quantum dot core. After adding 368 mg of zinc acetate, the mixture was left to stand for about 5 hours. The precipitate was filtered off and dried to finally give InP / ZnS quantum dots.

Example  7. InP Of ZnS Quantum dots  synthesis( In  : S = 1: 3)

After the quantum dot core synthesis, 368 mg of zinc acetate and 200 mg of 1-dodecanethiol were further added, and the synthesis was carried out in the same manner as in Example 5. The obtained InP / ZnS quantum dots were analyzed by transmission electron microscope (TEM) and the results are shown in FIG. 3.

Example  8 to 17 ( In  : S = 1: 0 ~ 2.7)

Example 7 except that 1-dodecanethiol to be mixed initially (Example 8) or synthesized by adjusting the sulfur in 1-dodecanethiol to 0.3 to 2.7 mmol (Examples 9 to 17) Synthesis was carried out in the same manner as.

Experimental Example

UV / Vis absorbance photometer (SINCO, S-3100) and photoluminescence analyzer (PL) (light source: 355 nm CW UV DPSS LASER, measurement for the identification of the InP quantum dot core and InP / ZnS quantum dots prepared in Examples 1 to 17 Instrument: OCEAN OPTICS USB4000). First, the UV / Vis absorption spectrum analysis results of InP quantum dot cores and InP / ZnS quantum dots prepared in Examples 1 to 7 are shown in FIG. 4. InP / ZnS quantum dots prepared in Example 7 were analyzed by X-ray diffraction analysis, and the results are shown in FIG. 5. As shown in FIG. 5, the quantum dots prepared in Example 7 were confirmed to be the same as the InP / ZnS structure according to a general manufacturing method. In addition, UV / Vis absorption spectra and photoluminescence (PL) spectra of InP / ZnS quantum dots prepared in Examples 7 to 17 were analyzed to determine the change in emission wavelength according to the amount of sulfur precursors. The peaks of the emission wavelengths are shown in Table 1 below. As can be seen from FIG. 6, FIG. 7 and Table 1, as the amount of dodecanethiol increases, the peaks of absorption and emission wavelengths shift toward shorter wavelengths.

In: S (molar ratio) Emission wavelength (nm) Example 7 1: 3 490 Example 8 1: 0 615 Example 9 1: 0.3 600 Example 10 1: 0.6 580 Example 11 1: 0.9 570 Example 12 1: 1.2 560 Example 13 1: 1.5 545 Example 14 1: 1.8 535 Example 15 1: 2.1 520 Example 16 1: 2.4 510 Example 17 1: 2.7 500

Claims (20)

After dissolving an indium (In) precursor, a surfactant, a sulfur precursor and a zinc precursor in an organic solvent, a phosphorus (P) precursor at a feed rate of 0.5 to 2.5 ml / hr comprising the synthesis of the indium phosphide quantum dot core Indium phosphide (InP) quantum dot core synthesis method.
The method of claim 1, wherein the organic solvent is C ₆ ~ C ₂₄ alkyl amine, alcohol, ketone ester, heterocyclic compound containing nitrogen or sulfur, alkanes, alkenes, alkynes, trialkylphosphine or trialkyl phosphine oxide Indium phosphide (InP) quantum dot core synthesis method characterized in that.
The indium phosphide (InP) of claim 1, wherein the indium precursor is at least one selected from the group consisting of indium elements, nitrates, sulfates, carbonates, halides, acetates, oxides, and hydrates thereof. ) Quantum dot core synthesis method.
The indium phosphide (InP) quantum dot of claim 1, wherein the surfactant is a C ₆ ~ C ₂₄ alkanes or alkenes having a -COOH group, -POOH group, -SOOH group or -NH ₂ group at the terminal Core synthesis method.
According to claim 1, wherein the surfactant is oleic acid (oleic acid), stearic acid (stearic acid), palmitic acid (palmitic acid), hexyl phosphonic acid (hexyl phosphonic acid), n-octyl phosphonic acid (n-octyl phosphonic acid) acid, tetradecyl phosphonic acid, octadecyl phosphonic acid, octadecyl phosphonic acid, n-octyl amine, n-octylamine, or hexadecyl amine. InP) Quantum dot core synthesis method.
The method of claim 1, wherein the phosphorus precursor is at least one selected from the group consisting of elemental phosphorus, phosphine, phosphite and phosphine oxide. Indium phosphide (InP) quantum dot core synthesis method.
The method of claim 1, wherein the phosphorus precursor is tris (trialkylsilyl) phosphine.
delete The method for synthesizing indium phosphide (InP) quantum dot core according to claim 1, wherein the synthesis temperature is 200 to 220 ° C.
The method for synthesizing an indium phosphide (InP) quantum dot core according to claim 1, wherein a molar ratio of indium in the indium precursor and phosphorus in the phosphorus precursor is 1: 0.1-10.
delete The method for synthesizing an indium phosphide (InP) quantum dot core according to claim 1, wherein the molar ratio of indium in the indium precursor and sulfur in the sulfur precursor is dissolved at 1: 0.1 to 3.
The method of claim 1, wherein the sulfur precursor is C ₂ ~ C ₂₄ alkanes or alkenes having a -SH group at the end of the indium phosphide (InP) quantum dot core synthesis method characterized in that.
The indium phosphide (InP) of claim 1, wherein the zinc precursor is at least one selected from the group consisting of zinc elements, nitrates, sulfates, carbonates, halides, acetates, oxides, and hydrates thereof. ) Quantum dot core synthesis method.
The method of claim 1, wherein the zinc precursor is zinc acetate.
A sulfur precursor and a zinc precursor are further mixed into a solution in which an indium phosphide (InP) quantum dot core prepared by the method of any one of claims 1 to 10 and 12 to 15 is mixed. Indium phosphide / zinc sulfide (InP / ZnS) core-shell quantum dot synthesis method.
The method of claim 16, wherein the sulfur precursor is a C ₂ ~ C ₂₄ alkanes or alkenes having a -SH group at the end of the indium phosphide / zinc sulfide (InP / ZnS) core-shell quantum dot synthesis method.
17. The indium phosphide / sulfide according to claim 16, wherein the zinc precursor is at least one selected from the group consisting of zinc elements, nitrates, sulfates, carbonates, halides, acetates, oxides and hydrates thereof. Zinc (InP / ZnS) core-shell quantum dot synthesis method.
17. The method of claim 16, wherein the zinc precursor is zinc acetate.
17. The method of claim 16, wherein the mixing time for forming the shell is mixed for 3 to 5 hours. Indium phosphide / zinc sulfide (InP / ZnS) core-shell quantum dot synthesis method.

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