KR101838583B1

KR101838583B1 - Quantum Dot of Indium-Gallium Metal Nitride, and a Colloidal Dispersion having the Same

Info

Publication number: KR101838583B1
Application number: KR1020150076290A
Authority: KR
Inventors: 박종남; 서요한
Original assignee: 울산과학기술원
Priority date: 2015-05-29
Filing date: 2015-05-29
Publication date: 2018-03-15
Also published as: KR20160141257A

Abstract

The present invention relates to a quantum dot of indium gallium-based metal nitride represented by the following formula (1) and a colloidal dispersion containing the indium gallium metal nitride, and more particularly to a quantum dot of indium gallium metal nitride produced using a novel metal precursor and a nitrogen source, And to a colloidal dispersion containing the same. The quantum dot of the metal nitride according to the present invention can be used as a photoactive layer having no toxicity, environment-friendly, excellent light-emitting property and high stability, and can be used in the form of a colloidal dispersion containing the metal- Can be coated on a substrate by an economical and simple ink process without a high-temperature deposition process of the present invention. By virtue of such properties, coating on a flexible substrate having low heat resistance is easy, and convenience of use of the quantum dot can be remarkably improved.
[Chemical Formula 1]
In _x Ga ₁ _- _x N
(In the above formula (1), x has a range of 0? X? 1.)

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to quantum dots of indium gallium-based metal nitride and colloidal dispersions containing the same,

The present invention relates to a quantum dot of indium gallium metal nitride and a colloidal dispersion containing the same. More specifically, the present invention relates to a quantum dot of indium gallium metal nitride and a colloidal dispersion thereof, which are free of toxicity, excellent in luminous efficiency and high in stability, And a colloidal dispersion containing the indium gallium-based metal nitride quantum dots.

The Quantum Dot is a semiconductor crystalline material having a diameter of several to several tens of nanometers or less. It can control various colors of light emitted according to the size of the quantum dot, and the absorption wavelength ranges from a short wavelength to a long wavelength , The emission wavelength has a narrow range and has a higher color index than that of the organic material. Particularly, many researchers are actively researching in the display field.

As examples of conventional quantum dots, there have been studied high light-emitting nanocrystals which can realize various colors using cadmium (Cd) based quantum dots, such as U.S.P. No. 8158193. However, the above cadmium- It is difficult to apply it widely to various fields.

InP quantum dots have been studied to replace Cd-based quantum dots, which are highly toxic, as described above. However, since quantum dots are vulnerable to moisture, oxygen, and heat, they have a disadvantage of low stability. In order to improve stability, Or doping, etc., have been studied. However, this method requires an additional process, which complicates the process and increases the cost. Thus, there is a growing need for metal nitride quantum dots having high stability and luminescence efficiency, even in the absence of toxicity.

However, in the case of metal nitride fine particles produced by the MBE (molecular beam epitaxy) process, which is a conventional process, for example, a method of scraping a thin film after forming a thin film by using CVD on a substrate, , The particle size can not be controlled, and a place where the bond with the substrate is broken during the scraping from the substrate acts as a defect site, so that it can not have optical properties and can not have substantially the characteristics of a quantum dot. In addition, the metal nitride fine particles produced by the above process are produced in the form of powder. When the metal nitride fine particles are dispersed in an organic solvent or the like, they can not be dispersed in a precipitated state and thus can not be used in the form of a colloidal dispersion. There is also a problem of low convenience.

US 8158193 B

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems occurring in the prior art,

There is provided a quantum dot of indium gallium-based metal nitride which can be produced in the form of a colloidal dispersion, and a colloidal dispersion method comprising the same, which is free of toxicity, excellent in luminous efficiency and high in stability, There is a purpose.

According to an aspect of the present invention,

A quantum dot of a metal nitride represented by the following Chemical Formula 1 is provided.

[Chemical Formula 1]

In _x Ga ₁ _- _x N

(In the above formula (1), x has a range of 0? X? 1.)

When the quantum dot of the metal nitride is dispersed in the organic solvent, the time for maintaining the dispersed state may be 3 months or more.

The organic solvent may include, but is not limited to, hexane, toluene, benzene, octane, chloroform, chlorobenzene, tetrahydrofuran (THF), pentane, heptane, decane, methylene chloride, 1,3-dioxane, 1,4-dioxane, diethyl ether, cyclohexane, and dichlorobenzene.

Further, the present invention provides a colloidal dispersion comprising a quantum dot of a metal nitride represented by the following general formula (1) as colloidal particles.

[Chemical Formula 1]

In _x Ga ₁ _- _x N

(In the above formula (1), x has a range of 0? X? 1.)

The solvent of the colloidal dispersion may be an organic solvent, and the organic solvent may include, but is not limited to, hexane, toluene, benzene, octane, chloroform, chlorobenzene, tetrahydrofuran (THF), pentane, heptane, decane , Methylene chloride, 1,4-dioxane, diethyl ether, cyclohexane, and dichlorobenzene. The solvent may be selected from the group consisting of methylene chloride, 1,4-dioxane, diethyl ether,

In the above formula (1), x may have a range of 0.01? X? 0.5.

The quantum dot of the metal nitride according to the present invention can be used as a photoactive layer having no toxicity, environment-friendly, excellent light-emitting property and high stability, and can be used in the form of a colloidal dispersion containing the metal- Can be coated on a substrate by an economical and simple ink process without a high-temperature deposition process of the substrate, and it is easy to coat even on a flexible substrate having low heat resistance owing to such characteristics, so that convenience of use of the quantum dot can be remarkably improved.

1 is a graph showing XRD characteristics of In _x Ga ₁ _- _x N quantum dots (CQDs) prepared in the present invention.
FIG. 2 is a graph showing bandgap characteristics of In _x Ga ₁ _- _x N quantum dots (CQDs) prepared in the present invention.
FIG. 3 is a graph showing the characteristics of PL (Photoluminescence) according to the composition and temperature of In _x Ga ₁ _- _x N prepared in the present invention.
4 is a graph showing X-ray absorption spectroscopy (XAFS) measurement results of the In _x Ga ₁ _- _x N quantum dots (CQDs) prepared in the present invention.
FIG. 5 is a graph showing the metal quantity characteristics of the present invention. FIG.
6 is a graph showing XPS In3d binding spectra characteristics of In _x Ga ₁ _- _x N prepared in the present invention.
7 is a TEM image of In _x Ga ₁ _- _x N quantum dots (CQDs) prepared in the present invention.
8 is a graph showing PL-QY (Photoluminescence Quantum yield) characteristics of In _x Ga ₁ _- _x N prepared in the present invention.
9 is a graph showing the characteristics of PL (Photoluminescence) according to the amount of oleic acid of In _x Ga ₁ _- _x N prepared in the present invention.
10 is a graph showing the characteristics of PL (Photoluminescence) according to the output of In _x Ga ₁ _- _x N produced in the present invention.
11 is a graph showing reduction characteristics of PL (Photoluminescence) according to the decay time of In _x Ga ₁ _- _x N prepared in the present invention.
12 is a graph showing X-ray absorption spectroscopy (XAS) characteristics of In _x Ga ₁ _- _x N prepared in the present invention.
13 is a graph showing energy level characteristics of In _x Ga ₁ _- _x N according to the ultraviolet electron spectroscopy (UPS) analysis of the present invention.
14 is a graph comparing PL-QY (Photoluminescence Quantum yield) characteristics of In _x Ga ₁ _- _x N quantum dots (CQDs) prepared in the present invention.
Fig. 15 is a photograph showing the difference in solubility between the In _x Ga ₁ _- _x N quantum dots produced in the present invention and the commercially available comparative example.
16 is a photograph showing the difference in luminescence characteristics between the In _x Ga ₁ _- _x N quantum dots produced in the present invention and the commercially available comparative example.
17 is a graph showing bandgap characteristics of another In _x Ga ₁ _- _x N quantum dot prepared in the present invention.

Hereinafter, the present invention will be described in detail.

The quantum dots of the metal nitride of the present invention are expressed by the following formula (1).

[Chemical Formula 1]

In _x Ga ₁ _- _x N

(In the above formula (1), x has a range of 0? X? 1.)

When the quantum dots of the metal nitride are dispersed in an organic solvent, the time for maintaining the dispersion state in which no precipitate is formed may be at least 3 months or more. Thus, the quantum dots of the metal nitride can be used in the form of colloidal dispersions dispersed in the organic solvent, so that the quantum dots can be coated on the substrate by a much simpler and more economical ink process without the conventional high temperature deposition process Due to these properties, the QDs can also be coated on flexible substrates with low heat resistance.

The organic solvent in which the quantum dots are dispersed is not particularly limited, but examples thereof include hexane, toluene, benzene, octane, chloroform, chlorobenzene, tetrahydrofuran (THF), pentane, heptane, decane, And may include at least one member selected from the group consisting of 1,4-dioxane, diethyl ether, cyclohexane, and dichlorobenzene.

The quantum dots of the metal nitride can be relatively easily changed in composition (In _x Ga ₁ _- _x N, where x is 0? X? 1) by controlling the input ratio of the metal precursor used in the manufacturing process. Similarly, since the compound has various luminescent properties depending on the composition, it can be utilized for a light emitting device having various colors and brightness by using such properties.

Further, the quantum dot of the metal nitride is not toxic because a heavy metal is not used, so that there is no limitation in application to various fields including display.

In the above formula (1), x is preferably, but not limited to, in the range of 0.01? X? 0.5, and the reason is that the smaller the ratio of indium to the composition ratio of indium and gallium, This is because the defect level decreases and the luminous efficiency rises.

The colloidal dispersion of the present invention includes quantum dots of metal nitride represented by the following formula (1) as colloidal particles.

[Chemical Formula 1]

In _x Ga ₁ _- _x N

(In the above formula (1), x has a range of 0? X? 1.)

Further, the colloidal dispersion of the present invention may include quantum dots of metal nitride having x in the range of 0.01? X? 0.5 in the above formula (1) as colloidal particles.

In the colloidal dispersion of the present invention, the solvent in which the colloidal dispersion is dispersed can be an organic solvent, and the organic solvent includes, but is not limited to, hexane, toluene, benzene, octane, chloroform, chlorobenzene, tetrahydrofuran (THF) An organic solvent such as tetrahydrofuran, dioxane, tetrahydrofuran, tetrahydrofuran, dioxane, diethyl ether, cyclohexane, and dichlorobenzene. .

The quantum dot according to the present invention can be produced by adding a precursor of indium, a precursor of gallium and a surfactant to a solvent to prepare a mixture, and then introducing a nitrogen source thereto to cause a thermal decomposition reaction. The composition of the quantum dots of the In _x Ga ₁ _- _x N metal nitride can be controlled by controlling the reaction mole number of the indium precursor, the gallium precursor, the surfactant and the solvent.

The indium precursor may be an organic indium compound, but is not limited to indium (III) acetylacetonate, indium (III) chloride, indium (III) acetate, Indium Myristate, Indium Myristate Acetate, and Indium Myristate 2, which are known to those skilled in the art, such as indium myristate acetate, indium myristate acetate, Acetate (Indium (III) Myristate 2 Acetate).

The gallium precursor may be an organic gallium compound, but is not limited to gallium (III) acetylacetonate, Gallium (III) acetate, Gallium (III) chloride, , Triethyl gallium, trimethyl gallium, Alkyl Gallium, Aryl Gallium, Gallium (III) Myristate, Gallium (III) Myristate Acetate) and gallium myristate 2 acetate (Gallium (III) Myristate 2 Acetate).

The surfactant may be, but is not limited to, a carboxylic acid-based compound, a phosphonic acid-based compound, or a mixture of the two compounds, and the carboxylic acid-based compound may be selected from the group consisting of oleic acid, The phosphonic acid-based compound may be at least one selected from the group consisting of palmitic acid, paletic acid, stearic acid, linoleic acid, myristic aicd and lauric acid, Hexylphosphonic acid, octadecylphosphonic acid, tetradecylphosphonic acid, hexadecylphosphonic acid, decylphosphonic acid, octylphosphonic acid, octadecylphosphonic acid, octadecylphosphonic acid, octadecylphosphonic acid, And Butylphosphonic acid. [0033] The term " anionic surfactant "

The solvent may include, but is not limited to, 2,6,10,15,19,23-hexamethyltetracosane (Squalane), 1-octadecene (ODE), trioctylamine (TOA), tributylphosphine oxide, octadecene, octadecylamine, Hexane, octane, trioctylphosphine (TOP) and trioctylphosphine oxide (TOPO), or a mixture of two or more of them.

The solvent may be 2 to 10 mL per mol of the sum of the molar number of the indium precursor and the molar amount of the gallium precursor. If the content of the solvent is less than the above range, there is a problem in the stability of the precursor solution, and if it is more than the above range, the reaction does not proceed properly.

The pyrolysis reaction is not limited thereto, but may be a hot injection method or a heating up method. The high-temperature injection and heating method has the advantage that the quantum dot can be manufactured at a high temperature in a short time.

Specifically, the hot injection may be performed by heating the mixture of the indium precursor, gallium precursor, surfactant, and solvent in an argon, nitrogen, ammonia, or vacuum atmosphere to a temperature of 150 to 400 ° C., And then pyrolysis is carried out by hot injection at a temperature of 400 ° C.

When the nitrogen source is injected at a high temperature, it may be mixed with a solvent and injected. The solvent may include, but is not limited to, 2,6,10,15,19,23-hexamethyltetracosane (Squalane), octadecene (ODE), trioctylamine TOA), tributylphosphine, tributylphosphine oxide, trioctylphosphine (TOP) and trioctylphosphine oxide (TOPO), or a mixture of two or more thereof.

Specifically, the heating up method is a method in which a nitrogen source is added to a mixture of the indium precursor, the gallium precursor, the surfactant, and the solvent, and then pyrolysis is performed at a temperature of 150 to 400 ° C in an argon, nitrogen, ammonia, It will proceed.

After the quantum dot is prepared by the above-described method, an anti-solvent may be added to precipitate the quantum dot. As the anti-solvent, any one or more selected from the group consisting of methanol, ethanol, propanol, butanol, and acetone may be used.

Further, by dispersing the precipitated quantum dots in an organic solvent, quantum dots of a colloid can be produced. The organic solvent may include, but is not limited to, hexane, toluene, benzene, octane, chloroform, chlorobenzene, tetrahydrofuran (THF), pentane, heptane, decane, methylene chloride, , 4-dioxane, diethyl ether, cyclohexane, and dichlorobenzene.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the embodiments of the present invention described below are illustrative only and the scope of the present invention is not limited to these embodiments. The scope of the present invention is indicated in the claims, and moreover, includes all changes within the meaning and range of equivalency of the claims. In the following Examples and Comparative Examples, "%" and "part" representing the content are on a mass basis unless otherwise specified.

< Example - Quantum dot Synthesis>

1. Reagents used

In the examples of the present invention, a mixture of 1-octadecene (ODE, 90%), oleic acid (OA, 90%), Indium (III) acetylacetonate (In (acac) ₃ , 99.99%), Gallium (III) acetylacetonate _{acac) 3, 99.99%),} hexamethyldisilazane (HMDS, 99.9%), Tris (trimethylsilyl) amine (TMSA, 99.9%), N, N-Bis (trimethylsilyl) methylamine (TMSMA, 99.9%) , and Ammonia (99.9%) a And all reagents were purchased from Sigma-aldrich

2. Hot Injection Method Qdot synthesis( Example 1 to 15)

Synthesis was carried out based on pyrolysis synthesis method using hot injection method and Schlenk line was used to block and remove water and oxygen.

In order to gallium precursors Ga (acac) _3, was used for In (acac) ₃ as indium precursor, to adjust the x of the In _x Ga _1-x N In (acac) ₃ to the x mol, Ga (acac) ₃ (1-x) mol, 4.52 mL of ODE, and 0.6 to 2.2 mmol of OA to synthesize a metal oleate solution. The reaction temperature was 300 ° C and the temperature was increased by 10 ° C per minute.

When the temperature of the metal olefinsate solution reached 300 ° C, a solution containing 0.9 mL of TOP and a nitrogen source was rapidly injected into the metal olefinsate solution using a syringe (hot injection), and the reaction was continued for 30 minutes The synthesis of the quantum dots ends.

After the temperature of the solution was lowered, the quantum dots were precipitated using methanol as an antisolvent, and the quantum dots were dispersed in hexane.

Examples of the quantum dots of various indium gallium metal nitrides according to the above manufacturing method are shown in Table 1 below by adjusting the composition ratios of indium and gallium (In _x Ga ₁ _- _x N), types of nitrogen source and their amounts, and amounts of OA input Respectively. Examples 14 and 15 use ammonia gas bubbled as a nitrogen source.

Quantum dot composition (x) value (1-x) value Type of nitrogen source and input (mmol) OA input
(mmol) Example 1 GaN 0 One HMDS, 0.5 1.2 Example 2 In ₀ _.25 Ga ₀ _.75 N 0.25 0.75 HMDS, 0.5 1.2 Example 3 In ₀ _.5 Ga ₀ _.5 N 0.5 0.5 HMDS, 0.5 1.2 Example 4 In ₀ _.75 Ga ₀ _.25 N 0.75 0.25 HMDS, 0.5 1.2 Example 5 InN One 0 HMDS, 0.5 1.2 Example 6 In ₀ _.25 Ga ₀ _.75 N 0.25 0.75 HMDS, 0.5 0.6 Example 7 In ₀ _.25 Ga ₀ _.75 N 0.25 0.75 HMDS, 0.5 2.2 Example 8 In ₀ _.25 Ga ₀ _.75 N 0.25 0.75 TMSA, 0.5 0.6 Example 9 In ₀ _.25 Ga ₀ _.75 N 0.25 0.75 TMSA, 0.5 1.2 Example 10 In ₀ _.25 Ga ₀ _.75 N 0.25 0.75 TMSA, 0.5 2.2 Example 11 In ₀ _.25 Ga ₀ _.75 N 0.25 0.75 TMS, 0.25 1.2 Example 12 In ₀ _.25 Ga ₀ _.75 N 0.25 0.75 TMSMA, 0.5 1.2 Example 13 In ₀ _.25 Ga ₀ _.75 N 0.25 0.75 TMS, 1.0 1.2 Example 14 In ₀ _.35 Ga ₀ _.75 N 0.35 0.75 Ammonia, 1 1.2 Example 15 In ₀ _.35 Ga ₀ _.75 N 0.35 0.75 Ammonia, 1 1.2

3. Heating up Method Qdot synthesis( Example 16-22)

Synthesis was carried out based on pyrolysis synthesis method using heating up method. Schlenk line was used to block and remove water and oxygen.

In order to gallium precursors Ga (acac) _3, was used for In (acac) ₃ as indium precursor, to adjust the x of the In _x Ga _1-x N In (acac) ₃ to the x mol, Ga (acac) ₃ (1-x) mol, ODE of 4.52 mL, and OA of 0.6 ~ 2.2 mmol. To this solution, 0.9 mL of TOP and 0.5 mmol of HMDS, which is a nitrogen source, were mixed together and the temperature of the solution was raised to 300 ° C. The synthesis of the quantum dots ends.

Thereafter, the temperature of the solution was lowered, the quantum dots were precipitated using methanol as an anti-solvent, and the quantum dots were dispersed in hexane.

Examples of quantum dots of various indium gallium metal nitride according to the above manufacturing method were prepared by controlling the composition ratio of indium and gallium (In _x Ga ₁ _- _x N) as shown in Table 2 below.

Quantum dot composition (x) value (1-x) value Type of nitrogen source and input (mmol) OA input
(mmol) Example 16 GaN 0 One HMDS, 0.5 1.2 Example 17 In ₀ _.25 Ga ₀ _.75 N 0.25 0.75 HMDS, 0.5 1.2 Example 18 In ₀ _.5 Ga ₀ _.5 N 0.5 0.5 HMDS, 0.5 1.2 Example 19 In ₀ _.75 Ga ₀ _.25 N 0.75 0.25 HMDS, 0.5 1.2 Example 20 InN One 0 HMDS, 0.5 1.2 Example 21 In ₀ _.25 Ga ₀ _.75 N 0.25 0.75 HMDS, 0.5 0.6 Example 22 In ₀ _.25 Ga ₀ _.75 N 0.25 0.75 HMDS, 0.5 2.2

< Experimental Example >

Experimental Example One. Of quantum dots (CQDs) XRD characteristic

The XRD characteristics of the quantum dots of the present invention were measured using Rigaku, D.MAZX 2500V / PC.

XRD results of In _x Ga ₁ _- _x N prepared in Example 1 (x = 0), Example 2 (x = 0.25) and Example 3 (x = 0.5) are shown in FIG. XRD results of In _x Ga _1-x N prepared in Example 4 (x = 0.5) and Example 4 (x = 0.75) are shown in FIG. 1 (b). 1 (c) shows the Ga3d binding position of In _x Ga ₁ _- _x N prepared in Example 2 (x = 0.25), Example 3 (x = 0.5) and Example 4 (x = 0.75) The N1s binding position is shown in Figure 1 (d).

From the above results, it was confirmed that InN has a cubic structure and GaN has a hexagonal structure. The crystal structure of each quantum dot was identified and the change of crystal structure according to the ratio of each metal was found.

Experimental Example 2. Of quantum dots (CQDs) Band gap characteristics

The bandgap characteristics of the quantum dots of the present invention were measured using a Cary Eclipse device manufactured by Varian, and the quantum dots were dispersed in an organic solvent hexane and the band gap was measured.

UV-vis absorption spectra of In _x Ga ₁ _- _x N prepared in Example 2 (x = 0.25), Example 3 (x = 0.5) and Example 4 (x = 0.75) The PL spectra is shown in Fig. 2 (b). The PL spectra and the UV-vis absorption spectra of In _x Ga ₁ _- _x N according to the amount of oleic acid (OA) are shown in FIG. 2 (c) and FIG. 2 (d)

The amount of oleic acid (OA) of InxGa1-xN prepared in Example 8 (OA = 0.6 mmol), Example 9 (OA = 1.2 mmol) and Example 10 (OA = 2.2 mmol) Vis absorption spectra are shown in Fig. 2 (e), and PL spectra are shown in Fig. 2 (f).

The UV-vis absorption spectra of the InxGa1-xN prepared according to Example 11 (TMSMA = 0.25 mmol), Example 12 (TMSMA = 0.5 mmol) and Example 13 (TMSMA = 1 mmol) (g), and the PL spectra is shown in Fig. 2 (h).

Example 14 (x = 0), Example 15 (x = 0.5) of In _x Ga ₁ manufactured by _- _x N of the UV-vis absorption 17 to the spectra of 17 (a) also, PL spectra of (b) and 17 (c).

From the above results, it was found that quantum dots can be prepared using HMDS, TMSA, TMSMA and ammonia as N-sources.

From the above results, it was found that the reactivity was the best when HMDS was used as an N-source, and the reactivity was better in the order of TMSA and TMSMA.

From the above results, it can be seen from the above results that Examples 2 to 4 using HMDS as an N-source were effective in increasing the particle size of the quantum dots, followed by band gap control in the order of TMSA and TMSMA .

The difference in PL-QY is also shown in Fig. HMDS is the most frequently used, and it can be seen that when TMSMA is used, PL-QY is about 8% lower than that of other N-sources.

Experimental Example 3. Depending on composition and temperature PL ( Photoluminescence ) Characteristics

The PL characteristics of the In _x Ga ₁ _- _x N quantum dots of the present invention were measured using an MIRA laser (λ = 375 nm, Exc power: 1.1 mW).

(X = 0.2) (Fig. 3 (b)), Example 3 (x = 0.5) (Fig. 3 (c) The variation of peak intensity with temperature in each composition was investigated by using Si substrate coated with In _x Ga ₁ _- _x N quantum dots prepared in Example 4 (x = 0.75) (Fig. 3 (d) Respectively. It can be seen that the emission wavelength and the intensity of the peak change depending on the metal composition, and the peak intensity decreases as the temperature increases.

Experimental Example 4. Of quantum dots (CQDs) X-ray absorption spectroscopy ( XAFS ) Characteristics

The X-ray absorption spectroscopic characteristics of the quantum dots of the present invention were measured using a Pohang radiation accelerator (belonging to POSTECH). At this time, indium acetylacetonate was used as a reference for calibrate.

The measured values of In _x Ga ₁ _- _x N quantum dots prepared in Example 2 (x = 0.25), Example 3 (x = 0.5), Example 4 (x = 0.75) and Example 5 For comparison, the values are converted into Fourier function values and shown in Fig. 4 (a). The converted value ranged from 2.2 to 3.4 Å. FIG. 4 (b) is a graph comparing the results converted into the Fourier function values at phases A, B, and C in FIG. 4 (a).

From the above results, it can be shown that the quantum dots synthesized by the present method have a multi-phase shape rather than a single phase, and the results show that the reason why a single peak does not appear in the PL spectra.

Experimental Example 5. Metal amount ( quantity ).

Example 2 (x = 0.25), Example 3 (x = 0.5) and Example 4 (x = 0.75) were prepared in order to examine the characteristics of the In _x Ga ₁ _- _x N of the present invention, ) Was measured using ICP-MS, and the result is shown in FIG. 5. As shown in FIG.

From the above results, it was found that the metal ratio of the generated In _x Ga ₁ _- _x N quantum dots is controlled by controlling the ratio of the metal (In, Ga) introduced during the production.

Experimental Example 6. XPS In3d binding Spectra characteristic

XPS In3d binding spectra results were obtained from various compositions of In _x Ga ₁ _-x N prepared in Example 2 (x = 0.25), Example 3 (x = 0.5) and Example 4 (x = 0.75) 6.

From the above results, it can be seen that when the metal composition of In and Ga is changed, the chemical bonding state of the quantum dots changes at a certain rate. Thus, when the metal nitride is synthesized using the present method, Can be freely adjusted.

Experimental Example 7. Of quantum dots (CQDs) TEM image

Example 2 (OA = 1.2 mmol) TEM image of Green condition of quantum dot is shown in FIG. 7 (a), and TEM image of Blue condition of quantum dot of Example 7 (OA = 2.2 mmol) is shown in FIG. 7 (b). As shown in the above results, it can be seen that the color changes to Green or Blue depending on the amount of O.A., and it is found that the color has a size of about 2.5 to 4 nm as shown in the photograph.

The single component images of Example 5 (x = 1) and Example 1 (x = 0) are shown in Figs. 7 (c) and 7 (d), respectively. From the above results, it can be seen that even a single component can be synthesized as spherical particles.

Experimental Example 8. PL - QY ( Photoluminescence Quantum yield ) Characteristics

PL-QY (Photoluminescence Quantum Yield) of In _x Ga ₁ _- _x N prepared in Example 2 (x = 0.25), Example 3 (x = 0.5) and Example 4 (x = 0.75) 8.

From the above results, it can be seen that the ratio of Green Pl-QY increases as the ratio of In decreases.

Experimental Example 9. Depending on the amount of oleic acid PL ( Photoluminescence ) Characteristics

The PL spectra of In _x Ga ₁ _- _x N prepared in Example 6 (OA = 0.6 mmol), Example 2 (OA = 1.2 mmol) and Example 7 (OA = 2.2 mmol) Respectively.

PL spectra of In _x Ga ₁ _- _x N prepared in Example 8 (OA = 0.6 mmol), Example 9 (OA = 1.2 mmol) and Example 10 (OA = 2.2 mmol) b).

As shown in FIGS. 9 (a) and 9 (b), when the amount of OA is small, it has a yellowish green color. When the amount of OA is increased, it is changed to Green. When the amount of OA is increased, As shown in FIG.

Experimental Example 10. Depending on output PL ( Photoluminescence ) Characteristics

10 (b)), Example 3 (x = 0.5) (Fig. 10 (c)) and Example (x = 0) 4 (x = 0.75) (Fig. 10 (d)) prepared in the in _x Ga ₁ _- shows the result of the PL is output from _x N in Figure 10 is measured.

MIRA laser (? = 375 nm, T = 20 K) was used for the PL measurement.

From the above results, it can be seen that as the output increases, the intensity of the peak becomes stronger. From this, the luminescence characteristics of the quantum dots are affected by surface defects or defects in the crystal, The recombination of electrons and holes in the luminescence of quantum dots is the main characteristic of quantum dot luminescence.

Experimental Example 11. Decay time ( decay time )In accordance PL ( Photoluminescence ) Reduction characteristics

The decay time measured from In _x Ga ₁ _- _x N produced in Example 1 (x = 0), Example 2 (x = 0.25), Example 3 (x = 0.5) and Example 4 Fig. 11 shows PL reduction characteristics according to the present invention. First, FIG. 11 (a) shows the result of calculation of time correlated single photon counting (TCSPC) at 520 nm. Fig. 11 (b) shows the results of TCSPC calculation at 550 nm. In addition, the average decay time at 520 nm and 550 nm is shown in Fig. 11 (c).

From the above results, it is possible to quantify the change of the decay time according to the mixing ratio of In and Ga metal. As a result, it can be understood that the PL intensity in the solution state decreases as the proportion of In metal increases.

Experimental Example 12. X-ray absorption spectroscopy ( XAS ) Characteristics

XANES measured from In _x Ga ₁ _- _x N prepared in Example 2 (x = 0.25), Example 3 (x = 0.5), Example 4 (x = 0.75) and Example 5 XAFS results are shown in Figs. 12 (a) and 12 (b), respectively. From the above results, it can be seen that the InGaN quantum dots synthesized through the present method are in a multi-phase state rather than a single phase state, and the results show that the PL peak is not a single peak type.

Experimental Example 13. Ultraviolet Electron Spectroscopy ( UPS ) Energy level characteristics by analysis

Example 2 (x = 0.25) of In _x Ga ₁ prepared _in-was from _x N measured energy levels characteristic of the ultraviolet ray electron spectroscopy, was also shown in 13 (a) to High binding energy cut-off region, valence band The region is shown in Fig. 13 (b). The valence band level was determined to be 7.24 eV.

From the above results, the band state of the InGaN quantum dots synthesized by the present method was found, and the energy level required for various electro-electronic devices was found.

Experimental Example 14. Of quantum dots (CQDs) colloidal stability compare

The solubilities of the GaN particles prepared in Example 1 and the GaN powders (Sigma-Aldrich, Aldrich 481769) purchased as a conventionally used product were compared as Comparative Example 1.

0.05 g of GaN was added to 50 ml of hexane and shaken sufficiently. Then, the change with time (0 hours, 0.5 hours, 2 hours, 3.5 hours and 5 hours) was photographed and shown in FIG.

The GaN of Example 1 tends to be stably dissolved even after a lapse of time. However, in the case of GaN of Comparative Example 1, there is a tendency that the GaN is not dissolved from the beginning (meaning that the cloudy solution is not dissolved) But, as time went on, it seemed to settled.

Experimental Example 15. Of quantum dots (CQDs) Luminescence characteristic

GaN particles prepared in Example 1 and GaN powder (Sigma-Aldrich, Aldrich 481769) purchased as a conventionally used product were set to Comparative Example 1, and their luminescent characteristics were compared.

0.05 g of GaN was added to 50 ml of hexane and sufficiently shaken to confirm the luminescence characteristics using a UV lamp.

It can be confirmed that the GaN produced in Example 1 emits light under the UV lamp condition, but it can be confirmed that the light emitting characteristic in Comparative Example 1 does not exist at all.

When GaN was synthesized by a conventional method as in the case of the GaN powder used in Comparative Example 1, a thin film was formed on a substrate by a chemical vapor deposition method, and then a thin film was scratched off or a solvothermal The synthesis should be carried out using the method. However, these methods are problematic in that when the GaN growth occurs, the defects are formed too much to cause luminescence (no substrate), and when the GaN grown on the substrate is scraped off, The broken site acts as a defect site (in the case of a substrate) and loses its luminescent characteristics.

Due to such a difference, there is a difference in light emission characteristics as shown in FIG.

Claims

A quantum dot of a metal nitride represented by the following Chemical Formula 1 and having a diameter of 2.5 to 4 nm.
[Chemical Formula 1]
In _x Ga _1-x N
(In the above formula (1), x has a range of 0.01? X? 0.5.)

The method according to claim 1,
Wherein the quantum dots of the metal nitride have a period of time of 3 months or more when the metal nitride is dispersed in an organic solvent.

The method of claim 2,
The organic solvent may be selected from the group consisting of hexane, toluene, benzene, octane, chloroform, chlorobenzene, tetrahydrofuran (THF), pentane, heptane, decane, methylene chloride, A quantum dot of a metal nitride, characterized in that it comprises at least one selected from the group consisting of cyanine and dichlorobenzene.

A colloidal dispersion represented by the following Chemical Formula 1 and comprising quantum dots of metal nitride having a diameter of 2.5 to 4 nm as colloidal particles.
[Chemical Formula 1]
In _x Ga _1-x N
(In the above formula (1), x has a range of 0.01? X? 0.5.)

The method of claim 4,
Wherein the solvent of the colloidal dispersion is an organic solvent.

The method of claim 5,
The organic solvent may be selected from the group consisting of hexane, toluene, benzene, octane, chloroform, chlorobenzene, tetrahydrofuran (THF), pentane, heptane, decane, methylene chloride, Wherein the colloidal dispersion contains at least one selected from the group consisting of cyan and dichlorobenzene.

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