KR102061617B1 - Colloid quantum dot composite passivated by graphene flakes and method for fabricating the same - Google Patents

Abstract

The disclosed colloidal quantum dot composite includes a quantum dot core comprising a semiconductor material and a passivation layer surrounding the quantum dot core, the passivation layer comprising a cationic surfactant and graphene flakes.

Description

COLLOID QUANTUM DOT COMPOSITE PASSIVATED BY GRAPHENE FLAKES AND METHOD FOR FABRICATING THE SAME}

The present invention relates to a method for producing a quantum dot composite. More specifically, the present invention relates to a colloidal quantum dot composite passivated with graphene flakes and a method of manufacturing the same.

Colloidal quantum dots are semiconductor nanocrystals having a core or core-shell structure of several nanometers in size, and can control emission characteristics of various wavelengths from ultraviolet to infrared depending on particle size. It is an inorganic nano material that is very promising as a fluorescent dye for bioimaging as well as photoelectric devices such as diodes and lasers.

However, the surface of the inorganic quantum dot is broken by the periodic crystal structure, causing surface defects due to the broken bonds of atoms on the surface, which greatly reduces the luminescence efficiency of the quantum dot or unwanted wide in the long wavelength band It causes the light emission of the line width to reduce the color purity. In order to minimize the decrease in luminous efficiency due to such surface defects, efforts have been made to improve the light stability of quantum dots by coordinating capping ligands including alkyl chains such as oleic acid, octadecylamine, hexadecylamine on the surface of the quantum dots. Nevertheless, there is still a problem that when exposed to oxygen or moisture and agglomerated by the photooxidation reaction, the optical properties are significantly reduced, making the practical application of the quantum dot is difficult.

Particularly, biological applications such as fluorescence imaging and fluorescence resonance energy transfer require quantum dots having stable optical properties in a dispersed state. Generally, lipophilic ligands are exchanged with hydrophilic ligands or interfaces containing both hydrophilic and lipophilic groups are used. The active agent is dispersed in an aqueous solution using a method of coating a double layer on the surface of the quantum dot coordinated with a lipophilic ligand. In this process, the lipophilic ligand may be desorbed, and the desorbed portion acts as a defect, making the environment easily oxidized by water or oxygen.

For example, Non-Patent Document 1 describes the reason why luminescence properties are deteriorated due to defect generation due to ligand desorption when redispersion of a quantum dot of Cadmium Selenide (CdSe) series into an aqueous solution using a surfactant. I'm reporting.

Therefore, the role of additional hydrophilic passivation on the surface of the quantum dot to maintain a stable optical performance of the quantum dot aqueous solution is important.

Currently commercially available cadmium-based semiconductor quantum dots have high color purity and excellent quantum efficiency, but blue-based quantum dots require a smaller core size (3 nanometers or less in diameter) than red or green (5 nanometers or more in diameter). The synthesis process is difficult, and surface defects are easily generated due to photooxidation, so that light stability is relatively low. Accordingly, instead of using a bicomponent core material such as Cadmium Sulfide (CdS) or Cadmium Selenide (CdSe) having a small core size, Cadmium Zinc Sulfide (CdZnS) having a large core size is used. The use of a core material in the form of a three-component alloy and zinc sulfide (ZnS) shell coating facilitates the synthesis and at the same time obtains excellent luminescence properties.

For effective application of such cadmium zinc sulfide / zinc sulfide core-shell quantum dots into environmentally friendly blue fluorescent dyes, an aqueous solution to prevent optical property degradation due to physicochemical property variations that may occur during water dispersion and to enhance light stability for a long time Research into further passivation film formation in the state is important.

On the other hand, recently, there is a report on the passivation effect of colloidal quantum dots using graphene having a two-dimensional planar structure of one carbon atom (Non-Patent Document 2). However, this is a result of simply applying a layer of quantum dots coated with a single layer on the substrate with a few tens of micrometers of graphene as an anti-oxidation layer, which has a disadvantage of protecting only a portion of the quantum dots having a size of several nanometers.

       Nanoscale 2013, 5, 9908-9916        2. Chem. Mater. 2015, 27, 5032-5039

An object of the present invention is to solve the above problems, to provide a colloidal quantum dot complex with improved stability.

Another object of the present invention to provide a method for producing the colloidal quantum dot composite.

The colloidal quantum dot composite according to an embodiment of the present invention includes a quantum dot core including a semiconductor material and a passivation layer surrounding the quantum dot core, wherein the passivation layer includes a cationic surfactant and graphene flakes.

According to one embodiment, the quantum dot core is Cadmium Selenide (CdSe), Cadmium Sulfide (CdS), Cadmium Telluride (CdTe), Zinc Selenide (Zinc Selenide, ZnSe), Zinc Sulfide (ZnS), Zinc Telluride (ZnTe), Mercury Selenide (HgSe), Mercury Sulfide (HgS), Mercury Telluride (HgTe), Selenide (Copper Indium Selenide, CuInSe2), Copper Indium Sulfide (CuInS ₂ ), Indium Phosphide (InP), Indium Arsenide (InAs), Gallium Arsenide (GaAs), Nitriding Gallium Nitride (GaN), Gallium Phosphide (GaP), Gallium Aluminum Arsenide (GaAlAs), Gallium Indium Arsenide (GaInAs), Lead Sulfide (PbS), In the group consisting of lead selenide (PbSe) and lead telluride (PbTe) Comprises at least one selected.

According to one embodiment, the cationic surfactant is Cetylpyridinium chloride (CTC), Behentrimonium chloride (BTAC-228), Benzalkonium chloride (BZK), Benzododec Benzododecinium bromide, Cetalkonium chloride (CKC), Cetrimonium bromide (CTAB), Cetrimonium chloride, Didecyldimethylammonium chloride (DDAC), At least one selected from the group consisting of dimethyldioctadecylammonium bromide (DODAB), dimethyldioctadecylammonium chloride (DODAC) and stearalkonium chloride.

According to one embodiment, the graphene flakes are non-oxidized graphene flakes having an oxygen content of less than 7%.

According to one embodiment, the quantum dot core is coordinated with a ligand containing a hydrophobic alkyl chain.

Method for producing a colloidal quantum dot composite according to an embodiment of the present invention, by providing a water and a cationic surfactant to the colloidal quantum dots, to form a colloidal quantum dots dispersed with the cationic surfactant, and the cation Providing graphene flakes to the colloidal quantum dots associated with the active surfactant, forming a passivation layer surrounding the quantum dots and comprising a cationic surfactant and graphene flakes.

According to one embodiment, the mixed mass ratio of the colloidal quantum dots and the graphene flakes is in the range of 20: 1 to 1: 1.

The colloidal quantum dot composite obtained in accordance with the present invention may be passivated with graphene flakes, thereby greatly improving stability. The colloidal quantum dot composite can be obtained by a relatively simple and low cost process in aqueous solution using cationic surfactants.

In addition, according to the present invention, by binding the non-oxidized graphene flakes having excellent light absorption characteristics in the ultraviolet / visible light region to the colloidal quantum dots, it is possible to suppress the photocorrosion or photo-oxidation reaction of the colloidal quantum dots.

1 is a flow chart illustrating a method of manufacturing a colloidal quantum dot composite passivated with graphene flakes according to an embodiment of the present invention.
2 is a cross-sectional view showing a colloidal quantum dot composite passivated with graphene flakes according to an embodiment of the present invention.
FIG. 3 shows transmission electron microscope images, interatomic microscope images, and X-ray photoelectron spectroscopy spectra of cadmium zinc sulfide / zinc sulfide core-shell quantum dots capped with CTAB obtained in Synthesis Example 1. FIG.
Figure 4 is a graph showing the optical properties of the aqueous solution of cadmium zinc sulfide / zinc sulfide core-shell quantum dots capped with CTAB obtained in Synthesis Example 1.
Figure 5 shows the UV-vis absorption spectrum and the photograph of the aqueous solution of the graphene flake aqueous solution used in Example 1.
6 shows zeta potential measurement results for quantum dots (CTAB-QD) obtained in Synthesis Example 1, graphene flakes (GQD) used in Example 1, and graphene-quantum dot composites (0.0625, 0.25, 1.0) obtained in Examples. A graph representing.
FIG. 7 shows the maximum light emission at 430 nm for the quantum dot obtained in Synthesis Example 1 (CTAB-QD, R _GQD = 0) and the quantum dot composite obtained in Example (R _GQD = 0.0625, R _GQD = 0.25, R _GQD = 1.0) Graph of intensity values plotted against time.
8 is a graph measuring the fluorescence lifetime at 430 nm after 294 hours when the fluorescence lifetime is measured by setting the excitation wavelength to 275 nm according to the mixing ratio with the graphene flakes (R _GQD = 0.0625, 0.25, 1.0). to be.
9 is a graph showing the emission spectra of the initial state, 74 hours, 165 hours, and 294 hours after the excitation wavelength is set to 275 nm according to the mixing ratio with the graphene flakes.
10 is a graph showing emission spectra of the initial state, 74 hours, 165 hours, and 294 hours after the excitation wavelength is set to 365 nm according to the mixing ratio with the graphene flakes.
11 is the quantum dot obtained in Synthesis Example 1 (CTAB-QD, R _GOQD = 0) and the quantum dot complex obtained in Comparative Example 1 (R _GOQD = 0.0625, R _GOQD = 0.25, R _GOQD = 1.0) at 430 nm It is a graph plotting the maximum light emission intensity value over time.

Hereinafter, a colloidal quantum dot composite passivated with graphene flakes according to an embodiment of the present invention and a manufacturing method thereof will be described in detail with reference to the accompanying drawings. As the inventive concept allows for various changes and numerous modifications, particular embodiments will be illustrated and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In the accompanying drawings, the dimensions of the structures are shown in an enlarged scale than actual for clarity of the invention.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, operation, component, or a combination thereof described in the specification, but one or more other features or numbers. It is to be understood that the present invention does not exclude in advance the possibility of the presence or the addition of steps, actions, components, or a 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 flow chart illustrating a method of manufacturing a colloidal quantum dot composite passivated with graphene flakes according to an embodiment of the present invention.

Referring to FIG. 1, the colloidal quantum dots are mixed with a cationic surfactant and water to be dispersed (S10).

The colloidal quantum dot may have a nanodimensional nanoparticle shape. For example, the colloidal quantum dot may include a Group 2-6 material, a Group 3-5 material, a Group 4-6 material, or a combination thereof.

For example, the Group 2-6 material may include Cadmium Selenide (CdSe), Cadmium Sulfide (CdS), Cadmium Telluride (CdTe), and Zinc Selenide (ZnSe). Zinc Sulfide (ZnS), Zinc Telluride (ZnTe), Mercury Selenide (HgSe), Mercury Sulfide (HgS), Mercury Telluride (HgTe) Indium Selenide (CuInSe ₂ ), Copper Indium Sulfide (CuInS ₂ ), and the like may be included.

For example, the Group 3-5 materials include Indium Phosphide (InP), Indium Arsenide (InAs), Gallium Arsenide (GaAs), Gallium Nitride (GaN), Gallium phosphide (GaP), gallium aluminum arsenide (GaAlAs), gallium indium arsenide (GaInAs), and the like.

For example, the Group 4-6 material may include lead sulfide (PbS), lead selenide (PbSe), lead telluride (PbTe), and the like.

In addition, the colloidal quantum dot may include a doped material such as Cu: ZnSe, MnSe: ZnSe, or the like.

In addition, the colloidal quantum dot may have a core-shell structure. According to one embodiment, the colloidal quantum dot may have a core-shell configuration of cadmium zinc sulfide / zinc sulfide.

The surface of the colloidal quantum dot may be coordinated with a ligand having a hydrophobic alkyl chain. Colloidal quantum dots having a ligand bond of the alkyl chain on the surface as described above, the dispersibility and stability in the solution can be improved.

For example, the ligand having an alkyl chain may include hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, and undecanoic acid. Undecanoic acid, Dodecanoic acid, Pentadecanoic acid, Hexadecanoic acid, Oleic acid, 1-hexanethiol, 1-heptane 1-heptanethiol, 1-octanethiol, 1-nonanethiol, 1-decanethiol, 1-undecanethiol ( 1-undecanethiol), 1-dodecanethiol, 1-pentadecanethiol, 1-hexadecanethiol, 1-hexadecanethiol, hexylamine, heptyl Heptylamine, Octylamine, Nonylamine, Nonylamine, Decylamine, Undecylamine, Dodecylamine, Pentadecylamine, Pentadecylamine, Hexadecylamine Hexadecylamine), oleylamine, tributyl phosphate, trioctyl phosphine oxide, and the like.

The colloidal quantum dots may be provided in a form dispersed in a volatile organic solvent having a low boiling point. For example, the volatile organic solvent may include chloroform, hexane, cyclohexane, and the like.

The cationic surfactant may bind to the colloidal quantum dot by van der Waals attraction. Thus, the colloidal quantum dots can be capped and dispersed by the cationic surfactant, and a bilayer of the ligand having the alkyl chain and the cationic surfactant can be formed.

For example, the cationic surfactant may be selected from cetylpyridinium chloride (CTC), behentrimonium chloride (BTAC-228), benzalkonium chloride (BZK), and benzododecenium. Bromide (Benzododecinium bromide), Cetalkonium chloride (CKC), Cetrimonium bromide (CTAB), Cetrimonium chloride, Didecyldimethylammonium chloride, DDAC Methyldioctadecylammonium bromide (DODAB), dimethyldioctadecylammonium chloride (DODAC), stearalkonium chloride, and the like.

Next, the graphene flakes are provided to the colloidal quantum dots combined with the cationic surfactant (S20).

According to one embodiment, the graphene flakes are non-oxidized graphene flakes. For example, the non-oxidized graphene flakes may be obtained from a graphite interlayer compound. For example, as described in the applicant's application (Patent No. 2015-0047326), the graphite and alkali metal salt hydrates or hydrates of alkali metal salts are mixed / heated to form a graphite intercalation compound in which metal ions are intercalated. Then, the non-graphene oxide flakes can be obtained by removing the inserted metal ions. The non-oxidized graphene flakes may preferably have a monolayer structure, for example, may have a thickness of 1 to 3nm.

For example, the non-oxidized graphene flakes may have an oxygen content of less than 7%, and the diameter of the non-oxidized graphene flakes may be several nm (quantum dot size) to several hundred nm.

The non-oxidized graphene flakes may be combined with the colloidal quantum dots to protect the quantum dots from external moisture and the like, and may improve light stability. However, when using graphene oxide flakes having a high oxygen content, there are no protective effects due to defects in the basal plane of the graphene oxide flakes and various oxygen functional groups (epoxides, etc.), but rather increase water affinity. The luminous properties may be lowered.

The mixing ratio of the colloidal quantum dots and the graphene flakes may affect the stability of the colloidal quantum dots. For example, the mixed weight ratio of the colloidal quantum dots and the graphene flakes may be in the range of 20: 1 to 1: 1, preferably 20: 1 to 5: 1, more preferably 20: 1 to 10: 1. When the concentration of the graphene flake is excessive, the emission intensity of the quantum dot composite may be lowered by the collision emission suppression phenomenon.

The graphene flakes may be combined with the colloidal quantum dots to form a passivation film. The dispersed graphene flakes may have a negative zeta potential and the colloidal quantum dots may have a positive zeta potential by being capped by the cationic surfactant. Thus, the graphene flakes may be coupled to the surface of the colloidal quantum dots by electrostatic attraction.

Accordingly, the colloidal quantum dot composite 100 may include a semiconductor material, a cationic surfactant, and graphene flakes, and for example, as illustrated in FIG. 2, the quantum dot core 110 including a semiconductor material. And a passivation layer 120 surrounding the quantum dot core 110 and including a cationic halide (cationic surfactant) and graphene flakes. For example, the cationic halide and the graphene flakes may be separated from each other to form an interface or mixed with each other to be dispersed.

The colloidal quantum dot composite obtained in accordance with the present invention may be passivated with graphene flakes, thereby greatly improving stability. The colloidal quantum dot composite can be obtained by a relatively simple and low cost process in aqueous solution using cationic surfactants.

In addition, according to the present invention, by binding the non-oxidized graphene flakes having excellent light absorption characteristics in the ultraviolet / visible light region to the colloidal quantum dots, it is possible to suppress the photocorrosion or photo-oxidation reaction of the colloidal quantum dots.

Accordingly, the colloidal quantum dot composite may be used in various electronic devices, optical devices, and the like using quantum dots, and in particular, a blue fluorescent dye for bioimaging, an optical sensor using a fluorescence resonance energy transfer phenomenon, which requires high optical stability. It can be effectively applied to light emitting diodes and the like.

Hereinafter, the effect of the colloidal quantum dot complex and a method of manufacturing the same according to the present invention will be described.

Synthesis Example  1­ With CTAB Capped Water dispersion Quantum dots  Produce

0.1 g of cadmium zinc sulfide / zinc sulfide core-shell quantum dot dispersion having a concentration of 15 mg / mL or less dispersed in chloroform and a concentration of 15 mg / mL is 0.1 g of tritrimonium bromide (CTAB), a cationic surfactant. Dropped into 5 mL of this dissolved water and stirred. Next, the mixed solution was stirred and heated at 65 ° C. to evaporate chloroform, thereby obtaining an aqueous solution including cadmium zinc sulfide / zinc sulfide core-shell quantum dots capped with CTAB.

Synthesis Example  2­ Deoxidation Graphene Flake  Produce

1 g of sodium potassium tartrate tetrahydrate and 0.1 g of natural graphite powder were mixed, and the temperature was heated to 30 ° C. to prepare a graphite interlayer compound (black natural graphite was expanded graphite interlayer compound to yellowish brown color). 1 g of the prepared graphite interlayer compound was exfoliated in 25 ml of water to prepare graphene quantum dots, and dialysis was performed to remove the used hydrate salt. The oxygen concentration of the obtained graphene flakes was measured at 4.7 at%.

Synthesis Example  3 oxidation Graphene Flake  Produce

1 g of graphite powder (4 nm or less in diameter), 60 mL of sulfuric acid, and 20 mL of nitric acid are placed in a 250 mL round flask and subjected to an ultrasonic process for 3 hours under ice bath conditions. After refluxing at 100 ° C. for 12 hours, the mixture was cooled, and 170 mL of deionized water was added thereto. The mixture was centrifuged at 20000 rpm for 20 minutes, and the supernatant was collected to remove acid ions primarily through dialysis using a membrane filter. After confirming that the solution turned yellow, the pH was adjusted to 7-8 by adding sodium hydroxide and further dialysis was performed for 3 days to remove the residue. The oxygen concentration of the obtained graphene flakes was measured at 27 at%.

Example 1

Cadmium sulfide / zinc sulfide core-shell capped with 0.1 mg / mL of an aqueous solution of graphene flakes (graphene quantum dots) having a diameter of 5 nanometers or less obtained in Synthesis Example 2 and CTAB, and a cadmium zinc sulfide / zinc sulfide core-shell Graphene quantum dot mass ratio to quantum dot mass (R _GQD = 0, 0.0625, 0.25, 1.0) was mixed and stirred at a constant rate for 24 hours to obtain an aqueous solution containing cadmium zinc sulfide / zinc sulfide-graphene quantum dot composite.

Comparative Example 1

Cadmium sulfide / zinc sulfide core-shell capped with 0.1 mg / mL of an aqueous solution of graphene flakes (graphene quantum dots) having a diameter of 5 nanometers or less obtained in Synthesis Example 3 and CTAB, and cadmium zinc sulfide / zinc sulfide core-shells Graphene quantum dot mass ratio to quantum dot mass (R _GOQD = 0, 0.0625, 0.25, 1.0) was mixed and stirred at a constant rate for 24 hours to obtain an aqueous solution containing cadmium zinc sulfide / zinc sulfide-graphene quantum dot composite.

FIG. 3 shows transmission electron microscope images, interatomic microscope images, and X-ray photoelectron spectroscopy spectra of cadmium zinc sulfide / zinc sulfide core-shell quantum dots capped with CTAB obtained in Synthesis Example 1. FIG. Referring to (a) and (b), it can be seen that the size of cadmium zinc sulfide / zinc sulfide core-shell quantum dots capped with CTAB is about 7 to 9 nanometers, and (c), (d) and (e). Referring to), it can be seen that the quantum dots include cadmium, zinc, and sulfur atoms.

Figure 4 is a graph showing the optical properties of the aqueous solution of cadmium zinc sulfide / zinc sulfide core-shell quantum dots capped with CTAB obtained in Synthesis Example 1. From the UV-vis absorption spectrum indicated by the dotted line, it can be seen that the absorption occurs strongly around 300 nm, and from the emission excitation and the emission spectrum, the emission characteristics at 430 nm and the change in emission intensity according to the excitation wavelength can be seen.

Figure 5 shows the UV-vis absorption spectrum and the photograph of the aqueous solution of the graphene flake aqueous solution used in Example 1. Referring to FIG. 5, it can be seen that the quantum dots passivated with the graphene flakes may increase light stability due to the high ultraviolet absorbance of the graphene flakes.

FIG. 6 shows zeta potential measurements for quantum dots (CTAB-QD) obtained in Synthesis Example 1, graphene flakes (GQD) used in Example 1, and graphene-quantum dot composites (0.0625, 0.25, 1.0) obtained in Example 1. FIG. A graph showing the results. 6, cadmium zinc sulfide / zinc sulfide core-shell quantum dots (CTAB-QD) capped with CTAB, a cationic surfactant, have a value of about +45 mV, and an aqueous graphene flake solution (GQD) is about 17.5 mV. Because of the value of, it can be seen that the combination of cadmium zinc sulfide / zinc sulfide core-shell quantum dots and graphene quantum dots by using the difference in the surface charge.

7 shows the maximum at 430 nm for the quantum dots obtained in Synthesis Example 1 (CTAB-QD, R _GQD = 0) and the quantum dot complex obtained in Example 1 (R _GQD = 0.0625, R _GQD = 0.25, R _GQD = 1.0) A graph of light emission intensity values plotted with time.

(a) is a result when measuring by setting an excitation wavelength to 275 nm. Referring to (a), the luminescence intensity of the quantum dot (CTAB-QD, R _GQD = 0) to which the graphene flakes are not coupled decreases rapidly with time, but for the graphene-quantum dot complex, R _GQD = 0.0625 and When 0.25, it can be seen that the decrease in the emission characteristics is reduced. In addition, when R _GQD = 1.0, it can be seen that the initial emission intensity decreased.

This may be a result of the graphene flakes attached to the surface defects of cadmium zinc sulfide / zinc sulfide core-shell quantum dots to prevent oxidation by moisture, when R _GQD = 1.0, the graphene flake concentration is excessive, The emission intensity may be reduced by the collision suppression phenomenon in the interior.

(b) is a result obtained by measuring the excitation wavelength at 365 nm, and (a) similar trend, but the passivation effect by graphene flake also appeared when R _GQD = 1.0. This is believed to be due to the electron energy band structure of the cadmium zinc sulfide / zinc sulfide-graphene quantum dot nanocomposite.

8 is a graph measuring the fluorescence lifetime at 430 nm after 294 hours when the fluorescence lifetime is measured by setting the excitation wavelength to 275 nm according to the mixing ratio with the graphene flakes (R _GQD = 0.0625, 0.25, 1.0). to be.

Referring to FIG. 8, after 294 hours in the graphene-quantum dot complex (R _GQD = 0.0625, 0.25), it is confirmed that the fluorescence lifetime is measured longer than the quantum dots (R _GQD = 0) to which the graphene flakes are not bound. Can be.

9 is a graph showing the emission spectra of the initial state, 74 hours, 165 hours, and 294 hours after mixing with the graphene flakes when measured with the excitation wavelength set to 275 nm, and FIG. It is a graph which shows the emission spectrum of the initial state after 74 hours, after 165 hours, and after 294 hours when measured by setting wavelength to 365 nm according to the mixing ratio with graphene flake.

9 and 10 (a), the quantum dot (R _GQD = 0) to which the graphene flakes are not bonded rapidly decreases with time, and the position of the emission wavelength is also red shifted. It can be seen. This may be a phenomenon due to surface defects caused by alkyl chain ligand desorption during CTAB capping.

On the other hand, referring to Figures 9 and 10 (b), (c) and (d), in the case of the graphene-quantum dot complex (R _GQD = 0.0625, 0.25, 1.0), the decrease in luminescence intensity is delayed (R _In the case of _GQD = 1.0 when the excitation wavelength is 365nm), it can be seen that the position of the emission wavelength does not change.

11 is the quantum dot obtained in Synthesis Example 1 (CTAB-QD, R _GOQD = 0) and the quantum dot complex obtained in Comparative Example 1 (R _GOQD = 0.0625, R _GOQD = 0.25, R _GOQD = 1.0) at 430 nm It is a graph plotting the maximum light emission intensity value over time.

Referring to FIG. 11, when the quantum dot is passivated using the graphene flakes having a high oxygen concentration, the luminescence intensity may not be delayed and the emission intensity may be lowered.

Although the above has been described with reference to the 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 present invention as set forth in the claims below. It will be appreciated.

The colloidal quantum dot composite according to the present invention and a method for manufacturing the same can be used in various electronic devices, optical devices, etc. using quantum dots, in particular, blue fluorescent dye for bioimaging, fluorescence resonance energy transfer that requires high light stability It can be effectively applied to light sensors, light emitting diodes and the like using the phenomenon.

Claims (11)

Providing water and cationic surfactant to the colloidal quantum dots to form colloidal quantum dots dispersed with the cationic surfactant; And
A non-oxidized graphene flake having an oxygen content of less than 7% and a diameter of 5 nanometers or less is provided to the colloidal quantum dots combined with the cationic surfactant, and surrounds the quantum dots, and the cationic surfactant and the non-oxidized graphene flakes are Forming a passivation layer comprising;
The mixed mass ratio of the colloidal quantum dot and the non-oxidized graphene flakes is 20: 1 to 5: 1 manufacturing method of the colloidal quantum dot composite. The method of claim 1, wherein the colloidal quantum dot, Cadmium Selenide (CdSe), Cadmium Sulfide (Cadmium Sulfide, CdS), Cadmium Telluride (CdTe), Zinc Selenide (Zinc Selenide, ZnSe), Zinc Sulfide (ZnS), Zinc Telluride (ZnTe), Mercury Selenide (HgSe), Mercury Sulfide (HgS), Mercury Telluride (HgTe), Selenide (Copper Indium Selenide, CuInSe2), Copper Indium Sulfide (CuInS ₂ ), Indium Phosphide (InP), Indium Arsenide (InAs), Gallium Arsenide (GaAs), Nitriding Gallium Nitride (GaN), Gallium Phosphide (GaP), Gallium Aluminum Arsenide (GaAlAs), Gallium Indium Arsenide (GaInAs), Lead Sulfide (PbS), In the group consisting of lead selenide (PbSe) and lead telluride (PbTe) Process for producing a colloidal quantum dot conjugate characterized in that it comprises at least one selected. delete delete delete delete The method of claim 1, wherein the cationic surfactant is Cetylpyridinium chloride (CTC), Behentrimonium chloride (BTAC-228), Benzalkonium chloride (BZK), Benzododec Benzododecinium bromide, Cetalkonium chloride (CKC), Cetrimonium bromide (CTAB), Cetrimonium chloride, Didecyldimethylammonium chloride (DDAC), At least one selected from the group consisting of dimethyldioctadecylammonium bromide (DODAB), dimethyldioctadecylammonium chloride (DODAC) and stearalkonium chloride. Of colloidal quantum dot complex Article methods. delete delete The method of claim 1, wherein the colloidal quantum dot is coordinated with a ligand including a hydrophobic alkyl chain. The method of claim 10, wherein the colloidal quantum dot is dispersed in a volatile organic solvent containing at least one of the group consisting of chloroform (Chloroform), hexane (Hexane), and cyclohexane (Cyclohexane),
Forming the dispersed colloidal quantum dots, the method of producing a colloidal quantum dot composite comprising the step of heating to remove the volatile organic solvent.

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