KR102121322B1 - Quantum rod and method of fabricating the same - Google Patents

Abstract

The present invention comprises a core comprising ZnO which is a zinc oxide; A quantum rod is provided surrounding the core and including a shell made of ZnS.
Such a quantum rod has a short wavelength of 400 to 520 nm by including a core made of ZnO and a shell made of ZnS, and has an effect of emitting blue visible light, and furthermore, an AR value that is a ratio of length to diameter (or width) of the quantum rod itself Since it becomes 6 or more, it has an effect of improving linear polarization characteristics of emitted light and driving characteristics due to an external electric field.

Description

Quantum rod and method of fabricating the same}

The present invention relates to a quantum rod, and relates to a quantum rod that can emit visible light of a short wavelength band showing a blue color and a manufacturing method thereof.

As the society has entered a full-fledged information age, the display field for processing and displaying a large amount of information has rapidly developed, and in response, a liquid crystal display device (LCD), a plasma display device (Plasma Display) Various flat panel display devices, such as panel device (PDP), field emission display device (FED), and organic light emitting diode display device (OELD) have been developed and are in the spotlight.

On the other hand, in recent years, research has been conducted to use a quantum rod (quantum rod) in a display device.

Quantum rod has many application possibilities with high luminous efficiency and excellent reproducibility. For example, the application of quantum rods to light-emitting elements for lighting, liquid crystal display devices, and light sources has been studied.

Quantum rod refers to the particles of the nano-sized Ⅱ??Ⅵ, Ⅲ??Ⅴ, Ⅰ??Ⅲ??VI, Ⅳ??Ⅵ semiconductor particles forming the core, and a shell to protect the core Contains organic ligands to aid dispersion.

The quantum rod has strong extinction coefficient and excellent quantum efficiency compared to general dyes, and thus generates strong fluorescence. When the size of the quantum rod diameter is adjusted, the wavelength of visible light emitted can be controlled.

In addition, the quantum rod has a linear polarization characteristic, and when an external electric field is applied by a stark effect, it separates electrons and holes and has optical characteristics to control light emission.

Therefore, the quantum rod has the advantage of improving the light efficiency of the display device using these characteristics.

Meanwhile, in order to use the quantum rod for a display device, red, green, and blue light-emitting quantum rods are required. Of these, only the red light-emitting quantum rod has been developed.

That is, a CdSe/CdS structured red light emitting quantum rod using CdSe as a core and CdS as a shell has been developed, and green and blue light emitting quantum rods have not been developed.

On the other hand, referring to Figure 1 showing the light emission mechanism of the quantum rod having a structure composed of a core made of CdSe and CdS as a shell, the quantum rod of the CdSe/CdS structure has an energy band value of about 1.6 eV and has a red wavelength of about 775 nm. It emits visible light.

On the other hand, the wavelength of the visible light emitted from the quantum rod is determined by the size of the core, that is, the diameter. Even if the core diameter of the quantum rod of the above-described CdSe/CdS structure is adjusted, only visible light in the wavelength range of 500 to 650 nm is generated. do.

Therefore, there is a problem in that a quantum rod that emits visible light having a short wavelength that is blue cannot be implemented using the quantum rod having the above-described CdSe/CdS structure.

An object of the present invention is to provide a quantum rod that emits visible light in a short wavelength band exhibiting blue color.

In order to solve the above problems, the quantum rod according to an embodiment of the present invention, a core including ZnO zinc oxide; A shell made of ZnS is wrapped around the core.

At this time, the core is formed of a single structure of ZnO, or the core comprises a first core of ZnO and a second core made of ZnS surrounding the first core to form a double shell structure.

In addition, the core has a rod shape and has a diameter (or width) to length ratio (aspect ratio) value of 6 or more. At this time, the diameter (or width) of the core is 1 to 99 nm, and the length of the core is 6 to 900 nm.

In addition, the quantum rod has a rod shape and its diameter (or width) to length ratio (aspect ratio) value is 6 or more, wherein the diameter (or width) of the quantum rod is greater than 1 nm and less than 100 nm, , Characterized in that the length of the quantum rod is greater than 6 nm and less than or equal to 1000 nm.

And it is characterized in that the visible light of 400 ~ 520nm wavelength is emitted from the core.

A method of manufacturing a quantum rod according to an embodiment of the present invention comprises the steps of preparing a core made of ZnO by mixing zinc acetate, potassium hydroxide and methanol; Forming an organic bond on the surface of the core made of ZnO; And forming a shell composed of ZnS surrounding the surface of the core by mixing the core formed of ZnO with the organic binder and sulfur (S) powder and zinc acetate and a solvent to react.

At this time, the step of forming an organic binder on the surface of the core made of ZnO includes: ultrasonic dispersing the core made of ZnO in DMSO (dimethyl sulfoxide), a solvent containing 1-butyl thiol; Binding the 1-butyl thiol to the core surface by stirring the dispersion-treated solution; And purifying the stirred solution using Chloroform and methanol.

And the step of forming a shell made of ZnS surrounding the surface of the core by mixing the core made of ZnO formed with the organic binder with sulfur (S) powder, zinc acetate, and a solvent to react with the 1-butyl thiol on the surface. Preparing a first mixture by mixing and drying the combined core and the solvents ODE (1-octadecene) and ODA (octadecylamine); The first compound prepared by mixing sulfur (S) powder with OED (1-octadecene) as a solvent while heating, and the second compound prepared by mixing zinc acetate with OED (1-octadecene) as a solvent by heating at room temperature Preparing a second mixture; Synthesizing the first and second mixtures by injecting a second mixture into the first mixture; And purifying the synthesized compound using toluene and methanol (MeOH) and then dispersing it in toluene.

And the first compound and the second compound are each prepared in a temperature atmosphere of 100 to 140 ℃, the synthesis of the first and second mixture proceeds to the first mixture in the temperature atmosphere of 260 to 300 ℃ the second mixture It is characterized by.

A method of manufacturing a quantum rod according to another embodiment of the present invention comprises the steps of preparing a core made of ZnO by mixing zinc acetate, potassium hydroxide and methanol; Preparing a mixture by mixing the core made of ZnO, zinc sulfate, and sulfur powder in an organic solvent and drying the mixture; And reacting the mixture with the organic binder in a closed reaction space to form a shell made of ZnS surrounding the surface of the core.

At this time, mixing the core made of ZnO, zinc sulfate and sulfur powder with an organic solvent and drying the mixture to prepare a mixture uses toluene as the organic solvent, and the core made of ZnO, zinc sulfate and sulfur powder. After mixing in toluene, drying, and stirring.

And the step of forming a shell made of ZnS surrounding the surface of the core by reacting the mixture with the organic binder in the closed reaction space, oleyamine or allylamine of C18 or less is used as the organic binder, and the oleyamine or allylamine is contained. And adding the mixture to a hydrothermal reactor and stirring in a temperature atmosphere of 260 to 300°C.

The quantum rod of the present invention has the effect of emitting blue visible light having a short wavelength of 400 to 520 nm by including a core made of ZnO and a shell made of ZnS.

In addition, since the AR value, which is a ratio of length to diameter (or width) of the quantum rod itself, is 6 or more, it has an effect of improving linear polarization characteristics of emitted light and driving characteristics by an external electric field.

1 is a view showing a light emitting mechanism of a quantum rod having a structure in which a core made of CdSe and CdS are shells.
2 is a schematic cross-sectional view of a quantum rod according to an embodiment of the present invention.
3A and 3B are TEM images of quantum rods finally manufactured by Synthesis Example 1 described above.
4 is a graph showing the PL (photoluminescence) spectrum of the quantum rod prepared by Synthesis Example 1.

Hereinafter, preferred embodiments according to the present invention will be described with reference to the drawings.

The quantum rod according to an embodiment of the present invention is characterized by having a core structure made of zinc oxide (ZnO) and a shell made of ZnS surrounding the core.

Referring to FIG. 2, which is a schematic cross-sectional view of a quantum rod according to an embodiment of the present invention, the quantum rod 100 according to an embodiment of the present invention includes a core 110 and a shell 120.

At this time, the core 110 is characterized in that it is made of zinc oxide (zinc) ZnO, the shell 120 is characterized in that it is made of a zinc (zinc) compound.

That is, the quantum rod 100 according to an embodiment of the present invention is provided with a single core 110 made of ZnO having a band gap of a relatively large width, or a first core made of ZnO (not shown) to ZnS A double-cell type core (not shown) in the form of a second core (not shown) is provided, and the shell 120 made of ZnS wraps the single core 110 or the double-cell type core (not shown). It is characterized by making.

The quantum rod 100 according to an embodiment of the present invention, wherein the zinc oxide ZnO is the core 110, and the zinc compound ZnS is the shell 120 surrounding the core 110, the core comprises a core made of CdSe. As compared to a conventional quantum rod, the energy band has a relatively large energy band value of about 2.7 to 3 eV, which has a short wavelength band, that is, a wavelength value of 400 to 520 nm, and emits visible light showing blue.

The quantum rod 100 determines the size of the core 110 constituting it, that is, the wavelength of light emitted by the diameter D1 of the core 110. That is, since the wavelength band of visible light emitted from the quantum rod 100 is proportional to the diameter D1 of the core 110 constituting it, the wavelength band of visible light emitted by adjusting the diameter D1 of the core 110 Can be adjusted.

In the case of the quantum rod 100 according to the embodiment of the present invention, the diameter (D1) or width of the core 110 constituting it is about 1 to 99 nm, and preferably about 3 to 97 nm.

In addition, in order to maximize the stark effect, the length L1 of the core 110 is 6 to 900 nm, which is 6 times or more the size of the diameter D1 or the width, so that the AR value is 6 or more.

Quantum rod 100 according to an embodiment of the present invention by a single or double cell type core 110 having a diameter (D1) and a length (L1) and made of ZnO or ZnO / ZnS is blue of short wavelength band Light is emitted.

On the other hand, the quantum rod 100 according to an embodiment of the present invention having such a configuration, the entire diameter D2 including the core 110 and the shell 120 is greater than 1 nm and less than 100 nm, and the length ( L2) is characterized by being larger than 6 nm and being 1000 nm or less.

At this time, the quantum rod 100 having such a configuration is characterized in that the diameter (D2) compared to the length (L2) ratio of the ratio (AR) ratio is 6 or more.

As described above, the quantum rod 100 according to an embodiment of the present invention having a core 110 of ZnO and a shell 120 of ZnS surrounding the core 110 synthesizes ZnO and KOH as reactants By manufacturing the ZnO core 110 having an AR value of 6 or more, and forming an organic binder on the surface of the ZnO core 110 having an AR value of 6 or more, and then synthesizing the cells using the above (see Synthesis Example 1 below). The shell 120 of ZnS surrounding the core 110 may be formed, or the shell 120 of ZnS surrounding the core 110 may be formed through a hydrothermal reaction (see Synthesis Example 2 below).

Hereinafter, a specific synthesis example of the quantum rod 100 according to the embodiment of the present invention will be described.

Core manufacturing method with an AR value of 6 or higher

A solution in which 7 g of zinc acetate was dissolved in 32 mL of methanol (MeOH) and a solution in which 16 g of potassium hydroxide (KOH) was dissolved in methanol (MeOH) were mixed at room temperature.

And, as described above, after stirring the mixed solution in a 70 ℃ temperature atmosphere for 3 days, the purified mixed solution was purified three times using methanol (MeOH) to have a pH of 7-8 and an AR value ZnO cores of 6 or more were synthesized.

Quantum Rod Synthesis Example 1 using an AR value of 6 or higher

Synthesis Example 1 is to prepare a quantum rod by synthesizing a cell using an organic binder, and the AR value of 6 or more ZnO 100mg and DMSO (dimethyl sulfoxide) 10mL and DMSO (dimethyl sulfoxide) in the core manufacturing method described above are used. ZnO in which 1-butyl thiol combined with the organic binder is prepared by ultrasonically dispersing 1-butyl thiol at 100 mM for 30 minutes, stirring at room temperature for 24 hours, and purifying three times using Chloroform and MeOH.

Thereafter, 10 mg of 1-butyl thiol-bonded ZnO is mixed with 20 mL of ODE (1-octadecene) and 1.5 g of ODA (octadecylamine) and dried at 120°C to prepare a first mixture containing ZnO.

Then, sulfur (S) powder and zinc acetate were respectively prepared in an OED at a temperature of 120°C in a concentration of 1 mM, and then sulfur-OED (1-octadecene) compounds and zinc acetate-ODE (1-octadecene) compounds were prepared at room temperature. Mix in to prepare a second mixture.

Finally, the first and second mixtures were synthesized by injecting the second mixture at a rate of 2 mL/min into the first mixture containing ZnO in a temperature atmosphere of 260 degrees, and the synthesized compounds were mixed with toluene and methanol. After purification using (MeOH) twice, and dispersing in toluene, ZnO is used as a core and a quantum rod having a shell structure of ZnS surrounding the core is prepared.

At this time, the synthesis of the above-described first and second mixture may be performed through a hydrothermal reactor having an atmosphere of high temperature and high pressure.

The quantum rod prepared by Synthesis Example 1 described above has a diameter greater than 1 nm and becomes 100 nm or less, and its length becomes greater than 6 nm and becomes 1000 nm or less, wherein the quantum rod has an AR value that is a ratio of length to diameter of 6 or more. It has the characteristics to be.

3A and 3B are views showing a TEM image of the quantum rod finally manufactured by Synthesis Example 1 described above, and FIG. 3B is an enlarged view of the quantum rod shown in FIG. 3A.

As shown, it can be seen that the quantum rod produced by Synthesis Example 1 according to the embodiment of the present invention has a uniaxially long rod shape.

In addition, each rod-shaped quantum rod has an example length of 49.02 nm and a width of 7.08 nm, thus showing that the length is about 7 times the width.

Therefore, it can be seen that the AR of the quantum rod in the form of a core of ZnO prepared according to Synthesis Example 1 and a shell of ZnS surrounding it is 6 or more.

Meanwhile, the PL (photoluminescence) spectrum of the quantum rod prepared by Synthesis Example 1 described above is illustrated in FIG. 4.

As shown in FIG. 4, the quantum rod 100 having a core of ZnO and a shell of ZnS and having an AR value of 6 or more as manufactured according to Synthesis Example 1 has a PL peak of about 461 nm to display a short wavelength visible light showing blue color. It can be seen that it emits.

As described above, the wavelength band of visible light emitted from the quantum rod 100 is determined by the diameter or size of the core 110.

In addition, the linear polarization characteristics of the light emitted from the quantum rod 100 and the driving characteristics by the external electric field are determined by the length of the shell 120.

For example, the larger the aspect ratio (AR), which is the ratio of the length to the diameter (or width) of the core to the length of the core, improves the linearity of the light emitted from the quantum rod, and further, the AR value must be greater than 2 to the external electric field. It is possible to drive by.

On the other hand, the quantum rod 100 according to the embodiment of the present invention obtained by Synthesis Example 1 described above is the length (L1) of the shell 120 and the diameter (D1) of the core (110) AR (aspect ratio) Since the value is 6 or more, it can be seen that driving by an external electric field is smooth, and further, the linear polarization property of light emitted from the quantum rod is very excellent.

Synthesis Example 2 of quantum rod using a core with an AR value of 6 or more

A mixed solution is prepared by mixing 10 mg of a core having an AR value of 6 or more with a core value of 6 or more, 10 mg of a hydrophilic reactant, zinc sulfate, 150 mg, and 44 mg of sulfur (S) powder in 1 ml of toluene. Did.

Next, the mixture was dried for 1 hour in a 120°C temperature atmosphere, and then stirred for 3 hours in the 120°C temperature atmosphere to prepare a mixture.

Subsequently, the mixture was placed in a hydrothermal reactor containing oleylamine and reacted while stirring for 12 hours at a temperature of 260°C.

At this time, the oleylamine is an organic binder having a lower boiling point than the reaction temperature and acting as a stabilizer and a role of a growth derivative to induce longitudinal growth of the ZnS shell, and such an organic conjugate is a hydrophobic organic ligand, a water-soluble organic conjugate (hydrophobic organic ligand), or a silicon-based organic binder (silicon-based organicligand).

The Oleyamine is mentioned as an example, and it is possible to use an amine-based solvent that has a boiling point lower than the reaction temperature and the mixture is soluble. That is, an aliphatic amine having C4 to 12 may be used, and such an aliphatic amine may be, for example, C4 to 12 with allylamine.

Next, by purifying three times using methanol (MeOH), ZnO was used as a core, and a quantum rod according to Synthesis Example 2 having an AR value of 6 or more was formed as a core, forming a shell structure surrounding ZnS.

The quantum rod according to Synthesis Example 2 thus prepared is also similar to the quantum rod prepared according to Synthesis Example 1, the quantum rod prepared by Synthesis Example 1 described above has a diameter greater than 1 nm and becomes 100 nm or less, and its length is 6 nm. Larger than 1000 nm.

In addition, the quantum rod produced by Synthesis Example 2 also has a property that an AR value that is a ratio of length to diameter is 6 or more.

In addition, the quantum rod manufactured by Synthesis Example 2 has an energy band value of about 2.7 to 3 eV, so it has a short wavelength band, that is, a wavelength value of 400 to 520 nm, which is characterized by emitting blue visible light.

On the other hand, since the auxiliary materials used in the manufacturing of the quantum rods mentioned in Synthesis Example 1 and Synthesis Example 2 for producing the quantum rod are easily damaged by moisture and oxygen, a drying process for removing moisture and oxygen has been performed. The drying process does not have to proceed, and in the case of a material that is not susceptible to moisture and oxygen, the drying process may be omitted.

And the agitation process mentioned in Synthesis Example 1 and Synthesis Example 2 is carried out in order to proceed for smooth mixing or reaction between the mixture or the compound. It is also not necessary to proceed and may be omitted if the reaction is well performed without stirring.

On the other hand, the hydrothermal reactors mentioned in Synthesis Examples 1 and 2 provide a closed reaction space, can arbitrarily control the internal temperature and pressure, and promote the reaction of the composite or improve the solubility of the composite. .

On the other hand, as described above with reference to preferred embodiments of the present invention, those skilled in the art variously modify the present invention without departing from the technical spirit and scope of the present invention described in the claims below. And it will be apparent that it can be changed.

100: Quantum Road
110: core
120: shell
D1: Core diameter (width)
D2: diameter (width) of the quantum rod
L1: Core length
L2: length of quantum rod

Claims (16)

delete delete delete delete delete delete delete Preparing a core made of ZnO by mixing zinc acetate with potassium hydroxide and methanol;
Forming an organic bond on the surface of the core made of ZnO;
Forming a shell made of ZnS surrounding the surface of the core by allowing the core made of ZnO formed with the organic binder to react with sulfur (S) powder and zinc acetate and a solvent.
Quantum rod manufacturing method comprising a.
The method of claim 8,
The step of forming an organic bond on the surface of the core made of ZnO,
Ultrasonically dispersing the core made of ZnO in dimethyl sulfoxide (DMSO), a solvent containing 1-butyl thiol;
Binding the 1-butyl thiol to the core surface by stirring the dispersion-treated solution;
A method for producing a quantum rod comprising the step of purifying the stirred solution using Chloroform and methanol.
The method of claim 9,
The step of forming a shell made of ZnS surrounding the surface of the core by mixing the core made of ZnO formed with the organic binder with sulfur (S) powder and zinc acetate and a solvent to react,
Preparing a first mixture by mixing and drying the core bound to the 1-butyl thiol and the solvent ODE (1-octadecene) and ODA (octadecylamine);
The first compound prepared by mixing sulfur (S) powder with OED (1-octadecene) as a solvent while heating, and the second compound prepared by mixing zinc acetate with OED (1-octadecene) as a solvent by heating at room temperature Preparing a second mixture;
Synthesizing the first and second mixtures by injecting a second mixture into the first mixture;
After purifying the synthesized compound using toluene and methanol (MeOH), dispersing it in toluene
Quantum rod manufacturing method comprising a.
The method of claim 10,
The first compound and the second compound are each prepared in a temperature atmosphere of 100 to 140 ℃,
The synthesis of the first and second mixtures is a method of manufacturing a quantum rod, characterized in that the second mixture is carried out in a temperature atmosphere of 260 to 300°C to the first mixture.
Preparing a core made of ZnO by mixing zinc acetate with potassium hydroxide and methanol;
Preparing a mixture by mixing the core made of ZnO, zinc sulfate, and sulfur powder in an organic solvent and drying the mixture;
Forming a shell made of ZnS surrounding the surface of the core by reacting the mixture with an organic binder in a closed reaction space.
Quantum rod manufacturing method comprising a.
The method of claim 12,
The step of preparing a mixture by mixing the core made of ZnO, zinc sulfate and sulfur powder in an organic solvent and drying the mixture,
A method of manufacturing a quantum rod comprising using toluene as the organic solvent, mixing the core made of ZnO, zinc sulfate, and sulfur powder with toluene, drying and stirring.
The method of claim 13,
The step of forming a shell made of ZnS surrounding the surface of the core by reacting the mixture with an organic binder in the closed reaction space,
The organic binder is C18 or less oleyamine or allylamine is used, the oleyamine or allylamine containing the mixture in a hydrothermal reactor containing a step of stirring in a temperature atmosphere of 260 to 300 ℃ quantum rod manufacturing method.
The method of claim 8 or 12,
Quantum rod manufacturing method characterized in that the visible light of 400 ~ 520nm wavelength is emitted from the core.
The method of claim 8 or 12,
The quantum rod has a rod shape and its diameter (or width) to length ratio (aspect ratio) value is 6 or more.

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