KR20240077193A - Multiple quantum dot and method for preparation thereof - Google Patents

Abstract

The present specification is intended to provide multi-shell quantum dots and a method of manufacturing the same. The multi-shell quantum dots described herein do not contain cadmium-based quantum dots and are therefore environmentally friendly.

Description

Multi-shell quantum dot and method for manufacturing same {MULTIPLE QUANTUM DOT AND METHOD FOR PREPARATION THEREOF}

The present invention relates to multi-shell quantum dots and methods for manufacturing the same.

Quantum dot (QD) is a nano-sized semiconductor material that exhibits the characteristic of increasing energy density due to the quantum confinement effect, in which the band gap (Band gqp) increases as the size decreases to the nanoscale. Therefore, it is possible to obtain a band gap corresponding to visible light by adjusting the size of the quantum dots. Additionally, in the case of quantum dots having a direct band gap, luminous efficiency can be further improved.

Since the quantum dots can easily adjust the wavelength in the visible light region and have excellent light stability, they can be widely used industrially. A representative example of industrial use of quantum dots is light emitting diodes (LEDs), and the light emitting diodes can be used in a variety of ways, such as backlight units of display devices as well as general lighting. Therefore, the industrial demand for quantum dots is great.

Mainly, in the field of conventional quantum dots, cadmium (Cd)-based quantum dots are widely known, but cadmium-based quantum dots have the disadvantage of being highly toxic and potentially hazardous to the environment, so their application fields are very limited.

Currently, in order to overcome the shortcomings of cadmium-based quantum dots, quantum dots composed of other materials are being developed, and among them, the development of indium (In)-based quantum dots is also being attempted in various aspects. However, indium-based quantum dots have a very low quantum yield compared to the cadmium-based quantum dots, the manufacturing process is complicated, and they are vulnerable to the external environment.

Therefore, there is a need to solve the above problems of indium-based quantum dots, and at the same time improve physical properties such as quantum efficiency, photochemical stability, and fluorescence characteristics of indium-based quantum dots, and improve the efficiency of the manufacturing process.

The present specification is intended to provide multi-shell quantum dots and a method of manufacturing the same.

In one embodiment of the present specification, it includes an In-containing core and a Zn-containing multiple shell, and the Zn-containing multiple shell includes a first shell containing Se and a second shell containing S, and the Provides multi-shell quantum dots where the maximum absorption wavelength of the In-containing core appears in the range of 510 nm to 540 nm.

Additionally, in one embodiment of the present specification, preparing a first precursor solution, a second precursor solution, and a third precursor solution; After reacting the In-based compound and the surfactant at a temperature of 270° C. or higher, cooling to room temperature to form an In-containing core that satisfies the following formula (1); forming a first shell by injecting the first precursor solution and the second precursor solution onto the In-containing core at a temperature of 300° C. or higher; and forming a second shell by injecting the first precursor solution and the third precursor solution onto the first shell, wherein the first precursor solution includes a Zn-containing compound, a dispersant, and an organic solvent, The second precursor solution includes Se powder and an organic solvent, and the third precursor solution includes S powder and a surfactant.

510 nm ≤ Maximum absorption wavelength of In-containing core ≤ 540 nm - Equation (1)

The multi-shell quantum dots described herein do not contain cadmium-based quantum dots and are therefore environmentally friendly.

The multi-shell quantum dots described herein can minimize lattice coupling between the core and shell compared to conventional quantum dots.

The multi-shell quantum dots described herein have a narrow half width, excellent color reproducibility, or high quantum efficiency.

The multi-shell quantum dots described in this specification can be applied to various industrial fields such as backlight units of light emitting diodes, liquid crystal displays, lighting devices, solar cells, and biosensors.

The multi-shell quantum dots and their manufacturing method described herein can easily achieve red light emission without inducing artificial additional growth of the core.

Since the multi-shell quantum dots and their manufacturing method described herein do not induce artificial additional growth of the core, uniform core synthesis is possible without additional nucleation formation, and quantum efficiency and stability can be improved accordingly.

The method for manufacturing multi-shell quantum dots described in this specification allows adjusting the injection amount of the precursor or changing the type of precursor for each manufacturing process, thereby enabling efficient production of multi-shell quantum dots. In particular, by changing the selenium precursor and/or controlling its injection amount, a multi-shell quantum dot and its manufacturing method that achieve high quantum efficiency and excellent stability without additional growth of the core can be implemented.

1 is an absorption spectrum of a core according to an exemplary embodiment of the present invention.
2 and 5 are emission spectra of multi-shell quantum dots according to an exemplary embodiment of the present invention.
Figure 3 is a graph of quantum efficiency of multi-shell quantum dots according to an exemplary embodiment of the present invention.
Figure 4 is a TEM photograph of particles of multi-shell quantum dots according to an exemplary embodiment of the present invention.
Figure 6 is a TEM photograph of the core particle of Comparative Example 2.

Hereinafter, with reference to the drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice it. The present invention may be modified and implemented in various forms, and is not limited to the embodiments described herein.

Terms and words used in this specification and claims are not to be construed limited to their ordinary or dictionary meanings, and the inventor can appropriately define the concept of terms to explain his or her invention in the best way. It must be interpreted based on the meaning and concept consistent with the technical idea of the present invention.

Throughout the specification, when a part is said to “include” a certain element, this means that it may further include other elements rather than excluding other elements, unless specifically stated to the contrary.

Throughout the specification, when a member is said to be located “on” another member, this includes not only the case where a member is in contact with another member, but also the case where another member exists between the two members.

In one embodiment of the present invention, multi-shell quantum dots are provided.

In one embodiment of the present invention, the multi-shell quantum dot includes an In-containing core and a Zn-containing multi-shell, wherein the Zn-containing multi-shell includes a first shell containing Se and a second shell containing S. Including, the maximum absorption wavelength of the In-containing core may appear in the region of 510 nm or more and 540 nm or less.

In another embodiment of the present invention, the maximum absorption wavelength of the In-containing core is about 510 nm or more, about 511 nm or more, about 512 nm or more, about 513 nm or more, about 514 nm or more, about 515 nm or more, or It may appear in a region of about 516 nm or less, or it may appear in a region of 540 nm or less, about 539 nm or less, about 538 nm or less, about 537 nm or less, or about 536 nm or less.

In this specification, the maximum absorption wavelength can be measured with a UV/Vis spectrophotometer (PerkinElmer, Lambda 35 model) after manufacturing the core. In this specification, the maximum absorption wavelength of the core can be confirmed through the absorption spectrum of FIG. 1.

In this specification, measurement of the maximum absorption wavelength of the core is a means for confirming the presence or absence of artificial additional growth of the core. As additional growth of the core progresses, absorption wavelengths may appear at longer wavelengths compared to the case where there is no additional growth of the core.

The present inventors found that by changing the injection amount and introduction method of shell precursors (particularly selenium precursors), without artificial additional growth of the core, the half width and efficiency were improved, and it was possible to implement multi-shell quantum dots with the desired maximum emission area. . Accordingly, the core of the present invention can exhibit an absorption wavelength at a relatively short wavelength, and the multi-shell quantum dots including the core reach the desired emission wavelength without artificial additional growth of the core and have excellent half width and efficiency.

In one embodiment of the present invention, the maximum emission wavelength of the multi-shell quantum dot may be between 620 nm and 640 nm.

In another embodiment of the present invention, the maximum emission wavelength of the multi-shell quantum dot is greater than about 620 nm, greater than about 621 nm, greater than about 622 nm, greater than about 623 nm, greater than about 624 nm, or greater than about 625 nm. Or, it may appear below about 640 nm, below about 639 nm, below about 638 nm, or below about 637 nm.

In this specification, the maximum emission wavelength can be measured with a quantum efficiency meter (Hamamatsu, C11347 model) after manufacturing multi-shell quantum dots. In this specification, the emission wavelength region of the multi-shell quantum dot can be confirmed through the emission spectrum of FIG. 2.

In this specification, the measurement of the maximum emission wavelength of the multi-shell quantum dot is a means to confirm whether the desired red emission wavelength is achieved by changing the precursor and controlling the injection amount without artificial additional growth of the core.

In one embodiment of the present invention, the multi-shell quantum dot may have a full width at half maximum FWHM of 50 nm or less in the region of the maximum emission wavelength.

In another embodiment of the present invention, the half width may be about 50 nm or less, about 49 nm or less, or about 48 nm or less in the region of the maximum emission wavelength.

In this specification, a narrow half width of 50 nm or less may mean converting and outputting light with high color purity.

In one embodiment of the present invention, the multi-shell quantum dots may have a quantum efficiency of 70% or more in the region of the maximum emission wavelength. In this specification, it can be confirmed through the quantum efficiency graph of the multi-shell quantum dot in FIG. 3.

In another embodiment of the present invention, the quantum efficiency may be about 70% or more, about 71% or more, or about 72% or more.

In this specification, quantum efficiency refers to the rate at which photons or electrons are converted into photons or electrons of different energy, and may mainly refer to external quantum efficiency (EQE).

In this specification, a quantum efficiency of 70% or more is considered a high level in this technical field.

In one embodiment of the present invention, the average particle size of the multi-shell quantum dots may be greater than 0 nm and less than or equal to 10 nm. In this specification, the average particle size can be confirmed through a TEM photograph of the particles of the multi-shell quantum dots of FIG. 4.

In one embodiment of the present invention, a method for manufacturing multi-shell quantum dots is provided.

In one embodiment of the present invention, the method for manufacturing multi-shell quantum dots is:

Preparing a first precursor solution, a second precursor solution, and a third precursor solution;

After reacting the In-based compound and the surfactant at a temperature of 270° C. or higher, cooling to room temperature to form an In-containing core that satisfies the following formula (1);

forming a first shell by injecting the first precursor solution and the second precursor solution onto the In-containing core at a temperature of 300° C. or higher; and

Forming a second shell by injecting the first precursor solution and the third precursor solution onto the first shell,

The first precursor solution may include a Zn-containing compound, a dispersant, and an organic solvent, the second precursor solution may include Se powder and an organic solvent, and the third precursor solution may include S powder and a surfactant.

510 nm ≤ Maximum absorption wavelength of In-containing core ≤ 540 nm - Equation (1)

In the present specification, the second precursor solution does not contain a surfactant, thereby preventing the problem of widening the half maximum width of the multi-shell quantum dots.

In one embodiment of the present invention, the Se content in the second precursor solution may be 0.5 mmol or more and 4.0 mmol or less.

In the present specification, if the Se content range is outside the range, the half width may become wider than 50 nm, the quantum efficiency may be lowered to less than 70%, or the maximum emission wavelength may be outside of 620 nm to 640 nm.

Referring to Figure 5, a graph of the emission wavelength of multi-shell quantum dots measured with a quantum efficiency meter (Hamamatsu, C11347 model) is depicted, where the vertical axis represents the normalized intensity and the horizontal axis represents the wavelength. In particular, when the second precursor solution has a Se content of 0.5 mmol or more and 4.0 mmol or less, the maximum emission wavelength satisfies the range of approximately 620 nm to 640 nm, while the range of the Se content in the second precursor solution is Otherwise, when the Se content is 0.2 mmol, 5.0 mmol, or 6.0 mmol, respectively, the maximum emission wavelength is located at approximately 600 nm or approximately 650 nm, respectively, which deviates from the desired maximum emission wavelength, or the maximum emission wavelength is approximately Even if it falls within the range of 620 nm to 640 nm, it can be seen that the quantum efficiency is low, below 70%.

In the present specification, the step of forming the In-containing core may be performed at a temperature of 270°C or higher, and preferably may be performed at a temperature of about 270°C or higher and about 350°C or lower, and after formation of the core, the step may be performed at room temperature (about Cool to 20°C or higher and about 40°C or lower, preferably about 25°C or higher and about 35°C or lower, or more preferably about 30°C or higher and about 35°C or lower.

In the present specification, the step of forming the first shell and the step of forming the second shell may be performed at a temperature of 300 ℃ or higher, preferably at a temperature of about 300 ℃ or higher and about 350 ℃ or lower. there is.

In the present specification, the step of forming the In-containing core may include the following method.

The first precursor solution is injected into a vessel and incubated under vacuum at about 100° C. to 170° C., such as about 120° C. to 160° C., or preferably about 130° C., for at least about 1 hour, or preferably about 2 hours. can be maintained. Afterwards, nitrogen gas is injected to replace the oxygen-free nitrogen atmosphere, and the temperature can be maintained at 50°C to 150°C. Next, the indium salt powder and other additives (e.g., dispersants, organic solvents, etc.) can be placed in a reaction vessel and maintained under vacuum at the above temperature for about 1 hour or more, or preferably about 2 hours. Thereafter, nitrogen gas can be injected to replace the nitrogen atmosphere, and then the temperature can be raised to 270°C or higher, or preferably to about 280°C. At the above temperature, the core can be synthesized by injecting a certain concentration of surfactant and then maintaining the same temperature for about 2 hours or less, or preferably about 1 hour. Next, it can be cooled to room temperature by removing the heating mantle, and purified and post-processed (In-containing core dispersed in toluene).

In the present specification, forming the first shell may include the following method.

The first precursor solution and additives may be placed in a reaction vessel and maintained in a vacuum state at a temperature of about 160°C or lower, preferably about 150°C, for about 1 hour or more, or preferably about 2 hours. Thereafter, nitrogen gas is injected to replace the atmosphere with nitrogen, and then the temperature can be raised to about 170°C or higher, or preferably about 180°C. At this temperature, the post-treated In-containing core can be injected and heated to a temperature of at least 300° C., or preferably about 320° C. At the above temperature, the first precursor solution may be added and then reacted, and the second precursor solution may be added and then reacted.

In the present specification, the step of forming the second shell may include the following method.

When the second precursor has sufficiently reacted, the first precursor solution and the third precursor solution may be separately added dropwise to the reaction vessel. You can leave it for a certain period of time and maintain the temperature.

Finally, the temperature of the reaction vessel is lowered to about 50° C., or preferably about After cooling to a temperature below 40°C, it can be purified and post-processed (redispersed in solvent).

In the present specification, by limiting the temperature range of each step as described above, lattice mismatch between the In-containing core and the first shell and/or the second shell, or between the first shell and the second shell Deterioration in quantum efficiency can be minimized.

In the present specification, the step of forming the In-containing core includes a step of cooling to room temperature, thereby eliminating artificial additional growth of the core. Referring to Figure 6, TEM pictures of the core taken at 10 nm scale and 5 nm scale, the core was artificially grown additionally. According to Figure 6, the size distribution of the core is very wide, and it is observed that the core size is mainly concentrated at about 2 to 2.5 nm, but it is confirmed that overall uniform core growth was not achieved.

In the present specification, the surfactant in the step of forming the In-containing core and the surfactant included in the third precursor solution may be the same or different.

In one embodiment of the present invention, the dispersant may be one or more types of unsaturated fatty acids.

In one embodiment of the present invention, the unsaturated fatty acid may be any one selected from the group consisting of lauric acid, palmitic acid, oleic acid, and stearic acid, but is not limited thereto.

In one embodiment of the present invention, the organic solvent may include one or more alkenes having 10 or more carbon atoms.

In one embodiment of the present invention, the alkene having 10 or more carbon atoms may be any one selected from the group consisting of 1-octadecene, 1-nonadecene, 1-hexadecene, 1-dodecene and 1-decene, It is not limited to this.

In one embodiment of the present invention, the surfactant includes one or more types, and may be selected from the group consisting of phosphine-based compounds, amine-based compounds, and combinations thereof.

In the present specification, the surfactant has properties capable of forming a coordination bond, and includes tris(trimethylsilyl)phosphine, trioctylphosphine oxide, trioctylphosphine, decylamine, didecylamine, tri tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, octadecylamine, undecylamine, dioctadecylamine, N ,N-dimethyldecylamine, N,N-dimethyldodecylamine, N,N-dimethylhexadecylamine, N,N- N,N-dimethyltetradecylamine, N,N-dimethyltridecylamine, N,N-dimethylundecylamine, octahexadecylamine ), N-methyloctadecylamine, dodecylamine, didodecylamine, tridodecylamine, cyclododecylamine, N-methyldodecylamine It may be one or more selected from the group consisting of (N-methyldodecylamine), octylamine, dioctylamine, and trioctylamine.

In this specification, a surfactant is a substance that enables surface treatment of quantum dots without loss of quantum efficiency.

In one embodiment of the present invention, the phosphine-based compound is tris(trimethylsilyl)phosphine, trioctylphosphine oxide, tributylphosphine, triisopropylphosphine, triphenylphosphine oxide, and tricyclohexylphosphine. and trioctylphosphine, but is not limited thereto.

In one embodiment of the present invention, the amine-based compound may include one or more selected from the group consisting of octylamine, dioctylamine, trioctylamine, hexadecylamine, octahexylamine, and dodecylamine. , but is not limited to this.

In one embodiment of the present invention, the backlight unit may include one or more types of multi-shell quantum dots described above.

In one embodiment of the present invention, the light emitting diode may include the above-described backlight unit.

As another example, the one or more types of multi-shell quantum dots described above may be included in liquid crystal displays (LCDs), lighting devices, solar cells, biosensors, etc. in addition to the backlight unit for the light emitting diode, but are not limited thereto.

Hereinafter, the present specification will be described in more detail through examples, but these are only for illustrating the present application and are not intended to limit the scope of the present application.

Example

Example 1.

1) Preparation of first precursor (zinc precursor) solution

10 mmol of zinc acetate and 20 mmol of oleic acid were added to 25 mL of 1-octadecine, maintained under vacuum at 130°C for 2 hours, and then nitrogen gas was injected to change the atmosphere to an oxygen-free atmosphere.

2) Preparation of second precursor (selenium precursor) solution

Selenium powder (Se content 5 mmol) was added to 25 mL of 1-octadecine, raised to 200°C to dissolve, and then maintained at 130°C.

3) Preparation of third precursor (sulfur precursor) solution

A sulfur precursor was prepared by adding 5 mmol of sulfur powder to 5 mL of trioctylphosphine.

4) Synthesis of the core

1 mmol of indium acetate powder, 3 mmol of palmitic acid, and 20 mL of 1-octadecine were placed in a reaction flask and maintained under vacuum at 150°C for 2 hours. Afterwards, nitrogen gas was injected to replace the atmosphere with nitrogen, and the temperature was raised to 280°C.

When the temperature reached 280°C, 2 mL of a 0.2 M mixture of trimethylsilylphosphine and trioctylphosphine was rapidly injected and maintained at 280°C for 1 hour to synthesize the core. Afterwards, the heating mantle was removed to cool the solution in the reaction flask to room temperature, purified with acetone, and then dispersed in toluene.

5) Shell synthesis

1 mmol of zinc acetate powder, 1 mL of oleic acid, and 20 mL of 1-octadecine were placed in a reaction flask and maintained under vacuum at 150°C for 2 hours. Afterwards, nitrogen gas was injected to replace the atmosphere with nitrogen, and the temperature was raised to 180°C.

When the temperature reached 180 °C, 2 mL of toluene in which the core was dispersed was quickly injected and the temperature was raised to 320 °C.

When the temperature reached 320 ° C, 10 mL of the zinc precursor was added and reacted for 30 minutes. The selenium precursor solution whose Se content was adjusted to 0.5 mmol or more and 4.0 mmol or less was injected and reacted at 320 ° C. for 30 minutes to 1 hour.

After the selenium precursor sufficiently reacted, 5 mL of the zinc precursor and 2 mL of the sulfur precursor were slowly added dropwise into the reaction flask and left for about 30 minutes, maintaining the temperature at 300°C to 320°C.

Afterwards, the solution in the flask was cooled to below 40°C, and then purified three times using acetone and hexene, and the obtained quantum dots were redispersed in a solvent and stored.

Comparative Example 1.

1) Preparation of the first precursor solution

A first precursor solution was prepared in the same manner as in Example 1.

2) Preparation of second precursor solution

A selenium precursor was prepared by dissolving 5 mmol of selenium powder in 25 mL of trioctyl phosphine.

3) Preparation of third precursor solution

A third precursor solution was prepared in the same manner as Example 1.

4) Core synthesis

The core was synthesized in the same manner as in Example 1 above.

5) Shell synthesis

The shell was synthesized in the same manner as in Example 1, except that a selenium precursor dissolved in trioctyl phosphine was used as the second precursor (selenium precursor).

Comparative Example 2.

1) Preparation of the first precursor solution

A first precursor solution was prepared in the same manner as in Example 1.

2) Preparation of second precursor solution

A second precursor solution was prepared in the same manner as in Example 1.

3) Preparation of third precursor solution

A third precursor solution was prepared in the same manner as Example 1.

4) Core synthesis

1 mmol of indium acetate powder, 3 mmol of palmitic acid, and 20 mL of 1-octadecine were placed in a reaction flask, and maintained under vacuum at 150°C for 2 hours. Afterwards, nitrogen gas was injected to replace the atmosphere with nitrogen (InP solution preparation). Next, the temperature was lowered to 40°C, and 2 mL of a 0.2 M mixture of trimethylsilylphosphine and trioctylphosphine was injected to synthesize the core.

Then, after 1 hour at 280°C, without removing the heating mantle, 20 mL of the InP mixture was slowly added dropwise for 1 hour to further grow the core. Afterwards, the heating mantle was removed, the reaction solution was cooled to room temperature, and then purified with acetone. Figure 6 is a TEM photo of a core that was artificially grown additionally.

5) Shell synthesis

The shell was synthesized in the same manner as in Example 1.

Experiment example

Experimental Example 1. Measurement of absorption wavelength of core

In Example 1 and Comparative Example 2, after the cores were synthesized, the absorption wavelength of each core was shown in Figure 1 using a UV/Vis spectrophotometer (PerkinElmer, Lambda 35 model). In Figure 1, the vertical axis represents normalized intensity, and the horizontal axis represents wavelength.

Referring to Figure 1, the absorption wavelength of the core of Example 1 is 531 nm, the absorption wavelength of the core of Comparative Example 2 is 566 nm, and the absorption wavelength of the artificially additionally grown core (Comparative Example 2) is similar to that of the other core (Comparative Example 2). Example 1) It can be confirmed that the absorption wavelength is longer.

Experimental Examples 2 to 4. Measurement of emission wavelength, half width, and quantum efficiency of multi-shell quantum dots

In Example 1, Comparative Example 1, and Comparative Example 2, after synthesizing the multi-shell quantum dots, the emission wavelength, half width, and quantum efficiency of each multi-shell quantum dot were measured using a quantum efficiency meter (Hamamatsu, C11347 model). The results are shown in Figure 2 and Table 1 below. In Figure 2, the vertical axis represents normalized intensity, and the horizontal axis represents wavelength.

From Table 1 and Figure 2 below, it was confirmed that quantum dots of different emission wavelengths were synthesized in Example 1 and Comparative Examples 1 and 2. Specifically, in Example 1, the synthesis of quantum dots exhibiting a red emission wavelength of 625 nm was confirmed by using a selenium-1-octadecine precursor in a core with light absorption of 531 nm.

On the other hand, in the case of Comparative Example 1 using the selenium-trioctylphosphine precursor, the half width increased significantly compared to Example 1 and the emission wavelength was confirmed at 595 nm, and after additional growth of the core, using the selenium-1-octadecine precursor, In the case of Comparative Example 2, in which the shell was synthesized, it was confirmed that the emission wavelength was in the 650 nm region and the quantum efficiency was noticeably lowered.

Therefore, it was confirmed that in Example 1, an emission wavelength of 625 nm was exhibited without additional growth of the core, and the half width and efficiency were the best.

Emission wavelength peak
(nm) half width
(nm) quantum efficiency
(%) Example 1 625 42 80 Comparative Example 1 595 71 53 Comparative Example 2 650 52 38

Experimental Example 5. Stability evaluation of multi-shell quantum dots

After purification of the multi-shell quantum dots of Example 1, they were recovered in powder form, exposed to natural light at room temperature, and quantum efficiency over time was measured to further confirm stability, as shown in Figure 3. In Figure 3, the vertical axis represents quantum efficiency (%), and the horizontal axis represents period (day).

Experimental Example 6. Particle analysis of multi-shell quantum dots

The quantum dots of Example 1 were dispersed in an organic solvent, and the measurement results of HR-TEM (model name: JEM-2100F, manufacturer: JEOL) are shown in Figure 4.

From Figure 4, it was confirmed that the particle size of the multi-shell quantum dots of Example 1 was about 7 nm.

Experimental Example 7. Measurement of optical properties of multi-shell quantum dots according to Se injection amount

Multi-shell quantum dots were synthesized in the same manner as described in Example 1 of the multi-shell quantum dots, except that the Se injection amount shown in Table 2 below was changed as follows. For reference, Sample No. 2 corresponds to the Se injection amount (10 mL) in Example 1.

Then, the emission wavelength, half width, and quantum efficiency of each multi-shell quantum dot were measured using a quantum efficiency meter (Hamamatsu, C11347 model), and the results are shown in Figure 5 and Table 2 below. In Figure 5, the vertical axis represents normalized intensity, and the horizontal axis represents wavelength.

From Table 2 and FIG. 5 below, Sample No. 12 has the Se content in the selenium precursor solution adjusted to 0.5 mmol to 4.0 mmol. It was confirmed that the quantum dots 1 to 4 satisfied all the conditions of an emission wavelength of 620 nm or more and 640 nm or less, a half width of 50 nm or less, and a quantum efficiency of 70% or more. On the other hand, Sample No. 1 was prepared with Se powder having a content outside the above range. It was confirmed that 5 to 7 did not satisfy one or more of the above conditions.

Specifically, sample no. 5 is the case where the Se injection amount was 5.0 mmol, and the quantum efficiency was less than 70% even if the emission wavelength of 620 nm or more and 640 nm or less was satisfied. In addition, Sample No. 6 was a case where the Se injection amount was 0.2 mmol, and the quantum efficiency was less than 70% while not satisfying the emission wavelength of 620 nm or more and 640 nm or less. Additionally, Sample No. 7 is a case where the Se injection amount was 6.0 mmol, the emission wavelength of 620 nm or more and 640 nm or less was not satisfied, the quantum efficiency was less than 70%, and the half maximum width exceeded 50 nm.

Sample No. Se dosage
(mmol) optical properties
(Emission wavelength, full width at half maximum (FWHM), quantum efficiency (QY) One 1.0 mmol 625 nm, FWHM 42 nm, QY 72% 2 2.0 mmol 625 nm, FWHM 42 nm, QY 80% 3 3.0 mmol 635 nm, FWHM 43 nm, QY 76% 4 4.0 mmol 635 nm, FWHM 43 nm, QY 75% 5 5.0 mmol 637 nm, FWHM 48 nm, QY 64% 6 0.2 mmol 600 nm, FWHM 49 nm, QY 65% 7 6.0 mmol 646 nm, FWHM 51 nm, QY 48%

Claims (14)

Contains an In-containing core and a Zn-containing multiple shell,
The Zn-containing-multiple shell includes a first shell comprising Se and a second shell comprising S,
A multi-shell quantum dot in which the maximum absorption wavelength of the In-containing core appears in the range of 510 nm to 540 nm. In claim 1,
A multi-shell quantum dot in which the maximum emission wavelength of the multi-shell quantum dot appears in the range of 620 nm to 640 nm. In claim 2,
The multi-shell quantum dot has a full width at half maximum (FWHM) in the region of 50 nm or less in the region of the maximum emission wavelength. In claim 2,
The multi-shell quantum dot has a quantum efficiency of 70% or more in the region of the maximum emission wavelength. In claim 1,
Multi-shell quantum dots wherein the average particle size of the multi-shell quantum dots is greater than 0 nm and less than or equal to 10 nm. Preparing a first precursor solution, a second precursor solution, and a third precursor solution;
After reacting the In-based compound and the surfactant at a temperature of 270° C. or higher, cooling to room temperature to form an In-containing core that satisfies the following formula (1);
forming a first shell by injecting a first precursor solution and a second precursor solution onto the In-containing core at a temperature of 300° C. or higher; and
Forming a second shell by injecting the first precursor solution and the third precursor solution onto the first shell,
The first precursor solution includes a Zn-containing compound, a dispersant, and an organic solvent,
The second precursor solution includes Se powder and an organic solvent,
A method for producing multi-shell quantum dots, wherein the third precursor solution includes S powder and a surfactant:
510 nm ≤ Maximum absorption wavelength of In-containing core ≤ 540 nm - Equation (1). In claim 6,
A method for producing multi-shell quantum dots, wherein the content of Se in the second precursor solution is 0.5 mmol or more and 4.0 mmol or less. In claim 6,
A method for producing multi-shell quantum dots, wherein the dispersant is one or more unsaturated fatty acids. In claim 8,
A method for producing multi-shell quantum dots, wherein the unsaturated fatty acid is any one selected from the group consisting of lauric acid, palmitic acid, oleic acid, and stearic acid. In claim 6,
A method for producing multi-shell quantum dots, wherein the organic solvent includes one or more alkenes having 10 or more carbon atoms. In claim 10,
A method for producing multi-shell quantum dots, wherein the alkene having 10 or more carbon atoms is any one selected from the group consisting of 1-octadecene, 1-nonadecene, 1-hexadecene, 1-dodecene, and 1-decene. In claim 6,
The method of producing a multi-shell quantum dot, wherein the surfactant includes at least one selected from the group consisting of phosphine-based compounds, amine-based compounds, and combinations thereof. In claim 12,
The phosphine compound is selected from the group consisting of tris(trimethylsilyl)phosphine, trioctylphosphine oxide, tributylphosphine, triisopropylphosphine, triphenylphosphine oxide, tricyclohexylphosphine and trioctylphosphine. A method for producing multi-shell quantum dots, which is any one of the selected methods. In claim 12,
A method for producing multi-shell quantum dots, wherein the amine-based compound is selected from the group consisting of octylamine, dioctylamine, trioctylamine, hexadecylamine, octahexylamine, and dodecylamine.