Quantum dot, method of manufacturing quantum dot, and electronic device

Abstract

Embodiments of the present disclosure may provide a quantum dot having an effective absorption efficiency of greater than or equal to 50%, each quantum dot including a core including Ag, In, Ga, and S, and a shell layer on the core, a method of manufacturing the same, and an electronic device.

Description

Technical Field

[0001] The present disclosure relates to quantum dots, a method of manufacturing quantum dots, and an electronic device. Background Art

[0002] Quantum dots (QDs) are semiconductor particles with dimensions on the order of a few nanometers, possessing excellent optical and electrical properties different from those of bulk semiconductor materials. For example, quantum dots have the property of emitting light through photoluminescence (PL) or electroluminescence (EL). In photoluminescence (PL), light is generated when electrons fall from the conduction band to the valence band, and in electroluminescence (EL), light is generated by external charges. Even when quantum dots are formed of the same material, the color of the emitted light may vary depending on the size of the quantum dots. Due to these properties, quantum dots have received extensive attention for use in fields such as next-generation light-emitting diodes (LEDs), biosensors, lasers, and solar cell nanomaterials.

[0003] Meanwhile, when other atoms or molecules approach, chemical bonds are easily formed on the core surface of quantum dots, which may lead to surface defects and reduce the luminescence efficiency. Therefore, in order to prevent the reduction of the luminescence efficiency of the core, quantum dots with a core / shell structure having a shell layer formed on the core surface have been developed.

[0004] However, despite the introduction of the shell layer, there is still a problem that the luminescence efficiency of quantum dots is limited to a certain level. Summary of the Invention

[0005] Technical problem

[0006] Embodiments of the present disclosure may provide quantum dots with improved luminescence efficiency, a method of manufacturing the quantum dots, and an electronic device.

[0007] Technical solution

[0008] In one aspect, embodiments of the present disclosure may provide a quantum dot including a core containing silver (Ag), indium (In), gallium (Ga), and sulfur (S), and a shell layer located on the core, wherein the quantum dot may have an effective absorption efficiency of greater than or equal to 50% defined by Formula [1].

[0009] [Formula 1]

[0010]

[0011] In Formula 1, Abs 300nm～470nm may be the integrated absorbance value of the quantum dot in the range of 300 nm to 470 nm when the integrated absorbance value of the quantum dot in the range of 300 nm to 800 nm is 1, and QY may be the quantum yield of the quantum dot.

[0012] When the effective absorption efficiency of the quantum dots can be greater than or equal to 50%, the quantum yield of the quantum dots can be greater than or equal to 70%.

[0013] The shell layer can include at least one of a Group I element and a Group III element; and a Group VI element.

[0014] The Group I element included in the shell layer can include one or more selected from Li, Na, K, Rb, Cs, Cu, Ag, and Au.

[0015] The Group III element included in the shell layer can include one or more selected from Au, Al, Ga, In, and Tl.

[0016] The Group VI element included in the shell layer can include one or more selected from S, Se, and Te.

[0017] The shell layer can include a first shell layer and a second shell layer. The first shell layer can be located on the core and can include a Group I element, a Group III element, and a Group VI element. The second shell layer can be located on the first shell layer and can include a Group III element and a Group VI element. The Group III element and the Group VI element included in the first shell layer and the second shell layer can be the same or different.

[0018] The first shell layer can include one of the following: AgAlS, AgAlSe, AgAlTe, AgGaS, AgGaSe, AgGaTe, AgInS, AgInSe, AgInTe, AgTiS, AgTiSe, AgTiTe, CuAlS, CuAlSe, CuAlTe, CuGaS, CuGaSe, CuGaTe, CuInS, CuInSe, CuInTe, CuTiS, CuTiSe, CuTiTe, AuAlS, AuAlSe, AuAlTe, AuGaS, AuGaSe, AuGaTe, AuInS, AuInSe, AuInTe, AuTiS, AuTiSe, and AuTiTe.

[0019] The second shell layer can include one of the following: AlS, AlSe, AlTe, GaS, GaSe, GaTe, InS, InSe, InTe, TiS, TiSe, and TiTe.

[0020] In another aspect, embodiments of the present disclosure can provide a method for manufacturing quantum dots.

[0021] The method for manufacturing quantum dots can include a core preparation step and a shell layer preparation step.

[0022] The core preparation step can be the following steps: Prepare the core by injecting a silver precursor, an indium precursor, a gallium precursor, a sulfur precursor, and a solvent into a first reactor and reacting them.

[0023] The shell preparation step can be the following steps: Prepare the shell by injecting the prepared core into a second reactor and reacting it, and the second reactor contains precursors including specific elements.

[0024] The quantum dots can have an effective absorption efficiency of greater than or equal to 50% as defined by the above formula [1].

[0025] When the effective absorption efficiency of the quantum dots can be greater than or equal to 50%, the quantum yield of the quantum dots can be greater than or equal to 70%.

[0026] The specific elements can include at least one of a Group I element and a Group III element; and a Group VI element.

[0027] The core preparation step can include Step 1-1 and Step 1-2.

[0028] Step 1-1 can be the following steps: Prepare a core solution by injecting and heating a silver precursor, an indium precursor, a gallium precursor, a sulfur precursor, and a solvent into a first reactor.

[0029] Step 1-2 can be the following steps: Add a purification solvent to the core solution and centrifuge the resulting product, and disperse the precipitate separated by centrifugation in a dispersion solvent.

[0030] The shell preparation step can include Step 2-1 and Step 2-2.

[0031] Step 2-1 can be the following steps: Inject at least one of a Group I precursor and a Group III precursor into a second reactor containing oleylamine.

[0032] Step 2-2 can be the following steps: Inject the purified core and a Group VI precursor including a Group VI element into the second reactor and react them.

[0033] The shell can include a first shell and a second shell. The first shell can be located on the core and can include a Group I element, a Group III element, and a Group VI element. The second shell can be located on the first shell and can include a Group III element and a Group VI element. The Group III elements and Group VI elements included in the first shell and the second shell can be the same or different.

[0034] The shell preparation step may include a first shell preparation step and a second shell preparation step. The first shell preparation step may prepare the first shell by injecting the prepared core into a first reactor containing a Group I precursor (including a Group I element), a Group III precursor (including a Group III element), and a Group VI precursor (including a Group VI element) and causing them to react. The second shell preparation step may prepare the second shell by injecting the prepared core and the first shell into a second reactor containing a Group III precursor (including a Group III element) and a Group VI precursor (including a Group VI element) and causing them to react.

[0035] In another aspect, embodiments of the present disclosure may provide an electronic device, which may include a display device and a controller for driving the display device. The display device includes light-emitting diodes, and the light-emitting diodes include quantum dots. The quantum dots may include a core and a shell located on the core. The core includes silver (Ag), indium (In), gallium (Ga), and sulfur (S). The effective absorption efficiency of the quantum dots is defined by the above formula [1] and may be greater than or equal to 50%.

[0036] Beneficial effects

[0037] In the quantum dots, the method for manufacturing quantum dots, and the electronic device according to embodiments of the present disclosure, the light-emitting efficiency of the quantum dots can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a cross-sectional view showing a quantum dot according to an embodiment of the present disclosure;

[0039] Figure 2 is a cross-sectional view showing a quantum dot according to another embodiment of the present disclosure;

[0040] Figure 3 is a cross-sectional view showing a quantum dot according to another embodiment of the present disclosure;

[0041] Figure 4 is a flowchart of a method for manufacturing quantum dots according to another embodiment of the present disclosure;

[0042] Figure 5 is a flowchart of a method for manufacturing quantum dots according to another embodiment of the present disclosure;

[0043] Figure 6 is a cross-sectional view showing an electronic device according to another embodiment of the present disclosure;

[0044] Figure 7 is a cross-sectional view showing a light-emitting diode according to another embodiment of the present disclosure;

[0045] Figure 8It is a graph showing the relationship between absorbance and wavelength for Examples 1 to 8 of the present disclosure;

[0046] Figure 9 It is a graph showing the relationship between absorbance and wavelength for Examples 9 to 14 and Comparative Examples 1 to 2 of the present disclosure. Detailed Description of the Invention

[0047] Some embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. When referring to the elements in the drawings with reference numerals, the same elements will be designated by the same reference numerals even if they are shown in different drawings. In addition, in the following description of the present disclosure, detailed descriptions of known functions and configurations included herein will be omitted if they may obscure the subject matter of the present disclosure.

[0048] It should be understood that the terms "comprising", "having", "consisting of" and any variations thereof used herein are intended to cover non-exclusive inclusion, unless the contrary is explicitly stated. The description of an element in the singular form herein is intended to include the description of the element in the plural form, unless the contrary is explicitly stated.

[0049] In addition, when describing the elements of the present disclosure, terms such as "first", "second", "A", "B", "(a)" or "(b)" may be used herein. These terms are not used to define the nature, order or sequence of the corresponding elements, but are only used to distinguish the corresponding elements from other elements.

[0050] It should be understood that when an element is referred to as being "connected", "coupled" or "joined" to another element, it can not only be "directly connected, coupled or joined" to another element, but also be "indirectly connected, coupled or joined" to another element through an "intermediate" element. Here, the intermediate element may be included in one or more of the two elements that are "connected", "coupled" or "joined" to each other.

[0051] In addition, it should be understood that when an element is referred to as being "above" or "on" another element, it can not only be "directly" above or on another element, but also be "indirectly" above or on another element or layer through an "intermediate" element. In contrast, when an element is referred to as being "directly" above or on another element, it should be understood that no intermediate element is inserted. In addition, when an element is referred to as being "above" or "on" a reference part, the element is above or below the reference part, not necessarily "above" or "on" the reference part in the opposite direction of gravity.

[0052] When using time - relative terms such as "after", "subsequent", "next", "before" to describe elements, operations, or manufacturing methods, these terms can be used to describe non - continuous or non - sequential processes or operations, unless the terms "direct" or "immediately" are used simultaneously.

[0053] In addition, when referring to any numerical value of an element or corresponding information, the numerical value of the element or corresponding information should be considered to include a tolerance or error range that may be caused by various factors (e.g., process factors, internal or external influences, noise, etc.), and this should be considered even if no relevant description is specified.

[0054] The "diameter" of a nanostructure refers to the diameter of the cross - section perpendicular to the first axis of the nanostructure, where the first axis has the largest length difference from the second and third axes (the second and third axes are the two axes with the closest lengths). The first axis is not necessarily the longest axis of the nanostructure; for example, for a disk - shaped nanostructure, the cross - section will be an approximately circular cross - section perpendicular to the short longitudinal axis of the disk. When the cross - section is not circular, the diameter is the average of the major and minor axes of the cross - section. For elongated or high aspect ratio nanostructures such as nanowires, the diameter is measured on a cross - section perpendicular to the longest axis of the nanowire. For spherical nanostructures, the diameter is measured from one side of the sphere through the center to the other side.

[0055] The term "quantum dot" (or "dot") refers to a nanocrystal that exhibits quantum confinement or exciton confinement. Quantum dots can be substantially homogeneous in material properties or, in certain embodiments, can be heterogeneous, e.g., including a core and at least one shell layer. The optical properties of quantum dots may be affected by their particle size, chemical composition, and / or surface composition, and can be determined by appropriate optical tests available in the art. The ability to adjust the size of nanocrystals (e.g., in the range of about 1 nm to about 15 nm) enables light emission coverage across the entire optical spectrum, thus providing great versatility in color rendering.

[0056] The term "shell layer" as used in this disclosure refers to a material deposited on a core or on a previously deposited shell layer, where the previously deposited shell layer has the same or different composition and is the result of a single deposition of the shell layer material. The exact shell layer thickness depends on the material and the input and conversion of the precursor, and can be reported in nanometers or monolayers. The "target shell layer thickness" used in this disclosure refers to the expected shell layer thickness used to calculate the required amount of precursor. The "actual shell layer thickness" used in this disclosure refers to the amount of shell layer material actually deposited after synthesis and can be measured by methods known in the art. For example, the actual shell layer thickness can be measured by comparing the particle diameters determined from transmission electron microscope (TEM) images of the nanocrystals before and after shell layer synthesis.

[0057] As used in the present disclosure, the term "group" refers to a group in the periodic table. The term "period" as used in the present disclosure refers to a period in the periodic table.

[0058] As used in the present disclosure, "Group 1" may refer to Group IA (or 1A) and Group IB (or 1B), and examples of Group 1 elements may include Li, Na, K, Rb, Cs, Cu, Ag, and Au, but are not limited thereto.

[0059] "Group 2" may refer to Group IIA (or 2A) and Group IIB (or 2B), and examples of Group 2 elements may include Be, Mg, Ca, Sr, Zn, Cd, and Hg, but are not limited thereto.

[0060] "Group 3" may refer to Group IIIA (or 3A) and Group IIIB (or 3B), and examples of Group 3 elements may include In, Ga, Al, and Tl, but are not limited thereto.

[0061] "Group 5" may refer to Group VA (or 5A), and examples of Group 5 elements may include P, As, Sb, Bi, and N, but are not limited thereto.

[0062] "Group 6" may refer to Group VIA (or 6A), and examples of Group 6 elements may include S, Se, and Te, but are not limited thereto.

[0063] As used in the present disclosure, the term "precursor" refers to a chemical compound that was previously manufactured to react with quantum dots. A precursor is a concept that refers to all chemicals including metals, ions, elements, compounds, complexes, clusters, etc. A precursor is not necessarily limited to the final material of any reaction, but refers to a material that can be produced in any predetermined step.

[0064] Hereinafter, quantum dots according to embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0065] Figure 1 is a cross-sectional view showing a quantum dot according to an embodiment of the present disclosure. Figure 2 is a cross-sectional view showing a quantum dot according to another embodiment of the present disclosure. Figure 3 is a cross-sectional view showing a quantum dot according to another embodiment of the present disclosure.

[0066] Reference Figure 1 , according to an embodiment of the present disclosure, the quantum dot 10 may include a core 12 and a shell 14. According to another embodiment of the present disclosure, as Figure 2 shown, the quantum dot 10 may include a core 12, a first shell 14, and a second shell 16, or may be as Figure 3As shown, another shell layer 18 is further included outside the second shell layer 16, or another intermediate shell layer (not shown) can be further included between the first shell layer 14 and the second shell layer 16. The following will describe the quantum dot 10 including the core 12 and the shell layer 14 as Figure 1 shown. However, this description can also be equally applicable to the quantum dots including the core / multiple shell structure as Figure 2 and 3 shown.

[0067] The core 12 can include Ag, In, Ga, and S. The core 12 may be doped with metals or non-metals. Before depositing the shell layer 14, the core 12 can be purified. The core 12 can be filtered to remove precipitates from the core solution.

[0068] The shell layer 14 can be located on the core 12.

[0069] The quantum dot 10 can include the core 12 and the shell layer 14 located on the core 12, where the core 12 includes silver (Ag), indium (In), gallium (Ga), and sulfur (S), and the quantum dot can have an effective absorption efficiency greater than or equal to 50% defined by formula [1].

[0070] [Formula 1]

[0071]

[0072] In formula 1, Abs 300nm～470nm can be the integrated absorbance value of the quantum dot in the range of 300 nm to 470 nm when the integrated absorbance value of the quantum dot in the range of 300 nm to 800 nm is 1, and QY can be the quantum yield of the quantum dot.

[0073] Please note that in formula 1, it has been described that Abs 300nm～470nm can be the integrated absorbance value of the quantum dot in the range of 300 nm to 470 nm when the integrated absorbance value of the quantum dot in the range of 300 nm to 800 nm is 1. However, Abs X1nm～X3nm can be the integrated absorbance value of the quantum dot in the range of X1 nm to X3 nm when the integrated absorbance value of the quantum dot in the entire range of X1 nm to X2 nm is 1. In this case, X1, X2, and X3 can be like 300, 800, and 470 in formula 1, but can vary as described below.

[0074] Since the larger the bandgap energy, the emitted light is in the short wavelength region and requires higher energy, so the absorption value in the entire range of X1 nm to X2 nm (e.g., 300 nm to 800 nm) is larger. The smaller the bandgap energy, the emitted light is in the long wavelength region, and compared with the light emission in the short wavelength region, the absorption value in the entire range is relatively smaller.

[0075] In addition, the more light is emitted in the short wavelength range, the larger the integral value in the short wavelength range. The more light is emitted in the long wavelength range, the smaller the integral value in the short wavelength range.

[0076] For a display device, the blue wavelength that enables the green quantum dots to emit light can be less than or equal to X3 nm, for example, less than or equal to 470 nm. In this way, the overlap between the excitation wavelength and the emission wavelength required to achieve luminescence can be avoided.

[0077] Since the absorbance in the short wavelength region varies with the emission wavelength, the effective absorption efficiency is represented by the integral value of the absorbance in the range of 300 nm to 470 nm when the absorbance in the range of 300 nm to 800 nm is 1, indicating the absorption according to the quantum yield without considering the emission wavelength.

[0078] Therefore, the effective absorption efficiency quantifies the luminescence energy according to the absorbance of the quantum dots and quantifies the ratio of the absorption rate to the emission value, rather than the ratio of the emission to the absorption. Therefore, quantum dots with a higher effective absorption efficiency are quantum dots with better absorption.

[0079] Since the above-mentioned quantum dot 10 has an effective absorption efficiency of greater than or equal to 50% defined by the above formula [1], the above-mentioned quantum dot 10 can be a quantum dot with good luminescence and light absorption properties.

[0080] In addition, when the effective absorption efficiency can be greater than or equal to 50%, the quantum yield of the quantum dot 10 can be greater than or equal to 70%. Conversely, the effective absorption efficiency of the quantum dot 10 can be greater than or equal to 50%, and the quantum yield can be greater than or equal to 70%. In this case, the quantum dot 10 can have a type 1 or type 2 bandgap alignment structure and a quantum yield of greater than or equal to 70% and can exhibit good luminescence and light absorption properties.

[0081] The shell 14 can include at least one of elements of Group I and Group III and elements of Group VI.

[0082] As described above, "Group I" can refer to Group IA (or 1A) and Group IB (or 1B), and examples of elements of Group I can include Li, Na, K, Rb, Cs, Cu, Ag, and Au, but are not limited to these.

[0083] The element of Group I included in the shell 14 can be the same as or different from the Ag included in the core 12. Since the shell 14 includes the element of Group I included in the core 12 at the same time, the vacancy defects on the surface of the core 12 can be removed or supplemented.

[0084] The shell layer 14 may include a Group I element, or may include two or more different Group I elements. For example, in the case where the shell layer 14 includes two or more different Group I elements, the shell layer 14 may include a Group IA (or 1A) element and a Group IB (or 1B) element. For example, the Group IA (or 1A) element may be Na, and the Group IB (or 1B) element may be Cu or Ag.

[0085] Since the shell layer 14 includes the Group I element included in the core 12, vacancy defects on the surface of the core 12 can be removed or supplemented.

[0086] As described above, "Group III" may refer to Group IIIA (or 3A) and Group IIIB (or 3B), and examples of Group III elements may include In, Ga, Al, and Tl, but are not limited to these. "Group VI" may refer to Group VIA (or 6A), and examples of Group VI elements may include S, Se, and Te, but are not limited to these.

[0087] The shell layer 14 may be doped with a metal or a non-metal. After the shell layer 14 is deposited, the core 12 / shell layer 14 may be purified. The core 12 / shell layer 14 may be filtered to remove precipitates from the core solution.

[0088] The shell layer 14 may include one of the following: AgAlS, AgAlSe, AgAlTe, AgGaS, AgGaSe, AgGaTe, AgInS, AgInSe, AgInTe, AgTiS, AgTiSe, AgTiTe, CuAlS, CuAlSe, CuAlTe, CuGaS, CuGaSe, CuGaTe, CuInS, CuInSe, CuInTe, CuTiS, CuTiSe, CuTiTe, AuAlS, AuAlSe, AuAlTe, AuGaS, AuGaSe, AuGaTe, AuInS, AuInSe, AuInTe, AuTiS, AuTiSe, and AuTiTe.

[0089] The shape or form of the quantum dot 10 is not particularly limited and may be any form available in the art. More specifically, the shape of the quantum dot 10 may be spherical, pyramidal, multi-armed, or cubic nanoparticles, nanotubes, nanowires, nanofibers, or nanosheet particles.

[0090] The quantum dot 10 can adjust the color of the emitted light according to the particle size, so the quantum dot 10 can have various emission colors, such as blue, red, and green.

[0091] According to one embodiment, the diameter of the quantum dot 10 may be 2 nm to 20 nm. The diameter of the quantum dot 10 may be 2 nm to 8 nm.

[0092] Figure 2 is a cross-sectional view showing a quantum dot according to another embodiment of the present disclosure. Figure 3 is a cross-sectional view showing a quantum dot according to another embodiment of the present disclosure.

[0093] Reference Figure 2 and Figure 3 , according to another embodiment of the present disclosure, the quantum dot 10 may include a core 12, a first shell 14, and a second shell 16, or may further include another shell 18 outside the second shell 16, or may further include another intermediate shell (not shown) between the first shell 14 and the second shell 16.

[0094] The core 12 and the first shell 14 of the quantum dot 10 according to another embodiment of the present disclosure may be substantially the same as the core 12 and the shell 14 described in reference Figure 1 . In other words, Figure 1 the quantum dot 10 including the core 12 and the shell 14 shown in Figure 2 and 3 may equally apply to the quantum dot 10 having a core / multiple shell structure as shown in

[0095] The second shell 16 may surround and be located on the first shell 14, and may include at least one group III element and at least one group VI element. The group III element included in the second shell 16 may be the same as or different from In and Ga included in the core. The group VI element included in the second shell 16 may be the same as or different from S included in the core.

[0096] The second shell 16 may include a group III element and at least one group VI element, but does not include the group I element included in the first shell 14. The group VI element included in the first shell 14 may be the same as or different from the group VI element included in the second shell 16.

[0097] The first shell 14 may be located on the core 12. The first shell 14 may include a group I element, a group III element, and a group VI element. The second shell 16 may be located on the first shell 14. The second shell 16 may include a group III element and a group VII element. In this case, the group III element and the group VI element included in the first shell and the second shell may be the same or different.

[0098] The second shell 16 may additionally include another doped group III element.

[0099] The first shell layer 14 and the second shell layer 16 simultaneously include a Group III element and at least one Group VI element included in the core 12, but the second shell layer 16 does not include a Group I element included in the core 12 and the first shell layer 14. Since the first shell layer 14 including the Group I element is not exposed to the outside, oxidation of the Group I element included in the first shell layer 14 can be prevented.

[0100] Since the first shell layer 14 includes the Group I element included in the core 12, vacancy defects on the surface of the core 12 can be removed or supplemented. Since the second shell layer 16 surrounds the first shell layer 14 and does not include the Group I element, oxidation of the Group I element included in the first shell layer 14 can be prevented, thereby ultimately ensuring the stability of the quantum dot 10.

[0101] Since the quantum dot 10 according to an embodiment of the present disclosure only includes components of the above elements and a multi-layer shell layer including the first shell layer 14 and the second shell layer 16, vacancy defects on the surface of the core 12 can be removed or supplemented, and oxidation of the Group I element included in the first shell layer 14 can be prevented.

[0102] Since the first shell layer 14 including the Group I element has a higher affinity for the core 12 than the second shell layer 16, the first shell layer 14 can be formed relatively more easily to be thicker.

[0103] As described above, as the first shell layer 14 is stacked, the Group I element may diffuse outward and be oxidized, which makes the stability of the quantum dot vulnerable. By stacking the second shell layer 16, which includes a Group III element and at least one Group VI element included in the core 12 but does not include the Group I element included in the core 12 and the first shell layer 14, oxidation of the Group I element included in the core 12 and the first shell layer 14 can be prevented, thereby improving the stability.

[0104] In this case, since the second shell layer 16 may be completely formed in an amorphous state, the thickness of the second shell layer 16 becomes greater than a certain thickness, and its crystallinity may be weakened and the stability may be reduced.

[0105] That is, the first shell layer 14 can be formed to be thicker because the crystallinity is improved due to the Group I element and thus becomes structurally stable, while the second shell layer 16 may not be thicker than a certain thickness because the second shell layer 16 is completely formed in an amorphous state, so that the overall crystallinity of the first shell layer 14 and the second shell layer 16 can be improved simultaneously.

[0106] In the quantum dot 10 according to an embodiment, the thickness of the first shell layer 14 may be relatively thick with respect to the thickness of the second shell layer 16. Therefore, the group I elements in the first shell layer 14 can improve the crystallinity of the first shell layer 14 and, at the same time, can improve the crystallinity of the second shell layer 16, which may be formed in an amorphous state.

[0107] The thickness of the first shell layer 14 may be 2.9 nm to 4.2 nm, and the thickness of the second shell layer 16 may be 0.8 nm to 2.5 nm. In addition, the thickness of the first shell layer 14 may be 2.9 nm to 3.9 nm, and the thickness of the second shell layer 16 may be 0.8 nm to 1.6 nm.

[0108] Since the thickness of the first shell layer 14 may be 2.9 nm to 4.2 nm and the thickness of the second shell layer 16 may be 0.8 nm to 2.5 nm, the full width at half maximum and the quantum yield of the quantum dot composed of multiple shell layers can be improved. At the same time, since the crystallinity of the quantum dot may be high, the surface stability of the quantum dot can be improved, and the luminescence efficiency and stability of the quantum dot can be improved.

[0109] In one aspect, at least one group I element included in the first shell layer 14 may not be oxidized. Since the quantum dot 10 includes the second shell layer 16 surrounding the first shell layer 14 and the second shell layer 16 does not include group I elements that are easily oxidized, the group I elements included in the first shell layer 14 may not be oxidized.

[0110] The first shell layer 14 may be completely crystalline, and the second shell layer 16 may be completely amorphous. The term "completely" crystalline or amorphous as used in the present disclosure means that more than 70% of the shell layer may be crystalline or amorphous, more than 85% of the shell layer may be crystalline or amorphous, or more than 95% of the shell layer may be crystalline or amorphous.

[0111] In addition, the second shell layer 16 may include one of the following: AlS, AlSe, AlTe, GaS, GaSe, GaTe, InS, InSe, InTe, TiS, TiSe, and TiTe.

[0112] In another aspect, an embodiment of the present disclosure may provide a method for manufacturing a quantum dot.

[0113] Figure 4 is a flowchart of a method for manufacturing a quantum dot according to another embodiment of the present disclosure.

[0114] Reference Figure 4 , the method 20 for manufacturing a quantum dot according to an embodiment of the present disclosure may include a core preparation step S22 and a shell preparation step S24.

[0115] In the method 20 of manufacturing quantum dots according to an embodiment of the present disclosure, unless otherwise specified, the characteristics of the core and the shell are the same as those of the core 12 and the shell 14 described for the quantum dots 10 according to the above embodiments.

[0116] The method 20 of manufacturing quantum dots can be performed by the following operations: preparing a core using a silver precursor, an indium precursor, a gallium precursor, and a sulfur precursor in a heated reactor, and then preparing the prepared core and the precursors for preparing the shell together using a hot injection method and a heating method. In addition, the hot injection method and the heating method can be performed in each of the core preparation step S22 and the shell preparation step S24.

[0117] The core preparation step S22 can be the following step: preparing a core by injecting a silver precursor, an indium precursor, a gallium precursor, a sulfur precursor, and a solvent into a first reactor and reacting them.

[0118] The shell preparation step S24 can be the following step: preparing a shell by injecting the prepared core into a second reactor and reacting it, the second reactor containing a precursor including a specific element.

[0119] The quantum dots prepared by the core preparation step S22 and the shell preparation step S24 can have an effective absorption efficiency of greater than or equal to 50% defined by the above formula [1].

[0120] Since the prepared quantum dots can have an effective absorption efficiency of greater than or equal to 50% defined by the above formula [1], the prepared quantum dots can be quantum dots with good light-emitting and light-absorbing characteristics.

[0121] In addition, when the effective absorption efficiency can be greater than or equal to 50%, the quantum yield of the quantum dots 10 can be greater than or equal to 70%. Conversely, the effective absorption efficiency of the quantum dots 10 can be greater than or equal to 50%, and the quantum yield can be greater than or equal to 70%. In this case, the quantum dots 10 can have a type 1 or type 2 bandgap alignment structure and a quantum yield of greater than or equal to 70%, and can exhibit good light-emitting and light-absorbing properties.

[0122] The specific element can include at least one of a group I element and a group III element; and a group VI element.

[0123] In this case, the shell preparation step S24 can be the following step: preparing a shell by injecting the prepared core into a second reactor and reacting it, the second reactor containing at least one of a group I precursor (including a group I element) and a group III precursor (including a group III element) and a group VI precursor (including a group VI element).

[0124] The core preparation step S22 can be the step of preparing the core. The core preparation step may include Step 1-1 and Step 1-2.

[0125] Step 1-1 can be the following step: Prepare a core solution by injecting and heating a silver precursor, an indium precursor, a gallium precursor, a sulfur precursor, and a solvent in a first reactor.

[0126] The silver precursor injected in Step 1-1 may include, for example, one or more selected from the following: silver(I) acetylacetonate, silver(I) chloride, silver(I) bromide, silver(I) iodide, silver(I) acetate, silver(I) nitrate, and silver(I) myristate.

[0127] The indium precursor injected in Step 1-1 may include, for example, one or more selected from the following: indium(III) acetylacetonate, indium(III) chloride, indium(III) acetate, trimethylindium, alkylindium, arylindium, indium(III) myristate, and indium(III) acetate myristate.

[0128] The gallium precursor injected in Step 1-1 may include, for example, one or more selected from the following: gallium(III) acetylacetonate, gallium(III) chloride, gallium(III) iodide, gallium(III) bromide, gallium(III) acetate, and gallium(III) nitrate.

[0129] The sulfur precursor injected in Step 1-1 may include, for example, one or more selected from the following: alkyl thiols (such as n-butyl mercaptan, isobutyl mercaptan, n-hexyl mercaptan, 1-octanethiol, decanethiol, 1-dodecanethiol, hexadecanethiol, and octadecanethiol), sulfur chlorides, sulfur (S), S-TOP, S-ODE, S-toluene, S-oleylamine, and N,N-dimethylthiourea.

[0130] The solvent injected in Step 1-1 may include, for example, one or more selected from oleylamine, 1-octadecene, and trioctylamine, but is not limited to these.

[0131] Each of the silver precursor, indium precursor, gallium precursor, and sulfur precursor injected in Step 1-1 can be a precursor solution mixed with a solvent.

[0132] A core solution including the core can be prepared through Step 1-1, and the core can be formed by reacting the silver precursor, indium precursor, gallium precursor, and sulfur precursor in a second reactor.

[0133] Step 1-2 can be the following step: Add a purification solvent to the core solution and centrifuge the resulting product, and disperse the precipitate separated by centrifugation in a dispersion solvent.

[0134] For example, steps 1-2 can be as follows: adding a purification solvent such as methanol, ethanol, acetone, and 2-propanol (IPA) to the core solution, centrifuging the resulting product, and dispersing the precipitate separated by centrifugation in a dispersion solvent such as hexane, toluene, octadecane, heptane, oleylamine, and 1-octadecene.

[0135] A purified core solution can be prepared through steps 1-2.

[0136] The shell preparation step S24 can include steps 2-1 and 2-2.

[0137] Step 2-1 can be as follows: injecting at least one Group III precursor such as an aluminum precursor, an indium precursor, a gallium precursor, and a thallium precursor into a second reactor containing oleylamine.

[0138] Step 2-2 can be as follows: injecting at least one of a sulfur precursor, a selenium precursor, and a tellurium precursor and the purified core solution into the second reactor and reacting them.

[0139] The Group I elements in the shell can include, for example, one or more selected from Li, Na, Cu, Ag, and Au, but are not limited to these. The Group III elements can include, for example, one or more selected from In, Ga, Al, and Tl, but are not limited to these. The Group VI elements can include, for example, one or more selected from S, Se, and Te, but are not limited to these.

[0140] The shell preparation step S24 can be as follows: preparing a first shell by injecting the prepared core and a Group VI precursor into a second reactor that contains a Group I precursor (including at least one Group I element) and a Group III precursor (including at least one Group III element).

[0141] The shell preparation step S24 can include steps 2-1 and 2-2.

[0142] Step 2-1 can be as follows: injecting a Group I precursor (including at least one Group I element) and a Group III precursor (including at least one Group III element) into a second reactor containing oleylamine.

[0143] Step 2-2 can be as follows: reacting the purified core solution and a Group VI precursor in a first reactor.

[0144] The first precursor injected in step 2-1 may include, for example, one or more selected from the group consisting of chlorides, iodides, oxides, and acetylacetonates chemically bonded to at least one first group element.

[0145] For example, when the first group element is Ag, the first precursor may be silver(I) chloride, silver(I) iodide, silver(I) oxide, or silver(I) acetylacetonate.

[0146] The group III precursor and the group VI precursor injected in steps 2-1 and 2-2 may include, for example, one or more selected from the group consisting of acetates, acetylacetonates, oxides, bromides, chlorides, and iodides chemically bonded to at least one group III element.

[0147] For example, when the group III precursor injected in step 2-1 is a gallium precursor, the gallium precursor may be one or more selected from the group consisting of gallium(III) acetate, gallium(III) acetylacetonate, gallium(III) oxide, gallium(III) bromide, gallium(III) chloride, and gallium(III) iodide.

[0148] When the group III precursor injected in step 2-1 is an indium precursor, the indium precursor has been described in the description related to step 1-1, and thus will not be elaborated further.

[0149] When the group VI precursor injected in step 2-2 is a sulfur precursor, the sulfur precursor has been described in the description related to step 1-1, and thus will not be elaborated further.

[0150] When the group VI precursor injected in step 2-2 is a selenium precursor, the selenium precursor may be, for example, one or more selected from the group consisting of selenium chloride, selenium (Se), Se-TOP, Se-DPP, Se-ODE, and organoselenium compounds (e.g., compounds such as dibenzyldiselenide, diphenyldiselenide, or hydrogen selenide).

[0151] When the group VI precursor injected in step 2-2 is a tellurium precursor, the tellurium precursor may be, for example, one or more selected from the group consisting of tellurium chloride, tellurium (Te), and hydrogen telluride.

[0152] See Figure 4 for a description of Figure 1 the method for manufacturing the quantum dot 10 including the core 12 and the shell 14 shown in Figure 5 Below, see Figure 2 for a description of Figure 3The quantum dot 10 shown in including a core 12 and three shell layers 14, 16, and 18 can be fabricated by adding the outermost shell layer 18 to the method for manufacturing the quantum dot 10 described in the reference Figure 5 as described.

[0153] Figure 5 is a flowchart of a method for manufacturing quantum dots according to another embodiment of the present disclosure.

[0154] Refer to Figure 5 , the method 30 for manufacturing quantum dots according to an embodiment of the present disclosure may include a core preparation step S32, a first shell layer preparation step S34, and a second shell layer preparation step S36.

[0155] In the method 30 for manufacturing quantum dots according to an embodiment of the present disclosure, unless otherwise specified, the characteristics of the core, the first shell layer, and the second shell layer are the same as those of the core 12, the first shell layer 14, and the second shell layer 16 described in the above embodiment for the quantum dot 10.

[0156] The core preparation step S32 and the first shell layer preparation step S34 may be substantially the same as the core preparation step S22 and the shell layer preparation step S24 described in the reference Figure 4 as described.

[0157] The second shell layer preparation step S36 may be the following step: preparing a second shell layer around the first shell layer by injecting the prepared core and the first shell layer into a second reactor and reacting them, where the second reactor contains a group III precursor (including at least one group III element) and a group VI precursor (including at least one group VI element).

[0158] The group III elements included in the second shell layer may include, for example, one or more selected from In, Ga, Al, and Tl, but are not limited to these. The group VI elements included in the second shell layer may include, for example, one or more selected from S, Se, and Te, but are not limited to these. The group VI element included in the second shell layer may be the same as or different from the S included in the core.

[0159] The group III precursor including a group III element and the group VI precursor including at least one group VI element used in the second shell layer preparation step S36 may be the group III precursor and the group VI precursor described in the first shell layer preparation step S34.

[0160] The thickness of the first shell prepared in the first shell preparation step S34 may be from 2.9 nm to 4.2 nm, while the thickness of the second shell prepared in the second shell preparation step S36 may be from 0.8 nm to 2.5 nm. In addition, the thickness of the first shell prepared in the first shell preparation step S34 may be from 2.9 nm to 3.9 nm, while the thickness of the second shell prepared in the second shell preparation step S36 may be from 0.8 nm to 1.6 nm.

[0161] The first shell prepared in the first shell preparation step S34 may be completely crystalline, while the second shell prepared in the second shell preparation step S36 may be completely amorphous.

[0162] On the other hand, in the quantum dots according to another embodiment, the thickness of the first shell prepared in the first shell preparation step S34 may be relatively thicker than the thickness of the second shell prepared in the second shell preparation step S36.

[0163] The first shell prepared in the first shell preparation step S34 may include one of the following: AgAlS, AgAlSe, AgAlTe, AgGaS, AgGaSe, AgGaTe, AgInS, AgInSe, AgInTe, AgTiS, AgTiSe, AgTiTe, CuAlS, CuAlSe, CuAlTe, CuGaS, CuGaSe, CuGaTe, CuInS, CuInSe, CuInTe, CuTiS, CuTiSe, CuTiTe, AuAlS, AuAlSe, AuAlTe, AuGaS, AuGaSe, AuGaTe, AuInS, AuInSe, AuInTe, AuTiS, AuTiSe, and AuTiTe.

[0164] In addition, the second shell prepared in the second shell preparation step S36 may include one of the following: AlS, AlSe, AlTe, GaS, GaSe, GaTe, InS, InSe, InTe, TiS, TiSe, and TiTe.

[0165] On the other hand, according to an embodiment of the present disclosure, there may be provided an ink composition including the quantum dots 10 described with reference to Figures 1 to 3 or the quantum dots prepared by the method described with reference to Figure 4 and Figure 5 Unless otherwise specified, in the ink composition according to an embodiment of the present disclosure, the quantum dots are the same as the quantum dots 10 according to the embodiment of the present disclosure.

[0166] An ink composition according to an embodiment of the present disclosure may be a light-converting ink composition including quantum dots 10, a photo-curable monomer, a photoinitiator, and a light diffusing agent.

[0167] According to an embodiment, relative to the total content of 100 parts by weight of the quantum dot ink composition, the content of the quantum dots 10 may be 20 parts by weight to 60 parts by weight, for example, 25 parts by weight to 50 parts by weight, or 30 parts by weight to 45 parts by weight. According to an embodiment, the ink composition may not include a solvent. In other words, the ink composition may be a solvent-free quantum dot ink composition. According to an embodiment, the ink composition may have a viscosity of 10 cP to 25 cP. According to an embodiment, the surface tension of the ink composition at 25 °C may be 30 mN / m or greater. When the above viscosity and / or surface tension ranges are satisfied, the ink composition as a solvent-free quantum dot ink composition may be appropriately used for various components in a solution process such as inkjet, for example, a color conversion component or an emission layer of an emission device.

[0168] According to an embodiment, an optical component formed using the ink composition may be provided. For example, the optical component may be a color conversion component.

[0169] According to another aspect, referring to Figure 6 , an electronic device 100 according to an embodiment may include a substrate 110, a light source 120 disposed on the substrate 110, and a color conversion component 130 disposed in the path of light emitted from the light source 120, and the color conversion component 130 may be formed using the above ink composition.

[0170] According to an embodiment, the light source 120 may be an emission device. For example, the light source 120 may be an organic light-emitting diode (OLED) or an inorganic light-emitting diode (ILED or QLED).

[0171] In another aspect, referring to Figure 7 , a light-emitting diode 200 according to another embodiment may include quantum dots 10. A light-emitting diode 200 according to other embodiments may include a positive electrode 210, a negative electrode 230, and an intermediate layer 220 disposed therebetween. The intermediate layer 220 may include an emission layer including the above ink composition containing quantum dots.

[0172] According to another aspect of the present disclosure, an electronic device including a display device and a controller for driving the display device may be provided, and the display device includes the above light-emitting diode.

[0173] An electronic device may include, for example, a display device, a lighting device, a solar cell, a portable or mobile terminal (e.g., a smartphone, a tablet computer, a PDA, an electronic dictionary, a PMP, etc.), a navigation terminal, a game console, various televisions, various computer monitors, etc., but is not limited thereto, and may include any type of device including the (one or more) components.

[0174] Those skilled in the art can easily apply the various electronic devices using the quantum dots 10 and the applications of the devices, and thus the detailed description thereof will be omitted.

[0175] Hereinafter, specific embodiments are given. However, the embodiments described below are only for specifically illustrating or describing the present disclosure, and the scope of the present disclosure is not limited thereto.

[0176] The following examples describe the method for manufacturing the quantum dots 10 including the core 12, the first shell 14, and the second shell 16 as described. Figure 2 The quantum dots 10 including the core 12, the first shell 14, and the second shell 16 as described.

[0177] In this case, the description may relate to the following examples: the first group element used in the first shell 14 and the second shell 16 is Ag, the third group element is Ga, and the sixth group element is S. In other words, an example of manufacturing AgInGaS / AgGaS / GaS quantum dots may be described exemplarily.

[0178] Since the method for preparing the core 12, the first shell 14, and the second shell 16 using the elements described in the above examples in the same manner as the following examples may be a typical technique, the detailed description thereof will be omitted.

[0179] Figure 1 The quantum dots 10 shown in may be quantum dots prepared by the core 12 and the first shell 14, while Figure 3 The quantum dots 10 shown in may be quantum dots prepared by the core 12, the first shell 14, the second shell 16, and adding the outermost shell 18.

[0180] [Embodiment]

[0181] (1) Prepare a precursor

[0182] (Preparation Example 1) Preparation of silver iodide (I)-oleylamine precursor solution

[0183] Place 0.56 g (2.4 mmol) of silver(I) iodide and 10 mL (30 mmol) of oleylamine in a 50 mL flask, reduce the pressure at room temperature (RT) for 1 hour, heat to 120 °C for 10 minutes, and then react for 1 hour. Cool the mixed solution to room temperature in an Ar atmosphere to prepare an Ag precursor solution. The Ag concentration of this precursor solution is 0.24 M.

[0184] Preparation Example 2: Preparation of indium(III) chloride-ethanol precursor solution

[0185] 0.11 g (0.5 mmol) of indium(III) chloride and 5 mL of ethanol were placed in a 10 mL vial to prepare an In precursor solution. The In concentration of this precursor solution was 0.10 M.

[0186] Preparation Example 3: Preparation of gallium(III) chloride-toluene precursor solution

[0187] 0.80 g (4.54 mmol) of gallium(III) chloride and 0.8 mL of toluene were placed in a 10 mL vial to prepare a Ga precursor solution. The Ga concentration of this precursor solution was 5.68 M.

[0188] Preparation Example 4: Preparation of gallium(III) acetylacetonate-toluene precursor solution

[0189] 1.67 g (4.54 mmol) of gallium(III) chloride and 16 mL of toluene were placed in a 20 mL vial to prepare a Ga precursor solution. The Ga concentration of this precursor solution was 0.28 M.

[0190] Preparation Example 5: Preparation of S-oleylamine precursor solution

[0191] 0.305 g (9.5 mmol) of S and 9.5 mL (28.5 mmol) of oleylamine were placed in a 50 mL flask, degassed under reduced pressure for 30 minutes at room temperature (RT), heated to 120 °C for 10 minutes, and then reacted for 1 hour. The mixed solution was cooled to room temperature in an Ar atmosphere to prepare an S precursor solution. The S concentration of the precursor solution was 1 M.

[0192] Preparation Example 6: Preparation of AgInGaS quantum dot core

[0193] (1) 0.3 g of gallium(III) acetylacetonate prepared in Preparation Example 4, trioctylphosphine oxide (TOPO), 5 ml of silver(I) iodide-oleylamine prepared in Preparation Example 1, indium(III) chloride-ethanol prepared in Preparation Example 2, and 1-octadecene were placed in a 50 mL round-bottom flask equipped with a reflux condenser and heated to 120 °C while maintaining at about 0.005 Torr using a vacuum pump for 30 minutes.

[0194] (2) Then, after replacing with an N2 atmosphere, 1 ml (0.03 g, 1 mmol) of the S-oleylamine solution prepared in Preparation Example 5 and 0.5 ml of 1-dodecanethiol were injected at 120 °C.

[0195] (3) After adding the S-oleylamine solution, it was maintained at 0.005 Torr at 120 °C for 30 minutes using a vacuum pump. Then, the reaction was terminated after stirring at 190 °C for 10 minutes.

[0196] (4) Inject 5 ml of a mixed solution of tris-dimethylaminophosphine ((PDEA)3) + trioctylphosphine (TOP) at 280 °C, and then cool to room temperature.

[0197] (5) Divide the prepared AgInGaS quantum dot solution into two equal parts and fill with 42.5 ml of ethanol to prepare a 50 ml AgInGaS core-ethanol solution.

[0198] (6) Centrifuge the solution at 5000 RPM for 5 minutes, and then disperse it in 1.2 ml of toluene. Centrifuge the dispersed AgInGaS core-toluene solution at 5000 RPM for 1 minute to remove impurities, and obtain the AgInGaS core quantum dot solution.

[0199] (2) Example 1: Preparation of AgInGaS / AgGaS / GaS quantum dots

[0200] (1) In the process of Preparation Example 6, prepare an AgInGaS quantum dot core solution using 0.9575 ml (Ag: 0.23 mmol) of silver iodide (I)-oleylamine, 2.5 ml (In: 0.25 mmol) of indium(III) chloride-ethanol, and 0.146 g (Ga: 0.4 mmol) of gallium(III) acetylacetonate.

[0201] (2) Prepare 16 ml of oleylamine in a 50 ml three-necked round bottom flask equipped with a reflux condenser, heat to 120 °C, and maintain under 0.005 Torr using a vacuum pump for 30 minutes. After replacing with a nitrogen atmosphere at 120 °C, inject the AgInGaS quantum dot core solution of (1), inject 0.8 ml of the gallium(III) chloride-toluene solution prepared in Preparation Example 3 with 0.80 g, 4.54 mmol, 0.014 g of silver iodide (I), and 2 ml of S-oleylamine, and remove toluene using a vacuum pump. Then, after replacing with a nitrogen atmosphere, the reaction is carried out at 310 °C for 60 minutes.

[0202] (3) Inject 5 ml of a mixed solution of tris-dimethylaminophosphine (PDEA)3) + trioctylphosphine (TOP) at 280 °C and cool to room temperature to obtain an AgInGaS / AgGaS quantum dot solution.

[0203] (4) Prepare 16 ml of oleylamine in a 50 ml three-necked round bottom flask equipped with a reflux condenser, heat to 120 °C, and maintain under 0.005 Torr using a vacuum pump for 30 minutes. After replacing with a nitrogen atmosphere at 120 °C, inject the AgInGaS / GaS quantum dot solution, inject 0.8 ml of the gallium(III) chloride-toluene solution and 2 ml of S-oleylamine, and remove toluene using a vacuum pump. Then, after replacing with a nitrogen atmosphere, the reaction is carried out at 310 °C for 100 minutes.

[0204] (5) Inject 5 ml of a mixed solution of tris-dimethylaminophosphine (PDEA)3+ and trioctylphosphine (TOP) at 280 °C and cool to room temperature to obtain an AgInGaS / AgGaS / GaS quantum dot solution.

[0205] (3) Example 2: Preparation of AgInGaS / Ag GaS / GaS quantum dots

[0206] Quantum dots were obtained in the same manner as in Example 1, but in the process of Preparation Example 6, 0.9575 ml (Ag: 0.23 mmol) of silver iodide (I)-oleylamine, 2.5 ml (In: 0.25 mmol) of indium(III) chloride-ethanol, and 0.146 g (Ga: 0.4 mmol) of gallium(III) acetylacetonate were used, and stirred at 200 °C for 10 minutes.

[0207] (4) Example 3: Preparation of AgInGaS / AgGaS / GaS quantum dots

[0208] Quantum dots were obtained in the same manner as in Example 1, but in the process of Preparation Example 6, 0.9575 ml (Ag: 0.23 mmol) of silver iodide (I)-oleylamine, 2.5 ml (In: 0.25 mmol) of indium(III) chloride-ethanol, and 0.146 g (Ga: 0.4 mmol) of gallium(III) acetylacetonate were used, and stirred at 210 °C for 10 minutes.

[0209] (5) Example 4: Preparation of AgInGaS / AgGaS / GaS quantum dots

[0210] Quantum dots were obtained in the same manner as in Example 1, but in the process of Preparation Example 6, 0.9575 ml (Ag: 0.23 mmol) of silver iodide (I)-oleylamine, 2.5 ml (In: 0.25 mmol) of indium(III) chloride-ethanol, and 0.146 g (Ga: 0.4 mmol) of gallium(III) acetylacetonate were used, and stirred at 220 °C for 10 minutes.

[0211] (6) Example 5: Preparation of AgInGaS / AgGaS / GaS quantum dots

[0212] Quantum dots were obtained in the same manner as in Example 1, but in the process of Preparation Example 6, 0.9575 ml (Ag: 0.23 mmol) of silver iodide (I)-oleylamine, 2.5 ml (In: 0.25 mmol) of indium(III) chloride-ethanol, and 0.146 g (Ga: 0.4 mmol) of gallium(III) acetylacetonate were used, and stirred at 230 °C for 10 minutes.

[0213] (7) Example 6: Preparation of AgInGaS / AgGaS / GaS quantum dots

[0214] Quantum dots were obtained in the same manner as in Example 1, but 0.9575 ml (Ag: 0.23 mmol) of silver(I) iodide-oleylamine, 2.5 ml (In: 0.25 mmol) of indium(III) chloride-ethanol, and 0.146 g (Ga: 0.4 mmol) of gallium(III) acetylacetonate were used in the preparation of Example 6, and the mixture was stirred at 240 °C for 10 minutes.

[0215] (8) Example 7: Preparation of AgInGaS / AgGaS / GaS quantum dots

[0216] Quantum dots were obtained in the same manner as in Example 1, but 0.9575 ml (Ag: 0.23 mmol) of silver(I) iodide-oleylamine, 2.5 ml (In: 0.25 mmol) of indium(III) chloride-ethanol, and 0.146 g (Ga: 0.4 mmol) of gallium(III) acetylacetonate were used in the preparation of Example 6, and the mixture was stirred at 250 °C for 10 minutes.

[0217] (9) Example 8: Preparation of AgInGaS / AgGaS / GaS quantum dots

[0218] Quantum dots were obtained in the same manner as in Example 1, but 0.9575 ml (Ag: 0.23 mmol) of silver(I) iodide-oleylamine, 2.5 ml (In: 0.25 mmol) of indium(III) chloride-ethanol, and 0.146 g (Ga: 0.4 mmol) of gallium(III) acetylacetonate were used in the preparation of Example 6, and the mixture was stirred at 260 °C for 10 minutes.

[0219] (10) Example 9: Preparation of AgInGaS / AgGaS / GaS quantum dots

[0220] Quantum dots were obtained in the same manner as in Example 1, but 1.67 ml (Ag: 0.4 mmol) of silver(I) iodide-oleylamine, 2.4 ml (In: 0.24 mmol) of indium(III) chloride-ethanol, and 0.0697 g (Ga: 0.19 mmol) of gallium(III) acetylacetonate were used in the preparation of Example 6, and the mixture was stirred at 200 °C for 10 minutes.

[0221] (11) Example 10: Preparation of AgInGaS / AgGaS / GaS quantum dots

[0222] Quantum dots were obtained in the same manner as in Example 1, but 1.67 ml (Ag: 0.4 mmol) of silver(I) iodide-oleylamine, 2.5 ml (In: 0.25 mmol) of indium(III) chloride-ethanol, and 0.0697 g (Ga: 0.19 mmol) of gallium(III) acetylacetonate were used in the preparation of Example 6, and the mixture was stirred at 200 °C for 10 minutes.

[0223] (12) Example 11: Preparation of AgInGaS / AgGaS / GaS quantum dots

[0224] Quantum dots were obtained in the same manner as in Example 1, but 1.67 ml (Ag: 0.4 mmol) of silver(I) iodide - oleylamine, 2.4 ml (In: 0.24 mmol) of indium(III) chloride - ethanol, and 0.0697 g (Ga: 0.19 mmol) of gallium(III) acetylacetonate were used during the preparation of Preparation Example 6, and the mixture was stirred at 210 °C for 10 minutes.

[0225] (13) Example 12: Preparation of AgInGaS / AgGaS / GaS quantum dots

[0226] Quantum dots were obtained in the same manner as in Example 1, but 1.67 ml (Ag: 0.4 mmol) of silver(I) iodide - oleylamine, 2.5 ml (In: 0.24 mmol) of indium(III) chloride - ethanol, and 0.0697 g (Ga: 0.19 mmol) of gallium(III) acetylacetonate were used during the preparation of Preparation Example 6, and the mixture was stirred at 210 °C for 10 minutes.

[0227] (14) Example 13: Preparation of AgInGaS / AgGaS / GaS quantum dots

[0228] Quantum dots were obtained in the same manner as in Example 1, but 1.67 ml (Ag: 0.4 mmol) of silver(I) iodide - oleylamine, 2.4 ml (In: 0.24 mmol) of indium(III) chloride - ethanol, and 0.0697 g (Ga: 0.19 mmol) of gallium(III) acetylacetonate were used during the preparation of Preparation Example 6, and the mixture was stirred at 220 °C for 10 minutes.

[0229] (15) Example 14: Preparation of AgInGaS / AgGaS / GaS quantum dots

[0230] Quantum dots were obtained in the same manner as in Example 1, but 1.67 ml (Ag: 0.4 mmol) of silver(I) iodide - oleylamine, 2.5 ml (In: 0.25 mmol) of indium(III) chloride - ethanol, and 0.0697 g (Ga: 0.19 mmol) of gallium(III) acetylacetonate were used during the preparation of Preparation Example 6, and the mixture was stirred at 220 °C for 10 minutes.

[0231] (16) Comparative Example 1: Preparation of AgInGaS / AgGaS quantum dots

[0232] (1) During the preparation of Preparation Example 6, an AgInGaS quantum dot core solution was prepared using 0.9575 ml (Ag: 0.23 mmol) of silver(I) iodide - oleylamine, 2.5 ml (In: 0.25 mmol) of indium(III) chloride - ethanol, and 0.146 g (Ga: 0.4 mmol) of gallium(III) acetylacetonate.

[0233] (2) Prepare 16 ml of oleylamine in a 50 ml three-necked round-bottom flask equipped with a reflux condenser. Heat it to 120 °C and maintain it under 0.005 Torr using a vacuum pump for 30 minutes. After replacing with a nitrogen atmosphere at 120 °C, inject the AgInGaS quantum dot core solution of (1), inject 0.8 ml of a gallium(III) chloride-toluene solution prepared in Preparation Example 3 with a mass of 0.80 g and a molar amount of 4.54 mmol, as well as 0.014 g of silver(I) iodide and 2 ml of S-oleylamine, and use a vacuum pump to remove toluene. Then, after replacing with a nitrogen atmosphere, the reaction is carried out at 310 °C for 60 minutes.

[0234] (3) Inject 5 ml of a tri-dimethylaminophosphine (PDEA)3)+trioctylphosphine (TOP) mixed solution at 280 °C and cool to room temperature to obtain an AgInGaS / AgGaS quantum dot solution.

[0235] (17) Comparative Example 2: Preparation of AgInGaS / GaS / AgGaS quantum dots

[0236] (1) During the process of Preparation Example 6, prepare an AgInGaS quantum dot core solution using 0.9575 ml (Ag: 0.23 mmol) of silver(I) iodide-oleylamine, 2.5 ml (In: 0.25 mmol) of indium(III) chloride-ethanol, and 0.146 g (Ga: 0.4 mmol) of gallium(III) acetylacetonate.

[0237] (2) Prepare 16 ml of oleylamine in a 50 ml three-necked round-bottom flask equipped with a reflux condenser. Heat it to 120 °C and maintain it under 0.005 Torr using a vacuum pump for 30 minutes. After replacing with a nitrogen atmosphere at 120 °C, inject the AgInGaS quantum dot core solution of (1), inject 0.8 ml of a gallium(III) chloride-toluene solution and 2 ml of S-oleylamine, and use a vacuum pump to remove toluene. Then, after replacing with a nitrogen atmosphere, the reaction is carried out at 310 °C for 100 minutes.

[0238] (3) Inject 5 ml of a tri-dimethylaminophosphine (PDEA)3)+trioctylphosphine (TOP) mixed solution at 280 °C and cool to room temperature to obtain an AgInGaS / GaS quantum dot solution.

[0239] (4) Prepare 16 ml of oleylamine in a 50 ml three-necked round-bottom flask equipped with a reflux condenser. Heat it to 120 °C and maintain it under 0.005 Torr using a vacuum pump for 30 minutes. After replacing with a nitrogen atmosphere at 120 °C, inject the AgInGaS / GaS quantum dot solution, inject 0.8 ml of a gallium(III) chloride-toluene solution, 0.014 g of silver(I) iodide and 2 ml of S-oleylamine, and use a vacuum pump to remove toluene. Then, after replacing with a nitrogen atmosphere, the reaction is carried out at 310 °C for 100 minutes.

[0240] (5) Inject 5 ml of a mixed solution of tris-dimethylaminophosphine (PDEA)3+ and trioctylphosphine (TOP) at 280 °C and cool to room temperature to obtain an AgInGaS / GaS / AgGaS quantum dot solution.

[0241] [Experimental Example]

[0242] For the quantum dots manufactured according to Examples 1 to 14 and Comparative Examples 1 to 2 above, the integrated absorbance value of the quantum dots with respect to wavelength, the optical properties of the quantum dots [emission peak, quantum yield, full width at half maximum (FWHM)], and the effective absorption efficiency were confirmed using a QE-2000 device from Otsuka Electronics.

[0243] The following Table 1 shows the evaluation results of the optical properties of the prepared quantum dots.

[0244] Table 1

[0245]

[0246]

[0247] In Examples 1 to 8 above, the reaction temperature in the preparation process of Example 6 was changed. In Examples 9 to 14 and Comparative Examples 1 and 2, the contents of the silver precursor, indium precursor, and gallium precursor and the reaction temperature in the preparation process of Example 6 were changed to measure the integrated absorbance value and quantum yield (QY) of the quantum dots in the range of 300 nm to 470 nm, and finally the effective absorption efficiency was obtained. Figure 8 It is a graph showing the relationship between absorbance and wavelength for Examples 1 to 8. Figure 9 It is a graph showing the relationship between absorbance and wavelength for Examples 9 to 14 and Comparative Examples 1 to 2.

[0248] As described above, since the larger the bandgap energy, the emitted light is in the short wavelength region and requires higher energy, the absorption value in the entire range of 300 nm to 800 nm is larger. The smaller the bandgap energy, the emitted light is in the long wavelength region, and compared with the light emission in the short wavelength region, the absorption value in the entire range is relatively small.

[0249] In addition, the more light is emitted in the short wavelength range, the larger the integrated value in the short wavelength range. The more light is emitted in the long wavelength range, the smaller the integrated value in the short wavelength range.

[0250] For a display device, the blue wavelength that makes the green quantum dots emit light can be less than or equal to 470 nm. In this way, the overlap between the excitation wavelength and the emission wavelength required to achieve light emission can be avoided.

[0251] Since the absorbance in the short wavelength region varies with the emission wavelength, the effective absorption efficiency is represented by the integral value of the absorbance in the range of 300 nm to 470 nm when the absorbance in the range of 300 nm to 800 nm is 1, indicating the absorption according to the quantum yield without considering the emission wavelength.

[0252] Therefore, the effective absorption efficiency quantifies the luminescence energy according to the absorbance of the quantum dots and quantifies the absorption rate compared to the emission value, rather than the emission compared to the absorption. Therefore, quantum dots with higher effective absorption efficiency are quantum dots with better absorption.

[0253] As shown in Table 1 and Figure 8 、 Figure 9 as shown, each of the quantum dots in Examples 1 to 14 has an effective absorption efficiency greater than or equal to 50%, while each of the quantum dots in Comparative Examples 1 to 2 has an effective absorption efficiency less than 50%.

[0254] In the examples, bandgap alignment occurs in the core 12 with a smaller bandgap. The first shell 14 is a type 1 structure that does not affect luminescence, the second shell 16 is a type 2 structure that affects luminescence, and the quantum dots have a quantum yield greater than or equal to 70%, having good luminescence and light absorption properties.

[0255] On the other hand, in Comparative Example 1, due to the single shell, the quantum confinement effect is less than that of the examples, showing lower luminescence efficiency and effective absorption efficiency. In Comparative Example 2, although it is a multi-shell, due to the reverse type bandgap structure, it shows significantly lower effective absorption efficiency at the same wavelength compared to the examples.

[0256] Through the AgInGaS / AgGaS / GaS quantum dots of Examples 1 to 14 and Comparative Examples 1 and 2, it is illustrated that AgInGaS / AgGaS / GaS quantum dots with an effective absorption efficiency greater than or equal to 50% can improve the luminescence efficiency.

[0257] In the above Examples 1 to 14, the Group I element used in the first shell and the second shell of the illustratively described AgInGaS / AgGaS / GaS quantum dots is Ag, the Group III element is Ga, and the Group VI element is S. However, for the same reasons as above, the following AgInGaS / first shell / second shell quantum dots can also improve the luminescence efficiency. In the AgInGaS / first shell / second shell quantum dots, the Group I element included in the first shell is an element other than Ag, the Group III element included in the first shell 14 and the second shell 16 is one of Al, In, and Tl other than Ga, and the Group VI element included in the first shell 14 and the second shell 16 is one of Se and Te other than S.

[0258] In addition, AgInGaS / shell quantum dots without the second shell can also improve the luminescence efficiency for the reasons described above.

[0259] The above description is provided to enable any person skilled in the art to implement and use the technical idea of the present invention, and the above description is provided in the context of a specific application and its requirements. Those skilled in the art will readily recognize that various modifications, additions, and substitutions can be made to the described embodiments, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of the present invention. The above description and the drawings provide examples of the technical idea of the present invention for illustrative purposes only. That is, the disclosed embodiments are intended to illustrate the scope of the technical idea of the present invention. Therefore, the scope of the present invention is not limited to the illustrated embodiments, but should be interpreted according to the broadest scope granted by the claims. The protection scope of the present invention should be interpreted according to the appended claims, and all technical ideas within the equivalent scope thereof should be interpreted as being included within the scope of the present invention.

[0260] Cross-reference to related applications

[0261] This application claims the priority benefit of Korean Patent Application No. 10-2022-0154930, filed on November 17, 2022, the entire content of which is hereby expressly incorporated herein by reference in its entirety as if fully set forth herein for all purposes.

Claims

1. A quantum dot, comprising: a core comprising silver (Ag), indium (In), gallium (Ga), and sulfur (S); and a shell on the core, wherein the quantum dot has an effective absorption efficiency of greater than or equal to 50% defined by formula [1]: [Formula 1] In Formula 1, Abs 300nm～470nm is the integrated absorbance value of the quantum dots in the range of 300 nm to 470 nm when the integrated absorbance value of the quantum dots in the range of 300 nm to 800 nm is 1, and QY is the quantum yield of the quantum dots.

2. The quantum dot according to claim 1, wherein, When the effective absorption efficiency of the quantum dot is greater than or equal to 50%, the quantum yield of the quantum dot is greater than or equal to 70%.

3. The quantum dot according to claim 1, wherein, The shell comprises: at least one of a Group I element and a Group III element; and a Group VI element.

4. The quantum dot according to claim 1, wherein, The Group I element included in the shell comprises one or more selected from Li, Na, K, Rb, Cs, Cu, Ag, and Au.

5. The quantum dot according to claim 1, wherein, The Group III element included in the shell comprises one or more selected from Au, Al, Ga, In, and Tl.

6. The quantum dot according to claim 1, wherein, The Group VI element included in the shell comprises one or more selected from S, Se, and Te.

7. The quantum dot according to claim 1, wherein, The shell comprises: a first shell disposed on the core, comprising a Group I element, a Group III element, and a Group VI element; and a second shell disposed on the first shell, comprising a Group III element and a Group VI element, wherein the Group III element and the Group VI element included in the first shell and the second shell are the same or different.

8. A method for manufacturing a quantum dot, the method comprising: a core preparation step of preparing a core by injecting a silver precursor, an indium precursor, a gallium precursor, a sulfur precursor, and a solvent into a first reactor and reacting them; and a shell preparation step of preparing a shell by injecting the prepared core into a second reactor and reacting it, the second reactor containing precursors comprising specific elements, wherein the quantum dot has an effective absorption efficiency of greater than or equal to 50% defined by formula [1]: [Formula 1] In Formula 1, Abs 300nm～470nm is the integrated absorbance value of the quantum dots in the range of 300 nm to 470 nm when the integrated absorbance value of the quantum dots in the range of 300 nm to 800 nm is 1, and QY is the quantum yield of the quantum dots.

9. The method according to claim 8, wherein When the effective absorption efficiency of the quantum dot is greater than or equal to 50%, the quantum yield of the quantum dot is greater than or equal to 70%.

10. The method according to claim 8, wherein, The specific elements comprise: at least one of a Group I element and a Group III element; and a Group VI element.

11. The method according to claim 8, wherein, The Group I element included in the shell comprises one or more selected from Li, Na, K, Rb, Cs, Cu, Ag, and Au.

12. The method according to claim 8, wherein, The Group III element included in the shell comprises one or more selected from Au, Al, Ga, In, and Tl.

13. The method according to claim 8, wherein, The Group VI element included in the shell comprises one or more selected from S, Se, and Te.

14. The method according to claim 8, wherein The shell comprises: a first shell disposed on the core, comprising a Group I element, a Group III element, and a Group VI element; and a second shell disposed on the first shell, comprising a Group III element and a Group VI element, wherein the Group III element and the Group VI element included in the first shell and the second shell are the same or different.

15. The method according to claim 14, wherein, The shell preparation step comprises: First shell preparation step, preparing the first shell by injecting the prepared core into the first reactor and reacting it, the first reactor accommodating: a first group precursor including the first group element, a third group precursor including the third group element, and a sixth group precursor including the sixth group element; and Second shell preparation step, preparing the second shell by injecting the prepared core and the first shell into the second reactor and reacting them, the second reactor accommodating: a third group precursor including the third group element, and a sixth group precursor including the sixth group element.

16. An electronic device, comprising: A display device, the display device including a light-emitting diode, the light-emitting diode including quantum dots; and A controller for driving the display device, wherein the quantum dots include: a core including silver (Ag), indium (In), gallium (Ga), and sulfur (S); and a shell on the core, wherein the quantum dots have an effective absorption efficiency of greater than or equal to 50% defined by formula [1]: [Formula 1] In Equation 1, Abs 300nm～470nm is the integrated absorbance value of the quantum dot in the range of 300 nm to 470 nm when the integrated absorbance value of the quantum dot in the range of 300 nm to 800 nm is 1, and QY is the quantum yield of the quantum dot.

17. The electronic device according to claim 16, wherein, When the effective absorption efficiency of the quantum dots is greater than or equal to 50%, the quantum yield of the quantum dots is greater than or equal to 70%.

18. The electronic device according to claim 16, wherein, The shell includes: at least one of a first group element and a third group element; and a sixth group element.

19. The electronic device according to claim 16, wherein, The shell includes: A first shell disposed on the core, including a first group element, a third group element, and a sixth group element; and A second shell disposed on the first shell, including a third group element and a sixth group element, wherein the third group element and the sixth group element included in the first shell and the second shell are the same or different.

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