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

Abstract

Embodiments of the present disclosure may provide a quantum dot, a method of producing the same, and an electronic device, each quantum dot including: a core including Ag, In, Ga, and S; and a first shell layer on the core, the first shell layer comprising at least one Group 1 element, at least one Group 3 element, and at least one Group 6 element, the molar ratio of Group 3 element to Group 1 element + Group 3 element + Group 6 element being between 1: 10 and 1: 2.

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 a size of a few nanometers, having 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. 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 been widely concerned 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 cause surface defects and reduce the luminescence efficiency. Therefore, in order to prevent the reduction of the luminescence efficiency of the core, quantum dots having a core / shell structure with a shell formed on the core surface have been developed.

[0004] However, despite the introduction of the shell, there is still a problem that the luminescence efficiency of quantum dots is limited to a certain level due to an increase in wavelength and full width at half maximum. Summary of the Invention

[0005] Technical Problem

[0006] Embodiments of the present disclosure may provide quantum dots, a method of manufacturing the quantum dots, and an electronic device, the quantum dots having a reduced wavelength and full width at half maximum of the quantum dots.

[0007] Embodiments of the present disclosure may provide quantum dots having excellent luminescence efficiency, a method of manufacturing the quantum dots, and an electronic device.

[0008] Technical Solution

[0009] In one aspect, embodiments of the present disclosure may provide a quantum dot including a core and a first shell.

[0010] The core may include silver (Ag), indium (In), gallium (Ga), and sulfur (S). The first shell may be disposed on the core. The first shell may include at least one group I element, at least one group III element, and at least one group VI element, wherein the molar ratio of the group III element to the group I element + group III element + group VI element in the first shell may be between 1:10 and 1:2.

[0011] Embodiments of the present disclosure may provide a quantum dot, which includes a core, a first shell layer, and a second shell layer.

[0012] The second shell layer may be disposed on the first shell layer. The second shell layer may include at least one group III element and at least one group VI element, and the molar ratio of the group III element to the group III element + group VI element in the second shell layer may be between 1:10 and 1:2.

[0013] The molar ratio of the group III element to the group I element + group III element + group VI element in the first shell layer may be between 3:10 and 1:2.

[0014] The molar ratio of the group III element to the group III element + group VI element in the second shell layer may be between 3:10 and 1:2.

[0015] The luminous efficiency of the core and the first shell layer of the quantum dot may be between 68.2% and 77.2%. The luminous efficiency of the core, the first shell layer, and the second shell layer may be between 85.3% and 95.4%.

[0016] At least one group I element included in the first shell layer may include one or more selected from Li, Na, K, Rb, Cs, Cu, Ag, and Au.

[0017] At least one group III element included in the first shell layer and the second shell layer may include one or more selected from Al, Ga, In, and Tl. The group III element included in the first shell layer and the group III element included in the second shell layer may be the same or different.

[0018] At least one group VI element included in the first shell layer and the second shell layer may include one or more selected from S, Se, and Te. The group VI element included in the first shell layer and the group VI element included in the second shell layer may be the same or different.

[0019] The first shell layer 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.

[0020] The second shell layer may include one of the following: AlS, AlSe, AlTe, GaS, GaSe, GaTe, InS, InSe, InTe, TiS, TiSe, and TiTe.

[0021] In another aspect, embodiments of the present disclosure may provide a method for manufacturing quantum dots.

[0022] The method for manufacturing quantum dots may include a core preparation step and a first shell layer preparation step.

[0023] The core preparation step may be a step of preparing a core. The core preparation step may 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.

[0024] The first shell layer preparation step may be the following step: preparing a first shell layer by injecting the prepared core into a first reactor and reacting it. The first reactor contains 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), and the molar ratio of the group III element to the group I element + group III element + group VI element in the first shell layer may be between 1:10 and 1:2.

[0025] The method for manufacturing quantum dots may include a core preparation step, a first shell layer preparation step, and a second shell layer preparation step.

[0026] The second shell layer preparation step may be the following step: preparing a second shell layer by injecting the prepared core / first shell layer into a second reactor and reacting it. 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), and the molar ratio of the group III element to the group III element + group VI element in the second shell layer may be between 1:10 and 1:2.

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

[0028] Step 1-1 may be the following step: preparing 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 may be the following step: adding a purification solvent to the core solution, centrifuging the resulting product, and dispersing the precipitate separated by centrifugation in a dispersion solvent.

[0030] The first shell layer preparation step may include step 2-1 and step 2-2.

[0031] Step 2-1 may be the following step: injecting at least one of a Group I precursor and a Group III precursor (including a Group III element) into a second reactor including oleylamine.

[0032] Step 2-2 may be the following step: injecting a purified core solution and a Group VI precursor including a Group VI element into a first reactor and reacting them.

[0033] The second shell preparation step may include Step 3-1 and Step 3-2.

[0034] Step 2-1 may be the following step: injecting a Group III precursor including a Group III element into a second reactor including oleylamine.

[0035] Step 2-2 may be the following step: injecting a purified core / first shell solution and a Group VI precursor including a Group VI element into a first reactor and reacting them.

[0036] On the other hand, 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, a first shell, and a second shell. The core may include silver (Ag), indium (In), gallium (Ga), and sulfur (S). The first shell may be disposed on the core and include at least one Group I element, at least one Group III element, and at least one Group VI element. The molar ratio of the Group III element to the Group I element + Group III element + Group VI element in the first shell may be between 1:10 and 1:2. The second shell may be disposed on the first shell and include at least one Group III element and at least one Group VI element. The molar ratio of the Group III element to the Group III element + Group VI element in the second shell may be between 1:10 and 1:2.

[0037] Advantageous Effects

[0038] In the quantum dots, the method for manufacturing quantum dots, and the electronic device according to embodiments of the present disclosure, since the amounts of constituent elements configured to form the shell are specified, the wavelength and full width at half maximum of the quantum dots can be reduced.

[0039] In the quantum dots, the method for manufacturing quantum dots, and the electronic device according to embodiments of the present disclosure, the luminous efficiency of the quantum dots may be more excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a cross-sectional view showing quantum dots according to embodiments of the present disclosure;

[0041] Figure 2is a cross-sectional view showing a quantum dot according to another embodiment of the present disclosure;

[0042] Figure 3 is a flowchart of a method for manufacturing a quantum dot according to another embodiment of the present disclosure;

[0043] Figure 4 is a cross-sectional view showing an electronic device according to another embodiment of the present disclosure;

[0044] Figure 5 is a cross-sectional view showing a light-emitting diode according to another embodiment of the present disclosure. Detailed Description of Specific Embodiments

[0045] Hereinafter, some embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. When referring to the elements in the drawings by reference numerals, the same elements will be designated by the same reference numerals even if 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.

[0046] 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 elements in the singular form herein is intended to include the description of elements in the plural form, unless the contrary is explicitly stated.

[0047] 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.

[0048] It should be understood that when an element is referred to as being "connected", "coupled" or "joined" to another element, it can be "directly connected, coupled or joined" to the other element, or can be "indirectly connected, coupled or joined" to the other 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.

[0049] In addition, it should be understood that when an element is referred to as being "above" or "on" another element, it can be not only "directly" above or on the other element, but also "indirectly" above or on the other 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. Further, when an element is referred to as being "above" or "on" a reference portion, the element is above or below the reference portion, not necessarily "above" or "on" the reference portion in the opposite direction of gravity.

[0050] When relative time terms such as "after", "subsequent", "next", "before" are used 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 "directly" or "immediately" are used simultaneously.

[0051] In addition, when referring to any numerical value of an element or corresponding information, it should be considered that the numerical value of the element or corresponding information includes 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.

[0052] 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 axis and the third axis (the second axis and the third axis 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 axis and the minor axis 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.

[0053] 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 the nanocrystals (e.g., in the range of about 1 nm to about 15 nm) can achieve light emission coverage across the entire optical spectrum, thus providing great versatility in color rendering.

[0054] As used herein, the term "shell" refers to a material deposited on a core or on a previously deposited shell, the previously deposited shell having the same or a different composition, the previously deposited shell being the result of a single deposition of the shell material. The exact shell thickness depends on the material as well as the input and conversion of the precursor, and can be reported in nanometers or monolayers. The "target shell thickness" used herein refers to the expected shell thickness used to calculate the required amount of precursor. The "actual shell thickness" used herein refers to the amount of shell material actually deposited after synthesis, and can be measured by methods known in the art. For example, the actual shell thickness can be measured by comparing the particle diameters determined from transmission electron microscopy (TEM) images of the nanocrystals before and after shell synthesis.

[0055] As used herein, the term "group" refers to a group in the periodic table. As used herein, the term "period" refers to a period in the periodic table.

[0056] The "first group" as used herein may refer to group IA (or 1A) and group IB (or 1B), and examples of elements of the first group may include Li, Na, K, Rb, Cs, Cu, Ag, and Au, but are not limited to these.

[0057] The "second group" may refer to group IIA (or 2A) and group IIB (or 2B), and examples of elements of the second group may include Be, Mg, Ca, Sr, Zn, Cd, and Hg, but are not limited to these.

[0058] The "third group" may refer to group IIIA (or 3A) and group IIIB (or 3B), and examples of elements of the third group may include In, Ga, Al, and Tl, but are not limited to these.

[0059] The "fifth group" may refer to group VA (or 5A), and examples of elements of the fifth group may include P, As, Sb, Bi, and N, but are not limited to these.

[0060] The "sixth group" may refer to group VIA (or 6A), and examples of elements of the sixth group may include S, Se, and Te, but are not limited to these.

[0061] As used herein, the term "precursor" refers to a chemical compound 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.

[0062] Embodiments of quantum dots according to the present disclosure will be described below with reference to the accompanying drawings.

[0063] Figure 1is 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.

[0064] Reference Figure 1 , according to an embodiment of the present disclosure, the quantum dot 10 may include a core 12, a first shell 14, and a second shell 16. The quantum dot 10 may also further include another shell 18 outside the second shell 16 as Figure 2 shown, or may further include another intermediate shell (not shown) between the first shell 14 and the second shell 16.

[0065] The core 12 may include Ag, In, Ga, and S. That is, the core 12 may be a quaternary compound including Ag such as a Group I element, In and Ga such as Group III elements, and S such as a Group VI element. The core 12 may be doped with a metal or a non-metal. Before depositing the first shell 14 and the second shell, the core 12 may be purified. The core 12 may be filtered to remove precipitates from the core solution.

[0066] The first shell 14 may include at least one of a Group I element and a Group III element and a Group VI element.

[0067] As described above, "Group I" may refer to Group IA (or 1A) and Group IB (or 1B), and examples of Group I elements may include Li, Na, K, Rb, Cs, Cu, Ag, and Au, but are not limited to these.

[0068] The Group I element included in the first shell 14 may be the same as or different from the Ag included in the core 12. Since the first shell 14 includes the Group I element included in the core 12, vacancy defects on the surface of the core 12 may be removed or supplemented.

[0069] The first shell 14 may include one Group I element, or may include two or more different Group I elements. For example, in the case where the first shell 14 includes two or more different Group I elements, the first shell 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.

[0070] Since the first shell 14 includes the Group I element included in the core 12, vacancy defects on the surface of the core 12 may be removed or supplemented.

[0071] As described above, "Group III" can refer to Group IIIA (or 3A) and Group IIIB (or 3B), and examples of Group III elements can include In, Ga, Al, and Tl, but are not limited to these. "Group VI" can refer to Group VIA (or 6A), and examples of Group VI elements can include S, Se, and Te, but are not limited to these.

[0072] The molar ratio of the Group III element in the first shell to the Group I element + Group III element + Group VI element can be between 1:10 and 1:2.

[0073] When the molar ratio of the Group III element to the Group I element + Group III element + Group VI element is less than 1:10, the anions in the precursor configured to form the component material in the cation complex system (such as I-III-IV) are more than the cations, and the first shell 14 may form other bonds with the core in addition to the I-III-VI composition to be obtained. Since the core 12 exists in the form without the first shell 14 on the core 12, it causes an increase in wavelength and full width at half maximum.

[0074] On the contrary, when the molar ratio of the Group III element to the Group I element + Group III element + Group VI element is greater than 1:2, the cations are far more than the anions, cation exchange occurs between the first shell and the core, the relative thickness of the shell increases, and the core grows unevenly. Therefore, the improvement of optical properties is limited.

[0075] However, when the molar ratio of the Group III element to the Group I element + Group III element + Group VI element is between 1:10 and 1:2, that is, when the amount of the precursor configured to form the first shell 14 is consistent, or when the cations are less than the anions, the first shell 14 can obtain a more excellent and homogeneous first shell 14 structure. As the amount of the Group III element increases, the result of the improved optical properties is the formation of a good III-VI first shell 14, which can be manifested as an increase in luminescence efficiency and a decrease in full width at half maximum.

[0076] The molar ratio of the Group III element in the first shell 14 to the Group I element + Group III element + Group VI element can be between 3:10 and 1:2. According to the above molar ratio, a more excellent and homogeneous first shell 14 structure can be obtained. As the amount of the Group III element further increases, the result of the improved optical properties is the formation of a good III-VI first shell 14, which can be manifested as an increase in luminescence efficiency and a decrease in full width at half maximum.

[0077] For example, the luminescence efficiency of only the core 12 and the first shell 14 can be between 68.2% and 77.2% (see Table 1 below).

[0078] The first shell layer 14 may be doped with a metal or a non-metal. After the deposition of the first shell layer 14, the core 12 / first shell layer 14 can be purified. The core 12 / first shell layer 14 can be filtered to remove precipitates from the core solution.

[0079] The first shell layer 14 may also include another doped group I element.

[0080] The second shell layer 16 can surround and be located on the first shell layer 14, and can include at least one group III element and at least one group VI element. The group III element included in the second shell layer 16 can be the same as or different from the In and Ga included in the core 12. The group VI element included in the second shell layer 16 can be the same as or different from the S included in the core 12.

[0081] The molar ratio of the group III element to the group III element + group VI element in the second shell layer can be between 1:10 and 1:2.

[0082] In the configuration of the second shell layer 16 that is not a composite system, since the molar ratio of the group III element to the group III element + group VI element in the second shell layer 16 is between 1:10 and 1:2, when the amount of the precursor configured to form the second shell layer 16 is consistent or the cations are less than the anions, a more uniform III-VI second shell layer 16 is formed more effectively, so that the optical properties can be improved by suppressing the interface defects between the first shell layer 14 and the second shell layer 16 rather than forming other components.

[0083] In addition, by controlling the stoichiometry of the reaction near the core 12 or the first shell layer 14, or the first shell layer 14 or the second shell layer 16, the second shell layer 16 can be effectively formed, thereby showing a reduction in the full width at half maximum and an increase in the luminescence efficiency.

[0084] The molar ratio of the group III element to the group III element + group VI element in the second shell layer 16 can be between 3:10 and 1:2. According to the above molar ratio, a more excellent and uniform second shell layer 16 structure can be obtained.

[0085] The luminescence efficiency of the core 12, the first shell layer 14, and the second shell layer 16 can be between 85.3% and 95.4% (see Table 1 below).

[0086] The second shell layer 16 may be doped with a metal or a non-metal. After the deposition of the second shell layer 16, the core 12 / first shell layer 14 / second shell layer 16 can be purified. The core 12 / first shell layer 14 / second shell layer 16 can be filtered to remove precipitates from the core solution.

[0087] The second shell layer 16 may also include another doped group III element.

[0088] The thickness of the first shell 14 can be from 2.9 nm to 4.2 nm, and the thickness of the second shell 16 can be from 0.8 nm to 2.5 nm. Additionally, the thickness of the first shell 14 can be from 2.9 nm to 3.9 nm, and the thickness of the second shell 16 can be from 0.8 nm to 1.6 nm.

[0089] The first shell 14 can be completely crystalline, and the second shell 16 can be completely amorphous. The term "completely" crystalline or amorphous as used in the present disclosure means that more than 70% of the shell can be crystalline or amorphous, more than 85% of the shell can be crystalline or amorphous, or more than 95% of the shell can be crystalline or amorphous.

[0090] The first shell 14 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.

[0091] Additionally, the second shell 16 can include one of the following: AlS, AlSe, AlTe, GaS, GaSe, GaTe, InS, InSe, InTe, TiS, TiSe, and TiTe.

[0092] The shape or form of the quantum dots 10 is not particularly limited and can be any form available in the art. More specifically, the shape of the quantum dots 10 can be spherical, pyramidal, multi-armed, or cubic nanoparticles, nanotubes, nanowires, nanofibers, or nanosheet particles.

[0093] The quantum dots 10 can adjust the color of the emitted light according to the particle size, and thus the quantum dots 10 can have various emission colors, such as blue, red, and green.

[0094] According to one embodiment, the diameter of the quantum dots 10 can be from 3 nm to 20 nm.

[0095] On the other hand, embodiments of the present disclosure can provide a method for manufacturing quantum dots.

[0096] Figure 3It is a flowchart of a method for manufacturing quantum dots according to another embodiment of the present disclosure.

[0097] Refer to Figure 3 , the method 20 for manufacturing quantum dots according to an embodiment of the present disclosure may include a core preparation step S22, a first shell preparation step S24, and a second shell preparation step S26.

[0098] In the method 20 for manufacturing quantum dots according to an embodiment of the present disclosure, unless otherwise specified, the characteristics of the core, the first shell, and the second shell are the same as those of the core 12, the first shell 14, and the second shell 16 described for the quantum dot 10 according to the above embodiment.

[0099] The method 20 for 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 first shell and the second shell together using a thermal injection method and a heating method. In addition, the thermal injection method and the heating method can be performed in each of the core preparation step S22, the first shell preparation step S24, and the second shell preparation step S26.

[0100] The core preparation step S22 can be a step of preparing a core.

[0101] The first shell preparation step S24 can be the following step: preparing a first shell by injecting the prepared core into a first reactor and reacting it, the first 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). The molar ratio of the group III element to the group I element + group III element + group VI element in the first shell can be between 1:10 and 1:2.

[0102] The second shell preparation step can be the following step: preparing a second shell by injecting the prepared core / first shell into a second reactor and reacting it, the second reactor containing a group III precursor (including at least one group III element) and a group VI precursor (including at least one group VI element). The molar ratio of the group III element to the group III element + group VI element in the second shell can be between 1:10 and 1:2.

[0103] The core preparation step S22 can be a step of preparing a core. The core preparation step may include step 1-1 and step 1-2.

[0104] Step 1-1 can be the following step: preparing 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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 thereto.

[0110] Each of the silver precursor, indium precursor, gallium precursor, and sulfur precursor injected in Step 1-1 may be a precursor solution mixed with a solvent.

[0111] Through Step 1-1, a core solution including a core can be prepared, and the core can be formed by reacting the silver precursor, indium precursor, gallium precursor, and sulfur precursor in a first reactor.

[0112] Step 1-2 may be the following step: adding a purification solvent to the core solution and centrifuging the resulting product, and dispersing the precipitate separated by centrifugation in a dispersion solvent.

[0113] For example, Step 1-2 may be the following step: 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.

[0114] The purified core solution can be prepared through Steps 1-2.

[0115] In Step 1-1, the core solution can be prepared by injecting and heating a silver precursor, an indium precursor, a gallium precursor, a sulfur precursor, and a solvent in a first reactor.

[0116] Step 2-1 can be the following step: injecting at least one of a Group I precursor and a Group III precursor (including a Group III element) into a second reactor containing oleylamine.

[0117] Step 2-2 can be the following step: injecting the purified core solution and a Group VI precursor into the first reactor and reacting them.

[0118] The Group I element in the first shell can include one or more selected from Li, Na, Cu, Ag, and Au, but is not limited to these. The first shell can include one Group I element, or can include two or more different Group I elements. The first shell can include at least one Group I element and other group elements described below. The first shell 14 may be doped with a metal or a non-metal. At least one Group I element in the first shell can include one or more selected from Cu, Ag, and Au.

[0119] The Group III element in the first shell can include one or more selected from In, Ga, Al, and Tl, but is not limited to these. The Group VI element can include one or more selected from S, Se, and Te, but is not limited to these.

[0120] The first shell preparation step S24 can be the following step: preparing the first shell by injecting the prepared core into a first reactor containing a Group I precursor (including at least one Group I element) and reacting them.

[0121] In one aspect, when the first shell further includes at least one Group III element and at least one Group VI element, the first shell preparation step S24 can be the following step: preparing the first shell by injecting the prepared core and a Group VI precursor into a first reactor containing a Group I precursor (including at least one Group I element) and a Group III precursor (further including at least one Group III element) and reacting them.

[0122] The first shell preparation step S24 can include Step 2-1 and Step 2-2.

[0123] Step 2-1 can be the following step: injecting at least one of a Group I precursor and a Group III precursor (including a Group III element) into a second reactor containing oleylamine.

[0124] Step 2-2 may be the following step: reacting the purified core solution with a Group VI precursor in a first reactor.

[0125] 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 Group I element.

[0126] For example, when the Group I element is Ag, the first precursor may be silver(I) chloride, silver(I) iodide, silver(I) oxide, or silver(I) acetylacetonate.

[0127] The Group III precursor and the Group VI precursor injected in Step 2-1 and Step 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.

[0128] 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.

[0129] 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 here.

[0130] 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 here.

[0131] 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 dibenzyl diselenide, diphenyl diselenide, or hydrogen selenide).

[0132] 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.

[0133] The second shell preparation step S26 may include Step 3-1 and Step 3-2.

[0134] Step 2-1 may be the following step: Injecting a Group III precursor (including Group III elements) into a second reactor containing oleylamine.

[0135] Step 2-2 may be the following step: Injecting a purified core / first shell solution and a Group VI precursor (including Group VI elements) into a first reactor and reacting them.

[0136] The Group III elements included in the second shell 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 may include, for example, one or more selected from S, Se, and Te, but are not limited to these. The Group VI elements included in the second shell may be the same as or different from the S included in the core.

[0137] In the first shell prepared in the first shell preparation step S24, the molar ratio of the Group III element to the Group I element + Group III element + Group VI element may be between 1:10 and 1:2. In the first shell 14, the molar ratio of the Group III element to the Group I element + Group III element + Group VI element may be between 3:10 and 1:2. According to the above molar ratio, a more excellent and uniform first shell 14 structure can be obtained. As the Group III element increases, the result of the improved optical properties is the formation of a good III-VI first shell 14, which can be manifested as an increase in luminous efficiency and a decrease in full width at half maximum.

[0138] In the second shell prepared in the second shell preparation step S26, the molar ratio of the Group III element to the Group III element + Group VI element may be between 1:10 and 1:2. In the second shell 16, the molar ratio of the Group III element to the Group III element + Group VI element may be between 3:10 and 1:2. According to the above molar ratio, a more excellent and uniform second shell 16 structure can be obtained.

[0139] The thickness of the first shell prepared in the first shell preparation step S24 may be 2.9 nm to 4.2 nm, while the thickness of the second shell prepared in the second shell preparation step S26 may be 0.8 nm to 2.5 nm. In addition, the thickness of the first shell prepared in the first shell preparation step S24 may be 2.9 nm to 3.9 nm, while the thickness of the second shell prepared in the second shell preparation step S26 may be 0.8 nm to 1.6 nm.

[0140] The first shell prepared in the first shell preparation step S24 may be completely crystalline, while the second shell prepared in the second shell preparation step S26 may be completely amorphous.

[0141] The first shell prepared in the first shell preparation step S24 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.

[0142] In addition, the second shell prepared in the second shell preparation step S26 may include one of the following: AlS, AlSe, AlTe, GaS, GaSe, GaTe, InS, InSe, InTe, TiS, TiSe, and TiTe.

[0143] On the other hand, according to an embodiment of the present disclosure, there may be provided an ink composition including quantum dots prepared by the quantum dots 10 described with reference to Figure 1 or the method 20 described with reference to Figure 3 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.

[0144] The ink composition according to an embodiment of the present disclosure may be a light-converting ink composition including quantum dots 10, a photocurable monomer, a photoinitiator, and a light diffusing agent.

[0145] According to an embodiment, with respect 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 can be suitably used for various components, such as a color conversion component or an emission layer of an emission device, in a solution process such as inkjet.

[0146] According to an embodiment, there may be provided an optical component formed using the ink composition. For example, the optical component may be a color conversion component.

[0147] According to another aspect, referring to FIG. 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 member 130 disposed in a path of light emitted from the light source 120, and the color conversion member 130 may be formed using the above ink composition.

[0148] According to an embodiment, the light source 120 may be an emitting device. For example, the light source 120 may be an organic light emitting diode (OLED) or an inorganic light emitting diode (ILED or QLED).

[0149] In another aspect, referring to FIG. 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 therebetween. The intermediate layer 220 may include an emission layer including an ink composition containing the above quantum dots.

[0150] According to another aspect of the present disclosure, an electronic device may be provided, the electronic device including a display device and a controller for driving the display device, the display device including the above light emitting diode.

[0151] The electronic device may include, for example, a display device, a lighting device, a solar cell, a portable or mobile terminal (e.g., a smart phone, 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.

[0152] Those skilled in the art can easily apply various electronic devices and device applications using quantum dots, and thus detailed descriptions thereof will be omitted.

[0153] 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.

[0154] This description may refer to an example in which the group 1 element used in the first shell layer is Ag, the group 3 element used in the first shell layer is Ga, and the group 6 element used in the first shell layer is S. Since the method of preparing the core body, the first shell layer, and the second shell layer using the elements described in the above example in the same manner as the following example may be a typical technique, detailed descriptions thereof will be omitted.

[0155] [Embodiment]

[0156] (1) Preparation of a precursor

[0157] (Preparation Example 1) Preparation of Silver Iodide (I)-Oleylamine Precursor Solution

[0158] 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.

[0159] (Preparation Example 2) Preparation of Indium (III) Chloride-Ethanol Precursor Solution

[0160] Place 0.11 g (0.5 mmol) of indium(III) chloride and 5 mL of ethanol in a 10 mL vial to prepare an In precursor solution. The In concentration of this precursor solution is 0.10 M.

[0161] (Preparation Example 3) Preparation of Gallium (III) Chloride-Toluene Precursor Solution

[0162] Place 0.80 g (4.54 mmol) of gallium(III) chloride and 0.8 mL of toluene in a 10 mL vial to prepare a Ga precursor solution. The Ga concentration of this precursor solution is 5.68 M.

[0163] (Preparation Example 4) Preparation of Gallium (III) Acetylacetonate-Toluene Precursor Solution

[0164] Place 1.67 g (4.54 mmol) of gallium(III) chloride and 16 mL of toluene in a 20 mL vial to prepare a Ga precursor solution. The Ga concentration of this precursor solution is 0.28 M.

[0165] (Preparation Example 5) Preparation of S-Oleylamine Precursor Solution

[0166] Place 0.305 g (9.5 mmol) of S and 9.5 mL (28.5 mmol) of oleylamine in a 50 mL flask, reduce the pressure at room temperature (RT) for 30 minutes, 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 S precursor solution. The S concentration of the precursor solution is 1 M.

[0167] (2) Preparation of AgInGaS Quantum Dot Core

[0168] 1) Place 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 in a 50 mL round-bottom flask equipped with a reflux condenser, and heat to 120 °C while maintaining at about 0.005 Torr using a vacuum pump for 30 minutes.

[0169] 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.

[0170] 3) After adding the S-oleylamine solution, it was held 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.

[0171] 4) 5 ml of a tris-(dimethylamino)phosphine ((PDEA)3) + trioctylphosphine (TOP) mixed solution was injected at 280 °C, and then it was cooled to room temperature.

[0172] 5) The prepared AgInGaS quantum dot solution was divided into two equal parts and filled with 42.5 ml of ethanol to prepare a 50 ml AgInGaS core-ethanol solution.

[0173] 6) The solution was centrifuged at 5000 RPM for 5 minutes and then dispersed in 1.2 ml of toluene. The dispersed AgInGaS core-toluene solution was centrifuged at 5000 RPM for 1 minute to remove impurities, and an AgInGaS core quantum dot solution was obtained.

[0174] (3) Example 1: Preparation of AgInGaS / AgGaS Quantum Dots (Ga / (Ag + Ga + S)) = 0.1

[0175] 1) 16 ml of oleylamine was prepared in a 50 ml three-necked round flask equipped with a reflux condenser, heated to 120 °C, and held at 0.005 Torr for 30 minutes using a vacuum pump. After replacing with a nitrogen atmosphere at 120 °C, the quantum dot core of (2) was injected, 0.5 mmol of silver(I) iodide, 0.8 mmol of gallium(III) chloride, and 5 mmol of sulfur were injected, and toluene was removed using a vacuum pump. Then, after replacing with a nitrogen atmosphere, the reaction was carried out at 310 °C for 60 minutes.

[0176] 2) 5 ml of a tris-(dimethylamino)phosphine ((PDEA)3) + trioctylphosphine (TOP) mixed solution was injected at 280 °C and cooled to room temperature to obtain an AgInGaS / AgGaS quantum dot solution.

[0177] 3) By ICP measurement, it was confirmed that the ratio of Ga included in the core of the quantum dots prepared above to Ag, Ga, and S included in the first shell was 0.1.

[0178] (4) Example 2: Preparation of AgInGaS / AgGaS Quantum Dots (Ga / (Ag + Ga + S)) = 0.2

[0179] 1) 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 quantum dot core of (2), inject 0.2 mmol of silver(I) iodide, 1 mmol of gallium(III) chloride, and 5 mmol of sulfur, 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.

[0180] 2) Inject 5 ml of a tris-(dimethylamino)phosphine ((PDEA)3) + trioctylphosphine (TOP) mixed solution at 280 °C and cool to room temperature to obtain an AgInGaS / AgGaS quantum dot solution.

[0181] 3) By ICP measurement, it was confirmed that the ratio of Ga included in the core of the quantum dots prepared above to Ag, Ga, and S included in the first shell was 0.2.

[0182] (5) Example 3: Preparation of AgInGaS / AgGaS Quantum Dots (Ga / (Ag + Ga + S)) = 0.3

[0183] 1) 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 quantum dot core of (2), inject mmol of silver(I) iodide, 3 mmol of gallium(III) chloride, and 4.2 mmol of sulfur, 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.

[0184] 2) Inject 5 ml of a tris-(dimethylamino)phosphine ((PDEA)3) + trioctylphosphine (TOP) mixed solution at 280 °C and cool to room temperature to obtain an AgInGaS / AgGaS quantum dot solution.

[0185] 3) By ICP measurement, it was confirmed that the ratio of Ga included in the core of the quantum dots prepared above to Ag, Ga, and S included in the first shell was 0.3.

[0186] (6) Example 4: Preparation of AgInGaS / AgGaS Quantum Dots (Ga / (Ag + Ga + S)) = 0.4

[0187] 1) 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 quantum dot core of (2), inject 0.13 mmol of silver(I) iodide, 5 mmol of gallium(III) chloride, and 6 mmol of sulfur, 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.

[0188] 2) Inject 5 ml of a mixed solution of tris-(dimethylamino)phosphine ((PDEA)3) + trioctylphosphine (TOP) at 280 °C and cool to room temperature to obtain an AgInGaS / AgGaS quantum dot solution.

[0189] 3) Through ICP measurement, it was confirmed that the ratio of Ga included in the core of the quantum dots prepared above to Ag, Ga, and S included in the first shell was 0.4.

[0190] (7) Example 5: Preparation of AgInGaS / AgGaS Quantum Dots (Ga / (Ag + Ga + S)) = 0.5

[0191] 1) 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 quantum dot core of (2), inject 0.13 mmol of silver(I) iodide, 7 mmol of gallium(III) chloride, and 6 mmol of sulfur, 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.

[0192] 2) Inject 5 ml of a mixed solution of tris-(dimethylamino)phosphine ((PDEA)3) + trioctylphosphine (TOP) at 280 °C and cool to room temperature to obtain an AgInGaS / AgGaS quantum dot solution.

[0193] 3) Through ICP measurement, it was confirmed that the ratio of Ga included in the core of the quantum dots prepared above to Ag, Ga, and S included in the first shell was 0.5.

[0194] (8) Example 6: Preparation of AgInGaS / AgGaS / GaS Quantum Dots (Ga / (Ga + S)) = 0.1

[0195] 1) 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 Example 5 the quantum dot solution, inject 0.8 mmol of gallium(III) chloride and 5 mmol of sulfur, 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.

[0196] 2) Inject 5 ml of a mixed solution of tris-(dimethylamino)phosphine ((PDEA)3) + trioctylphosphine (TOP) at 280 °C and cool to room temperature to obtain an AgInGaS / AgGaS / GaS quantum dot solution.

[0197] 3) Through ICP measurement, it was confirmed that the ratio of Ga included in the first shell of the quantum dots prepared above to Ga and S included in the second shell was 0.1.

[0198] (9) Example 7: Preparation of AgInGaS / AgGaS / GaS Quantum Dots (Ga / (Ga + S)) = 0.2

[0199] 1) 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 Example 5 the quantum dot solution, inject 1 mmol of gallium(III) chloride and 4.5 mmol of sulfur, 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.

[0200] 2) Inject 5 ml of a tris-(dimethylamino)phosphine ((PDEA)3) + trioctylphosphine (TOP) mixed solution at 280 °C and cool to room temperature to obtain an AgInGaS / AgGaS / GaS quantum dot solution.

[0201] 3) By ICP measurement, it was confirmed that the ratio of Ga included in the first shell of the quantum dots prepared above to Ga and S included in the second shell was 0.2.

[0202] (10) Example 8: Preparation of AgInGaS / AgGaS / GaS Quantum Dots (Ga / (Ga + S)) = 0.3

[0203] 1) 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 Example 5 the quantum dot solution, inject 2.4 mmol of gallium(III) chloride and 5.2 mmol of sulfur, 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] 2) Inject 5 ml of a tris-(dimethylamino)phosphine ((PDEA)3) + trioctylphosphine (TOP) mixed solution at 280 °C and cool to room temperature to obtain an AgInGaS / AgGaS / GaS quantum dot solution.

[0205] 3) By ICP measurement, it was confirmed that the ratio of Ga included in the first shell of the quantum dots prepared above to Ga and S included in the second shell was 0.3.

[0206] (11) Example 9: Preparation of AgInGaS / AgGaS / GaS Quantum Dots (Ga / (Ga + S)) = 0.4

[0207] 1) 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 Example 5The quantum dot solution was injected with 4.2 mmol of gallium(III) chloride and 5.2 mmol of sulfur, and toluene was removed using a vacuum pump. Then, after replacing with a nitrogen atmosphere, the reaction was carried out at 310 °C for 100 minutes.

[0208] 2) 5 ml of a tris-(dimethylamino)phosphine ((PDEA)3) + trioctylphosphine (TOP) mixed solution was injected at 280 °C and cooled to room temperature to obtain an AgInGaS / AgGaS / GaS quantum dot solution.

[0209] 3) By ICP measurement, it was confirmed that the ratio of Ga included in the first shell of the quantum dots prepared above to Ga and S included in the second shell was 0.4.

[0210] (12) Example 10: Preparation of AgInGaS / AgGaS / GaS Quantum Dots (Ga / (Ga + S)) = 0.5

[0211] 1) 16 ml of oleylamine was prepared in a 50 ml three-necked round-bottom flask equipped with a reflux condenser, heated to 120 °C, and maintained under a vacuum of 0.005 Torr for 30 minutes. After replacing with a nitrogen atmosphere at 120 °C, the Example 5 quantum dot solution was injected, 6.2 mmol of gallium(III) chloride and 4.2 mmol of sulfur were injected, and toluene was removed using a vacuum pump. Then, after replacing with a nitrogen atmosphere, the reaction was carried out at 310 °C for 100 minutes.

[0212] 2) 5 ml of a tris-(dimethylamino)phosphine ((PDEA)3) + trioctylphosphine (TOP) mixed solution was injected at 280 °C and cooled to room temperature to obtain an AgInGaS / AgGaS / GaS quantum dot solution.

[0213] 3) By ICP measurement, it was confirmed that the ratio of Ga included in the first shell of the quantum dots prepared above to Ga and S included in the second shell was 0.5.

[0214] (13) Comparative Example 1: First Shell (Ga / (Ag + Ga + S)) = 0.05 (AgInGaS / AgGaS)

[0215] 1) 16 ml of oleylamine was prepared in a 50 ml three-necked round-bottom flask equipped with a reflux condenser, heated to 120 °C, and maintained under a vacuum of 0.005 Torr for 30 minutes. After replacing with a nitrogen atmosphere at 120 °C, the quantum dot core of (2) was injected, 0.1 mmol of silver(I) iodide, 3 mmol of gallium(III) chloride, and 48 mmol of sulfur were injected, and toluene was removed using a vacuum pump. Then, after replacing with a nitrogen atmosphere, the reaction was carried out at 310 °C for 60 minutes.

[0216] 2) Inject 5 ml of a mixed solution of tris-(dimethylamino)phosphine ((PDEA)3) + trioctylphosphine (TOP) at 280 °C and cool to room temperature to obtain an AgInGaS / AgGaS quantum dot solution.

[0217] 3) Through ICP measurement, it was confirmed that the ratio of Ga included in the core of the quantum dots prepared above to Ag, Ga, and S included in the first shell was 0.05.

[0218] (14) Comparative Example 2: Second Shell (Ga / (Ga + S)) = 0.05 (AgInGaS / AgGaS / GaS)

[0219] 1) 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 Comparative Example 1 the quantum dot core, inject 3 mmol of gallium(III) chloride and 48 mmol of sulfur, 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.

[0220] 2) Inject 5 ml of a mixed solution of tris-(dimethylamino)phosphine ((PDEA)3) + trioctylphosphine (TOP) at 280 °C and cool to room temperature to obtain an AgInGaS / AgGaS / GaS quantum dot solution.

[0221] 3) Through ICP measurement, it was confirmed that the ratio of Ga included in the first shell of the quantum dots prepared above to Ga and S included in the second shell was 0.05.

[0222] (15) Comparative Example 3: First Shell (Ga / (Ag + Ga + S)) = 0.05 (AgInGaS / AgGaS)

[0223] 1) 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 quantum dot core of (2), inject 0.1 mmol of silver(I) iodide, 41 mmol of gallium(III) chloride, and 3 mmol of sulfur, 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.

[0224] 2) Inject 5 ml of a mixed solution of tris-(dimethylamino)phosphine ((PDEA)3) + trioctylphosphine (TOP) at 280 °C and cool to room temperature to obtain an AgInGaS / AgGaS quantum dot solution.

[0225] 3) Through ICP measurement, it was confirmed that the ratio of Ga included in the core of the quantum dots prepared above to Ag, Ga, and S included in the first shell was 0.95.

[0226] (16) Comparative Example 4: Second Shell (Ga / (Ga + S)) = 0.09 (AgInGaS / AgGaS / GaS)

[0227] 1) 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 Comparative Example 3 the quantum dot core, inject 41 mmol of gallium(III) chloride and 3 mmol of sulfur, 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.

[0228] 2) Inject 5 ml of a tris-(dimethylamino)phosphine ((PDEA)3) + trioctylphosphine (TOP) mixed solution at 280 °C and cool to room temperature to obtain an AgInGaS / AgGaS / GaS quantum dot solution.

[0229] 3) By ICP measurement, it was confirmed that the ratio of Ga included in the first shell of the quantum dots prepared above to Ga and S included in the second shell was 0.95.

[0230] [Experimental Example]

[0231] For the quantum dots manufactured according to Examples 1 to 10 and Comparative Examples 1 to 4 above, the optical properties [emission peak, quantum yield, full width at half maximum (FWHM)] of the quantum dots were confirmed using a QE-2000 device of Otsuka Electronics.

[0232] Table 1 below shows the evaluation results of the optical properties of the prepared quantum dots.

[0233] [Table 1]

[0234]

[0235]

[0236] When the anions of the precursor configured to form the constituent materials in a cationic composite system such as AgGaS are more than the cations (Comparative Examples 1 and 2), it may form other bonds with the core in addition to the AgGaS component to be obtained, and components such as In-Ga-S, Ag-In-Ga-S, and Ag-In-S or Ga-S, In-S, and Ag-S may be obtained. Therefore, it leads to an increase in wavelength and full width at half maximum.

[0237] Conversely, when the cations are far more than the anions (Comparative Examples 3 and 4), cation exchange occurs in the prepared core, and due to the relatively increased thickness of the first shell and the uneven growth of the core, the improvement of optical properties is limited. Therefore, the improvement of optical properties is limited.

[0238] However, when the amount of the precursor configured to form the first shell is consistent or the cations are less than the anions (e.g., Examples 1 to 5), a more excellent and uniform first shell structure can be obtained. The result of the improvement in optical properties caused by the increase in Ga is the formation of a good Ga shell, which is manifested as an increase in luminous efficiency and a decrease in full width at half maximum.

[0239] In the configuration of the second shell that is not a composite system (e.g., Examples 6 to 10), the amount of the precursor configured to form the second shell is consistent, or the cations are less than the anions, and a uniform GaS second shell is formed more effectively. Therefore, the optical properties can be improved by suppressing the interface defects between the first shell and the second shell rather than forming other components. By controlling the stoichiometry in the reaction adjacent to the core or the first shell, the first shell or the second shell, the second shell is formed effectively, thereby showing a decrease in full width at half maximum and an increase in luminous efficiency.

[0240] Through Examples 1 to 10 and Comparative Examples 1 to 4 of AgInGaS / AgGaS / GaS quantum dots, it has been described that when the molar ratio of Ga to Ag+Ga+S in the first shell is between 1:10 and 1:2, and the molar ratio of Ga to Ga+S in the second shell is between 1:10 and 1:2, the wavelength and full width at half maximum of the quantum dots decrease, and the luminous efficiency of the quantum dots is improved.

[0241] In Examples 1 to 10 described above, the AgInGaS / AgGaS / GaS quantum dots are typically described as follows: the Group I element used in the first shell and the second shell is Ag, the Group III element is Ga, and the Group VI element is S. However, even if 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, for the AgInGaS / first shell / second shell quantum dots for the same reason, the molar ratio of Ga to Ag+Ga+S in the first shell is between 1:10 and 1:2, and the molar ratio of Ga to Ga+S in the second shell is between 1:10 and 1:2, which can reduce the wavelength and full width at half maximum and improve the luminous efficiency.

[0242] 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 drawings are provided for illustrative purposes only as examples of the technical idea of the present invention. 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 in 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 scope of their equivalents should be interpreted as being included within the scope of the present invention.

[0243] Cross-Reference to Related Applications

[0244] This application claims the benefit of priority of Korean Patent Application No. 10-2022-0154931, filed on November 17, 2022, the entire contents of which are hereby expressly incorporated herein by reference 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 first shell on the core, the first shell comprising at least one group I element, at least one group III element, and at least one group VI element, wherein the molar ratio of the group III element in the first shell to the sum of the group I element + group III element + group VI element is between 1:10 and 1:

2.

2. The quantum dot according to claim 1, further comprising: a second shell on the first shell, the second shell comprising at least one group III element and at least one group VI element, wherein the molar ratio of the group III element in the second shell to the sum of the group III element + group VI element is between 1:10 and 1:

2.

3. The quantum dot according to claim 1, wherein, The molar ratio of the group III element in the first shell to the sum of the group I element + group III element + group VI element is between 3:10 and 1:

2.

4. The quantum dot according to claim 2, wherein, The molar ratio of the group III element in the second shell to the sum of the group III element + group VI element is between 3:10 and 1:

2.

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

6. The quantum dot according to claim 2, wherein, The at least one group III element included in the first shell and the second shell comprises one or more selected from Al, Ga, In, and Tl, and the group III element included in the first shell and the group III element included in the second shell are the same or different.

7. The quantum dot according to claim 2, wherein, The at least one group VI element included in the first shell and the second shell comprises one or more selected from S, Se, and Te, and the group VI element included in the first shell and the group VI element included in 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 first shell preparation step of preparing a first shell by injecting the prepared core into a first reactor and reacting it, the first reactor containing at least one of a group I precursor and a group III precursor and a group VI precursor, the group I precursor comprising a group I element, the group III precursor comprising a group III element, the group VI precursor comprising a group VI element, wherein the molar ratio of the group III element in the first shell to the sum of the group I element + group III element + group VI element is between 1:10 and 1:

2.

9. The method according to claim 8, further comprising: Second shell preparation step: The second shell is prepared by injecting the prepared core and the first shell into a second reactor and reacting them. The second reactor contains a Group III precursor and a Group VI precursor. The Group III precursor includes at least one Group III element, and the Group VI precursor includes at least one Group VI element. Wherein, the molar ratio of the Group III element in the second shell to the sum of the Group III element and the Group VI element is between 1:10 and 1:

2.

10. The method according to claim 8, wherein, The molar ratio of the Group III element in the first shell to the sum of the Group I element, the Group III element, and the Group VI element is between 3:10 and 1:

2.

11. The method according to claim 9, wherein, The molar ratio of the Group III element in the second shell to the sum of the Group III element and the Group VI element is between 3:10 and 1:

2.

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

13. The method according to claim 9, wherein At least one Group III element included in the first shell and the second shell includes one or more selected from Al, Ga, In, and Tl, and The Group III element included in the first shell is the same as or different from the Group III element included in the second shell.

14. The method according to claim 9, wherein, At least one Group VI element included in the first shell and the second shell includes one or more selected from S, Se, and Te, and The Group VI element included in the first shell is the same as or different from the Group VI element included in the second shell.

15. An electronic device, comprising: A display device including a light-emitting diode, and the light-emitting diode includes 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 first shell on the core, the first shell includes at least one Group I element, at least one Group III element, and at least one Group VI element. Wherein, the molar ratio of the Group III element in the first shell to the sum of the Group I element, the Group III element, and the Group VI element is between 1:10 and 1:

2.

16. The electronic device according to claim 15, wherein, The quantum dots further include: A second shell located on the first shell, the second shell includes at least one Group III element and at least one Group VI element. Wherein, the molar ratio of the Group III element in the second shell to the sum of the Group III element and the Group VI element is between 1:10 and 1:

2.

17. The electronic device according to claim 15, wherein, The molar ratio of the Group III element in the first shell to the sum of the Group I element, the Group III element, and the Group VI element is between 3:10 and 1:

2.

18. The electronic device according to claim 16, wherein, The molar ratio of the Group III element in the second shell to the sum of the Group III element and the Group VI element is between 3:10 and 1:2.

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