Quantum dots, and quantum dot-polymer composites and electronic devices comprising the same

Abstract

Disclosed are quantum dots, quantum dot-polymer composites, and electronic devices including the same. The quantum dot includes: a core including a first semiconductor nanocrystal; a first shell on the core including a second semiconductor nanocrystal, the second semiconductor nanocrystal including a Group III-VI compound; and a second shell on the first shell including a third semiconductor nanocrystal, the third semiconductor nanocrystal having a composition different from that of the second semiconductor nanocrystal; wherein one of the first semiconductor nanocrystal and the third semiconductor nanocrystal includes a Group III-V compound.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2020-0091655, filed on July 23, 2020, in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Disclosed are quantum dots, as well as quantum dot-polymer composites and electronic devices. Background Art

[0004] Different from bulk (body) material, the physical properties (for example, energy band gap, melting point etc.) known as intrinsic properties of nanoparticles can be controlled by changing their particle size.For example, the semiconductor nanocrystal particles also referred to as quantum dots are crystalline materials with the size of several (several) nanometers.Such semiconductor nanocrystal particles have such small size that they have large surface area per unit volume and present quantum confinement effect, and therefore have a different property from the characteristic of the bulk material with identical composition.Quantum dots can absorb light from an excitation source to be excited, and can emit energy corresponding to their energy band gap. Summary of the Invention

[0005] One embodiment provides quantum dots capable of achieving improved optical properties, such as luminous efficiency and full width at half maximum (FWHM).

[0006] Another embodiment provides a quantum dot-polymer composite including the aforementioned quantum dots.

[0007] Another embodiment provides an electronic device including the aforementioned quantum dots or quantum dot-polymer composite.

[0008] According to an embodiment, a quantum dot includes: a core including a first semiconductor nanocrystal; a first shell including a second semiconductor nanocrystal on the core, the second semiconductor nanocrystal including a III-VI compound; and a second shell including a third semiconductor nanocrystal on the first shell, the third semiconductor nanocrystal having a composition different from that of the second semiconductor nanocrystal, wherein one of the first semiconductor nanocrystal and the third semiconductor nanocrystal includes a III-V compound.

[0009] One of the first semiconductor nanocrystal and the third semiconductor nanocrystal may include a Group III-V compound, and the other may include a Group II-VI compound.

[0010] The first semiconductor nanocrystal may include a Group III-V compound, the third semiconductor nanocrystal may include a Group II-VI compound, and a ratio (m2 / m3) of an effective mass (m2) of the second semiconductor nanocrystal to an effective mass (m3) of the third semiconductor nanocrystal may be in a range greater than or equal to about 0.4 and less than or equal to about 2.5.

[0011] The second semiconductor nanocrystal may have a thickness less than about 0.39 m e , for example, less than or equal to about 0.34 m e The effective mass of the electron.

[0012] The first semiconductor nanocrystal may include a Group III-V compound and the third semiconductor nanocrystal may include a Group II-VI compound, wherein the electron effective mass (m e2 ) and the electron effective mass (m e3 ) (m e2 -m e3 ) (or the absolute value of the difference) may be less than or equal to about 0.2 m e , and the effective mass of the hole in the second semiconductor nanocrystal (m h2 ) and the hole effective mass (m h3 ) (m h2 -m h3 ) (or the absolute value of the difference) may be less than or equal to about 1.5 m e .

[0013] The III-V compound of the first semiconductor nanocrystal may further include a Group II element. The III-V compound of the first semiconductor nanocrystal may include InP, GaP, InAs, GaAs, InSb, GaSb, InGaP, InAsP, InSbP, InGaAs, InZnP, GaZnP, InZnAs, or a combination thereof.

[0014] The second semiconductor nanocrystals may include gallium (Ga), such as gallium chalcogenide.

[0015] The second semiconductor nanocrystal may include (M 1 )2(X 1 )3 represents a compound (wherein M 1 is selected from In, Ga, and combinations thereof, and X 1 selected from S, Se, Te, and combinations thereof), a compound represented by Chemical Formula 1, or a combination thereof:

[0016] [Chemical Formula 1]

[0017] (M 2 2-x M 3 x )(X 2 3-y X 3 y )

[0018] In Chemical Formula 1,

[0019] M 2 and M 3 Each independently selected from In, Ga, and combinations thereof, X 2 and X 3 Each is independently selected from S, Se, Te, and combinations thereof, x is in the range of 0 or greater and 2 or less, and y is in the range of 0 or greater and 3 or less.

[0020] The II-VI compound may include zinc chalcogenide, and in particular, may include one or more selected from the group consisting of ZnSe, ZnTeSe, ZnSeS, ZnTeS, ZnS, and combinations thereof. The II-VI compound may include zinc, sulfur, and selenium, or zinc, selenium, and tellurium.

[0021] In the quantum dots, a molar ratio of the Group III element to the Group V element may be in the range of about 1 to about 50, for example, about 3 to about 20.

[0022] In the quantum dots, a molar ratio of the Group III element to the Group II element may be greater than about 0 and less than or equal to about 5, for example, in a range of about 0.05 to about 2.

[0023] In the quantum dots, a molar ratio of the Group III element to the Group VI element may be greater than about 0 and less than or equal to about 5, for example, about 0.05 to about 2.

[0024] In the quantum dot, the first semiconductor nanocrystals may include indium (In), the second semiconductor nanocrystals may include gallium (Ga), and a molar ratio of gallium to indium (Ga / In) may be in a range of about 0.05 to about 4.5.

[0025] The second shell may include at least one selected from the group consisting of: a II-VI compound, a III-V compound, and combinations thereof.

[0026] The second shell may include a plurality of layers, and the plurality of layers may include different types of Group II-VI compounds.

[0027] A layer relatively close to the core among the plurality of layers may include Se. A layer relatively far from the core among the plurality of layers may include S.

[0028] The energy band gap of the second semiconductor nanocrystal may be greater than the energy band gap of the first semiconductor nanocrystal and the energy band gap of the third semiconductor nanocrystal.

[0029] The second shell may include a plurality of layers, and the third semiconductor nanocrystal included in a layer closest to the first shell among the plurality of layers may have a smaller energy band gap than the second semiconductor nanocrystal of the first shell.

[0030] A lattice mismatch ratio (mismatch degree) between the first semiconductor nanocrystal and the second semiconductor nanocrystal may be less than or equal to about 15%.

[0031] The maximum emission peak of the quantum dot may have a full width at half maximum (FWHM) of less than or equal to about 40 nm, and the quantum dot may have a quantum efficiency of greater than or equal to about 55%.

[0032] According to another embodiment, a quantum dot-polymer composite including the aforementioned quantum dots is provided. The quantum dot-polymer composite may include: a polymer matrix; and the aforementioned quantum dots dispersed in the polymer matrix.

[0033] The polymer matrix may include at least one selected from the group consisting of a thiol-ene polymer, a (meth)acrylate-based polymer, a urethane-based resin, an epoxy-based polymer, a vinyl-based polymer, and a silicone resin. The quantum dot-polymer composite may further include metal oxide particulates.

[0034] According to another embodiment, an electronic device includes: a first electrode and a second electrode facing each other; and

[0035] an active layer between the first electrode and the second electrode;

[0036] The active layer includes the aforementioned quantum dots.

[0037] According to another embodiment, an electronic device includes a light source and a light emitting element,

[0038] wherein the light emitting element comprises the aforementioned quantum dots, and

[0039] The light source is configured to provide incident light to the light emitting element.

[0040] The incident light may have a photoluminescence peak wavelength within a range of greater than or equal to about 400 nm and less than or equal to about 500 nm.

[0041] The electronic device may be an electroluminescent device, an organic light emitting diode (OLED), a sensor, an image sensor, a solar cell, or a liquid crystal display (LCD) device.

[0042] In an embodiment, a quantum dot comprises: a core comprising a first semiconductor nanocrystal comprising indium and phosphorus; a first shell comprising a second semiconductor nanocrystal comprising gallium and sulfur; and a second shell comprising a third semiconductor nanocrystal comprising zinc and sulfur; zinc and selenium; or a combination thereof.

[0043] The quantum dots can exhibit improved luminescence properties (e.g., improved excitation light absorption and reduced full width at half maximum (FWHM)). The quantum dots can be used in various display devices and biomarkers (e.g., biosensors or bioimaging), photodetectors, solar cells, hybrid composites, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a schematic diagram showing a cross-sectional structure of a quantum dot according to an embodiment.

[0045] Figure 2 is a schematic cross-sectional view of an electroluminescent display device according to one embodiment.

[0046] Figure 3 is a schematic cross-sectional view of an electroluminescent display device according to another embodiment.

[0047] Figure 4 is a schematic cross-sectional view of an electroluminescent display device according to another embodiment.

[0048] Figure 5 is a schematic diagram of a photoluminescent display device according to one embodiment.

[0049] Figure 6A and 6B is a schematic diagram of a photoluminescent display device according to another embodiment.

[0050] Figure 7 A transmission electron microscope (TEM) image of the quantum dots prepared in Example 2 is shown.

[0051] Figure 8 Graphs showing the results of X-ray photoelectron spectroscopy (XPS) analysis of quantum dots according to Example 2.

[0052] Figure 9 Graphs showing the photoluminescence analysis results of quantum dots according to Example 2 and Comparative Example 1.

[0053] Figure 10 is a graph showing the results of UV-Vis spectrum analysis of quantum dots according to Example 2 and Comparative Example 1. DETAILED DESCRIPTION

[0054] The present disclosure will be described more fully hereinafter in the following detailed description, wherein some but not all embodiments of the present disclosure are described with reference to the accompanying drawings. The present disclosure can be embodied in many different forms and is not to be construed as being limited to the embodiments set forth herein. If not otherwise defined, all terms (including technical and scientific terms) in the specification sheets may be defined as commonly understood by those skilled in the art. Terms defined in common dictionaries may not be idealized or exaggeratedly interpreted unless clearly defined. In addition, unless explicitly described to the contrary, the word "comprising" will be understood to imply the inclusion of the stated elements, but does not exclude any other elements.

[0055] In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like reference numerals refer to like elements throughout the specification.

[0056] It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

[0057] Furthermore, the singular includes the plural unless otherwise mentioned.

[0058] As used herein, when no definition is otherwise provided, "substituted" refers to a compound or moiety wherein at least one of its hydrogen atoms is replaced with a substituent selected from the group consisting of C1-C30 alkyl, C2-C30 alkenyl, C2-C30 alkynyl, C6-C30 aryl, C7-C30 alkylaryl, C1-C30 alkoxy, C1-C30 heteroalkyl, C3-C30 heteroalkylaryl, C3-C30 cycloalkyl, C3-C15 cycloalkenyl, C6-C30 cycloalkynyl, C2-C30 heterocycloalkyl, halogen (-F, -Cl, -Br, or -I), hydroxyl (-OH), nitro (-NO2), cyano (-CN), amino (-NRR', wherein R and R' are independently hydrogen or C1 -C6 alkyl), an azido group (-N3), an amidine group (-C(=NH)NH2), a hydrazine group (-NHNH2), a hydrazone group (=N(NH2)), an aldehyde group (-C(=O)H), a carbamoyl group (-C(O)NH2), a thiol group (-SH), an ester group (-C(=O)OR, wherein R is a C1-C6 alkyl group or a C6-C12 aryl group), a carboxyl group (-COOH) or a salt thereof (-C(=O)OM, wherein M is an organic or inorganic cation), a sulfonic acid group (-SO3H) or a salt thereof (-SO3M, wherein M is an organic or inorganic cation), a phosphate group (-PO3H2) or a salt thereof (-PO3MH or -PO3M2, wherein M is an organic or inorganic cation), and combinations thereof.

[0059] As used herein, a "hydrocarbon group" refers to a group comprising carbon and hydrogen (e.g., an alkyl, alkenyl, alkynyl, or aryl group). A hydrocarbon group may be a monovalent or higher valent group formed by removing one or more hydrogen atoms from an alkane, alkene, alkyne, or aromatic hydrocarbon. In a hydrocarbon group, at least one methylene group may be replaced by an oxygen moiety, a carbonyl moiety, an ester moiety, -NH-, or a combination thereof.

[0060] As used herein, "alkyl" refers to a linear or branched saturated monovalent hydrocarbon group (methyl, ethylhexyl, etc.).

[0061] As used herein, "alkenyl" refers to a straight-chain or branched monovalent hydrocarbon group having one or more carbon-carbon double bonds.

[0062] As used herein, "alkynyl" refers to a straight-chain or branched monovalent hydrocarbon group having one or more carbon-carbon triple bonds.

[0063] As used herein, "aryl" refers to a group formed by removing at least one hydrogen from an aromatic hydrocarbon (eg, phenyl or naphthyl).

[0064] As used herein, "hetero" refers to compounds comprising 1 to 3 heteroatoms of N, O, S, Si, P, or combinations thereof.

[0065] As used herein, "dispersion" refers to a dispersion in which the dispersed phase is a solid and the continuous phase comprises a liquid. For example, "dispersion" refers to a colloidal dispersion in which the dispersed phase has a size greater than or equal to about 1 nm, such as greater than or equal to about 2 nm, greater than or equal to about 3 nm, or greater than or equal to about 4 nm and several micrometers (μm) or less (e.g., less than or equal to about 2 μm, or less than or equal to about 1 μm).

[0066] As used herein, "Group" refers to a Group of the Periodic Table.

[0067] As used herein, when no definition is otherwise provided, “Group II” refers to Group IIA and Group IIB, and examples of Group II may include Zn, Hg, and Mg, but are not limited thereto.

[0068] As used herein, when no definition is otherwise provided, “Group III” may include Group IIIA and Group IIIB, and examples of Group III metals include Al, In, Ga, and Tl, but are not limited thereto.

[0069] As used herein, when no definition is otherwise provided, "Group V" includes Group VA and includes nitrogen, phosphorus, arsenic, antimony, and bismuth, but is not limited thereto.

[0070] As used herein, when no definition is otherwise provided, "Group VI" includes Group VIA and includes, but is not limited to, sulfur, selenium, and tellurium.

[0071] Semiconductor nanocrystal particles, also known as (e.g., colloidal) quantum dots, are crystalline materials of several nanometers in size and can have a large surface area per unit volume and can exhibit quantum confinement effects. Quantum dots can absorb light from an excitation source to become excited and can emit energy corresponding to their energy band gap.

[0072] Quantum dots have potential applicability for a variety of electronic devices due to their unique photoluminescent properties. The quantum dots with properties currently applicable to electronic devices, etc. are mainly based on cadmium quantum dots. However, cadmium causes serious environmental / health problems and is therefore one of the restricted elements. Quantum dots that do not contain cadmium (hereinafter, also referred to as non-cadmium quantum dots) can be, for example, nanocrystals based on III-V groups. Compared with those based on cadmium quantum dots, quantum dots that do not contain cadmium have insufficient luminescent properties (e.g., blue light absorptivity) and stability. Blue light (e.g., having a wavelength of less than or equal to about 460nm) can be used as an energy excitation source for quantum dots. Quantum dots based on cadmium have high absorption intensity for blue light, but in the case of non-cadmium quantum dots, the absorption intensity at the blue light place is not high, which can result in reduced brightness of display devices.

[0073] Since polarized light passing through liquid crystal shows color when passing through an absorptive color filter, conventional liquid crystal displays (hereinafter, LCDs) have the following problems: brightness deteriorates due to a narrow viewing angle and low light transmittance of an absorptive color filter. A photoluminescent color filter is one of the alternatives for overcoming the technical limitations of a display device including an absorptive color filter. A quantum dot-based color filter uses blue light instead of white light as excitation light, and a color filter is provided in front of the device to convert the excitation light into desired light (e.g., green light / red light). Therefore, a quantum dot-based color filter can solve technical problems such as liquid crystal displays (e.g., narrow viewing angle and significant light loss). Light having linearity can be scattered in all directions when passing through a liquid crystal layer, thereby solving the viewing angle problem and avoiding optical loss caused by an absorptive color filter.

[0074] However, when using a color filter based on quantum dots, the excitation light propagating in the forward direction (forward direction) of the device can become a serious problem and needs to be blocked. The currently available cadmium-free quantum dots do not provide sufficient absorptivity to deal with this problem. The introduction of light scatterers can be considered to improve the absorptivity. However, this can lead to an increase in manufacturing costs. Light scatterers have a high external light reflectivity, which can lead to an increase in external light reflection and can provide additional difficulties in the process due to the increase in solids. In order to block the excitation light, it has been proposed to use a blue light filter, which can cause an increase in cost and an increase in external light reflection, thereby leading to optical loss, contrast deterioration and reduced clarity (sharpness) of the display device.

[0075] On the other hand, in order to achieve high color reproducibility for displays using quantum dots, quantum dots with a lower half-width (FWHM) may be required. However, compared to cadmium-based cores, such as CdSe cores, quantum dots based on III-V compounds containing indium (In) and phosphorus (P) in the core have a smaller band gap and a larger Bohr radius, so the variation in FWHM depending on the size of the core is large. In addition, since the core containing indium and phosphorus is sensitive to surface oxidation, the FWHM of core-shell quantum dots can be further increased compared to the core. It is difficult for quantum dots based on III-V compound cores (such as InP) to emit light of a desired wavelength (e.g., greater than about 470 nm, greater than or equal to about 475 nm, or greater than or equal to about 480 nm and less than or equal to about 580 nm) while emitting light at a reduced level of FWHM (e.g., less than or equal to about 40 nm, or less than or equal to about 35 nm).

[0076] The quantum dot according to the embodiment may exhibit increased excitation light absorptivity and reduced full width at half maximum (FWHM) without including cadmium because it has a configuration to be described later, which may solve the above-mentioned problems.

[0077] Reference Figure 1 Quantum dots (also referred to as quantum dots) according to embodiments are described. Figure 1 Schematically shows a cross-sectional structure of a quantum dot according to an embodiment.

[0078] refer to Figure 1 , a quantum dot 1 according to an embodiment includes: a core 2 including a first semiconductor nanocrystal; a first shell 4 including a second semiconductor nanocrystal on the core 2, the second semiconductor nanocrystal including a Group III-VI compound; and a second shell 6 including a third semiconductor nanocrystal on the first shell 4, wherein one of the first semiconductor nanocrystal and the third semiconductor nanocrystal includes a Group III-V compound.

[0079] One of the first semiconductor nanocrystal and the third semiconductor nanocrystal may include a Group III-V compound, and the other may include a Group II-VI compound.

[0080] In an embodiment, the first semiconductor nanocrystal may include a III-V compound, and the third semiconductor nanocrystal may include a II-VI compound. In this case, the quantum efficiency of the quantum dot 1 may be controlled by adjusting the ratio (m2 / m3) of the effective mass (m2) of the second semiconductor nanocrystal to the effective mass (m3) of the third semiconductor nanocrystal to a certain range.

[0081] Effective mass is the apparent mass of the charge carriers (electrons or holes) present in the crystal. In order to illustrate the behavior of charge carriers in the crystal, there are difficulties when considering the interaction with many atoms in the lattice. However, by introducing effective mass, the behavior of charge carriers can be easily predicted by maximizing the physical laws applied to free electrons. Effective mass can be calculated as follows by equation 1 between the Ek energy band of free electrons and the mass of electrons, and can also be measured by experiments such as cyclotron resonance.

[0082] [Equation 1]

[0083]

[0084] In Equation 1,

[0085] m* is the effective mass, E is the kinetic energy, k is the wave vector, and h (=h / 2π) is the reduced Planck constant.

[0086] The first semiconductor nanocrystal may include a III-V compound, and the third semiconductor nanocrystal includes a II-VI compound, wherein a ratio (m2 / m3) of an effective mass (m2) of the second semiconductor nanocrystal relative to an effective mass (m3) of the third semiconductor nanocrystal may be greater than about 2.5 and less than or equal to about 2.5. If the (electron and / or hole) effective mass (m2) of the second semiconductor nanocrystal included in the first shell and the (electron and / or hole) effective mass (m3) of the third semiconductor nanocrystal included in the second shell are within a similar range to each other (i.e., the ratio (m2 / m3) of the effective masses is greater than about 0.4 and less than or equal to about 2.5), the quantum efficiency of the quantum dot may be improved.

[0087] The ratio of the effective masses (m2 / m3) may be, for example, greater than or equal to about 0.5, greater than or equal to about 0.6, greater than or equal to about 0.7, greater than or equal to about 0.8, greater than or equal to about 0.9, or greater than or equal to about 1.0 and less than or equal to about 2.4, less than or equal to about 2.3, less than or equal to about 2.2, less than or equal to about 2.1, less than or equal to about 2.0, less than or equal to about 1.9, less than or equal to about 1.8, less than or equal to about 1.7, less than or equal to about 1.6, less than or equal to about 1.5, less than or equal to about 1.3, or less than or equal to about 1.2.

[0088] The electron effective mass (m e2 ) and the electron effective mass (m e3 ) (m e2 -m e3 ) (or the absolute value of the difference) may be less than or equal to about 0.2 m e , less than or equal to about 0.15m e , less than or equal to about 0.1m e , or less than or equal to approximately 0.05m e In addition, the effective mass of the hole in the second semiconductor nanocrystal (m h2 ) and the hole effective mass (m h3 ) (m h2 -m h3 ) (or the absolute value of the difference) may be less than or equal to about 1.5 m e , less than or equal to about 1.0m e , less than or equal to about 0.7m e , less than or equal to about 0.5m e , or less than or equal to about 0.3m e .

[0089] The second semiconductor nanocrystal may have a thickness less than about 0.39 m e , less than or equal to approximately 0.34m e , less than or equal to about 0.30m e , less than or equal to about 0.25m e , or less than or equal to approximately 0.20m e In addition, the second semiconductor nanocrystal may have an electron effective mass of less than about 1.76m e , less than or equal to about 1.5m e , less than or equal to about 1.2m e , or less than or equal to approximately 0.9m e The effective mass of the hole.

[0090] The Group III-V compound included in the first semiconductor nanocrystal of the core 2 and the third semiconductor nanocrystal included in the second shell 6 may include indium and phosphorus. The first semiconductor nanocrystal or the third semiconductor nanocrystal may further include a Group II element. The Group III-V compound may include InP, GaP, InAs, GaAs, InSb, GaSb, InGaP, InAsP, InSbP, InGaAs, InZnP, GaZnP, InZnAs, or a combination thereof.

[0091] The second semiconductor nanocrystal including the Group III-VI compound included in the first shell 4 may be controlled so that the quantum dot 1 may emit light of a desired wavelength and the quantum efficiency of the quantum dot 1 may be improved.

[0092] Although not wishing to be bound by a particular theory, the core 2 comprising the first semiconductor nanocrystal has defects on the surface during the shell formation process, making it difficult to form a uniform shell. As a result, the manufactured quantum dot 1 may have an increased number of traps on the surface or a non-uniform shape or size distribution. However, the first shell 4 comprising a Group III-VI compound (e.g., a gallium chalcogenide) passivates the core 2 relatively uniformly, so that the degree of electron-hole overlap in the quantum dot 1 can be increased, surface defects can be reduced, and the quantum dot 1 can have a uniform shape or size distribution.

[0093] The second semiconductor nanocrystal may include gallium (Ga). For example, the second semiconductor nanocrystal may include gallium chalcogenide.

[0094] The second semiconductor nanocrystal may include (M 1 )2(X 1 )3 represents a compound (wherein M 1 is selected from In, Ga and combinations thereof, and X 1 selected from S, Se, Te, and combinations thereof), a compound represented by Chemical Formula 1, or a combination thereof:

[0095] [Chemical Formula 1]

[0096] (M 2 2-x M 3 x )(X 2 3-y X 3 y )

[0097] In Chemical Formula 1,

[0098] M 2 and M 3 Each independently selected from In, Ga, and combinations thereof, X 2and X 3 Each is independently selected from S, Se, Te, and combinations thereof, x is in the range of 0 or greater and 2 or less, and y is in the range of 0 or greater and 3 or less.

[0099] Specific examples of the second semiconductor nanocrystals may include InS, In2S3, InSe, In2Se3, InTe, In2Te3, GaS, Ga2S3, GaSe, Ga2Se3, GaTe, Ga2Te3, In2Se 3-y Te y 、Ga2Se 3-y Te y 、In2S 3-y Se y 、Ga2S 3-y Se y etc., and y ranges from 0-3, for example, 1-2.

[0100] The II-VI compound included in the first semiconductor nanocrystal of the core 2 and the third semiconductor nanocrystal included in the second shell 6 may include zinc chalcogenide. The zinc chalcogenide may be a compound including zinc and a chalcogen element (e.g., selenium, tellurium, sulfur, or a combination thereof). In particular, it may include one or more selected from the following: ZnSe, ZnTeSe, ZnSeS, ZnTeS, ZnS, and a combination thereof. The II-VI compound may include zinc, sulfur, and selenium, or zinc, selenium, and tellurium. In an embodiment, the II-VI compound may include zinc and sulfur. The II-VI compound includes zinc and sulfur, and may further include selenium, tellurium, or a combination thereof.

[0101] The molar ratio of the group III element to the group V element in the quantum dot 1 may be in the range of about 1 to about 50. In an embodiment, the molar ratio of the group III element to the group V element may be greater than or equal to about 1, greater than or equal to about 2, greater than or equal to about 3, or greater than or equal to about 4 and less than or equal to about 50, less than or equal to about 45, less than or equal to about 40, less than or equal to about 35, less than or equal to about 30, less than or equal to about 25, or less than or equal to about 20. Within the molar ratio within the above range, the luminous efficiency and full width at half maximum (FWHM) of the quantum dot 1 are easily controlled.

[0102] In quantum dot 1, when the first semiconductor nanocrystal includes indium (In) and the second semiconductor nanocrystal includes gallium (Ga), the molar ratio of gallium to indium (Ga / In) may be in the range of about 0.05 to about 4.5. In embodiments, the molar ratio of gallium to indium (Ga / In) may be greater than or equal to about 0.05, greater than or equal to about 0.1, greater than or equal to about 0.15, greater than or equal to about 0.2, greater than or equal to about 0.25, greater than or equal to about 0.3, greater than or equal to about 0.35, or greater than or equal to about 0.4 and less than or equal to about 4.5, less than or equal to about 4.0, less than or equal to about 3.5, less than or equal to about 3.0, less than or equal to about 2.5, less than or equal to about 2.0, less than or equal to about 1.9, less than or equal to about 1.8, less than or equal to about 1.7, or less than or equal to about 1.6.

[0103] In addition, in the quantum dot 1, the molar ratio of the group III element to the group II element may be greater than about 0 and less than or equal to about 5, for example, greater than or equal to about 0.01, greater than or equal to about 0.02, greater than or equal to about 0.03, greater than or equal to about 0.04, or greater than or equal to about 0.05 and less than or equal to about 5, less than or equal to about 4, less than or equal to about 3, or less than or equal to about 2. Within the above range of moles, the luminous efficiency and full width at half maximum (FWHM) of the quantum dot 1 are easily controlled.

[0104] In addition, in the quantum dot 1, the molar ratio of the Group III element to the Group VI element may be greater than about 0 and less than or equal to about 5, for example, greater than or equal to about 0.01, greater than or equal to about 0.02, greater than or equal to about 0.03, greater than or equal to about 0.04, or greater than or equal to about 0.05 and less than or equal to about 5, less than or equal to about 4, less than or equal to about 3, or less than or equal to about 2. Within the molar ratio within the above range, the luminous efficiency and full width at half maximum (FWHM) of the quantum dot 1 are easily controlled.

[0105] The content and molar ratio of each element in the quantum dots 1 described herein can be confirmed by appropriate analytical methods (e.g., inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray photoelectron spectroscopy (XPS), ion chromatography, TEM-EDS (transmission electron microscopy energy dispersive X-ray spectroscopy, etc.).

[0106] The second shell 6 may include a third semiconductor nanocrystal selected from the group consisting of a II-VI compound, a III-V compound, and a combination thereof. The II-VI compound and the III-V compound are the same as described above.

[0107] The second shell 6 may include a plurality of layers, and the plurality of layers may include different types of II-VI compounds. Among the plurality of layers, the layer relatively close to the core (i.e., the layer closest to the first shell) may include Se. Among the plurality of layers, the layer relatively far from the core (i.e., the layer farthest from the first shell) may include S. For example, the second shell 6 may include a first layer formed above the first shell 4 and a second layer formed thereon, wherein the first layer and the second layer may include different types of II-VI compounds. In an embodiment, the first layer may include zinc and selenium, and the second layer may include zinc and sulfur.

[0108] In an embodiment, the energy band gap of the second semiconductor nanocrystal may be greater than the energy band gap of the first semiconductor nanocrystal and the energy band gap of the third semiconductor nanocrystal. In the energy band arrangement, the equilibrium band edge and the conduction band edge of the first semiconductor nanocrystal may be within the energy band gap of the second semiconductor nanocrystal. The equilibrium band edge and the conduction band edge of the third semiconductor nanocrystal may also be within the energy band gap of the second semiconductor nanocrystal.

[0109] The second semiconductor nanocrystal (Group III-VI) may have a band gap larger than the band gap of the first semiconductor nanocrystal. For example, the energy band gap of the second semiconductor nanocrystal may be greater than about 1.0 times and about 3.0 times or less, about 2.5 times or less, about 2.0 times or less, or about 1.5 times or less of the energy band gap of the first semiconductor nanocrystal.

[0110] In an embodiment, the second shell 6 may include a plurality of layers, and the third semiconductor nanocrystals included in a layer closest to the first shell 4 among the plurality of layers may have a smaller energy band gap than the second semiconductor nanocrystals of the first shell 4 .

[0111] In an embodiment, the second shell 6 may include a plurality of layers, and the third semiconductor nanocrystals included in a layer closest to the first shell 4 among the plurality of layers may have a larger energy band gap than the second semiconductor nanocrystals of the first shell 4 .

[0112] In an embodiment, the energy band gap of the second semiconductor nanocrystal and the energy band gap of the third semiconductor nanocrystal may be the same or different. In an embodiment, the energy band gap of the second semiconductor nanocrystal may be larger than the energy band gap of the third semiconductor nanocrystal. In an embodiment, the energy band gap of the second semiconductor nanocrystal may be smaller than the energy band gap of the third semiconductor nanocrystal.

[0113] The second semiconductor nanocrystals including the III-VI compound included in the first shell 4 exist between the core 2 and the second shell 6 to reduce defects in the quantum dots, improve efficiency and reduce full width at half maximum (FWHM), and enable uniform coating of the second shell 6 .

[0114] The lattice mismatch rate of the first semiconductor nanocrystal and the second semiconductor nanocrystal can be less than or equal to about 15%, for example, less than or equal to about 14%, less than or equal to about 13%, less than or equal to about 12%, less than or equal to about 11%, or less than or equal to about 10%. As a result, the possibility of crystallization defects in the core including the first semiconductor nanocrystal and the first shell including the second semiconductor nanocrystal can be reduced or mitigated. Here, the lattice mismatch rate can be calculated according to Equation 2.

[0115] [Equation 2]

[0116] la1-a2l / a1×100

[0117] Wherein a1 is the lattice constant of the first semiconductor nanocrystal, and a2 is the lattice constant of the second semiconductor nanocrystal.

[0118] The quantum dot 1 may further include a third shell (not shown) including a fourth semiconductor nanocrystal disposed on the second shell 6, wherein the fourth semiconductor nanocrystal includes a III-VI compound, a II-VI compound, a III-V compound, or a combination thereof. As the III-VI compound of the fourth semiconductor nanocrystal, the aforementioned second semiconductor nanocrystal may be used. The III-VI compound of the fourth semiconductor nanocrystal may have a composition that is the same as or different from the III-VI compound of the second semiconductor nanocrystal. The II-VI compound and the III-V compound of the fourth semiconductor nanocrystal are the same as those described above.

[0119] The thickness of the core 2 and each shell (the first shell 4 and the second shell 6) can be adjusted in consideration of the desired emission wavelength and composition of the quantum dot 1. In the quantum dot 1 according to the embodiment, the diameter of the core 2 may be greater than or equal to about 1 nm, greater than or equal to about 1.1 nm, greater than or equal to about 1.2 nm, greater than or equal to about 1.3 nm, greater than or equal to about 1.4 nm, greater than or equal to about 1.5 nm, greater than or equal to about 1.6 nm, greater than or equal to about 1.7 nm, greater than or equal to about 1.8 nm, greater than or equal to about 1.9 nm, greater than or equal to about 2 nm, greater than or equal to about 2.1 nm, greater than or equal to about 2.2 nm, greater than or equal to about 2.3 nm, greater than or equal to about 2.4 nm, greater than or equal to about 2.5 nm, greater than or equal to about 2.6 nm, greater than or equal to about 2.7 nm, greater than or equal to about 2.8 nm, greater than or equal to about 2.9 nm, or greater than or equal to about 3.0 nm. The diameter of core 2 may be less than or equal to about 4 nm, less than or equal to about 3.5 nm, less than or equal to about 3.5 nm, less than or equal to about 3.4 nm, less than or equal to about 3.3 nm, less than or equal to about 3.2 nm, less than or equal to about 3.1 nm, less than or equal to about 3 nm, less than or equal to about 2.9 nm, or less than or equal to about 2.8 nm.

[0120] The thickness of the first shell 4 may be greater than or equal to about 0.2 nm, for example, greater than or equal to about 0.3 nm, or greater than or equal to about 0.4 nm. The thickness of the first shell 4 may be less than or equal to about 1.5 nm, for example, less than or equal to about 1.4 nm, less than or equal to about 1.35 nm, less than or equal to about 1.33 nm, less than or equal to about 1.32 nm, less than or equal to about 1.31 nm, less than or equal to about 1.3 nm, less than or equal to about 1.2 nm, less than or equal to about 1.1 nm, less than or equal to about 1.0 nm, less than or equal to about 0.9 nm, less than or equal to about 0.8 nm, less than or equal to about 0.7 nm, or less than or equal to about 0.6 nm.

[0121] The thickness of the second shell 6 may be greater than or equal to about 0.5 nm, greater than or equal to about 0.6 nm, greater than or equal to about 0.7 nm, greater than or equal to about 0.8 nm, greater than or equal to about 0.9 nm, greater than or equal to about 1 nm, greater than or equal to about 1.1 nm, greater than or equal to about 1.2 nm, greater than or equal to about 1.3 nm, greater than or equal to about 1.4 nm, or greater than or equal to about 1.5 nm and less than or equal to about 4 nm, less than or equal to about 3.5 nm, less than or equal to about 3.0 nm, less than or equal to about 2.9 nm, less than or equal to about 2.8 nm, less than or equal to about 2.7 nm, less than or equal to about 2.6 nm, less than or equal to about 2.4 nm, less than or equal to about 2.3 nm, less than or equal to about 2.2 nm, less than or equal to about 2.1 nm, or less than or equal to about 2.0 nm.

[0122] When forming the third shell, it may be formed within the thickness range of the second shell described above.

[0123] By having the aforementioned composition and structure, the quantum dots of the embodiment may exhibit improved size distribution.

[0124] The quantum dots may emit blue or green light, and the maximum emission peak of the quantum dots may be less than or equal to about 560 nm, for example, less than or equal to about 550 nm, less than or equal to about 540 nm, less than or equal to about 530 nm, less than or equal to about 520 nm, less than or equal to about 510 nm, less than or equal to about 500 nm, less than or equal to about 495 nm, less than or equal to about 493 nm, and greater than or equal to about 450 nm, for example, greater than or equal to about 455 nm, or greater than or equal to about 460 nm. The full width at half maximum (FWHM) of the quantum dots according to the embodiment may be less than or equal to about 40 nm, less than or equal to about 35 nm, less than or equal to about 34 nm, less than or equal to about 33 nm, less than or equal to about 32 nm, less than or equal to about 31 nm, less than or equal to about 30 nm, less than or equal to about 29 nm, less than or equal to about 28 nm, less than or equal to about 27 nm, or less than or equal to about 26 nm.

[0125] In the UV-Vis absorption spectrum curve of the quantum dots, an absorption peak may be presented at less than or equal to about 550 nm, for example, less than or equal to about 540 nm, less than or equal to about 530 nm, less than or equal to about 520 nm, less than or equal to about 510 nm, less than or equal to about 500 nm, less than or equal to about 490 nm, less than or equal to about 480 nm, less than or equal to about 470 nm, less than or equal to about 465 nm, less than or equal to about 464 nm, less than or equal to about 463 nm, less than or equal to about 462 nm, less than or equal to about 461 nm, or less than or equal to about 460 nm.

[0126] Quantum dots according to embodiments may exhibit a quantum efficiency of greater than or equal to about 55%, for example, greater than or equal to about 60%, greater than or equal to about 65%, greater than or equal to about 70%, greater than or equal to about 75%, greater than or equal to about 80%, greater than or equal to about 85%, greater than or equal to about 90%, greater than or equal to about 95%, or about 100%.

[0127] According to the quantum dot of embodiment, it can have the size of about 4nm or more, about 5nm or more, or about 6nm or more. According to the quantum dot of embodiment, it can have the size of about 20nm or less, about 19nm or less, about 18nm or less, about 17nm or less, about 16nm or less, about 15nm or less, about 14nm or less, about 13nm or less, about 12nm or less, or about 10nm or less. Here, the size of quantum dot can refer to diameter (or when quantum dot does not have spherical shape, the diameter calculated by electron microscope 2D image of quantum dot under the assumption that it has spherical shape). Here, size can be the size of single quantum dot or the average size of the group of quantum dot. The size of quantum dot can be obtained, for example, using image analysis program (for example, image J) for transmission electron microscope image.

[0128] The quantum dot may include an organic ligand on its surface. The organic ligand may include RCOOH, RNH2, R2NH, R3N, RSH, RH2PO, R2HPO, R3PO, RH2P, R2HP, R3P, ROH, RCOOR', RPO(OH)2, RHPOOH, RR'POOH (wherein, R and R' may each independently include a substituted or unsubstituted C1-C40 aliphatic hydrocarbon group (e.g., C1-C40 alkyl, C2-C40 alkenyl, C2-C40 alkynyl, etc.), a substituted or unsubstituted C6-C40 aromatic hydrocarbon group (e.g., C6-C20 aryl, C3-C20 heteroaryl, etc.), or a combination thereof). The organic ligand may be coordinated to the surface of the prepared quantum dot (nanocrystal) so that the nanocrystal is well dispersed in the solution phase and / or affects the luminescence and electrical properties of the quantum dot. Specific examples of the organic ligand may include: methyl mercaptan, ethyl mercaptan, propyl mercaptan, butyl mercaptan, pentyl mercaptan, hexyl mercaptan, octyl mercaptan, dodecyl mercaptan, hexadecyl mercaptan, octadecyl mercaptan, benzyl mercaptan; methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, octylamine, dodecylamine, hexadecylamine, octadecylamine, dimethylamine, diethylamine, dipropylamine; formic acid, acetic acid, propionic acid, butyric acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, dodecanoic acid, hexadecanoic acid, octadecanoic acid, oleic acid, benzoic acid; phosphines such as substituted or unsubstituted methylphosphines (e.g., trimethylphosphine, methyldiphenylphosphine, etc.), substituted or unsubstituted ethylphosphines (e.g., triethylphosphine, ethyldiphenylphosphine, etc.), substituted or unsubstituted Substituted propylphosphine, substituted or unsubstituted butylphosphine, substituted or unsubstituted pentylphosphine, substituted or unsubstituted octylphosphine (e.g., trioctylphosphine (TOP)), etc.; phosphine oxides such as substituted or unsubstituted methylphosphine oxide (e.g., trimethylphosphine oxide, methyldiphenylphosphine oxide, etc.), substituted or unsubstituted ethylphosphine oxide (e.g., triethylphosphine oxide, ethyldiphenylphosphine oxide, etc.), substituted or unsubstituted propylphosphine oxide, substituted or unsubstituted butylphosphine oxide, substituted or unsubstituted octylphosphine oxide (e.g., trioctylphosphine oxide (TOPO)), etc.; diphenylphosphine, triphenylphosphine compounds, or oxide compounds thereof; phosphonic acid, etc., but are not limited thereto. The organic ligand may be used alone or as a mixture of two or more. The organic ligand may be a mixture of a carboxylic acid and an amine.

[0129] The organic ligand may not include compounds having both a carboxylic acid group and a thiol group (eg, glutathione).Such quantum dots may be water-insoluble.

[0130] The aforementioned quantum dots can be easily synthesized using a variety of preparation methods known to those skilled in the art (particularly, methods for preparing quantum dots comprising a core and a shell). The quantum dots according to the embodiment can be prepared by colloidal synthesis and thus can include an organic ligand and / or an organic solvent, which will be described later, on their surface. The organic ligand and / or organic solvent can be bound to the surface of the quantum dots.

[0131] Based on the above description Figure 1 A quantum dot having a configuration of may be prepared by a process comprising: preparing a core comprising a first semiconductor nanocrystal; forming a first shell comprising a Group III-VI compound on the core; and forming a second shell comprising a third semiconductor nanocrystal on the first shell.

[0132] The metal and non-metal precursors may be appropriately selected according to the composition of the core, the first shell, and the second shell. The metal precursor may include metal powder, alkylated metals, metal carboxylates, metal hydroxides, metal halides, metal oxides, metal inorganic salts (e.g., nitrates), metal sulfates, metal acetylacetonates, or combinations thereof, but is not limited thereto. The non-metal precursor may be selected from compounds containing non-metal elements used in quantum dot synthesis.

[0133] In the following preparation process, a case in which the first semiconductor nanocrystal included in the core includes a Group III-V compound will be described.

[0134] First, to form a core, a Group III element precursor and a Group V element precursor are reacted in an organic solvent in the presence of an organic ligand.

[0135] The organic ligand is the same as described above.

[0136] The organic solvent may be selected from: C6-C22 primary amines such as hexadecylamine; C6-C22 secondary amines such as dioctylamine; C6-C40 tertiary amines such as trioctylamine; nitrogen-containing heterocyclic compounds such as pyridine; C6-C40 aliphatic hydrocarbons (e.g., alkanes, alkenes, alkynes, etc.) such as hexadecane, octadecane, octadecene, or squalane; C6-C30 aromatic hydrocarbons such as phenyldodecane, phenyltetradecane, or phenylhexadecane; phosphines substituted with C6-C22 alkyl groups such as trioctylphosphine; phosphine oxides substituted with C6-C22 alkyl groups such as trioctylphosphine oxide; C12-C22 aromatic ethers such as phenyl ether or benzyl ether, and combinations thereof. The type and amount of the solvent may be appropriately selected in consideration of the types of the precursor and the organic ligand.

[0137] The type of group III element precursor and group V element precursor is not particularly limited and can be appropriately selected.When the group III element is indium, the example of indium precursor can include trimethyl indium, carboxylic acid indium such as indium acetate, indium palmitate and indium stearate, indium hydroxide, indium chloride, indium oxide, indium nitrate, indium sulfate, or its combination.When the group V element is phosphorus, the example of phosphorus precursor can include tris (trimethylsilyl) phosphine, tris (dimethylamino) phosphine, triethyl phosphine, tributyl phosphine, trioctyl phosphine, triphenyl phosphine, tricyclohexyl phosphine or its combination.

[0138] When the first semiconductor nanocrystal included in the described core comprised the heteroelement that is selected from zinc, aluminium and its combination, these precursors can react with III group element precursor and V group element precursor to prepare described core.The example of zinc precursor can comprise Zn metal powder, alkylated Zn compound (dimethyl zinc, diethyl zinc etc.), Zn alkoxide, carboxylic acid Zn, Zn nitrate, Zn perchlorate, Zn sulfuric acid, Zn acetylacetonate, Zn halogenide, Zn cyanide, Zn hydroxide, Zn oxidation, Zn peroxide or its combination.Can suitably select the type of precursor that is used for aluminium.The example of aluminium precursor can comprise aluminium metal powder, carboxylic acid aluminium is such as aluminium oleate, aluminium monostearate, aluminium octoate, or aluminium acetylacetonate, aluminium halide is such as aluminium chloride, aluminium alkoxide is such as aluminium isopropylate, aluminium oxide, alkylated aluminium, or its combination.

[0139] The core is formed by reacting a Group III element precursor, a Group V element precursor, and optionally a heteroelement precursor. The reaction can be carried out at a temperature of about 280°C or greater, for example, about 290°C or greater. The reaction temperature can be about 350°C or less. The reaction time is controlled to be less than about 1 hour, for example, about 50 minutes or less. The reaction time can be about 20 minutes or greater, for example, about 30 minutes or greater.

[0140] The core formed can be separated by adding a non-solvent, but present disclosure is not limited thereto. For example, when a non-solvent is added to the prepared final reaction solution, the nanocrystals coordinated with the organic ligand can be separated (e.g., precipitated). The separated core can be washed with the non-solvent. The non-solvent can be a polar solvent miscible with the solvent used in the reaction but can not disperse nanocrystals.

[0141] The non-solvent can be determined depending on the solvent used in the reaction, and can be, for example, acetone, ethanol, butanol, isopropanol, ethylene glycol, water, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), diethyl ether, formaldehyde, acetaldehyde, a solvent with a solubility parameter similar to that of the aforementioned non-solvent, or a combination thereof. Centrifugation, precipitation, chromatography, or distillation can be used for separation. When necessary, the separated nanocrystals can be washed by adding a washing solvent. The washing solvent is not particularly limited, and a solvent with a solubility parameter similar to that of the ligand can be used, and examples thereof can include hexane, heptane, octane, chloroform, toluene, and benzene.

[0142] To form the first shell on the core, a Group III element precursor and a Group VI element precursor may be reacted in an organic solvent in the presence of an organic ligand and the core.

[0143] The Group III element precursor is the same as that described for the core. When the Group III element is gallium, examples of the gallium precursor may include trimethylgallium, triethylgallium, gallium carboxylates such as gallium acetate, gallium palmitate, gallium stearate, gallium acetylacetonate, gallium hydroxide, gallium chloride, gallium oxide, gallium nitrate, gallium sulfate, or a combination thereof. When the Group III element is indium, examples of the indium precursor may include trimethylindium, triethylindium, indium carboxylates such as indium acetate, indium palmitate, or indium stearate, indium acetylacetonate, indium hydroxide, indium chloride, indium oxide, indium nitrate, indium sulfate, or a combination thereof.

[0144] The Group VI element precursor may include a chalcogen. For example, when the Group VI element is sulfur, examples of the sulfur precursor may include sulfur powder, hexane hexanol, octanethiol, decanethiol, dodecanethiol, hexadecylthiol, mercaptopropylsilane, alkylphosphines such as sulfur-trioctylphosphine (S-TOP) or sulfur-tributylphosphine (S-TBP), arylphosphines such as sulfur-triphenylphosphine (S-TPP), sulfur-trioctylamine (S-TOA), bistrimethylsilylsulfide, ammonium sulfide, sodium sulfide, or a combination thereof. In addition, when the Group VI element is selenium, the selenium precursor may include selenium-trioctylphosphine (Se-TOP), selenium-tributylphosphine (Se-TBP), selenium-triphenylphosphine (Se-TPP), selenium-diphenylphosphine (Se-DPP), or a combination thereof. When the Group VI element is tellurium, examples of the tellurium precursor may include tellurium-tributylphosphine (Te-TBP), tellurium-triphenylphosphine (Te-TPP), tellurium-diphenylphosphine (Te-DPP), or a combination thereof, but are not limited thereto.

[0145] The reaction for forming the first shell may be carried out at a temperature of about 80° C. or greater, for example, about 90° C. or greater, about 100° C. or greater, about 110° C. or greater, about 120° C. or greater, or about 140° C. or greater and about 300° C. or less, about 290° C. or less, about 280° C. or less, about 270° C. or less, or about 260° C. or less.

[0146] The reaction time for forming the first shell can be adjusted taking into account the reactivity of the precursor, the reaction temperature, and the desired thickness of the first shell. In an embodiment, the reaction time can be adjusted to less than about 4 hours, for example, less than or equal to about 3 hours. The reaction time can be greater than or equal to about 20 minutes, for example, greater than or equal to about 30 minutes.

[0147] The particles on which the first shell is formed can be separated by adding a non-solvent to the reaction system. The separated particles can optionally be washed. In the formation of the first shell, the details of the organic ligand, non-solvent, etc. are the same as those described in the core.

[0148] In order to form the second shell on the first shell, in the presence of an organic ligand and the core on which the first shell is formed, a Group II element precursor and a Group VI element precursor; or a Group III element precursor and a Group V element precursor are reacted in an organic solvent. When the Group II element is zinc, the example of the zinc precursor may include Zn metal powder, alkylated Zn compounds (e.g., dimethyl zinc, diethyl zinc, etc.), Zn alkoxides, Zn carboxylates, Zn nitrates, Zn perchlorates, Zn sulfates, Zn acetylacetonates, Zn halides, Zn cyanides, Zn hydroxides, Zn oxides, Zn peroxides, or a combination thereof. The Group VI element precursor is the same as that described for the second semiconductor nanocrystal.

[0149] The reaction for forming the second shell may be carried out at a temperature greater than about 200° C., for example, greater than or equal to about 210° C., greater than or equal to about 220° C., greater than or equal to about 230° C., greater than or equal to about 240° C., greater than or equal to about 250° C., greater than or equal to about 260° C., greater than or equal to about 270° C., greater than or equal to about 280° C., or greater than or equal to about 290° C. and less than or equal to about 350° C., for example, less than or equal to about 340° C.

[0150] The reaction time for forming the second shell can be adjusted taking into account the reactivity of the precursor, the reaction temperature, and the desired thickness of the second shell. In an embodiment, the reaction time can be adjusted to less than about 3 hours, such as less than or equal to about 2 hours, or less than or equal to about 1 hour. The reaction time can be greater than or equal to about 20 minutes, such as greater than or equal to about 30 minutes.

[0151] In each of the above steps, the type / content or content ratio of the precursors may be determined in consideration of the composition of the final quantum dot (core, first shell, and second shell) and the reactivity between the precursors.

[0152] Prior to each reaction of the processes described above (e.g., core formation, first shell formation, and second shell formation), the metal precursor may be pre-heated (vacuum treatment) at a predetermined temperature (e.g., greater than or equal to about 100° C.) together with a solvent and, optionally, an organic ligand compound under vacuum, followed by switching to an inert gas atmosphere, and then heated again to a predetermined temperature (e.g., greater than or equal to about 100° C.).

[0153] The injection of the metal precursor and / or non-metal precursor can be performed sequentially or simultaneously, and the injection temperature of the precursor can be appropriately determined. For example, when the first shell and / or the second shell are each formed in multiple layers, the metal and / or non-metal precursors for the first shell and the second shell can be introduced several times at different ratios during the reaction time.

[0154] The quantum dots may be non-dispersible or non-soluble in water, the aforementioned non-solvents, or a combination thereof.

[0155] The quantum dots may be dispersed in the aforementioned organic solvent. For example, the quantum dots may be dispersed in C6-C40 aliphatic hydrocarbons, C6-C40 substituted or unsubstituted aromatic hydrocarbons, or a combination thereof.

[0156] The aforementioned quantum dots may be included in a quantum dot composition. The quantum dot composition may include an organic solvent and / or a liquid vehicle, and may further include, optionally, a polymerizable monomer including a carbon-carbon double bond and a (photo)initiator. The content of the quantum dots in the composition may be appropriately adjusted taking into account the final use and composition of the composition. The content of quantum dots may be greater than or equal to about 0.1 wt %, greater than or equal to about 1 wt %, greater than or equal to about 2 wt %, greater than or equal to about 3 wt %, greater than or equal to about 4 wt %, greater than or equal to about 5 wt %, greater than or equal to about 6 wt %, greater than or equal to about 7 wt %, greater than or equal to about 8 wt %, greater than or equal to about 9 wt %, greater than or equal to about 10 wt %, greater than or equal to about 15 wt %, greater than or equal to about 20 wt %, greater than or equal to about 25 wt %, greater than or equal to about 30 wt %, greater than or equal to about 35 wt %, or greater than or equal to about 40 wt %, based on the solid content of the composition. Additionally, the quantum dots may be present in an amount less than or equal to about 70 wt %, less than or equal to about 65 wt %, less than or equal to about 60 wt %, less than or equal to about 55 wt %, or less than or equal to about 50 wt %, based on the solids content of the composition.

[0157] The quantum dot composition may be a photosensitive composition capable of forming a pattern using a photolithography process or an inkjet composition capable of forming a pattern using an inkjet process.

[0158] The quantum dot composition may further include a compound comprising a carboxylic acid group. Such a compound may include, for example, a monomeric compound comprising a carboxylic acid group and a carbon-carbon double bond, a monomeric compound comprising a polyaromatic ring and a carboxylic acid group (-COOH), or a combination thereof.

[0159] For a detailed description of the quantum dot composition (eg, photosensitive composition), reference may be made to US-2017-0059988-A1, the entire contents of which are incorporated herein by reference.

[0160] The quantum dot-polymer composite may be configured in a form in which the aforementioned quantum dots are dispersed in a polymer matrix.

[0161] The content of the quantum dots in the polymer matrix can be appropriately selected and is not particularly limited. For example, the content of the quantum dots in the polymer matrix can be greater than or equal to about 0.1 wt % and less than or equal to about 70 wt %, based on the total weight of the composite, but is not limited thereto. In particular, the amount of quantum dots in the polymer matrix can be greater than or equal to about 0.3 wt %, greater than or equal to about 0.5 wt %, or greater than or equal to about 1.0 wt % and less than or equal to about 65 wt %, less than or equal to about 60 wt %, less than or equal to about 55 wt %, or less than or equal to about 50 wt %, based on the total weight of the composite.

[0162] The polymer matrix may include a thiol-ene polymer, a (meth)acrylate-based polymer, a urethane-based resin, an epoxy-based resin, a vinyl-based polymer, a silicone resin, or a combination thereof. The thiol-ene polymer is disclosed in US 2015-0218444 A1, the entire contents of which are incorporated herein by reference. The (meth)acrylate-based polymer, urethane-based resin, epoxy-based resin, vinyl-based polymer, and silicone resin may be synthesized by known methods or may be commercially available.

[0163] The quantum dot-polymer composite may further include metal oxide particles (filler and / or light diffuser), which are in the form of fine particles. The metal oxide particles may include, for example, one or more of the following: SiO2, ZnO, TiO2, ZrO2, and combinations thereof.

[0164] The quantum dot-polymer composite may be in the form of a sheet.

[0165] The quantum dot-polymer complex may be in the form of a quantum dot stacked structure disposed on a substrate. The quantum dot stacked structure may have a quantum dot-polymer complex pattern comprising at least one repeating segment emitting light of a predetermined wavelength. The quantum dot-polymer complex pattern may comprise at least one repeating segment selected from a first segment emitting a first type of light and a second segment emitting a second type of light. The first segment and the second segment may each independently comprise quantum dots emitting light of a different wavelength.

[0166] In a method for manufacturing a quantum dot stacked structure, a film of a quantum dot composition is formed on a substrate, selected areas of the film are exposed to light having a predetermined wavelength (e.g., a wavelength less than or equal to about 400 nm), and the exposed film is developed with an alkaline developer to obtain a pattern of the quantum dot-polymer composite.

[0167] The quantum dot composition is as described above. The aforementioned quantum dot composition can be applied to a predetermined thickness on a substrate using a suitable method such as spin coating or slit coating to form a film, and the formed film can be subjected to a pre-bake (PRB) if necessary. The pre-bake conditions such as temperature, time and atmosphere are known and can be appropriately selected.

[0168] The formed (or optionally pre-baked) film can be exposed to light having a predetermined wavelength (e.g., a wavelength less than or equal to about 400 nm) under a mask having a predetermined pattern, and the wavelength and intensity of the light can be selected taking into account the type and amount of photoinitiator, the type and amount of quantum dots, etc.

[0169] When the exposed film is treated with an alkaline developer (e.g., by dipping or spraying), the portion of the film not irradiated with light dissolves and a desired pattern is obtained. If necessary, the obtained pattern may be post-baked (POB) at a temperature of about 150° C. to about 230° C. for a predetermined time (e.g., about 10 minutes or more, or about 20 minutes or more), for example, to improve the crack resistance and solvent resistance of the pattern.

[0170] When the pattern of the quantum dot-polymer complex has multiple repeating segments, multiple compositions including quantum dots having desired emission properties (photoluminescence peak wavelength, etc.) (for example, quantum dots emitting red light, quantum dots emitting green light, or optionally quantum dots emitting blue light) can be prepared for forming each repeating segment, and then the aforementioned pattern forming process for each composition can be repeated a required number of times (for example, 2 times or more, or 3 times or more) to obtain a quantum dot-polymer complex having the desired pattern.

[0171] An ink composition comprising the aforementioned quantum dots and a liquid vehicle can be used for pattern formation. For example, the ink composition comprising quantum dots, a liquid vehicle, and a monomer is deposited on a desired area of ​​a substrate and polymerized after optionally removing the liquid vehicle, or the liquid vehicle is removed to form a pattern. The quantum dot-polymer composite pattern can be a pattern in which two or more segments emitting different colors (e.g., RGB color segments) repeat, and the quantum dot-polymer composite pattern can be used as a photoluminescent color filter in a display device.

[0172] The aforementioned quantum dots may be included in electronic devices. Such electronic devices may include, but are not limited to, (electroluminescent or photoluminescent) display devices, light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), quantum dot LEDs, sensors, solar cells, image sensors, photodetectors, or liquid crystal display devices.

[0173] The aforementioned quantum dots may be included in electronic devices. Such electronic devices may include, but are not limited to, portable terminals, monitors, notebook PCs, televisions, electric signage, cameras, and automobiles. The electronic device may be a portable terminal, monitor, notebook PC, or television that includes a display device containing quantum dots. The electronic device may be a camera or portable terminal that includes an image sensor containing quantum dots. The electronic device may be a camera or automobile that includes a photodetector containing quantum dots.

[0174] In the following, reference will be made to Figure 2 An electroluminescent device is described as an example of an electronic device. Figure 2 is a schematic cross-sectional view of an electroluminescent display device according to one embodiment.

[0175] refer to Figure 2 The electroluminescent device 100 includes a first electrode 101 and a second electrode 105 facing each other, and an active layer 103 provided between the first electrode 101 and the second electrode 105 and including the aforementioned quantum dots.

[0176] In particular, in the quantum dots of the active layer 103, electrons and holes injected from the first electrode 101 and the second electrode 105 recombine to form excitons, and the active layer 103 can be a light-emitting layer capable of emitting light of a certain wavelength using the energy of the formed excitons. Furthermore, electronic devices including quantum dots can be photodetectors or solar cells. In particular, the quantum dots of the active layer 103 can be light-absorbing layers that absorb external photons and separate them into electrons and holes, thereby providing electrons and holes to the first electrode 101 and the second electrode 105.

[0177] The hole assist layer 102 may be disposed between the first electrode 101 and the active layer 103 , and the electron assist layer 104 may be disposed between the second electrode 105 and the active layer 103 .

[0178] The electroluminescent device 100 may further include a substrate (not shown). The substrate may be disposed on the first electrode 101 side or on the second electrode 105 side. The substrate may be a substrate comprising an insulating material (e.g., an insulating transparent substrate). In addition, the substrate may include glass, various polymers such as polyesters (e.g., polyethylene terephthalate (PET), polyethylene naphthalate (PEN)), polycarbonate, polyacrylate, polyimide, polyamide-imide, etc., inorganic materials such as polysiloxanes (e.g., polydimethylsiloxane (PDMS)), Al2O3, ZnO, etc., or a combination thereof, or may be made of a silicon wafer. In this document, "transparent" means that the transmittance of light of a certain wavelength (e.g., light emitted from the quantum dots) through it is greater than or equal to about 85%, greater than or equal to about 88%, greater than or equal to about 90%, greater than or equal to about 95%, greater than or equal to about 97%, or greater than or equal to about 99%. The thickness of the substrate may be appropriately selected considering the substrate material, etc., but is not particularly limited. The transparent substrate may be flexible.

[0179] One of the first electrode 101 and the second electrode 105 may be an anode and the other may be a cathode. For example, the first electrode 101 may be an anode and the second electrode 105 may be a cathode.

[0180] The first electrode 101 can be made of a conductor such as a metal, a conductive metal oxide, or a combination thereof. The first electrode 101 can be made of, for example, a metal such as nickel, platinum, vanadium, chromium, copper, zinc, gold, or alloys thereof; a conductive metal oxide such as zinc oxide, indium oxide, tin oxide, indium tin oxide (ITO), indium zinc oxide (IZO), or fluorine-doped tin oxide; or a combination of a metal and an oxide such as ZnO and Al, or SnO2 and Sb, but not limited thereto. The second electrode 105 can be made of a conductor such as a metal, a conductive metal oxide, and / or a conductive polymer. The second electrode 105 can be made of, for example, a metal such as aluminum, magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, silver, gold, platinum, tin, lead, cesium, barium, or alloys thereof; a multilayer structure material such as LiF / Al, lithium oxide (Li2O) / Al, Liq / Al, LiF / Ca, and BaF2 / Ca, but not limited thereto. The conductive metal oxide is the same as described above.

[0181] The work functions of the first electrode 101 and the second electrode 105 are not particularly limited and can be appropriately selected. The work function of the first electrode 101 can be higher or lower than the work function of the second electrode 105.

[0182] At least one of the first electrode 101 and the second electrode 105 may be a light-transmitting electrode, and the light-transmitting electrode may be, for example, a conductive metal oxide such as zinc oxide, indium oxide, tin oxide, indium tin oxide (ITO), indium zinc oxide (IZO), or fluorine-doped tin oxide, or a single or multilayer metal thin film. When either the first electrode 101 or the second electrode 105 is an opaque electrode, it may be made of an opaque conductor such as aluminum (Al), silver (Ag), or gold (Au).

[0183] The thickness of the first electrode 101 and / or the second electrode 105 is not particularly limited and can be appropriately selected in consideration of device efficiency. For example, the thickness of these electrodes can be greater than or equal to about 5 nm, for example, greater than or equal to about 50 nm and less than or equal to about 100 μm, for example, less than or equal to about 10 μm, less than or equal to about 1 μm, less than or equal to about 900 nm, less than or equal to about 500 nm, or less than or equal to about 100 nm.

[0184] The active layer 103 includes the quantum dots described above. The active layer 103 may include one or more monolayers of quantum dot layers. The multiple monolayers may be 2 or more, 3 or more, or 4 or more, and may be 20 or less, 10 or less, 9 or less, 8 or less, 7 or less, or 6 or less. The active layer 103 may have a thickness greater than or equal to about 5 nm, such as greater than or equal to about 10 nm, greater than or equal to about 20 nm, or greater than or equal to about 30 nm and less than or equal to about 200 nm, such as less than or equal to about 150 nm, less than or equal to about 100 nm, less than or equal to about 90 nm, less than or equal to about 80 nm, less than or equal to about 70 nm, less than or equal to about 60 nm, or less than or equal to about 50 nm. The active layer 103 may have a thickness of about 10 nm to about 150 nm, about 10 nm to about 100 nm, or about 10 nm to about 50 nm.

[0185] The electroluminescent device 100 may further include a hole-assisting layer 102. The hole-assisting layer 102 may be disposed between the first electrode 101 and the active layer 103. The hole-assisting layer 102 may include a hole injection layer, a hole transport layer, an electron blocking layer, or a combination thereof. The hole-assisting layer 102 may be a single-component layer or a multilayer structure in which adjacent layers include different components.

[0186] The HOMO energy level of the hole assisting layer 102 may match the HOMO energy level of the active layer 103 to improve the mobility of holes transferred from the hole assisting layer 102 to the active layer 103. As an example, the hole assisting layer 102 may include a hole injection layer disposed near the first electrode 101 and a hole transport layer disposed near the active layer 103.

[0187] The material included in the hole auxiliary layer 102 (e.g., a hole transport layer or a hole injection layer) is not particularly limited, and may include, for example, at least one selected from the group consisting of poly(9,9-dioctyl-fluorene-co-N-(4-butylphenyl)-diphenylamine) (TFB), polyarylamine (polyarylamine), poly(N-vinylcarbazole) (PVK), poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), polyaniline, polypyrrole, N,N,N',N'-tetrakis(4-methylpyrrole), polyvinylpyrrolidone, ... oxyphenyl)-benzidine (TPD), 4,4'-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), m-MTDATA (4,4',4"-tris[phenyl(m-tolyl)amino]triphenylamine), 4,4',4"-tris(N-carbazolyl)-triphenylamine (TCTA), 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), p-type metal oxides (e.g., NiO, WO3, MoO3, etc.), carbon-based materials such as graphene oxide, and combinations thereof, but not limited thereto.

[0188] When an electron blocking layer is included, the electron blocking layer may include at least one selected from the group consisting of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), poly(9,9-dioctyl-fluorene-co-N-(4-butylphenyl)-diphenylamine) (TFB), polyarylamine (polyarylamine), poly(N-vinylcarbazole), polyaniline, polypyrrole, N,N,N',N'-tetrakis(4-methoxyphenyl)-benzidine (TPD), 4,4'-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), m-MTDATA, 4,4',4"-tris(N-carbazolyl)-triphenylamine (TCTA), and combinations thereof, but is not limited thereto.

[0189] In the hole assist layer, the thickness of each layer can be appropriately selected. For example, the thickness of each layer can be greater than or equal to about 5 nm, greater than or equal to about 10 nm, greater than or equal to about 15 nm, or greater than or equal to about 20 nm and less than or equal to about 50 nm, such as less than or equal to about 40 nm, less than or equal to about 35 nm, or less than or equal to about 30 nm, but is not limited thereto.

[0190] The electron auxiliary layer 104 may be arranged between the active layer 103 and the second electrode 105. The electron auxiliary layer 104 may include, for example, an electron injection layer that promotes electron injection, an electron transport layer that promotes electron transport, and a hole blocking layer that blocks the movement of holes, or a combination thereof. For example, the electron injection layer may be arranged between the electron transport layer and the second electrode 105. For example, the hole blocking layer may be arranged between the active layer and the electron transport (injection) layer, but is not limited thereto. The thickness of each layer may be appropriately selected, for example, the thickness of each layer may be greater than or equal to about 1 nm and less than or equal to about 500 nm, but is not limited thereto. The electron injection layer may be an organic layer formed by vapor deposition, and the electron transport layer may include inorganic oxide nanoparticles.

[0191] The electron transport layer may include, for example, at least one selected from the group consisting of 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA), bathocuproine (BCP), tris[3-(3-pyridyl)-

[0014] borane (3TPYMB), LiF, Alq3, Gaq3, Inq3, Znq2, Zn(BTZ)2, BeBq2, ET204 (8-(4-(4,6-di(naphthalene-2-yl)-1,3,5-triazin-2-yl)phenyl)quinolone), 8-hydroxyquinoline lithium (Liq), n-type metal oxides (e.g., ZnO, HfO2, etc.), and combinations thereof, but are not limited thereto. In the foregoing, "q" is 8-hydroxyquinoline, "BTZ" is 2-(2-hydroxyphenyl)benzothiazole, and "Bq" is 10-hydroxybenzo[h]quinoline.

[0192] In addition, the electron transport layer may include a plurality of nanoparticles. The nanoparticles may include metal oxides containing zinc, such as zinc oxide, zinc magnesium oxide, or a combination thereof. The metal oxide may include Zn 1-x M x O (wherein M is Mg, Ca, Zr, W, Li, Ti, Y, Al, or a combination thereof, and 0≤x≤0.5). In the chemical formula, x may be greater than or equal to about 0.01 and less than or equal to about 0.3, for example, less than or equal to about 0.25, less than or equal to about 0.2, or less than or equal to about 0.15. The absolute value of the LUMO of the aforementioned quantum dots included in the active layer may be less than the absolute value of the LUMO of the metal oxide. The average size of the nanoparticles may be greater than or equal to about 1 nm, for example, greater than or equal to about 1.5 nm, greater than or equal to about 2 nm, greater than or equal to about 2.5 nm, or greater than or equal to about 3 nm and less than or equal to about 10 nm, less than or equal to about 9 nm, less than or equal to about 8 nm, less than or equal to about 7 nm, less than or equal to about 6 nm, or less than or equal to about 5 nm.

[0193] The hole blocking layer (HBL) may include, for example, at least one selected from the group consisting of 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA), bathocuproine (BCP), tris[3-(3-pyridyl)-

[0014] borane (3TPYMB), LiF, Alq3, Gaq3, Inq3, Znq2, Zn(BTZ)2, BeBq2, and combinations thereof, but are not limited thereto.

[0194] The thickness of each of the electron assisting layer 104 (eg, electron injection layer, electron transport layer, or hole blocking layer) may be greater than or equal to about 5 nm. The present invention may further include but is not limited to: 5 nm, about 6 nm or more, about 7 nm or more, about 8 nm or more, about 9 nm or more, about 10 nm or more, about 11 nm or more, about 12 nm or more, about 13 nm or more, about 14 nm or more, about 15 nm or more, about 16 nm or more, about 17 nm or more, about 18 nm or more, about 19 nm or more, or about 20 nm or more and about 120 nm or less, about 110 nm or less, about 100 nm or less, about 90 nm or less, about 80 nm or less, about 70 nm or less, about 60 nm or less, about 50 nm or less, about 40 nm or less, about 30 nm or less, or about 25 nm or less.

[0195] refer to Figure 3 , an electroluminescent device according to one embodiment may have a normal structure. The electroluminescent device 200 may include an anode 10 disposed on a transparent substrate 201 and a cathode 50 facing the anode 10. The anode 10 may include a transparent electrode based on a metal oxide, and the cathode 50 facing the anode 10 may include a conductive metal with a relatively low work function. For example, the anode 10 may include an indium tin oxide (ITO, a work function of about 4.6 eV to about 5.1 eV) electrode, and the cathode 50 may include an electrode including magnesium (Mg, a work function of about 3.66 eV), aluminum (Al, a work function of about 4.28 eV), or a combination thereof. In addition, a hole auxiliary layer 20 may be disposed between the anode 10 and the quantum dot active layer 30. The hole auxiliary layer 20 may include a hole injection layer and / or a hole transport layer. The hole injection layer may be disposed near the anode 10 and the hole transport layer may be disposed near the quantum dot active layer 30. In addition, an electron auxiliary layer 40 may be disposed between the quantum dot active layer 30 and the cathode 50. The electron assist layer 40 may include an electron injection layer and / or an electron transport layer. The electron injection layer may be disposed near the cathode 50 and the electron transport layer may be disposed near the quantum dot active layer 30.

[0196] refer to Figure 4, an electroluminescent device according to another embodiment may have an inverted structure. The electroluminescent device 300 having an inverted structure may include a cathode 50 disposed on a transparent substrate 100 and an anode 10 facing the cathode 50. The cathode 50 may include a transparent electrode based on a metal oxide, and the anode 10 facing the cathode 50 may include a conductive metal with a relatively high work function. For example, the cathode 50 may be an indium tin oxide (ITO, a work function of about 4.6eV-about 5.1eV) electrode, and the anode 10 may be an electrode including gold (Au, a work function of about 5.1eV), silver (Ag, a work function of about 4.26eV), aluminum (Al, a work function of 4.28eV), or a combination thereof. In addition, an electron auxiliary layer 40 may be disposed between the quantum dot active layer 30 and the cathode 50. The electron auxiliary layer 40 may include an electron injection layer and / or an electron transport layer. The electron injection layer may be disposed close to the cathode 50 and the electron transport layer may be disposed close to the quantum dot active layer 30. The electron auxiliary layer 40 may include, for example, the metal oxide in the electron transport layer, and crystalline Zn oxide or n-type doped metal oxide. In addition, the hole auxiliary layer 20 may be disposed between the anode 10 and the quantum dot active layer 30. The hole auxiliary layer 20 may include a hole injection layer and / or a hole transport layer. The hole injection layer may be disposed near the anode 10, and the hole transport layer may be disposed near the quantum dot active layer 30. The hole transport layer may include TFB, PVK, or a combination thereof, and the hole injection layer may include MoO3 or other p-type metal oxides.

[0197] In the electroluminescent device, light of a certain wavelength generated in the active layer 30 is emitted to the outside through the light-transmitting electrode and the transparent substrate. Figure 3 When a metal oxide-based transparent electrode (eg, indium tin oxide (ITO)) as a light-transmitting electrode is applied to the anode 10, light formed in the active layer is emitted to the outside through the anode 10 and the transparent substrate 201. Figure 4 When a metal oxide-based transparent electrode (eg, indium tin oxide (ITO)) as a light-transmitting electrode is applied to the cathode 50 , light formed in the active layer is emitted to the outside through the cathode 50 and the transparent substrate 201 .

[0198] The aforementioned electronic device can be manufactured by a suitable method. For example, the electroluminescent device can be manufactured by forming a hole-assisting layer (or electron-assisting layer) on a substrate on which an electrode is formed, forming an active layer including quantum dots (for example, a pattern of the aforementioned quantum dots), and forming an electron-assisting layer (or hole-assisting layer) and an electrode. The electrode, hole-assisting layer, and electron-assisting layer can each be independently formed by a suitable method, and can be formed, for example, by vapor deposition or coating, but is not particularly limited.

[0199] Other electronic devices including the aforementioned quantum dots may include a light source and a light-emitting element. The light-emitting element may include the aforementioned quantum dots, and the light source may be configured to provide incident light to the light-emitting element. Such electronic devices may be photoluminescent display devices.

[0200] The incident light provided by the light source may have a photoluminescence peak wavelength within a range of about 400 nm or greater, for example, about 430 nm or greater, or about 440 nm or greater, and about 500 nm or less, for example, about 490 nm or less, or about 480 nm or less. The light-emitting element may have a form in which the aforementioned quantum dots are dispersed in a polymer matrix. For example, the light-emitting element may be a quantum dot-polymer composite implemented in the form of a sheet.

[0201] The photoluminescent display device according to an embodiment may further include a liquid crystal panel, and the sheet of the quantum dot-polymer composite may be disposed between the light source and the liquid crystal panel.

[0202] In the following, reference will be made to Figure 5 A photoluminescent display device is described. Figure 5 FIG is a schematic diagram of a photoluminescent display device according to an embodiment. Figure 5 , the photoluminescent display device 400 may include a backlight unit 410 and a liquid crystal panel 450, and the backlight unit 410 may include a quantum dot-polymer composite sheet (QD sheet) 414. Specifically, the backlight unit 410 may have a structure in which a reflector 411, a light guide plate (LGP) 412, a light source 413 (such as a blue LED), a quantum dot-polymer composite sheet (QD sheet) 414, an optical film 415, and a prism / dual brightness enhancement film (such as DBEF, not shown) are stacked. The liquid crystal panel 450 may be disposed on the backlight unit 410 and may have a structure including a TFT (thin film transistor) 452, a liquid crystal 453, and a color filter 454 between two polarizers 451 and 451'. The quantum dot-polymer composite sheet (QD sheet) 414 may include quantum dots that emit red light by absorbing light from the light source 413 and quantum dots that emit green light. The blue light provided by the light source 413 can be converted into white light by combining with the red light and green light emitted from the quantum dots when passing through the quantum dot-polymer composite sheet. The white light can be separated into blue light, green light, and red light by the color filter in the liquid crystal panel in each pixel and can be emitted to the outside.

[0203] Another example of the photoluminescent display device may be in the form of a quantum dot stacked structure in which the light emitting element is provided on a substrate. The quantum dot stacked structure is as described above and may have a quantum dot-polymer composite pattern. For example, referring to Figure 6A and6B , the photoluminescent display devices 500a and 500b may be arranged at positions where quantum dot-polymer composite patterns 520a and 520b face light sources 510a and 510b. The quantum dot-polymer composite pattern may include first segments 521a and 521b containing green quantum dots and second segments 522a and 522b containing red quantum dots, and optionally further include third segments 523a and 523b that do not contain quantum dots. The quantum dot-polymer composite pattern may be in contact with the light source ( Figure 6B ) or set at regular intervals ( Figure 6A The light source may include a plurality of light-emitting units 5101a, 5102a, 5103a, 5101b, 5102b, and 5103b, and at least one of the light-emitting units 5101a, 5102a, 5101b, and 5102b may be provided to correspond to each of the first and second segments, respectively. If necessary, at least one of the light-emitting units 5103a and 5103b may be further provided to correspond to the third segment.

[0204] The light sources 510a and 510b may emit light at a predetermined wavelength (e.g., blue light, green light, or a combination thereof). For example, the light sources may emit light having an emission peak wavelength within a range of approximately 400 nm or more, approximately 420 nm or more, approximately 430 nm or more and approximately 500 nm or less, approximately 490 nm or less, or approximately 480 nm or less.

[0205] Light sources 510a and 510b may be electroluminescent devices. In particular, the light source may include a first electrode and a second electrode facing each other, and an electroluminescent layer disposed between the first electrode and the second electrode. For example, light sources 510a and 510b may be organic light-emitting diodes (OLEDs) including an organic light-emitting material in the electroluminescent layer. The organic light-emitting diode (OLED) may include at least two pixel electrodes 5121a, 5122a, 5123a, 5121b, 5122b, and 5123b formed on a substrate, pixel defining layers 5131a, 5132a, 5131b, and 5132b formed between at least two adjacent pixel electrodes, organic light-emitting layers 5141a, 5142a, 5143a, 5141b, 5142b, and 5143b formed on each pixel electrode, and common electrode layers 515a and 515b formed on the organic light-emitting layers. Under the organic light emitting diode (OLED), a thin film transistor (not shown) and substrates 511 a and 511 b may be disposed.

[0206] Light emitted from the light source (e.g., blue light) enters the first and second segments of the quantum dot-polymer composite pattern and can thus be converted into green light and red light, respectively. In addition, the blue light emitted from the light source can pass through the third segment that does not include the quantum dot-polymer composite pattern. For each pixel, these green light, red light, and blue light can be emitted to the outside. In particular, the first segment emitting green light can be a green pixel area, the second segment emitting red light can be a red pixel area, and the third segment emitting blue light can be a blue pixel area.

[0207] In addition to the quantum dot-polymer composite pattern, the photoluminescent display device may include filter layers 530a and 530b. The filter layers may block light in a portion of the visible light region and transmit light in the remaining wavelength region. For example, the filter layers 530a and 530b may block blue light in the wavelength region emitted from the light source, but transmit light other than the blue light (e.g., green light, red light, and / or yellow light as a mixture thereof). In particular, the filter layers 530a and 530b may block greater than or equal to about 80%, greater than or equal to about 90%, or even greater than or equal to about 95% of light greater than or equal to about 400 nm and less than about 480 nm, but have a light transmittance of greater than or equal to about 70%, greater than or equal to about 80%, greater than or equal to about 90%, or even about 100% for the remaining light greater than or equal to about 500 nm to less than or equal to 700 nm. These filter layers can improve the color purity of a display device or increase the light conversion efficiency of the quantum dot composite pattern.

[0208] The filter layers 530a and 530b may be provided on the first segments 521a and 521b emitting green light and the second segments 522a and 522b emitting red light. The filter layer may not be provided on the portion corresponding to the third segment (blue pixel region) 523a and 513b not having the quantum dot-polymer composite pattern. For example, the filter layers 530a and 530b may be formed as an integral structure on the remaining portion of the quantum dot-polymer composite pattern except for the portion overlapping with the third segment. Alternatively, the filter layers 530a and 530b may be provided separately from each other at the location where the first segment and the second segment of the quantum dot-polymer composite pattern overlap. In particular, the filter layer has a first region and a second region corresponding to the first segment and the second segment of the quantum dot-polymer composite pattern, respectively, and these first region and the second region may be optically isolated by a black matrix or the like. The first area of ​​the filter layer can be configured to correspond to a first segment (green pixel area) emitting green light, blocking blue light and red light, and selectively transmitting light within a predetermined wavelength range (for example, greater than or equal to about 500 nm, greater than or equal to about 510 nm, or greater than or equal to about 515 nm and less than or equal to about 550 nm, less than or equal to about 540 nm, less than or equal to about 535 nm, less than or equal to about 530 nm, less than or equal to about 525 nm, or less than or equal to about 520 nm). In addition, the second area of ​​the filter layer can be configured to correspond to a second segment (red pixel area) emitting red light, block blue light and green light, and selectively transmit light within a predetermined range (for example, greater than or equal to approximately 600 nm, greater than or equal to approximately 610 nm, or greater than or equal to approximately 615 nm and less than or equal to approximately 650 nm, less than or equal to approximately 640 nm, less than or equal to approximately 635 nm, less than or equal to approximately 630 nm, less than or equal to approximately 625 nm, or less than or equal to approximately 620 nm).

[0209] The filter layers 530a and 530b may absorb desired wavelengths and thus block light of the corresponding wavelengths. These filters may include dyes and / or pigments that absorb light of the wavelengths to be blocked, and the dyes and / or pigments may be disposed in the polymer matrix.

[0210] In addition, the filter layers 530a and 530b can emit light of a desired wavelength and thus block light of the corresponding wavelength. These filter layers may include multiple layers (e.g., inorganic material layers) having different refractive indices. In particular, the filter layers may be provided in the form of alternating stacks of two layers having different refractive indices (e.g., a layer having a high refractive index and a layer having a low refractive index).

[0211] Photoluminescent display devices 500a and 500b may include an additional filter layer (not shown) further disposed between the light source and the light-emitting element. The additional filter layer may reflect light emitted from the quantum dot-polymer composite pattern (e.g., green light and / or red light) but transmit light emitted from the light source (e.g., blue light). For example, the filter layer may reflect greater than or equal to about 80%, greater than or equal to about 90%, or even greater than or equal to about 95% of the remaining light between about 500 nm and less than or equal to about 700 nm, but may have a light transmittance of greater than or equal to about 70%, greater than or equal to about 80%, greater than or equal to about 90%, or even greater than or equal to about 100% for light between about 400 nm and less than about 480 nm. The additional filter layer may recycle red, green, and / or yellow light and improve the light conversion efficiency of the quantum dot composite pattern.

[0212] The photoluminescent display devices 500a and 500b may be manufactured by separately manufacturing a quantum dot stacked structure (the quantum dot-polymer composite pattern) and the light source, or directly forming the quantum dot-polymer composite pattern on the light source.

[0213] Specific examples are presented below. However, the examples described below are only for the purpose of specifically illustrating or explaining the embodiments, and the scope of the present invention is not limited thereto.

[0214] The energy band gap (Eg), lattice parameters, and electron / hole effective masses of the semiconductor compounds prepared in Examples are shown in Table 1.

[0215] (Table 1)

[0216]

[0217]

[0218] * m e :The mass of a free electron (9.1*10 -31 kg)

[0219] [Example]

[0220] Analytical methods

[0221] [1] UV-Vis spectroscopy

[0222] An Agilent Cary 5000 spectrometer was used for UV spectroscopy analysis and to obtain UV-visible absorption spectra.

[0223] [2] Photoluminescence analysis

[0224] The photoluminescence (PL) spectra of the quantum dots were obtained using a Hitachi F-7000 spectrometer with an excitation wavelength of 458 nm.

[0225] [3] Inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis

[0226] Inductively coupled plasma atomic emission spectrometry (ICP-AES) was performed using a Shimadzu ICPS-8100.

[0227] [4] X-ray photoelectron spectroscopy (XPS) analysis

[0228] XPS elemental analysis was performed by using Quantum 2000 manufactured by Physical Electronics, Inc. under the following conditions: an acceleration voltage of 0.5 keV to 15 keV, 300 W, and 200×200 μm 2 Minimum analysis area.

[0229] [5] Transmission electron microscopy analysis

[0230] Transmission electron microscopy images of the prepared nanocrystals were obtained using a UT F30 Tecnai electron microscope.

[0231] Preparation Example 1-1: Synthesis of InP Core

[0232] 0.6mmol indium acetate, 1.8mmol palmitic acid and 10mL 1-octadecene are placed in reactor and under vacuum at 120 ℃, heat.One hour later, the atmosphere in reactor is changed into nitrogen.After reactor is heated at 280 ℃, 0.3mmol tris (trimethylsilyl) phosphine (TMS3P) solution is injected quickly wherein, then reacted together 10 minutes.Subsequently, acetone is added to the reaction solution that is quickly cooled to room temperature (24 ℃), then centrifugal to obtain precipitate, and described precipitate is dispersed in toluene.

[0233] Preparation Example 1-2: Synthesis of InZnP Core

[0234] 0.12mmol indium acetate, 0.36mmol zinc acetate and 1.08mmol palmitic acid are dissolved in 1-octadecene solvent in 200mL reactor, then heated at 120 ℃ under vacuum. One hour later, the atmosphere in the reactor is converted into nitrogen. After the reactor is heated at 280 ℃, a mixed solution of 0.15mmol tris(trimethylsilyl)phosphine (TMS3P) and 1mL trioctylphosphine is quickly injected thereto, then reacted 20 minutes. Subsequently, acetone is added to the reaction solution that is quickly cooled to room temperature, then centrifuged, and the precipitate obtained therefrom is dispersed in toluene.

[0235] Example 1: Synthesis of InP / Ga2S3 / ZnS Quantum Dots

[0236] Triethylgallium and an organic ligand including oleic acid are placed in a 300mL reaction flask containing octadecene (ODE), and then vacuum treated at 120°C. The inside of the flask is replaced with nitrogen (N2). When the temperature of the reactor is increased to the reaction temperature (260°C), the core of Preparation Example 1-1 is quickly placed in the reaction flask, and S / TOP is subsequently injected thereinto, and then reacted for 10 minutes. Here, triethylgallium and S / TOP are used in a molar ratio such that the stoichiometric ratio of Ga:S meets 1:1.5.

[0237] When the reaction was completed, ethanol was added to the reaction solution rapidly cooled to room temperature, followed by centrifugation, and the precipitate obtained therefrom was dispersed in toluene to obtain InP / Ga2S3 (core / first shell) nanoparticles.

[0238] In a 200 mL reaction flask, 1.2 mmol of zinc acetate and 2.4 mmol of oleic acid were dissolved in a trioctylamine solvent and then vacuum treated at 120° C. for 10 minutes. The interior of the flask was replaced with nitrogen (N2) and then heated to 280° C. Subsequently, InP / Ga2S3 (core / first shell) nanoparticles were quickly added thereto, and 0.01 mmol of S / TOP was added thereto, followed by heating to 320° C. for a second shell formation reaction for 60 minutes.

[0239] Subsequently, acetone was added to the reaction solution rapidly cooled to room temperature, followed by centrifugation, and the precipitate obtained therefrom was dispersed in toluene to prepare an InP / Ga2S3 / ZnS quantum dot dispersion.

[0240] Example 2: Synthesis of InZnP / Ga2S3 / ZnS Quantum Dots

[0241] An InZnP / Ga2S3 / ZnS quantum dot dispersion was prepared according to the same method as in Example 1, except that the cores of Preparation Example 1-2 were used instead of the cores of Preparation Example 1-1.

[0242] Example 3: Synthesis of InZnP / Ga2S3 / ZnSe / ZnS Quantum Dots

[0243] Triethylgallium and an organic ligand including oleic acid are placed in a 300 mL reaction flask containing octadecene (ODE) and then vacuum treated at 120 ° C. The interior of the flask is replaced with nitrogen (N2). When the temperature of the reactor is increased to the reaction temperature (260 ° C), the core of Preparation Example 1-2 is quickly placed in the reaction flask, and then S / TOP is injected therein and then reacted for 10 minutes. Here, triethylgallium and S / TOP are used in a molar ratio such that the stoichiometric ratio of Ga:S meets 1:1.5.

[0244] When the reaction was completed, ethanol was added to the reaction solution rapidly cooled to room temperature, followed by centrifugation, and the precipitate obtained therefrom was dispersed in toluene to obtain InZnP / Ga2S3 (core / first shell) nanoparticles.

[0245] In a 200 mL reaction flask, 1.2 mmol of zinc acetate and 2.4 mmol of oleic acid were dissolved in a trioctylamine solvent and then vacuum treated at 120° C. for 10 minutes. The interior of the flask was replaced with nitrogen (N2) and then heated to 280° C. Then, InZnP / Ga2S3 (core / first shell) nanoparticles were quickly added thereto, followed by the addition of 0.3 mmol of Se / TOP, followed by heating to 320° C. and reacting for 60 minutes to perform a ZnSe shell formation reaction and obtain InZnP / Ga2S3 / ZnSe nanoparticles.

[0246] In a 200 mL reaction flask, 1.2 mmol of zinc acetate and 2.4 mmol of oleic acid were dissolved in a trioctylamine solvent and then vacuum treated at 120° C. for 10 minutes. The interior of the flask was replaced with nitrogen (N2) and then heated to 280° C. Then, InZnP / Ga2S3 / ZnSe nanoparticles were quickly added thereto, followed by 1.2 mmol of S / TOP, which was then heated to 320° C. and reacted for 60 minutes to perform a ZnS shell formation reaction and obtain InZnP / Ga2S3 / ZnSe / ZnS quantum dots.

[0247] Comparative Example 1: Synthesis of InZnP / ZnS Quantum Dots

[0248] In a 200 mL reaction flask, 1.2 mmol of zinc acetate and 2.4 mmol of oleic acid were dissolved in a trioctylamine solvent and then vacuum treated at 120° C. for 10 minutes. The interior of the flask was replaced with nitrogen (N2) and then heated to 280° C. Subsequently, the InZnP core of Preparation Example 1-2 was quickly added thereto, followed by the addition of 1.2 mmol of S / TOP and the subsequent heating to 320° C. for a shell formation reaction for 60 minutes.

[0249] Subsequently, acetone was added to the reaction solution rapidly cooled to room temperature, followed by centrifugation, and the precipitate obtained therefrom was dispersed in toluene to prepare an InZnP / ZnS quantum dot dispersion.

[0250] Comparative Example 2: Synthesis of InZnP / Ga2S3 Quantum Dots

[0251] Triethylgallium and an organic ligand including oleic acid are placed in a 300 mL reaction flask containing octadecene (ODE) and then vacuum treated at 120 ° C. The interior of the flask is replaced with nitrogen (N2). When the temperature of the reactor is increased to the reaction temperature (260 ° C), the InZnP core of Preparation Example 1-2 is quickly placed in the reaction flask and then reacted for 10 minutes. Here, triethylgallium and S / TOP are used in a molar ratio such that the stoichiometric ratio of Ga:S meets 1:1.5.

[0252] When the reaction was completed, ethanol was added to the reaction solution rapidly cooled to room temperature, followed by centrifugation, and the precipitate obtained therefrom was dispersed in toluene to prepare an InZnP / Ga2S3 quantum dot dispersion.

[0253] Composition analysis of quantum dots

[0254] Transmission electron microscopy analysis was performed on the quantum dots according to Examples 1 to 3 and Comparative Examples 1 and 2. Among them, the transmission electron microscopy (TEM) image of the quantum dots according to Example 2 is shown in FIG. Figure 7 middle. Figure 7 A transmission electron microscope (TEM) image of quantum dots according to Example 2 is shown. Figure 7 , InZnP / Ga2S3 / ZnS quantum dots have a non-spherical particle shape (particle size: about 4 nm).

[0255] Inductively coupled plasma atomic emission spectroscopy was performed on the quantum dots according to Examples 1 to 3 and Comparative Examples 1 and 2, and the results of Example 2 are shown in Table 2.

[0256] (Table 2)

[0257]

[0258] Referring to Table 2, the quantum dots according to Example 2 satisfy the claimed molar ratio range.

[0259] XPS analysis was performed on the quantum dots according to Examples 1 to 3 and Comparative Examples 1 and 2 to investigate the composition. The analysis results of Example 2 are shown in FIG. Figure 8 middle. Figure 8 Graph showing the results of X-ray photoelectron spectroscopy (XPS) analysis of quantum dots according to Example 2. Figure 8 , the quantum dots exhibit a peak at 1118.5 eV, and this peak corresponds to the peak of Ga2S3. On the other hand, Figure 8 The absence of a peak at 1117.9 eV confirms the absence of gallium oxide (Ga2O3). Therefore, the quantum dots according to Example 2 include Ga2S3 having excellent stability. Figure 8 The results show that its first shell consists of Ga2S3.

[0260] Photoluminescence (PL) and UV-Vis spectroscopy analysis of quantum dots

[0261] Photoluminescence (PL) characteristics analysis and ultraviolet-visible (UV-Vis) spectroscopy analysis were performed on the quantum dots according to Examples 1 to 3 and Comparative Examples 1 and 2, and the results are shown in Table 3. The photoluminescence analysis results and UV-Vis spectroscopy analysis results of the quantum dots according to Example 2 and Comparative Example 1 are shown in Table 3. Figure 9 and Figure 10 middle. Figure 9 is a graph showing the photoluminescence analysis results of quantum dots according to Example 2 and Comparative Example 1, and Figure 10 is a graph showing the UV-Vis spectrum analysis results of the quantum dots according to Example 2 and Comparative Example 1.

[0262] (Table 3)

[0263]

[0264]

[0265] In Table 3, FWHM means half width and PLQY means photoluminescence quantum yield. Figure 9 and 10 The quantum dots according to Example 2 exhibited a maximum luminescence peak at 493 nm, which belongs to the blue light region, and exhibited light absorption at 460 nm, and the quantum dots according to Example 3 exhibited a maximum luminescence peak at 535 nm, which belongs to the green light region, and exhibited light absorption at 510 nm. In addition, compared with the quantum dots of Comparative Examples 1 and 2, the quantum dots of Examples 2 and 3 exhibited a greatly reduced full width at half maximum (FWHM) of the maximum luminescence peak and increased quantum efficiency. Therefore, the quantum dots of Examples 2 and 3 exhibited excellent light absorption.

[0266] While the present disclosure has been described with reference to what are presently considered to be practical example embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0267] <Description of symbols>

[0268] 1: Quantum dot 2: Core

[0269] 4: First shell 6: Second shell

[0270] 100: Electronic device 101: First electrode

[0271] 105: Second electrode 103: Active layer

[0272] 102, 20: hole assist layer 104, 40: electron assist layer

[0273] 200, 300: Electroluminescent device 10: Anode

[0274] 50: cathode 30: quantum dot active layer

[0275] 400, 500a, 500b: Photoluminescent display device

[0276] 410: Backlight unit

[0277] 450: LCD panel 411: Reflector

[0278] 412: Light Guiding

[0279] 414: Quantum dot-polymer composite sheet

Claims

1. Quantum dots, including a core comprising a first semiconductor nanocrystal comprising a Group III-V compound comprising InP, GaP, InAs, GaAs, InSb, GaSb, InGaP, InAsP, InSbP, InGaAs, InZnP, GaZnP, InZnAs, or a combination thereof; a first shell on the core comprising a second semiconductor nanocrystal, the second semiconductor nanocrystal comprising a Group III-VI compound comprising a gallium chalcogenide; and a second shell on the first shell comprising a third semiconductor nanocrystal, the third semiconductor nanocrystal having a composition different from a composition of the second semiconductor nanocrystal, the third semiconductor nanocrystal comprising a Group II-VI compound comprising ZnSe, ZnTeSe, ZnSeS, ZnTeS, ZnS, or a combination thereof; In the quantum dots, the molar ratio of the group III element to the group V element in the group III-V compound and the group III-VI compound is 1:1 to 50:

1.

2. The quantum dot of claim 1, wherein a ratio m2 / m3 of an effective mass m2 of the second semiconductor nanocrystal to an effective mass m3 of the third semiconductor nanocrystal is in a range of greater than or equal to 0.4 and less than or equal to 2.

5.

3. The quantum dot of claim 1, wherein the second semiconductor nanocrystal has a thickness less than 0.39 m e The effective mass of the electron.

4. The quantum dot of claim 1, wherein the second semiconductor nanocrystal has a thickness less than 1.76 m e The effective mass of the hole.

5. The quantum dot of claim 1, wherein the electron effective mass m of the second semiconductor nanocrystal is e2 and the electron effective mass m of the third semiconductor nanocrystal e3 The difference between e2 -m e3 Less than or equal to 0.2m e .

6. The quantum dot according to claim 1, wherein the effective hole mass m of the second semiconductor nanocrystal is h2 and the hole effective mass m of the third semiconductor nanocrystal h3 The difference between h2 -m h3 Less than or equal to 1.5m e .

7. The quantum dot of claim 1, wherein the Group II-VI compound comprises zinc, sulfur, and selenium, or zinc, selenium, and tellurium. 8 . The quantum dot of claim 1 , wherein a molar ratio of the group III element to the group V element in the quantum dot is in the range of 2.5-20. 9 . The quantum dot of claim 1 , wherein in the quantum dot, a molar ratio of the group III element to the group II element is greater than 0 and less than or equal to 5. 10 . The quantum dot of claim 1 , wherein a molar ratio of the group III element to the group II element in the quantum dot is 0.05-2. The quantum dot according to claim 1 , wherein a molar ratio of the Group III element to the Group VI element in the quantum dot is greater than 0 and less than or equal to 5. 12 . The quantum dot of claim 1 , wherein a molar ratio of the group III element to the group VI element in the quantum dot is 0.05-2.

13. The quantum dot of claim 1, wherein in the quantum dot, the first semiconductor nanocrystal comprises indium (In), the second semiconductor nanocrystal comprises gallium (Ga), and a molar ratio of gallium to indium (Ga / In) is in the range of 0.05-4.

5.

14. The quantum dot according to claim 1, wherein The second shell comprises a plurality of layers, and The plurality of layers include different types of II-VI compounds. The quantum dot of claim 14 , wherein a layer relatively close to the core among the plurality of layers comprises Se. The quantum dot of claim 14 , wherein a layer disposed relatively far from the core among the plurality of layers comprises S. 17 . The quantum dot of claim 1 , wherein the energy band gap of the second semiconductor nanocrystal is larger than the energy band gap of the first semiconductor nanocrystal and the energy band gap of the third semiconductor nanocrystal.

18. The quantum dot of claim 1, wherein the second shell includes a plurality of layers, and a third semiconductor nanocrystal included in a layer closest to the first shell among the plurality of layers has a smaller energy band gap than the second semiconductor nanocrystal of the first shell.

19. The quantum dot of claim 1, wherein a lattice mismatch ratio between the first semiconductor nanocrystal and the second semiconductor nanocrystal is less than or equal to 15%.

20. The quantum dot of claim 1, wherein a maximum emission peak of the quantum dot has a full width at half maximum (FWHM) less than or equal to 40 nm.

21. The quantum dot of claim 1, wherein the quantum dot has a quantum efficiency greater than or equal to 55%.

22. Quantum dot-polymer composites, including a polymer matrix; and quantum dots dispersed in the polymer matrix, The quantum dots include the quantum dots according to any one of claims 1 to 21.

23. The quantum dot-polymer composite of claim 22, wherein the polymer matrix comprises at least one selected from the group consisting of a thiol-ene polymer, a (meth)acrylate-based polymer, a urethane-based resin, an epoxy-based polymer, a vinyl-based polymer, and a silicone resin.

24. The quantum dot-polymer composite of claim 22, wherein the composite further comprises metal oxide particles.

25. Electronic equipment, including a first electrode and a second electrode facing each other; as well as an active layer located between the first electrode and the second electrode; The active layer comprises the quantum dots according to any one of claims 1 to 21.

26. The electronic device of claim 25, further comprising a hole assist layer.

27. The electronic device of claim 25, further comprising an electronic assist layer.

28. Electronic equipment, including Light sources and light-emitting elements, wherein the light emitting element comprises the quantum dot according to any one of claims 1 to 21, and The light source is configured to provide incident light to the light emitting element. 29 . The electronic device of claim 28 , wherein the incident light has a photoluminescence peak wavelength within a range of greater than or equal to 400 nm and less than or equal to 500 nm.

30. The electronic device of claim 28, wherein the light emitting element comprises a quantum dot-polymer composite.

31. The electronic device of claim 28, wherein The light emitting element includes a substrate and a quantum dot stacked structure on the substrate. The quantum dot stacked structure includes a quantum dot-polymer composite pattern, and The quantum dot-polymer composite pattern includes at least one repeating segment that emits light of a predetermined wavelength.

32. An electronic device comprising the quantum dots according to any one of claims 1 to 21.

33. Quantum dots, including a core comprising a first semiconductor nanocrystal comprising indium and phosphorus; a first shell comprising a second semiconductor nanocrystal comprising gallium and sulfur; and A second shell includes a third semiconductor nanocrystal including zinc and sulfur; zinc and selenium; or a combination thereof.

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