Core-shell quantum dots, method for manufacturing the same, quantum dot composites, quantum dot compositions, display devices and electronic devices comprising the same

Abstract

Disclosed are core-shell quantum dots, methods for manufacturing the same, quantum dot composites, quantum dot compositions, display devices, and electronic devices comprising the same. The core-shell quantum dots include: a core including a first semiconductor nanocrystal and including zinc, tellurium, and selenium, and a semiconductor nanocrystal shell disposed on the core and including zinc chalcogenide, wherein the core-shell quantum dots do not include cadmium, lead, mercury, or a combination thereof, wherein in an X-ray photoelectron spectrum of the quantum dots, the peak area of ​​Te oxide as an area percentage is relative to Te3d 5 / 2 The peak area is less than or equal to about 25%.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application Nos. 10-2019-0129447 and 10-2020-0117036 filed on October 17, 2019 and September 11, 2020, in the Korean Intellectual Property Office, and all rights and interests therefrom, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Disclosed are core-shell quantum dots, a method for manufacturing the core-shell quantum dots, and an electronic device comprising the core-shell quantum dots. Background Art

[0004] Different from bulk (body) material, the physical properties (for example, energy band gap and melting point) of semiconductor nanoparticles can be controlled by changing the size of nanoparticles. For example, semiconductor nanocrystalline particles (also referred to as quantum dots) are crystalline materials with a size within several nanometers. Because semiconductor nanocrystalline particles have relatively small sizes, the semiconductor nanocrystalline particles have large surface areas per unit volume, and thus, the particles present quantum confinement effects and have different properties from bulk materials of the same chemical composition. Quantum dots can absorb energy from an excitation source such as light or an applied electric current, and when relaxed to ground state, quantum dots emit light energy corresponding to the band gap energy of quantum dots. Summary of the invention

[0005] Embodiments provide cadmium-free quantum dots that can exhibit enhanced, eg, improved, optical properties such as luminous efficiency and stability such as oxidative stability.

[0006] Embodiments provide methods of making the aforementioned cadmium-free quantum dots.

[0007] Embodiments provide a quantum dot composite including the aforementioned cadmium-free quantum dots.

[0008] Embodiments provide electronic devices, such as display devices, including the aforementioned cadmium-free quantum dots.

[0009] In an embodiment, a core-shell quantum dot (hereinafter, sometimes referred to as a quantum dot) includes: a core including a first semiconductor nanocrystal, the first semiconductor nanocrystal including zinc, tellurium and selenium; and a semiconductor nanocrystal shell disposed on the core, the shell including zinc chalcogenide,

[0010] wherein the quantum dots do not include cadmium, lead, mercury, or a combination thereof, and

[0011] In the X-ray photoelectron spectrum of the quantum dots, the peak area of ​​Te oxide as area percentage is5 / 2 The peak area is less than or equal to about 25%.

[0012] In the core-shell quantum dots, a molar ratio of tellurium to selenium may be greater than or equal to about 0.1:1.

[0013] The molar ratio of tellurium to selenium may be greater than or equal to about 0.5:1, or greater than or equal to about 0.9:1.

[0014] In the core-shell quantum dots, the molar ratio of tellurium to selenium may be greater than or equal to about 1:1, greater than or equal to about 1.1:1, or greater than or equal to about 1.2:1. The molar ratio of tellurium to selenium may be greater than or equal to about 1.3:1, or greater than or equal to about 1.5:1.

[0015] In the core-shell quantum dots, a molar ratio of tellurium to selenium may be greater than or equal to about 1.9:1, greater than or equal to about 2:1, or greater than or equal to about 2.1:1.

[0016] The core-shell quantum dots may have a molar ratio of tellurium to selenium of less than or equal to about 4:1, less than or equal to about 3:1, or less than or equal to about 2.5:1.

[0017] In the X-ray photoelectron spectrum of the core-shell quantum dots, the peak area of ​​Te oxide is 5 / 2 The peak area is less than or equal to about 20%.

[0018] In the X-ray photoelectron spectrum of the core-shell quantum dots, the peak area of ​​Te oxide as area percentage is 5 / 2 The peak area is less than or equal to about 18%.

[0019] In the X-ray photoelectron spectrum of the core-shell quantum dots, the peak area of ​​Te oxide as area percentage is 5 / 2 The peak area is less than or equal to about 10%.

[0020] The core-shell quantum dots may include additional metals such as aluminum, gallium, lithium, or combinations thereof.

[0021] The core-shell quantum dots may be water-insoluble.

[0022] In the core of the core-shell quantum dot, the molar ratio of tellurium to selenium may be greater than or equal to about 0.2:1, greater than or equal to about 0.5:1, greater than or equal to about 1:1, greater than or equal to about 1.5:1, or greater than or equal to about 2:1.

[0023] In the core of the core-shell quantum dot, the molar ratio of tellurium to selenium may be less than or equal to about 5:1, less than or equal to about 4:1, less than or equal to about 3:1, less than or equal to about 2.5:1, or less than or equal to about 2:1.

[0024] The core-shell quantum dot is a first semiconductor nanocrystal and may include ZnTe x Se 1-x (wherein x is greater than or equal to about 0.4, or greater than or equal to about 0.5, and less than or equal to about 0.95, or less than or equal to about 0.9).

[0025] The shell of the core-shell quantum dot may include zinc chalcogenide, and the zinc chalcogenide may include selenium, sulfur, or a combination thereof.

[0026] In the core-shell quantum dots, the molar ratio of sulfur to selenium (S / Se) may be greater than 0:1, greater than or equal to about 0.01:1, greater than or equal to about 0.02:1, greater than or equal to about 0.1:1, greater than or equal to about 0.5:1, greater than or equal to about 0.6:1, greater than or equal to about 0.7:1, greater than or equal to about 0.8:1, greater than or equal to about 0.9:1, or greater than or equal to about 1:1. In the core-shell quantum dots, the molar ratio of sulfur to selenium (S:Se) may be less than or equal to about 4:1, less than or equal to about 3.5:1, less than or equal to about 3:1, less than or equal to about 2.5:1, less than or equal to about 2:1, less than or equal to about 1.5:1, less than or equal to about 1:1, or less than or equal to about 0.9:1.

[0027] The maximum photoluminescence peak of the core-shell quantum dots may be at a wavelength greater than about 450 nm, greater than about 460 nm, greater than about 470 nanometers (nm), greater than or equal to about 480 nm, greater than or equal to about 490 nm, or greater than or equal to about 500 nm.

[0028] The maximum photoluminescence peak of the core-shell quantum dots may be at a wavelength of less than or equal to about 600 nm, for example, less than or equal to about 590 nm, less than or equal to about 580 nm, less than or equal to about 570 nm, or less than or equal to about 560 nm.

[0029] The maximum photoluminescence peak of the core-shell quantum dots may have a wavelength within the range defined by any of the above minimum wavelengths and any of the above maximum wavelengths, respectively. For example, the maximum photoluminescence peak wavelength of the core-shell quantum dots is within the range of greater than about 450 nm and less than or equal to about 600 nm.

[0030] The maximum light emission peak of the core-shell quantum dots may have a full width at half maximum (FWHM) of less than about 50 nm, less than or equal to about 45 nm, less than or equal to about 40 nm, or less than or equal to about 30 nm.

[0031] The core-shell quantum dots may have a quantum efficiency greater than or equal to about 35%.

[0032] The core-shell quantum dots may include organic ligands, and the organic ligands may include RCOOH, RNH 2 , R 2 NH, R 3 N, RSH, RH 2 PO, R 2 HPO, R 3 PO, RH 2 P.R 2 HP, R 3 P、ROH、RCOOR'、RHPO(OH)、RPO(OH) 2 , R 2 POOH, a polymeric organic ligand, or a combination thereof, wherein R and R' are the same or different and are each independently a substituted or unsubstituted C1-C40 aliphatic hydrocarbon group, a substituted or unsubstituted C6-C40 aromatic hydrocarbon group, or a combination thereof.

[0033] The core-shell quantum dots may further include gallium.

[0034] In an embodiment, a method of making the core-shell quantum dots comprises:

[0035] preparing a core particle including the core by: reacting a zinc precursor, a selenium precursor, and a tellurium precursor at a core forming temperature to form nanocrystals;

[0036] adding a treating agent to a reaction medium including the nanocrystals for post-treatment,

[0037] wherein the treating agent comprises an organic thiol compound, sulfur dispersed in a (C1-C20 alkyl)phosphine, a bis(tri(C1-C20 alkyl)silyl)sulfide, a metal compound (e.g., comprising zinc), or a combination thereof; and

[0038] A zinc precursor is reacted with a chalcogen precursor in the presence of the core particle and a shell-forming organic ligand at a shell-forming temperature to form a semiconductor nanocrystalline shell on the core particle.

[0039] In an embodiment, the semiconductor nanocrystal shell includes zinc and at least one of selenium and sulfur.

[0040] In an embodiment, the metal compound may include a metal halide, an organic metal compound or complex (e.g., an organic carboxylate (organic carboxylate, organic carboxylate)-metal compound, an organic amine-metal compound, or a combination thereof), an organic-inorganic (complex) compound including a metal (e.g., by reacting a metal carboxylate such as a metal oleate and a sulfur compound such as a thiol compound such as dodecanethiol, S / TOP, or bis(trimethylsilyl)sulfide (TMSi 2The organic-inorganic compound may include a bond between the metal and sulfur.

[0041] The post-treatment may be performed at a temperature greater than or equal to about 50°C and less than or equal to about the core forming temperature. The post-treatment may be performed at a temperature less than or equal to about 300°C, less than or equal to about 280°C, or less than or equal to about 200°C.

[0042] The core forming temperature may be greater than or equal to about 280°C, or greater than or equal to about 300°C.

[0043] The shell forming temperature may be greater than or equal to about 250°C.

[0044] The thiol compound may have a C1-C30 hydrocarbon group.

[0045] The metal halide may include zinc chloride.

[0046] In an embodiment, the quantum dot composite comprises: a matrix (e.g., a polymer matrix); and a plurality of quantum dots dispersed in the matrix, wherein the plurality of quantum dots quantum dots include the aforementioned core-shell quantum dots. The polymer matrix may include a cross-linked polymer, a binder polymer including a carboxylic acid group, or a combination thereof.

[0047] The cross-linked polymer may include a polymerization product of a photopolymerizable monomer including a carbon-carbon double bond, a polymerization product of the photopolymerizable monomer and a polythiol compound having at least two thiol groups (eg, at a terminal of the polythiol compound), or a combination thereof.

[0048] The quantum dot composite may further include metal oxide fine particles (eg, dispersed in the matrix).

[0049] In an embodiment, the display device includes a light-emitting element (e.g., a photoluminescent element) and optionally a light source, wherein the light-emitting element includes the core-shell quantum dots or a quantum dot polymer composite including the core-shell quantum dots. If present, the light source may be configured to provide incident light to the light-emitting element.

[0050] The incident light may have a photoluminescence peak wavelength of about 440 nanometers (nm) to about 560 nm (or about 450 nm to about 460 nm).

[0051] The light emitting element may include a sheet of the quantum dot polymer composite.

[0052] The light emitting element may include a stacked structure including a substrate and a light emitting layer (eg, a photoluminescent layer) disposed on the substrate. The light emitting layer may include a patterned quantum dot polymer composite.

[0053] The pattern may include, for example, at least one, two, or three repeating segments (parts) configured to emit light of a predetermined wavelength.

[0054] The display device may be configured to have a color reproducibility of greater than or equal to about 80% based on the BT2020 standard.

[0055] In other embodiments, the electronic device may include: a first electrode and a second electrode, each having a surface opposite to the other; and an active layer including the core-shell quantum dots, for example, disposed between the first and second electrodes.

[0056] The electronic device may further include a charge assisting layer (eg, a hole assisting layer) disposed between the first electrode and the active layer.

[0057] The electronic device may further include a charge assisting layer (eg, an electron assisting layer) disposed between the first electrode and the active layer.

[0058] In embodiments, cadmium-free core-shell quantum dots can be provided that are capable of emitting light (e.g., emitting green light) at a desired wavelength (e.g., greater than about 470 nm) with improved efficiency and reduced FWHM. The core-shell quantum dots of embodiments can be applied to, for example, a variety of display devices, biomarkers (biosensors, bioimaging), photodetectors, solar cells, hybrid composites, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The above and other advantages and features of the present disclosure will become more apparent by further describing exemplary embodiments thereof in detail with reference to the accompanying drawings, in which:

[0060] Figure 1A A process of manufacturing a quantum dot composite pattern using a composition according to an embodiment is schematically shown.

[0061] Figure 1B The process of making a quantum dot composite pattern using an ink composition is schematically shown.

[0062] Figure 2 is an exploded view of a display device according to an embodiment.

[0063] Figure 3A is a schematic cross-sectional view of a display device according to an embodiment.

[0064] Figure 3B is a schematic cross-sectional view of a display device according to an embodiment.

[0065] Figure 4is a schematic cross-sectional view of a display device according to an embodiment.

[0066] Figure 5A is a schematic cross-sectional view of a light emitting device according to an embodiment.

[0067] Figure 5B is a schematic cross-sectional view of a light emitting device according to an embodiment.

[0068] Figure 5C is a schematic cross-sectional view of a light emitting device according to an embodiment.

[0069] Figure 6 1 is the X-ray photoelectron spectrum (XPS) of the core particles synthesized in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0070] The advantages and features of the present disclosure, and methods for achieving the same, will become apparent with reference to the following example embodiments in conjunction with the accompanying drawings attached hereto. However, the embodiments should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art.

[0071] Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used with the meanings commonly understood by personnel with ordinary knowledge in the art. It will be further understood that terms, such as those defined in common dictionaries, should be interpreted to have meanings consistent with their meanings in the context of the relevant art, and may not be interpreted ideally or exaggeratedly, unless clearly defined. The terms used herein are only used for the purpose of describing specific embodiments and are not intended to be limiting.

[0072] As used herein, the singular forms "one (kind) (indefinite article) (a, an)" and "the" are intended to include plural forms, including "at least one (kind)", unless the content clearly indicates otherwise. "At least one (kind)" will not be interpreted as limiting "one (kind)". "Or" means "and / or". As used herein, the term "and / or" includes any and all combinations of one or more of the relevant listed items. It will be further understood that the terms "comprising" or "including" when used in this specification indicate the presence of the stated features, regions, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more additional features, regions, wholes, steps, operations, elements, components, and / or their collections.

[0073] In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. The same reference numerals refer to the same elements throughout the specification.

[0074] 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. Conversely, when an element is referred to as being "directly on" another element, there are no intervening elements.

[0075] It will be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, components, regions, layers and / or segments (parts), these elements, components, regions, layers and / or segments (parts) should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or segment (part) from another element, component, region, layer or segment. Therefore, without departing from the teachings herein, the "first element", "component", "region", "layer" or "segment (part)" discussed below may be referred to as a second element, component, region, layer or segment (part).

[0076] As used herein, "about" includes the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations, or within ±5%, relative to the stated value.

[0077] Exemplary embodiments are described herein with reference to cross-sectional views as schematic diagrams of idealized embodiments. Thus, deviations from the shapes of the figures as a result of, for example, manufacturing techniques and / or tolerances are expected. Therefore, the embodiments described herein should not be construed as being limited to the specific shapes of the regions as shown herein, but rather include deviations in shape caused by, for example, manufacturing. For example, a region illustrated or described as flat may typically have rough and / or nonlinear features. In addition, the illustrated sharp corners may be rounded. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to illustrate the precise shapes of the regions, and are not intended to limit the scope of the claims.

[0078] As used herein, when no definition is otherwise provided, "substituted" may refer to a compound or group in which a hydrogen atom is replaced by a substituent such as a C1-C30 alkyl, a C2-C30 alkenyl, a C2-C30 alkynyl, a C6-C30 aryl, a C7-C30 alkaryl, a C1-C30 alkoxyl, a C1-C30 heteroalkyl, a C3-C30 heteroalkaryl, a C3-C30 cycloalkyl, a C3-C15 cycloalkenyl, a C6-C30 cycloalkynyl, a C2-C30 heterocycloalkyl, a halogen (-F, -Cl, -Br, or -I), a hydroxyl (-OH), a nitro (-NO), or a cycloalkyl. 2), cyano (-CN), amino (-NRR', wherein R and R' are independently hydrogen or C1-C6 alkyl), azido (-N 3 ), amidino (-C(=NH)NH 2 ), hydrazino (-NHNH 2 ), hydrazone (=N(NH 2 )), aldehyde group (-C(=O)H), carbamoyl group (-C(O)NH 2 ), thiol group (-SH), ester group (-C(=O)OR, wherein R is C1-C6 alkyl or C6-C12 aryl), carboxyl group (-COOH) or its salt (-C(=O)OM, wherein M is an organic or inorganic cation), sulfonic acid group (-SO 3 H) or its salt (-SO 3 M, where M is an organic or inorganic cation), a phosphate group (-PO 3 H 2 ) or its salt (-PO 3 MH or -PO 3 M 2 , wherein M is an organic or inorganic cation), or a combination thereof.

[0079] As used herein, a hydrocarbon group refers to a group (e.g., an alkyl, alkenyl, alkynyl, or aryl) comprising carbon and hydrogen (or consisting of carbon and hydrogen). A hydrocarbon group may be a group having a valence of 1 or greater formed by removing a hydrogen atom, e.g., at least one hydrogen atom, from an alkane, an alkene, an alkyne, or an aromatic hydrocarbon. In a hydrocarbon group, a methylene group, e.g., at least one methylene group, may be replaced by an oxygen moiety, a carbonyl moiety, an ester moiety, -NH-, or a combination thereof.

[0080] As used herein, "aliphatic" refers to a saturated or unsaturated straight chain or branched hydrocarbon group. The aliphatic group may be, for example, an alkyl, alkenyl, or alkynyl group.

[0081] As used herein, "alkyl" refers to a straight-chain or branched, saturated, monovalent hydrocarbon group (methyl, ethyl, hexyl, etc.).

[0082] As used herein, "alkenyl" refers to a straight-chain or branched monovalent hydrocarbon group having one or more carbon-carbon double bonds.

[0083] As used herein, "alkynyl" refers to a straight chain or branched monovalent hydrocarbon group having one or more carbon-carbon triple bonds.

[0084] Herein, "aromatic" refers to an organic compound or group that includes an unsaturated cyclic group having delocalized π electrons, such as at least one unsaturated cyclic group having delocalized π electrons. The term encompasses both hydrocarbon aromatic compounds and heteroaromatic compounds.

[0085] As used herein, "aryl" refers to a group formed by removing hydrogen, for example, at least one hydrogen, from an aromatic hydrocarbon (eg, phenyl or naphthyl).

[0086] As used herein, "hetero" refers to one or more (eg, 1-3) heteroatoms including N, O, S, Si, P, or a combination thereof.

[0087] As used herein, the word "Group" refers to a Group of the Periodic Table.

[0088] As used herein, “Group III” may refer to Group IIIA and Group IIIB, and examples of Group III metals may be In, Ga, and Tl, but are not limited thereto.

[0089] As used herein, “Group V” may refer to Group VA, and examples may include nitrogen, phosphorus, arsenic, antimony, and bismuth, but are not limited thereto.

[0090] As used in the present disclosure, "average" (eg, average size of quantum dots) may be a mean or a median. In an embodiment, the average may be a "mean" average.

[0091] As used herein, quantum efficiency may be a relative quantum yield or an absolute quantum yield that can be easily measured by any commercially available equipment. Quantum efficiency (or quantum yield) can be measured in a solution state or a solid state (such as with a complex). In an embodiment, "quantum yield (or quantum efficiency)" may be the ratio of photons emitted by a quantum dot complex, such as a nanostructure or a group of nanostructures, to photons absorbed. In an embodiment, quantum efficiency may be measured by any method known to those of ordinary skill in the art. For example, quantum efficiency may be measured by an absolute method and a relative method. The absolute method directly obtains quantum yield by: detecting all sample fluorescence using an integrating sphere. In a relative method, the fluorescence intensity of a standard sample (e.g., a standard dye) may be compared with the fluorescence intensity of an unknown sample to calculate the quantum yield of the unknown sample. Depending on the photoluminescence wavelength, coumarin 153, coumarin 545, rhodamine 101 inner salt, anthracene, and rhodamine 6G may be used as standard dyes, but are not limited thereto.

[0092] The quantum yield (QY) can be easily and reproducibly determined by using a commercially available apparatus (eg, from Hitachi Co. Ltd or Hamamatsu Co. Ltd) and referring to the manual provided by the manufacturer.

[0093] The FWHM and the maximum PL peak wavelength can be determined by a photoluminescence spectrum obtained by a spectrophotometer (or fluorescence spectrophotometer).

[0094] As used herein, the expression "does not include cadmium (or other harmful heavy metals)" may refer to the following: wherein the concentration of cadmium (or another heavy metal that appears to be harmful, see below) may be less than or equal to about 100 parts per million by weight (ppmw), less than or equal to about 50 ppmw, less than or equal to about 10 ppmw, less than or equal to about 1 ppmw, less than or equal to about 0.1 ppmw, less than or equal to about 0.01 ppmw, or about zero. In embodiments, substantially no cadmium (or other heavy metal) may be present, or if present, the amount of cadmium (or other heavy metal) may be less than or equal to the detection limit of a given analytical tool (e.g., inductively coupled plasma atomic emission spectrometry) or as its impurity level.

[0095] Semiconductor nanocrystal particles (e.g., quantum dots) can absorb light from an excitation source and can emit light corresponding to the energy band gap of the quantum dots. The energy band gap of the quantum dots can change with the size and composition of the quantum dots. For example, when the size of the quantum dots increases, the quantum dots can have a narrower energy band gap and can exhibit an increased emission wavelength. Semiconductor nanocrystals can be used as luminescent materials in a variety of fields such as display devices, energy devices, or bioluminescent devices.

[0096] Quantum dots with relatively improved photoluminescent properties may include toxic heavy metals such as cadmium (Cd), lead (Pb), and / or mercury (Hg). The toxic heavy metals such as cadmium may cause environmental problems, health problems, or a combination thereof, and are one of the restricted elements in accordance with the Restriction of Hazardous Substances Directive (RoHS) in many countries. Therefore, it is desirable to develop cadmium-free quantum dots with improved photoluminescent properties. Cadmium-free indium phosphide quantum dots (QDs) may, for example, be used in practical devices.

[0097] In order to be applied to quantum dot display devices (e.g., including a color conversion layer containing quantum dots), such as being used therein, and in order to achieve a display device with relatively high color reproducibility according to the next generation color standard such as BT2020, it is desirable to have a relatively narrow half width (FWHM) of quantum dots. For example, in order for the device to achieve an improvement in color reproducibility according to the BT2020 standard, for example, it is desirable that the luminescent material used herein has a reduced level of FWHM. However, compared to a Cd-based core (e.g., a CdSe core), a III-V compound-based quantum dot including indium and phosphorus has a smaller band gap and a larger Bohr radius, and therefore the change in FWHM depending on the size of the quantum dot may be significant. Therefore, InP-based quantum dots may not have a desired FWHM of emitted light at a desired wavelength (e.g., greater than about 470nm, greater than or equal to about 475nm, greater than or equal to about 480nm and less than or equal to about 580nm). Additionally, cores including indium and phosphorus may be sensitive to surface oxidation, and quantum dots including the same may have increased FWHM when including a shell, e.g., a shell coated on the core of the quantum dot, and thus achieving a desired level of quantum efficiency along with a desired FWHM may be difficult.

[0098] The inventors have found that as cadmium-free quantum dots, nanocrystalline particles based on ZnTeSe can have a desired FWHM and emit light of a desired wavelength (e.g., greater than about 470 nm, greater than or equal to about 475 nm, greater than or equal to about 480 nm and less than or equal to about 580 nm). Moreover, the inventors found in their studies that, compared with indium phosphide-based quantum dots or cadmium-based quantum dots, such emission is not truly dependent on the average particle size of the quantum dots. In other words, ZnTeSe nanocrystalline particles can be advantageous because they can exhibit a small variation (or relatively narrow) FWHM at the maximum emission wavelength, even if the average particle size variation in a population of quantum dots is relatively large.

[0099] However, a quantum dot structure including a ZnTeSe-based core and an inorganic shell coated thereon may have difficulty in exhibiting desired luminescent properties. Without wishing to be bound by any theory, according to the inventors' research, it is believed that a zinc telluride-based core is very sensitive to oxidation of tellurium during shell formation. Without wishing to be bound by any theory, it is believed that the formation of an inorganic shell (e.g., an inorganic shell including zinc sulfide) on a ZnTeSe core may result in a significant amount of oxide (e.g., tellurium oxide), which may be formed primarily after the formation of the core nanocrystals and before the complete formation of the shell.

[0100] The core-shell quantum dots of the embodiment and the method for manufacturing the quantum dots will be described in detail below. In the method of the embodiment, the treating agent is added during the core formation, and thereby, a ligand with enhanced binding to the core is introduced, and when the core is stored or undergoes a shell formation process, this can minimize the reaction (e.g., oxidation) of the core if exposed to oxygen.

[0101] In an embodiment, the core-shell quantum dot comprises: a core comprising a first semiconductor nanocrystal, the first semiconductor nanocrystal comprising zinc, tellurium, and selenium; and a semiconductor nanocrystal shell comprising zinc chalcogenide disposed on the core (or at least a portion of a surface of the core).

[0102] The core-shell quantum dots of the embodiments do not include cadmium, lead, mercury, or a combination thereof, and in their X-ray photoelectron spectroscopy spectra, Te oxides (e.g., TeO, TeO 2 、TeO 3 , or a combination thereof) for the peak area of ​​Te3d 5 / 2 The peak area of ​​the Te oxide is less than or equal to about 25 percent (%). The peak of the Te oxide may refer to the peak of Te3d 5 / 2 Adjacent oxide peaks.

[0103] The core-shell quantum dot (or the core) may include a predetermined amount of tellurium. The amount of elemental components included in the quantum dots as described herein may be determined by appropriate analytical instruments and methods known to ordinary technicians (e.g., inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray photoelectron spectroscopy (XPS), ion chromatography, transmission electron microscopy energy dispersive X-ray spectroscopy (TEM-EDS), etc.).

[0104] The core may have a structure in which selenium is alloyed (doped) in zinc telluride crystals. In the core or in the core-shell quantum dot, the amount of tellurium may be greater than the amount of selenium.

[0105] In the core-shell quantum dot of the embodiment, the core may include a first semiconductor nanocrystal including zinc, tellurium, and selenium. The first semiconductor nanocrystal may include ZnTe x Se 1-x(where x is greater than or equal to about 0.12, greater than or equal to about 0.15, greater than or equal to about 0.17, greater than or equal to about 0.2, greater than or equal to about 0.3, greater than or equal to about 0.4, greater than or equal to about 0.5, greater than or equal to about 0.51, greater than or equal to about 0.52, greater than or equal to about 0.53, greater than or equal to about 0.54, greater than or equal to about 0.55, greater than or equal to about 0.56, greater than or equal to about 0.57, greater than or equal to about 0.58, greater than or equal to about 0.59, greater than or equal to about 0.6, greater than or equal to about 0.61, greater than or equal to about 0.62, greater than or equal to about 0.63, greater than or equal to about 0.64, greater than or equal to about 0.65, greater than or equal to about 0.66, greater than or equal to about 0.67, about 0.68 or more, about 0.69 or more, about 0.70 or more, about 0.71 or more, about 0.72 or more, about 0.73 or more, about 0.74 or more, about 0.75 or more, or about 0.8 or more and about 0.9 or less, about 0.89 or less, about 0.88 or less, about 0.87 or less, about 0.86 or less, about 0.85 or less, about 0.84 or less, about 0.83 or less, about 0.82 or less, about 0.8 or less, about 0.75 or less, about 0.7 or less, about 0.65 or less, or about 0.6 or less.

[0106] In the core, the molar ratio of tellurium to selenium (Te:Se) may be greater than or equal to about 0.2:1, greater than or equal to about 0.25:1, greater than or equal to about 0.3:1, greater than or equal to about 0.35:1, greater than or equal to about 0.4:1, greater than or equal to about 0.45:1, greater than or equal to about 0.5:1, greater than or equal to about 0.55:1, greater than or equal to about 0.6:1, greater than or equal to about 0.65:1, greater than or equal to about 0.7:1, greater than or equal to about 0.75:1, greater than or equal to about 0.8:1, greater than or equal to about 0.85:1, greater than or equal to about 0.9:1, greater than or equal to about 0.93:1, greater than or equal to about 0.95:1, greater than or equal to about 1 :1, greater than or equal to about 1.1:1, greater than or equal to about 1.2:1, greater than or equal to about 1.3:1, greater than or equal to about 1.4:1, greater than or equal to about 1.5:1, greater than or equal to about 1.6:1, greater than or equal to about 1.7:1, greater than or equal to about 1.8:1, greater than or equal to about 1.9:1, greater than or equal to about 2:1, greater than or equal to about 2.1:1, greater than or equal to about 2.2:1, greater than or equal to about 2.3:1, greater than or equal to about 2.4:1, greater than or equal to about 2.5:1, greater than or equal to about 2.6:1, greater than or equal to about 2.7:1, greater than or equal to about 2.8:1, greater than or equal to about 2.9:1, or greater than or equal to about 3:1.

[0107] In the core, the molar ratio of tellurium to selenium (Te:Se) may be less than or equal to about 5:1, less than or equal to about 4.5:1, less than or equal to about 4:1, less than or equal to about 3.9:1, less than or equal to about 3.8:1, less than or equal to about 3.7:1, less than or equal to about 3.6:1, less than or equal to about 3.5:1, less than or equal to about 3.4:1, less than or equal to about 3.3:1, less than or equal to about 3.2:1, less than or equal to about 3.1:1, less than or equal to about 3:1, less than or equal to about 2.9:1, less than or equal to about 2.8:1, less than or equal to about 2.7:1, less than or equal to about 2.6:1, less than or equal to about 2.5:1, less than or equal to about 2.4:1 1, less than or equal to about 2.3:1, less than or equal to about 2.2:1, less than or equal to about 2.1:1, less than or equal to about 2.0:1, less than or equal to about 1.9:1, less than or equal to about 1.8:1, less than or equal to about 1.7:1, less than or equal to about 1.6:1, less than or equal to about 1.5:1, less than or equal to about 1.4:1, less than or equal to about 1.3:1, less than or equal to about 1.2:1, less than or equal to about 1.1:1, less than or equal to about 1:1, less than or equal to about 0.9:1, less than or equal to about 0.8:1, less than or equal to about 0.7:1, less than or equal to about 0.6:1, less than or equal to about 0.5:1, or less than or equal to about 0.4:1.

[0108] In the core-shell quantum dots of embodiments, the molar ratio of tellurium to selenium (Te:Se) may be greater than about 0.05:1, such as greater than or equal to about 0.055:1, greater than or equal to about 0.06:1, greater than or equal to about 0.065:1, or greater than or equal to about 0.07:1.

[0109] In the core-shell quantum dots of the embodiments, the molar ratio of tellurium to selenium (Te:Se) may be greater than or equal to about 0.1:1, greater than or equal to about 0.15:1, greater than or equal to about 0.2:1, greater than or equal to about 0.25:1, greater than or equal to about 0.3:1, greater than or equal to about 0.35:1, greater than or equal to about 0.4:1, greater than or equal to about 0.45:1, greater than or equal to about 0.5:1, greater than or equal to about 0.55:1, greater than or equal to about 0.6:1, greater than or equal to about 0.65:1, greater than or equal to about 0.7:1, greater than or equal to about 0.75:1, greater than or equal to about 0.8:1, greater than or equal to about 0.85:1, greater than or equal to about 0.9:1, or greater than or equal to about 0.9:1. greater than or equal to about 1:1, greater than or equal to about 1.1:1, greater than or equal to about 1.2:1, greater than or equal to about 1.3:1, greater than or equal to about 1.4:1, greater than or equal to about 1.5:1, greater than or equal to about 1.6:1, greater than or equal to about 1.7:1, greater than or equal to about 1.8:1, greater than or equal to about 1.9:1, greater than or equal to about 2:1, greater than or equal to about 2.1:1, greater than or equal to about 2.2:1, greater than or equal to about 2.3:1, greater than or equal to about 2.4:1, greater than or equal to about 2.5:1, greater than or equal to about 2.6:1, greater than or equal to about 2.7:1, greater than or equal to about 2.8:1, greater than or equal to about 2.9:1, or greater than or equal to about 3:1.

[0110] In the core-shell quantum dots of the embodiments, the molar ratio of tellurium to selenium may be less than or equal to about 4:1, less than or equal to about 3.9:1, less than or equal to about 3.8:1, less than or equal to about 3.7:1, less than or equal to about 3.6:1, less than or equal to about 3.5:1, less than or equal to about 3.4:1, less than or equal to about 3.3:1, less than or equal to about 3.2:1, less than or equal to about 3.1:1, less than or equal to about 3:1, less than or equal to about 2.9:1, less than or equal to about 2.8:1, less than or equal to about 2.7:1, less than or equal to about 2.6:1, less than or equal to about 2.5:1, or less than or equal to about 2.4:1, less than or equal to about 2.3:1, less than or equal to about 2.4:1. less than or equal to about 1:1, less than or equal to about 0.9:1, less than or equal to about 0.8:1, less than or equal to about 0.7:1, less than or equal to about 0.6:1, less than or equal to about 0.5:1, less than or equal to about 0.4:1, less than or equal to about 0.3:1, or less than or equal to about 0.2:1.

[0111] In the core-shell quantum dots of embodiments, the molar ratio of tellurium to zinc (Te:Zn) may be greater than about 0.03:1 as determined by inductively coupled plasma atomic emission spectrometry analysis. In the core-shell quantum dots of the embodiments, the molar ratio of tellurium to zinc (Te:Zn) may be greater than or equal to about 0.05:1, greater than or equal to about 0.07:1, greater than or equal to about 0.09:1, greater than or equal to about 0.1:1, greater than or equal to about 0.13:1, greater than or equal to about 0.15:1, greater than or equal to about 0.17:1, greater than or equal to about 0.19:1, greater than or equal to about 0.2:1, greater than or equal to about 0.21:1, greater than or equal to about 0.23:1, greater than or equal to about 0.25:1, greater than or equal to about 0.3:1, greater than or equal to about 0.35:1, or greater than or equal to about 0.4:1 (e.g., when determined by inductively coupled plasma atomic emission spectrometry analysis).

[0112] In the core-shell quantum dots of the embodiments, the molar ratio of tellurium to zinc (Te:Zn) may be less than about 1:1, e.g., less than or equal to about 0.9:1, less than or equal to about 0.8:1, less than or equal to about 0.7:1, less than or equal to about 0.6:1, less than or equal to about 0.5:1, less than or equal to about 0.4:1, less than or equal to about 0.3:1, less than or equal to about 0.2:1, or less than or equal to about 0.1:1 (e.g., as determined by inductively coupled plasma atomic emission spectrometry analysis).

[0113] In the core-shell quantum dots of the embodiment, the molar ratio of zinc to tellurium (Zn:Te) may be greater than or equal to about 0.5:1, greater than or equal to about 1:1, greater than or equal to about 1.1:1, greater than or equal to about 1.5:1, greater than or equal to about 2:1, greater than or equal to about 3:1, greater than or equal to about 4:1 and less than or equal to about 40:1, less than or equal to about 35:1, less than or equal to about 30:1, less than or equal to about 25:1, less than or equal to about 20:1, less than or equal to about 15:1, less than or equal to about 10:1, less than or equal to about 6:1, less than or equal to about 4:1, less than or equal to about 3:1, less than or equal to about 2.5:1, less than or equal to about 2.4:1, less than or equal to about 2.3:1, or less than or equal to about 2.25:1.

[0114] The core-shell quantum dots of the embodiment may further include sulfur. In the embodiment, the molar ratio of sulfur to zinc may be greater than or equal to about 0.05:1, greater than or equal to about 0.1:1, greater than or equal to about 0.15:1, greater than or equal to about 0.2:1, greater than or equal to about 0.25:1, greater than or equal to about 0.3:1, or greater than or equal to about 0.35:1 and less than or equal to about 0.95:1, less than or equal to about 0.9:1, less than or equal to about 0.85:1, less than or equal to about 0.8:1, less than or equal to about 0.75:1, less than or equal to about 0.7:1, less than or equal to about 0.65:1, less than or equal to about 0.6:1, less than or equal to about 0.5:1, less than or equal to about 0.4:1, or less than or equal to about 0.3:1.

[0115] In the core-shell quantum dots of the embodiment, the molar ratio of sulfur to tellurium (S / Te) may be greater than 0, greater than or equal to about 0.1:1, greater than or equal to about 0.2:1, greater than or equal to about 0.3:1, greater than or equal to about 0.4:1, greater than or equal to about 0.45:1, greater than or equal to about 0.5:1, greater than or equal to about 0.55:1, greater than or equal to about 0.6:1, greater than or equal to about 0.65:1, greater than or equal to about 0.7:1, greater than or equal to about 0.75:1, greater than or equal to about 0.8:1, greater than or equal to about 0.85:1, or greater than or equal to about 0.9:1. 1 and less than or equal to about 8:1, less than or equal to about 7:1, less than or equal to about 6:1, less than or equal to about 5:1, less than or equal to about 4.5:1, less than or equal to about 4:1, less than or equal to about 3.5:1, less than or equal to about 3:1, less than or equal to about 2.5:1, less than or equal to about 2:1, less than or equal to about 1.5:1, less than or equal to about 1:1, less than or equal to about 0.9:1, less than or equal to about 0.8:1, less than or equal to about 0.7:1, less than or equal to about 0.6:1, less than or equal to about 0.5:1, or less than or equal to about 0.4:1.

[0116] In the core-shell quantum dots of the embodiments or in the core (or the first semiconductor nanocrystal) of the embodiments, the molar ratio of selenium to tellurium (Se:Te) may be greater than or equal to about 0.1:1, greater than or equal to about 0.15:1, greater than or equal to about 0.2:1, greater than or equal to about 0.25:1, greater than or equal to about 0.3:1, greater than or equal to about 0.35:1, greater than or equal to about 0.4:1, greater than or equal to about 0.5:1, greater than or equal to about 0.55:1, greater than or equal to about 0.6:1, greater than or equal to about 0.65:1 , greater than or equal to about 0.7:1, greater than or equal to about 0.75:1, greater than or equal to about 0.8:1, greater than or equal to about 0.85:1, greater than or equal to about 0.9:1, greater than or equal to about 0.95:1, greater than or equal to about 1:1, greater than or equal to about 1.5:1, greater than or equal to about 2:1, greater than or equal to about 2.5:1, greater than or equal to about 3:1, greater than or equal to about 3.5:1, greater than or equal to about 4:1, greater than or equal to about 4.5:1, greater than or equal to about 5:1, or greater than or equal to about 5.5:1.

[0117] In the core-shell quantum dots of embodiments or in the core (the first semiconductor nanocrystal) of embodiments, the molar ratio of selenium to tellurium (Se:Te) may be less than or equal to about 7:1, less than or equal to about 6.5:1, less than or equal to about 6:1, less than or equal to about 5.5:1, less than or equal to about 5:1, less than or equal to about 4.5:1, less than or equal to about 4:1, less than or equal to about 3.5:1, less than or equal to about 3:1, less than or equal to about 2.5:1, less than or equal to about 2:1, less than or equal to about 1.5:1, less than or equal to about 1:1, less than or equal to about 0.9:1, less than or equal to about 0.85:1, less than or equal to about 0.8:1, less than or equal to about 0.7:1, less than or equal to about 0.6:1, less than or equal to about 0.5:1, or less than or equal to about 0.45:1.

[0118] In the core-shell quantum dots of the embodiments, the molar ratio of the sum of sulfur and selenium to tellurium may be less than or equal to about 15:1, less than or equal to about 14:1, less than or equal to about 13:1, less than or equal to about 12:1, less than or equal to about 11:1, less than or equal to about 10:1, less than or equal to about 9:1, less than or equal to about 8:1, less than or equal to about 7:1, less than or equal to about 6:1, less than or equal to about 5:1, less than or equal to about 4:1, or less than or equal to about 3. In the core-shell quantum dots of the embodiments, the molar ratio of the sum of sulfur and selenium to tellurium may be greater than or equal to about 1:1, greater than or equal to about 1.5:1, or greater than or equal to about 2:1.

[0119] The core-shell quantum dots may not include manganese, copper, or a combination thereof. The quantum dots may not include a III-V group compound. The III-V group compound may include indium phosphide, indium zinc phosphide, gallium phosphide, or a combination thereof. The core-shell quantum dots may not exhibit a peak attributable to the III-V group compound (e.g., indium phosphide or gallium phosphide) in an X-ray diffraction analysis.

[0120] The core-shell quantum dots of embodiments may further include gallium, aluminum, lithium, or a combination thereof, for example, in the core, in the semiconductor nanocrystal shell, or in both the core and the shell. For example, in embodiments, the semiconductor nanocrystal shell may not include gallium, aluminum, lithium, or a combination thereof. In further embodiments, the semiconductor nanocrystal shell may include gallium, aluminum, lithium, or a combination thereof.

[0121] In the core-shell quantum dots of the embodiments, if present, the molar ratio of gallium, aluminum, lithium, or a combination thereof to tellurium may be greater than or equal to about 0.005:1, greater than or equal to about 0.009:1, greater than or equal to about 0.01:1, greater than or equal to about 0.02:1, greater than or equal to about 0.03:1, greater than or equal to about 0.04:1, greater than or equal to about 0.05:1, greater than or equal to about 0.06:1, greater than or equal to about 0.07:1, greater than or equal to about 0.08:1, greater than or equal to about 0.09:1, or greater than or equal to about 0.10:1. :1, greater than or equal to about 0.1:1, greater than or equal to about 0.11:1, greater than or equal to about 0.12:1, greater than or equal to about 0.13:1, greater than or equal to about 0.14:1, greater than or equal to about 0.15:1, greater than or equal to about 0.16:1, greater than or equal to about 0.17:1, greater than or equal to about 0.18:1, greater than or equal to about 0.19:1, greater than or equal to about 0.2:1, greater than or equal to about 0.21:1, greater than or equal to about 0.22:1, greater than or equal to about 0. 23:1, greater than or equal to about 0.24:1, greater than or equal to about 0.25:1, greater than or equal to about 0.26:1, greater than or equal to about 0.27:1, greater than or equal to about 0.28:1, greater than or equal to about 0.29:1, greater than or equal to about 0.3:1, greater than or equal to about 0.31:1, greater than or equal to about 0.32:1, greater than or equal to about 0.33:1, greater than or equal to about 0.34:1, greater than or equal to about 0.35:1, greater than or equal to about 0.36:1, greater than or equal to about 0.37:1, greater than or equal to about 0.38:1, greater than or equal to about 0.39:1, greater than or equal to about 0.4:1, greater than or equal to about 0.41:1, greater than or equal to about 0.42:1, greater than or equal to about 0.43:1, greater than or equal to about 0.44:1, greater than or equal to about 0.45:1, greater than or equal to about 0.46:1, greater than or equal to about 0.47:1, greater than or equal to about 0.48:1, greater than or equal to about 0.49:1, or greater than or equal to about 0.50:1.

[0122] In the core-shell quantum dots of the embodiments, if present, the molar ratio of gallium, aluminum, lithium, or a combination thereof to tellurium may be less than or equal to about 1.5:1, less than or equal to about 1:1, less than or equal to about 0.9:1, less than or equal to about 0.85:1, less than or equal to about 0.8:1, less than or equal to about 0.75:1, less than or equal to about 0.7:1, less than or equal to about 0.65:1, less than or equal to about 0.6:1, or less than or equal to about 0.55:1.

[0123] Without wishing to be bound by any theory, the presence of gallium, aluminum, and / or lithium may contribute to the enhanced luminescent properties of the core-shell quantum dots.

[0124] In an embodiment, the semiconductor nanocrystal shell may include: zinc; and at least one of selenium (Se) or sulfur (S) (eg, sulfur, selenium, or a combination thereof). The semiconductor nanocrystal shell may be ZnSe, ZnS, ZnSeS, or a combination thereof.

[0125] The semiconductor nanocrystal shell may be a multilayer shell including a plurality of layers. In the plurality of layers of the shell, adjacent layers may have semiconductor nanocrystal materials of different compositions. The multilayer shell may include a first shell layer disposed directly on the core and a second shell layer disposed on or above the first layer. The first shell layer may include a second semiconductor nanocrystal. The second shell layer may include a third semiconductor nanocrystal having a composition different from that of the second semiconductor nanocrystal. The second shell layer may be the outermost shell of the core-shell quantum dot. The second semiconductor nanocrystal may include zinc and selenium, and optionally sulfur. The second semiconductor nanocrystal may not include sulfur. The third semiconductor nanocrystal may include zinc and sulfur. The third semiconductor nanocrystal may not include selenium. In an embodiment, the first shell layer may include ZnSe, ZnSeS, ZnS, or a combination thereof. The second shell layer may consist of ZnS.

[0126] In the multilayer shell, the thickness of each shell layer can be appropriately selected. The thickness of the shell layer can be greater than or equal to about 1 monolayer (ML), such as greater than or equal to about 2 ML, greater than or equal to about 3 ML, greater than or equal to about 4 ML, greater than or equal to about 5 ML and less than or equal to about 10 ML, such as less than or equal to about 9 ML, less than or equal to about 8 ML, less than or equal to about 7 ML, less than or equal to about 6 ML, or less than or equal to about 5 ML. The thickness of each shell layer in the multilayer shell can be selected taking into account the desired composition of the final core-shell quantum dot.

[0127] In an embodiment, the shell or the shell layers in the multi-layer shell may each include a gradient alloy having a composition that changes in a radial direction, such as radially from the core toward the outermost surface of the core-shell quantum dot. In an embodiment, the amount of sulfur in the semiconductor nanocrystal shell may increase toward the surface of the core-shell quantum dot. For example, in the shell, the amount of sulfur may increase in a direction away from the core, such as radially from the core toward the outermost surface of the core-shell quantum dot.

[0128] In the core-shell quantum dots of the embodiments, the amount of tellurium oxide can be significantly reduced or kept controlled and limited. Without wishing to be bound by any theory, the core-shell quantum dots of the embodiments can be prepared as follows: using a core prepared by the method described in detail below (e.g., including a treatment agent before shell formation), and optionally controlling the preparation conditions for shell formation, the formation of tellurium oxide in the core can be suppressed.

[0129] Thus, the core-shell quantum dots of the embodiments may exhibit substantially no tellurium oxide or very limited amounts of tellurium oxide as determined by XPS. In the core-shell quantum dots of the embodiments, the amount of tellurium oxide may be determined by XPS analysis and quantified by measuring the peak area of ​​the energy spectrum.

[0130] In the XPS spectrum, the peak area (intensity) can each be easily and reproducibly measured therefrom, for example, by using software for analysis of XPS spectrum such as "XPSPEAK 4.1" or software provided for an XPS apparatus.

[0131] In the XPS analysis of the core-shell quantum dots, the peak area of ​​the Te oxide peak as area percentage (see below) is plotted against the Te 3d 5 / 2 The peak area may be less than or equal to about 25%, less than or equal to about 20%, less than or equal to about 19%, less than or equal to about 18%, less than or equal to about 17%, less than or equal to about 16%, less than or equal to about 15%, 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%.

[0132] Area percentage = [peak area (tellurium oxide) / peak area (Te 3d 5 / 2 (Zn-Te))]×100

[0133] According to the research of the present inventors, the amount of Te oxide as determined by XPS analysis can substantially (significantly) affect the luminescent properties (e.g., quantum efficiency) of the core-shell quantum dots, and in order to achieve the desired level of luminescent properties, the amount of Te oxide may have to be controlled by the preparation method of core-shell quantum dots developed by the present inventors and described herein.

[0134] X-ray photoelectron spectroscopy is a tool that can be used to identify or characterize photoelectrons emitted or expelled from a material (compound, metal compound, or metal alloy) after irradiating the material with X-rays. Specifically, the material is irradiated with X-rays, and the energy of the photoelectrons emitted from the solid sample is measured. The emitted photoelectrons can provide information about the binding energy of the core electrons of a given element in the material.

[0135] XPS is a non-destructive measurement technique that can provide information about the state of electrons and the composition of materials. In addition, XPS can be used to provide the relative concentration of elements in a material, and in some cases, the concentration can be quantitatively measured. The binding energy of the core electrons is an intrinsic property of the element, and therefore, the results of XPS can provide information about the elements that make up the provided material sample and the composition and binding state of the material sample. XPS is a well-established analytical tool in the field of material analysis, such as semiconductor materials, and such measurement methods are commercially available and are known to easily provide results with desirable accuracy or reproducibility. Moreover, XPS can provide a spectrum that is amplified for the element of interest (i.e., tellurium) to obtain a multiplex spectrum, and this can provide additional information. In an embodiment, the core-shell quantum dots are subjected to tellurium (e.g., for Te 3d 5 / 2 ) and by high-resolution peak scanning, quantitative analytical information on the amount of tellurium oxide relative to tellurium in the material sample can be obtained.

[0136] The excitation source used for XPS analysis may include a monochromatic and focused Al Kα source (E=1486.6 eV), but is not limited thereto.

[0137] In the case of Te, the zinc chalcogenide and the Te oxide may exhibit peaks at different positions, respectively. In an embodiment, tellurium of ZnTe or ZnTeSe may exhibit a peak at around 572 eV (e.g., 572.7 eV), and the Te oxide may exhibit a peak at a position higher than Te of the zinc chalcogenide (e.g., about 575 eV to about 577 eV) (e.g., 575.6 eV, 576.2 eV, or 577.3 eV). Te3d 5 / 2 Peaks were fitted using a single mixture Gaussian plus Lorentzian fit and their backgrounds were subtracted using Shirley background subtraction.

[0138] ZnTe-based core (or ZnTe-based x Se (1-x) An alloy core) can provide core-shell quantum dots that can emit light of a desired wavelength, for example, less than or equal to about 600 nm, or less than or equal to about 580 nm and greater than or equal to about 490 nm, or greater than or equal to about 500 nm, even without including toxic heavy metals.

[0139] However, from the research of the present inventors, the shell formation on such a core may not provide the final core-shell quantum dots with the desired luminescent properties such as luminescent wavelength and luminescent efficiency (especially when the core has a relatively large amount of tellurium). Without wishing to be bound by any theory, the II-VI compound core including tellurium may have poor oxidative stability, and therefore, during the shell formation, oxidation of tellurium may occur, which may have an adverse effect on the optical properties of the resulting core-shell quantum dots.

[0140] In contrast, core-shell quantum dots prepared as follows may include relatively small amounts or substantially no tellurium oxide, as measured by XPS analysis. Thus, embodiment core-shell quantum dots may exhibit one or more improved optical properties (eg, increased quantum efficiency).

[0141] The core-shell quantum dots (or a plurality thereof) may have an (average) particle size of greater than or equal to about 2 nanometers (nm), greater than or equal to about 3 nm, greater than or equal to about 4 nm, greater than or equal to about 5 nm, greater than or equal to about 6 nm, greater than or equal to about 7 nm, greater than or equal to about 7.5 nm, greater than or equal to about 8 nm, greater than or equal to about 8.5 nm, greater than or equal to about 9 nm, greater than or equal to about 9.5 nm, or greater than or equal to about 10 nm.

[0142] The size (or average size) of the core-shell quantum dots (or a plurality thereof) may be less than or equal to about 50 nm, for example, less than or equal to about 45 nm, less than or equal to about 40 nm, less than or equal to about 35 nm, less than or equal to about 30 nm, less than or equal to about 25 nm, less than or equal to about 24 nm, less than or equal to about 23 nm, less than or equal to about 22 nm, less than or equal to about 21 nm, less than or equal to about 20 nm, less than or equal to about 19 nm, less than or equal to about 18 nm, less than or equal to about 17 nm, less than or equal to about 16 nm, less than or equal to about 15 nm, less than or equal to about 14 nm, less than or equal to about 13 nm, less than or equal to about 12 nm, less than or equal to about 11 nm, 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. As used herein, the size of a quantum dot may refer to a diameter or equivalent diameter obtained from a two-dimensional image analyzed by electron microscopy (e.g., under the assumption of a circle). As used herein, "size" may refer to the size of a single quantum dot or the (e.g., mean or median) average of a plurality of quantum dots. The size of the quantum dot may be determined by using the results (e.g., images) of (transmission) electron microscopy analysis and any commercially available image analysis computer program (e.g., Image J).

[0143] In the core-shell quantum dots of the embodiment, the size (or average size) of the core may be greater than or equal to about 1 nm, for example, greater than or equal to about 2 nm, greater than or equal to about 2.5 nm, greater than or equal to about 3 nm, greater than or equal to about 3.5 nm, greater than or equal to about 4 nm, or greater than or equal to about 4.5 nm. The size (or average size) of the core may be less than or equal to about 7 nm, less than or equal to about 6 nm, less than or equal to about 5 nm, less than or equal to about 4 nm, less than or equal to about 3 nm, or less than or equal to about 2 nm.

[0144] The first absorption peak of the core-shell quantum dots may exist in a wavelength range of greater than or equal to about 370 nm, greater than or equal to about 375 nm, greater than or equal to about 380 nm, greater than or equal to about 385 nm, greater than or equal to about 390 nm, greater than or equal to about 395 nm, greater than or equal to about 400 nm, greater than or equal to about 405 nm, greater than or equal to about 410 nm, greater than or equal to about 420 nm, greater than or equal to about 430 nm, greater than or equal to about 440 nm, greater than or equal to about 450 nm, greater than or equal to about 460 nm, greater than or equal to about 465 nm, greater than or equal to about 470 nm, greater than or equal to about 475 nm, or greater than or equal to about 480 nm.

[0145] The first absorption peak of the core-shell quantum dots may exist in a wavelength range of less than or equal to about 530 nm, less than or equal to about 525 nm, less than or equal to about 520 nm, less than or equal to about 515 nm, less than or equal to about 510 nm, less than or equal to about 505 nm, less than or equal to about 500 nm, less than or equal to about 495 nm, less than or equal to about 490 nm, less than or equal to about 485 nm, less than or equal to about 480 nm, less than or equal to about 475 nm, less than or equal to about 465 nm, less than or equal to about 460 nm, less than or equal to about 455 nm, less than or equal to about 450 nm, or less than or equal to about 445 nm.

[0146] Compared to other Zn, Te, and Se based quantum dots, the core-shell quantum dots of embodiments may exhibit improved quantum efficiency, for example, a quantum efficiency greater than or equal to about 10%. The core-shell quantum dots of the embodiments may emit light with a quantum efficiency of greater than or equal to about 11%, greater than or equal to about 12%, greater than or equal to about 13%, greater than or equal to about 14%, greater than or equal to about 15%, greater than or equal to about 16%, greater than or equal to about 17%, greater than or equal to about 18%, greater than or equal to about 19%, greater than or equal to about 20%, greater than or equal to about 21%, greater than or equal to about 22%, greater than or equal to about 23%, greater than or equal to about 24%, greater than or equal to about 25%, greater than or equal to about 26%, greater than or equal to about 27%, greater than or equal to about 28%, greater than or equal to about 29%, greater than or equal to about 30%, greater than or equal to about 35%, greater than or equal to about 40%, greater than or equal to about 45%, or greater than or equal to about 50%.

[0147] The maximum photoluminescence peak wavelength of the core-shell quantum dots may exist in a range of greater than or equal to about 450 nm, greater than or equal to about 455 nm, greater than or equal to about 460 nm, greater than or equal to about 465 nm, greater than or equal to about greater than about 470 nm, for example, greater than or equal to about 471 nm, greater than or equal to about 472 nm, greater than or equal to about 473 nm, greater than or equal to about 474 nm, greater than or equal to about 475 nm, greater than or equal to about 476 nm, greater than or equal to about 477 nm, greater than or equal to about 478 nm, greater than or equal to about 479 nm, greater than or equal to about 480 nm, greater than or equal to about 485 nm, greater than or equal to about 490 nm, greater than or equal to about 495 nm, greater than or equal to about 500 nm, greater than or equal to about 505 nm, greater than or equal to about 510 nm, greater than or equal to about 515 nm, or greater than or equal to about 520 nm.

[0148] The core-shell quantum dots may have a maximum PL peak wavelength of less than or equal to about 600 nm, less than or equal to about 590 nm, less than or equal to about 580 nm, less than or equal to about 570 nm, less than or equal to about 560 nm, less than or equal to about 550 nm, for example, less than or equal to about 540 nm, or less than or equal to about 535 nm. The quantum dots of the embodiments may emit green light. The green light may have a maximum luminescence peak wavelength of about 500 nm to about 560 nm (e.g., greater than or equal to about 515 nm and less than or equal to about 535 nm).

[0149] The core-shell quantum dots may have a maximum PL peak wavelength within a wavelength range of greater than or equal to about 460 nm to less than or equal to about 580 nm, greater than or equal to about 465 nm to less than or equal to about 550 nm, greater than or equal to about 470 nm to less than or equal to about 540 nm, or greater than or equal to about 480 nm to less than or equal to about 540 nm.

[0150] Embodiment (cadmium-free) core-shell quantum dots may have a FWHM of less than about 50 nm, less than or equal to about 45 nm, less than or equal to about 40 nm, less than or equal to about 39 nm, less than or equal to about 38 nm, less than or equal to about 37 nm, less than or equal to about 36 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, less than or equal to about 26 nm, or less than or equal to about 25 nm.

[0151] Embodiment (cadmium-free) core-shell quantum dots may have a FWHM greater than about 5 nm, greater than or equal to about 10 nm, greater than or equal to about 15 nm, greater than or equal to about 18 nm, or greater than or equal to about 20 nm.

[0152] The core-shell quantum dot may include an organic ligand, for example, on its surface, for example, bound thereto. The organic ligand may include RCOOH, RNH 2 , R 2 NH, R 3 N, RSH, RH 2 PO, R 2 HPO, R 3 PO, RH 2 P.R 2 HP, R 3 P, ROH, RCOOR', RPO(OH) 2 , RHPOOH, R 2 POOH, polymeric organic ligands, or combinations thereof, wherein R and R' are the same or different and are independently C1-C40 (e.g., C3-C30 or C6-C24) substituted or unsubstituted aliphatic hydrocarbon groups (alkyl, alkenyl, or alkynyl) groups, or C6-C40 substituted or unsubstituted aromatic hydrocarbon groups, or combinations thereof. Two or more different organic ligands may be used.

[0153] The organic ligand can be coordinated to, for example, the surface of the quantum dot to help the nanocrystals to be well dispersed in the solution. Examples of the organic ligand can include methyl mercaptan, ethyl mercaptan, propyl mercaptan, butyl mercaptan, pentyl mercaptan, hexyl mercaptan, octyl mercaptan, dodecanethiol, hexadecyl mercaptan, octadecyl mercaptan, or 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, or benzoic acid; phosphines such as substituted or unsubstituted methyl phosphine (e.g., trimethyl phosphine, methyl diphenyl phosphine, etc.), substituted or unsubstituted ethyl phosphine (e.g., triethyl phosphine, ethyl diphenyl phosphine, etc.), substituted or unsubstituted propyl phosphine, substituted or unsubstituted butyl phosphine, substituted or unsubstituted pentyl phosphine, or substituted or unsubstituted octyl phosphine (e.g., trioctyl phosphine (TOP)); phosphine oxides such as substituted or unsubstituted methyl phosphine oxide (e.g., triethyl phosphine, ethyl diphenyl phosphine, etc.); substituted or unsubstituted ethylphosphine oxide (e.g., triethylphosphine oxide, ethyldiphenylphosphine oxide, etc.), substituted or unsubstituted propylphosphine oxide, substituted or unsubstituted butylphosphine oxide, or substituted or unsubstituted octylphosphine oxide (e.g., trioctylphosphine oxide (TOPO)); diphenylphosphine, diphenylphosphine oxide, triphenylphosphine, or triphenylphosphine oxide; mono- or di-(C5-C20 alkyl)phosphinic acid such as mono- or di-hexylphosphinic acid, mono- or di-octylphosphinic acid, mono- or di-dodecylphosphinic acid, mono- or di-tetradecylphosphinic acid, mono- or di-hexadecylphosphinic acid, mono- or di-octadecylphosphinic acid, or a combination thereof; C5-C20 alkylphosphinic acid, C5-C20 alkylphosphinic acid such as hexylphosphinic acid, octylphosphinic acid, dodecylphosphinic acid, tetradecylphosphinic acid, hexadecylphosphinic acid, octadecylphosphinic acid, or a combination thereof; and the like, but are not limited thereto. Two or more different organic ligand compounds may be used.

[0154] In an embodiment, the organic ligand compound may be RCOOH and an amine (eg, RNH 2 , R 2 NH, R 3 The organic ligand may not include an organic compound having a thiol moiety and an amino group, a carboxylic acid group, or a combination thereof.

[0155] The organic ligand may not include a multifunctional compound having a thiol moiety and at least one of an amino group and a carboxylic acid group (ie, an amino group, a carboxylic acid, or a combination thereof). The organic ligand may not include a glutathione compound. The quantum dot may be water-insoluble.

[0156] When dispersed in water, the core-shell quantum dots may exhibit an average particle size of about 300 nm or more, about 400 nm or more, about 500 nm or more, or about 900 nm or more as determined by dynamic light scattering (DLS) analysis. When dispersed in an organic solvent (e.g., toluene, octane, etc.), the core-shell quantum dots may be configured to form an organic solution having an average particle size of about 500 nm or less, about 400 nm or less, about 300 nm or less, about 200 nm or less, about 100 nm or less, or about 90 nm or less as determined by DLS analysis. Examples of the organic solvents will be described below.

[0157] In an embodiment, a method of making the core-shell quantum dots comprises:

[0158] preparing a core particle including a first semiconductor nanocrystal core including zinc, tellurium, and selenium by reacting a zinc precursor, a selenium precursor, and a tellurium precursor at a core forming temperature to form a first nanocrystal, and adding a treatment agent to a reaction medium including the nanocrystal for post-treatment, and

[0159] A zinc precursor is reacted with a chalcogen precursor (e.g., including a selenium precursor, a sulfur precursor, or a combination thereof) in the presence of the core particle and a shell-forming organic ligand at a shell-forming temperature to form a semiconductor nanocrystal shell including the zinc chalcogenide on the core particle, or at least a portion of the surface of the core particle.

[0160] In an embodiment, the treating agent includes: a sulfur compound such as an organic thiol compound, sulfur dispersed in an alkylphosphine solvent (S / TOP), bis(trialkylsilyl)sulfide, or a combination thereof; a metal compound (eg, including zinc); or a combination thereof.

[0161] The metal compound may include a metal halide, an organic metal compound, or a combination thereof. The metal compound used in the treating agent may include zinc. The organic metal compound (or complex) may include, for example, an organic carboxylate-metal compound, an organic amine-metal compound, a metal carboxylate such as a metal oleate and a sulfur compound such as a thiol compound such as dodecanethiol, S / TOP, TMSi 2 S, or a combination thereof. The organometallic compound may include a bond between a metal and sulfur.

[0162] The organic thiol compound may have a C1-C30 hydrocarbon group (e.g., a linear or branched alkyl, alkenyl, or alkynyl group). The organic thiol compound may include a compound represented by RSH (wherein R is, for example, an unsubstituted C1-C30 aliphatic hydrocarbon group such as an alkyl, alkenyl, or alkynyl group).

[0163] The metal halide may include zinc chloride. The organic carboxylate-metal compound may be prepared by reacting a metal precursor such as a metal acetate, a metal acetylacetonate, or a metal chloride with a carboxylic acid compound (e.g., a fatty acid such as oleic acid) in an organic solvent such as octadecene or trioctylamine at an elevated temperature, such as about 50°C or greater, or 60°C or greater and less than or equal to about 200°C.

[0164] The organic amine-metal compound can be prepared by reacting a metal precursor such as a metal acetate, a metal acetylacetonate, or a metal chloride with an organic amine compound (e.g., a fatty amine such as oleylamine) in an organic solvent such as octadecene at an elevated temperature, e.g., about 50° C. or greater, or 60° C. or greater and less than or equal to about 200° C.

[0165] The organometallic compound having a bond between the metal and sulfur can be prepared by reacting a metal carboxylate with a sulfur compound (e.g., dodecanethiol, S / TOP, TMSi 2 S, or a combination thereof) are mixed and reacted at a temperature of about 50° C. or less, about 30° C. or less, or at a low temperature below 0° C., for example in an organic solvent such as an alkane or alkene solvent (e.g., octadecene) or an alkylphosphine solvent such as TOP.

[0166] The treating agent may be added in a dissolved state in a suitable organic solvent such as a (C1-C20 or C5-C12 alkyl)phosphine such as trioctylphosphine, or a ketone solvent such as acetone.

[0167] The preparation of the core particle may include:

[0168] preparing a zinc precursor organic solution comprising a zinc precursor and a first organic ligand in a first organic solvent; and

[0169] While the zinc precursor organic solution is heated at a first reaction temperature, a selenium precursor, a tellurium precursor, a hydride compound, and at least one second organic ligand are added.

[0170] The first reaction temperature (e.g., for core formation) may be 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., greater than or equal to about 290° C., or greater than or equal to about 300° C. The first reaction temperature may be less than or equal to about 350° C., for example, less than or equal to about 340° C., less than or equal to about 330° C., less than or equal to about 320° C., or less than or equal to about 310° C. The reaction time for core formation is not particularly limited and may be appropriately selected.

[0171] The reaction temperature for shell formation may be appropriately selected in any suitable range of about 200° C. or more, such as about 210° C. or more, about 220° C. or more, about 230° C. or more, about 240° C. or more, about 250° C. or more, about 260° C. or more, about 270° C. or more, about 280° C. or more, or about 290° C. or more and about 340° C. or less, such as about 325° C. or less, or about 310° C. or less. The reaction time for shell formation may be appropriately selected according to the desired shell composition.

[0172] The post-treatment may be performed at a temperature of about 50° C. or more, about 60° C. or more, about 80° C. or more, about 100° C. or more, about 150° C. or more, about 200° C. or more, or about 240° C. or more and less than or equal to the core forming temperature. The post-treatment may be performed at a temperature of about 300° C. or less, about 290° C. or less, about 280° C. or less, about 270° C. or less, about 250° C. or less, about 200° C. or less, about 180° C. or less, or about 150° C. or less.

[0173] The details of the composition of the core-shell quantum dots and the core and the semiconductor nanocrystal shell are the same as those described above. The synthesized core can be separated from the reaction system (e.g., between shell synthesis) (e.g., by adding a non-solvent). The details of the non-solvent will be described in detail below.

[0174] In an embodiment, the tellurium precursor used during the core synthesis may include tellurium dispersed in a second organic solvent, and the concentration of tellurium in the tellurium precursor may be greater than about 0.1 mol / liter (M), for example, greater than or equal to about 0.5 M, greater than or equal to about 1 M, greater than or equal to about 1.5 M, greater than or equal to about 2 M, or greater than or equal to about 2.5 M. The concentration of tellurium may be less than or equal to about 10 M, less than or equal to about 5 M, or less than or equal to about 4 M. By adopting a tellurium concentration within the above range, the reactivity of tellurium may be increased and a core having improved quality may be prepared.

[0175] In an embodiment of synthesizing the core, the selenium precursor, tellurium precursor, metal hydride compound, and second organic ligand may be mixed together at a temperature of less than about 80°C, e.g., less than or equal to about 75°C, less than or equal to about 70°C, less than or equal to about 65°C, less than or equal to about 60°C, less than or equal to about 55°C, less than or equal to about 50°C, or less than or equal to about 45°C to form a single stock solution prior to being added to the zinc precursor organic solution.

[0176] The amount of the treating agent used in the reaction may be appropriately selected in consideration of the types of the precursor and the treating agent. In an embodiment, the treating agent may be used in an amount of greater than or equal to about 0.1 mol, greater than or equal to about 0.3 mol, greater than or equal to about 0.5 mol, greater than or equal to about 0.7 mol, greater than or equal to about 0.9 mol, greater than or equal to about 1 mol, or greater than or equal to about 1.2 mol and less than or equal to about 5 mol, less than or equal to about 4 mol, less than or equal to about 3 mol, less than or equal to about 2 mol, less than or equal to about 1 mol, less than or equal to about 0.9 mol, less than or equal to about 0.7 mol, or less than or equal to about 0.5 mol per 1 mol of the zinc precursor.

[0177] The metal hydride compound may include lithium, aluminum, or a combination thereof. The metal hydride compound may include an aluminum hydride compound, a lithium hydride compound, or a combination thereof. The metal hydride compound may include an organic metal hydride compound (e.g., having a hydrocarbon group such as at least one hydrocarbon group), an inorganic metal hydride compound, or a combination thereof. The metal hydride compound may include an alkyl lithium hydride (e.g., a lithium dialkyl borohydride, wherein each alkyl group may have 1-6 carbon atoms), a lithium aluminum hydride compound, or a combination thereof.

[0178] The amount of the metal hydride is not particularly limited and can be appropriately selected. The amount of the metal hydride may be greater than or equal to about 0.01 mole, greater than or equal to about 0.05 mole, greater than or equal to about 0.1 mole, greater than or equal to about 0.5 mole, or greater than or equal to about 1 mole per 1 mole of antimony. The amount of the metal hydride may be less than or equal to about 10 moles, less than or equal to about 5 moles, or less than or equal to about 3 moles per 1 mole of antimony.

[0179] In the preparation of the core, the molar ratio of tellurium to selenium (Te:Se) introduced into the reaction system may be greater than about 0.25:1, greater than or equal to about 0.3:1, greater than or equal to about 0.4:1, greater than or equal to about 0.5:1, greater than or equal to about 0.7:1, greater than or equal to about 0.9:1, greater than or equal to about 1:1, greater than or equal to about 1.1:1, greater than or equal to about 1.2:1, greater than or equal to about 1.3:1, greater than or equal to about 1.4:1, greater than or equal to about 1.5:1, greater than or equal to about 1.6:1, greater than or equal to about 1.7:1, greater than or equal to about 1.8:1, greater than or equal to about 1.9:1, greater than or equal to about 2:1, or greater than or equal to about 2.5:1.

[0180] In the preparation of the core, the molar ratio of tellurium to selenium (Te:Se) introduced into the reaction system may be less than or equal to about 10:1, less than or equal to about 9:1, less than or equal to about 8:1, less than or equal to about 7:1, less than or equal to about 6:1, less than or equal to about 5:1, less than or equal to about 4:1, less than or equal to about 3:1, less than or equal to about 2:1, or less than or equal to about 1.5:1.

[0181] In the preparation of the core, the molar ratio of zinc to tellurium may be appropriately selected in consideration of a desired composition, a precursor, etc. According to an embodiment, in the preparation of the core, the amount of zinc relative to one mole of tellurium may be greater than or equal to about 1 mole, greater than or equal to about 2 moles, greater than or equal to about 3 moles, greater than or equal to about 4 moles, or greater than or equal to about 5 moles. According to an embodiment, in the preparation of the core, the amount of zinc relative to one mole of tellurium may be less than or equal to about 20 moles, less than or equal to about 15 moles, less than or equal to about 10 moles, less than or equal to about 9 moles, less than or equal to about 8 moles, less than or equal to about 7 moles, less than or equal to about 6 moles, less than or equal to about 5 moles, less than or equal to about 4 moles, less than or equal to about 3 moles, or less than or equal to about 2 moles.

[0182] In an embodiment, the formation of the shell can be carried out by heating a metal shell precursor (i.e., a metal precursor for the shell) and an organic ligand in an organic solvent at a predetermined temperature (e.g., at a temperature greater than or equal to about 100° C., e.g., greater than or equal to about 120° C.) under vacuum (or vacuum treatment), changing the atmosphere of the reaction system to an inert gas, and heating it at a predetermined reaction temperature.

[0183] The core and non-metallic shell precursors (e.g., sulfur and / or selenium precursors) may be added to the (heated) reaction system to carry out the reaction. The non-metallic shell precursors may be injected simultaneously or sequentially during the reaction taking into account the desired shell composition. The metal shell precursor may include a zinc precursor, a gallium precursor, or a combination thereof.

[0184] A shell having a desired composition (eg, a gradient composition or a multi-layered composition) can be formed.

[0185] In an embodiment, the formation of the semiconductor nanocrystal shell may include reacting the zinc precursor with at least one (or both) of the selenium precursor or the sulfur precursor. In an embodiment, the formation of the semiconductor nanocrystal shell may include reacting a gallium precursor and a sulfur precursor. In an embodiment, the formation of the semiconductor nanocrystal shell may include reacting the zinc precursor and the selenium precursor, and then reacting the zinc precursor and the sulfur precursor. For example, in an embodiment, a zinc precursor may react with a selenium precursor to form a first shell layer including zinc and selenium, and then react with a sulfur precursor to form a second shell layer including zinc and sulfur. In an embodiment, a zinc precursor may react with a selenium and sulfur precursors to form a semiconductor nanocrystal shell (e.g., ZnSeS) including zinc, selenium, and sulfur.

[0186] In the above method, the zinc precursor may include Zn powder, ZnO, alkylated Zn compounds (e.g., C2-C30 alkyl (e.g., dialkyl) zinc such as dimethyl zinc, diethyl zinc), Zn alkoxide (e.g., zinc ethoxide), carboxylic acid Zn (e.g., zinc acetate or aliphatic carboxylic acid zinc such as long-chain aliphatic carboxylic acid zinc such as zinc oleate), Zn nitrate, Zn perchlorate, Zn sulfate, Zn acetylacetonate, Zn halide (e.g., zinc chloride), Zn cyanide, Zn hydroxide, zinc carbonate, zinc peroxide, or a combination thereof. Examples of the zinc precursor may include dimethyl zinc, diethyl zinc, zinc acetate, zinc acetylacetonate, zinc iodide, zinc bromide, zinc chloride, zinc fluoride, zinc carbonate, zinc cyanide, zinc nitrate, zinc oxide, zinc peroxide, zinc perchlorate, zinc sulfate, or a combination thereof.

[0187] The gallium precursor may include an alkylphosphine-gallium (e.g., TOP-gallium), a gallium carboxylate, a gallium-organic compound complex prepared by dispersing alkylated gallium in a mono-, di-, or tri-(C1-C20 or C5-C12 alkyl) phosphine solvent. The gallium-organic compound complex may include a compound obtained by reacting a gallium carboxylate with an aliphatic amine, a fatty carboxylate, a mono-, di-, or tri-(C1-C20 or C5-C12 alkyl) phosphine, or a combination thereof at an elevated temperature of about 50° C. or more and about 200° C. or less.

[0188] 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, but is not limited thereto.

[0189] The tellurium precursor may include tellurium-trioctylphosphine (Te-TOP), tellurium-tributylphosphine (Te-TBP), tellurium-triphenylphosphine (Te-TPP), tellurium-diphenylphosphine (Te-DPP), or a combination thereof, but is not limited thereto.

[0190] The sulfur precursor may include hexanethiol, octylthiol, decanethiol, dodecanethiol, hexadecylthiol, mercaptopropylsilane, sulfur-trioctylphosphine (S-TOP), sulfur-tributylphosphine (S-TBP), sulfur-triphenylphosphine (S-TPP), sulfur-trioctylamine (S-TOA), sulfur-octadecene (S-ODE), bistrimethylsilyl sulfide, ammonium sulfide, sodium sulfide, or a combination thereof.

[0191] The first, second and / or third organic solvents may be the same as or different from each other. The first, second and / or third organic solvent (hereinafter referred to as organic solvent) may be a C6-C22 primary amine such as hexadecylamine, a C6-C22 secondary amine such as dioctylamine, a C6-C40 tertiary amine such as trioctylamine, a nitrogen-containing heterocyclic compound such as pyridine, a C6-C40 olefin such as octadecene, a C6-C40 aliphatic hydrocarbon such as hexadecane, octadecane, or squalane, an aromatic hydrocarbon substituted with a C6-C30 alkyl group such as phenyldodecane, phenyltetradecane, or phenylhexadecane, a primary, secondary or tertiary phosphine substituted with a C6-C22 alkyl group such as at least one (e.g., 1, 2 or 3) C6-C22 alkyl group (e.g., trioctylphosphine), a phosphine oxide substituted with a C6-C22 alkyl group such as at least one (e.g., 1, 2 or 3) C6-C22 alkyl group (e.g., trioctylphosphine oxide), a C12-C22 aromatic ether such as phenyl ether or benzyl ether, or a combination thereof.

[0192] The first organic ligand and the second organic ligand may be the same. The first organic ligand and the second organic ligand may be different. The details for the first and second organic ligands and the shell-forming organic ligands are the same as those set forth above with respect to the organic ligands.

[0193] In an embodiment, the first organic ligand may include a fatty acid (e.g., including a hydrocarbon group of at least C5, at least C10, or at least C15), and the second organic ligand may include an organic amine (e.g., a primary amine including an aliphatic or aromatic hydrocarbon group of at least C5, at least C10, or at least C15), an aromatic phosphine compound, or a combination thereof. The primary amine may include RNH 2 , wherein R is an aliphatic hydrocarbon group such as an alkyl, alkenyl, or alkynyl group, a C6-C40 aryl group, or a combination thereof.

[0194] The aliphatic hydrocarbon group may have a carbon number greater than or equal to about 5, greater than or equal to about 10, greater than or equal to about 15, greater than or equal to about 16, greater than or equal to about 17, greater than or equal to about 18, greater than or equal to about 19, or greater than or equal to about 20; and / or less than or equal to about 50, less than or equal to about 40, or less than or equal to about 30.

[0195] The amounts of the first organic ligand and the second organic ligand may be selected in consideration of the type of the organic ligand and the type of the precursor.

[0196] The amount of the first organic ligand (or the amount of the second ligand or the amount of the shell-forming organic ligand) relative to 1 mole of the zinc precursor may be greater than or equal to about 0.1 mole, greater than or equal to about 0.2 mole, greater than or equal to about 0.3 mole, greater than or equal to about 0.4 mole, greater than or equal to about 0.5 mole, greater than or equal to about 0.6 mole, greater than or equal to about 0.7 mole, greater than or equal to about 0.8 mole, greater than or equal to about 0.9 mole, greater than or equal to about 1 mole, greater than or equal to about 2 moles, greater than or equal to about 3 moles, greater than or equal to about 4 moles, or greater than or equal to about 5 moles. The amount of the first organic ligand (or the amount of the second ligand or the amount of the shell-forming organic ligand) relative to 1 mole of the zinc precursor may be less than or equal to about 20 moles, less than or equal to about 19 moles, less than or equal to about 18 moles, less than or equal to about 17 moles, less than or equal to about 16 moles, less than or equal to about 15 moles, less than or equal to about 14 moles, less than or equal to about 13 moles, less than or equal to about 12 moles, less than or equal to about 10 moles, less than or equal to about 9 moles, less than or equal to about 8 moles, less than or equal to about 7 moles, less than or equal to about 6 moles, less than or equal to about 5 moles, less than or equal to about 4 moles, less than or equal to about 3 moles, less than or equal to about 2 moles, or less than or equal to about 1 mole.

[0197] The molar ratio between the first organic ligand and the second organic ligand (the first organic ligand: the second organic ligand) may be 1:0.1 or greater, 1:0.5 or greater, 1:0.9 or greater, or 1:1 or greater, and / or 1:10 or less; 1:5 or less, 1:2.5 or less, or 1:1.5 or less; or a combination thereof.

[0198] In an embodiment, the selenium precursor, tellurium precursor, metal hydride compound may be injected into the zinc precursor organic solution in a mixed state, optionally together with the organic ligand. In an embodiment, the selenium precursor, tellurium precursor, and metal hydride compound may be injected into the zinc precursor organic solution sequentially.

[0199] In the reaction system for core formation and the reaction system for shell formation, the amount of each precursor and its concentration can be selected taking into account the desired composition of the core and the shell, the reactivity between the core and shell precursors, etc. In an embodiment, the ratio between the precursors can be controlled taking into account the desired composition of the final quantum dots (e.g., the ratio between elements such as Zn, S, Se, Te, or a combination thereof). The composition of the final quantum dots can be determined by appropriate analytical tools such as inductively coupled plasma atomic emission spectroscopy.

[0200] After the formation of the core or the core-shell quantum dot, a non-solvent is added to the nanocrystal particles coordinated with the ligand compound, for example, combined to promote the separation or isolation of the core particles or core-shell quantum dots. The non-solvent can be a polar solvent that is miscible with the solvent used in the core formation reaction or the core-shell quantum dot formation reaction and cannot disperse the manufactured nanocrystals. The non-solvent can be selected in consideration of 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 the aforementioned non-solvent, or a combination thereof. The separation of nanocrystal particles can involve centrifugation, sedimentation, chromatography, or filtration. If desired, the separated nanocrystal particles can be added to a washing (or dispersion) solvent and washed (or dispersed).

[0201] The type of washing (or dispersing) solvent is not particularly limited, and a solvent having a solubility parameter similar to that of the ligand may be used, and examples thereof may include hexane, heptane, octane, chloroform, toluene, benzene, and the like.

[0202] In an embodiment, the organic ligand may not include a multifunctional organic compound having a thiol moiety and at least one of an amino group and a carboxylic acid group. For example, the organic ligand may not include a glutathione compound.

[0203] The quantum dots may be water-insoluble.

[0204] When dispersed in water, the quantum dots may have an average particle size of greater than or equal to about 300 nm as determined by dynamic light scattering (DLS) analysis. When dispersed in an organic solvent (e.g., toluene, octane, etc.), the quantum dots may be configured to form an organic solution having an average particle size of less than 50 nm, such as less than or equal to about 30 nm, or less than or equal to about 20 nm as determined by DLS analysis.

[0205] In an embodiment, the quantum dot composition includes: the aforementioned (e.g., multiple) core-shell quantum dots (hereinafter, may be referred to as quantum dots for short); and a (photo)polymerizable monomer optionally having a carbon-carbon double bond, such as at least one carbon-carbon double bond. The composition may further include an organic solvent, a liquid carrier (vehicle), a dispersant (e.g., a binder monomer or polymer), a (photo)initiator, or a combination thereof. The binder may disperse the quantum dots in the composition. The binder monomer or polymer may include a compound containing a carboxylic acid group. The composition may be a photosensitive composition.

[0206] The details of the quantum dots in the composition are the same as those set forth above. The amount of quantum dots in the composition (or the composite to be described below) may be appropriately adjusted in consideration of the desired end use of the composition (or the composite) (e.g., photoluminescent color filters, etc.). In an embodiment, the amount of the quantum dots may be greater than or equal to about 1 weight percent (wt%), such as greater than or equal to about 2 weight %, greater than or equal to about 3 weight %, greater than or equal to about 4 weight %, greater than or equal to about 5 weight %, greater than or equal to about 6 weight %, greater than or equal to about 7 weight %, greater than or equal to about 8 weight %, greater than or equal to about 9 weight %, greater than or equal to about 10 weight %, greater than or equal to about 15 weight %, greater than or equal to about 20 weight %, greater than or equal to about 25 weight %, greater than or equal to about 30 weight %, greater than or equal to about 35 weight %, or greater than or equal to about 40 weight %, based on the total weight or total solid content of the composition. The amount of the quantum dots can be less than or equal to about 70 wt %, such as 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 or total solids content of the composition. The amount of a given component based on the total solids content of the composition can correspond to the amount of a given component in a composite prepared from the composition.

[0207] In the composition according to the embodiment, the dispersant may help to obtain appropriate dispersibility of the quantum dots. The dispersant may include an organic compound (monomer or polymer) including a carboxylic acid group. The binder polymer may be an insulating polymer.

[0208] The organic compound comprising a carboxylic acid group may include a copolymer of a monomer mixture including: a first monomer including a carboxylic acid group and a carbon-carbon double bond, a second monomer including a carbon-carbon double bond and a hydrophobic portion and not including a carboxylic acid group, and optionally a third monomer including a carbon-carbon double bond and a hydrophilic portion and not including a carboxylic acid group;

[0209] A polymer containing a polyaromatic ring (hereinafter, cardo binder) having a backbone structure in which two aromatic rings are bonded to a quaternary carbon atom which is a constituent atom of another cyclic part in the main chain and including a carboxylic acid group (—COOH); or

[0210] Its combination.

[0211] The dispersant may include a first monomer, a second monomer, and optionally a third monomer.

[0212] In the composition, the amount of the dispersant or the binder (polymer or monomer) may be greater than or equal to about 0.5 wt %, such as greater than or equal to about 1 wt %, greater than or equal to about 5 wt %, greater than or equal to about 10 wt %, greater than or equal to about 15 wt %, or greater than or equal to about 20 wt %, based on the total weight or total solid content of the composition, but is not limited thereto. The amount of the binder polymer may be less than or equal to about 55 wt %, less than or equal to about 45 wt %, less than or equal to about 35 wt %, such as less than or equal to about 33 wt %, or less than or equal to about 30 wt %, based on the total weight or total solid content of the composition.

[0213] The composition may include a polymerizable (e.g., photopolymerizable) monomer containing a carbon-carbon double bond. The monomer may include a (e.g., photopolymerizable) acryl-based monomer, i.e., a monomer containing an acryl group. The polymerizable monomer may be a precursor for an insulating polymer.

[0214] The amount of the polymerizable monomer may be greater than or equal to about 0.5 wt %, such as greater than or equal to about 1 wt %, or greater than or equal to about 2 wt %, based on the total weight or total solid content of the composition. The amount of the photopolymerizable monomer may be less than or equal to about 30 wt %, such as less than or equal to about 28 wt %, less than or equal to about 25 wt %, less than or equal to about 23 wt %, less than or equal to about 20 wt %, less than or equal to about 18 wt %, less than or equal to about 17 wt %, less than or equal to about 16 wt %, or less than or equal to about 15 wt %, based on the total weight or total solid content of the composition.

[0215] The composition may include a (photo or thermal) initiator that can be used for (photo) polymerization of the monomer. A (photo or thermal) initiator is a compound that accelerates a free radical reaction (e.g., free radical polymerization of a monomer) by generating free radical chemicals under mild conditions (e.g., by heat or light). As shown, the initiator may be a thermal initiator or a photoinitiator. The compound used for the initiator is not particularly limited and may be appropriately selected.

[0216] In the composition, the amount of the initiator may be appropriately adjusted in consideration of the type of the polymerizable monomer and the amount of the polymerizable monomer. In an embodiment, the initiator may be used in an amount ranging from at least about 0.01 wt %, at least about 1 wt % and less than or equal to about 10 wt %, less than or equal to about 9 wt %, less than or equal to about 8 wt %, less than or equal to about 7 wt %, less than or equal to about 6 wt %, or less than or equal to about 5 wt %, based on the total weight or total solid content of the composition, but not limited thereto.

[0217] The composition or a composite prepared therefrom may further include (e.g., at the end of the (poly- or mono-functional) thiol compound) including at least one (e.g., at least two, three or four) thiol groups, metal oxide fine particles, or a combination thereof.

[0218] The metal oxide fine particles may include TiO 2 、SiO 2 、BaTiO 3 , Ba 2 TiO 4 , ZnO, or a combination thereof. As used herein, the term "metal oxide" may include oxides of metals or metalloids. The metal oxide fine particles may be non-light emitting.

[0219] The diameter of the metal oxide fine particles is not particularly limited and can be appropriately selected. The diameter of the metal oxide fine particles can be greater than or equal to about 100 nm, for example, greater than or equal to about 150 nm, or greater than or equal to about 200 nm and less than or equal to about 1,000 nm, or less than or equal to about 800 nm.

[0220] The multifunctional thiol compound may be a dithiol compound, a trithiol compound, a tetrathiol compound, or a combination thereof. For example, the thiol compound may be a diol (e.g., ethylene glycol) di-3-mercaptopropionate, a diol (e.g., ethylene glycol) dithioglycolate, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(2-mercaptoacetate), 1,6-hexanedithiol, 1,3-propanedithiol, 1,2-ethanedithiol, polyethylene glycol dithiol comprising 1-10 ethylene glycol repeating units, or a combination thereof.

[0221] The amount of the (mono- and / or poly-)thiol compound may be less than or equal to about 50 wt %, less than or equal to about 45 wt %, less than or equal to about 40 wt %, less than or equal to about 35 wt %, less than or equal to about 30 wt %, less than or equal to about 25 wt %, less than or equal to about 20 wt %, less than or equal to about 15 wt %, less than or equal to about 10 wt %, less than or equal to about 9 wt %, less than or equal to about 8 wt %, less than or equal to about 7 wt %, less than or equal to about 6 wt %, or less than or equal to about 5 wt %, based on the total weight (or total solid content) of the composition. The amount of the thiol compound may be greater than or equal to about 0.1 wt %, such as greater than or equal to about 0.5 wt %, greater than or equal to about 1 wt %, greater than or equal to about 5 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 %, or greater than or equal to about 25 wt %, based on the total weight (or total solid content) of the composition or the composite.

[0222] In the composition, the amount of the metal oxide fine particles may be greater than or equal to about 1 weight %, greater than or equal to about 5 weight %, or greater than or equal to about 10 weight % and less than or equal to about 50 weight %, less than or equal to about 40 weight %, less than or equal to about 30 weight %, less than or equal to about 25 weight %, less than or equal to about 20 weight %, less than or equal to about 15 weight %, less than or equal to about 10 weight %, or less than or equal to about 5 weight %, based on the total weight (or total solid content) of the composition or the composite.

[0223] The composition may further include an organic solvent (or liquid carrier, hereinafter referred to as an organic solvent). Non-limiting examples of the organic solvent may include ethyl 3-ethoxypropionate; glycols such as ethylene glycol, diethylene glycol, or polyethylene glycol; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, ethylene glycol diethyl ether, or diethylene glycol dimethyl ether; glycol ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, or diethylene glycol monobutyl ether acetate; propylene glycol; propylene glycol ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol dimethyl ether, dipropylene glycol dimethyl ether, propylene glycol diethyl ether, or dipropylene glycol diethyl ether; propylene glycol ether acetates such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol dimethyl ether, dipropylene glycol diethyl ether, or dipropylene glycol diethyl ether. glycol monomethyl ether acetate, or dipropylene glycol monoethyl ether acetate; amides such as N-methylpyrrolidone, dimethylformamide, or dimethylacetamide; ketones such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), or cyclohexanone; petroleum such as toluene, xylene, or solvent naphtha; esters such as ethyl acetate, butyl acetate, or ethyl lactate; ethers such as diethyl ether, dipropyl ether, or dibutyl ether; chloroform, C1-C40 aliphatic hydrocarbons (e.g., alkanes, olefins, or alkynes), halogen (e.g., chlorine) substituted C1-C40 aliphatic hydrocarbons (e.g., dichloroethane, chloroform, etc.), C6-C40 aromatic hydrocarbons (e.g., toluene, xylene, etc.), halogen (e.g., chlorine) substituted C6-C40 aromatic hydrocarbons, or combinations thereof.

[0224] The type and amount of the organic solvent can be appropriately selected by taking into account the above main components (i.e., the quantum dots, dispersant, polymerizable monomer, initiator, and thiol compound if used) and the additives and the amounts of the additives described below. The composition can include the organic solvent in the remaining amount other than the desired content of the (non-volatile) solids.

[0225] The composition (e.g., inkjet composition) may have a viscosity at 25° C. of about 4 centipoise (cPs) or more, about 5 cPs or more, about 5.5 cPs or more, about 6.0 cPs or more, or about 7.0 cPs or more. The composition (e.g., inkjet composition) may have a viscosity at 25° C. of about 12 cPs or less, about 10 cPs or less, or about 9 cPs or less.

[0226] If the composition is applied to an inkjet process, the composition may be discharged onto a substrate at room temperature, and a quantum dot polymer composite or a pattern of a quantum dot polymer composite may be formed, for example, by heating. Together with the above viscosity, the ink composition may have a surface tension at 23° C. of greater than or equal to about 21 millinewtons / meter (mN / m), greater than or equal to about 22 mN / m, greater than or equal to about 23 mN / m, greater than or equal to about 24 mN / m, greater than or equal to about 25 mN / m, greater than or equal to about 26 mN / m, greater than or equal to about 27 mN / m, greater than or equal to about 28 mN / m, greater than or equal to about 29 mN / m, greater than or equal to about 30 mN / m, or greater than or equal to about 31 mN / m and less than or equal to about 40 mN / m, less than or equal to about 39 mN / m, less than or equal to about 38 mN / m, less than or equal to about 36 mN / m, less than or equal to about 35 mN / m, less than or equal to about 34 mN / m, less than or equal to about 33 mN / m, or less than or equal to about 32 mN / m. The surface of the ink composition may be less than or equal to about 31 mN / m, less than or equal to about 30 mN / m, less than or equal to about 29 mN / m, or less than or equal to about 28 mN / m.

[0227] The composition may further include a variety of additives for photoresist compositions or inkjet compositions. The additives may include light diffusing agents (light diffusing agents), leveling agents, coupling agents, etc., for which, reference may be made to the details described in, for example, US-2017-0052444-A1.

[0228] In an embodiment, the composition according to the embodiment can be prepared by a method including: preparing a quantum dot dispersion including the quantum dots, a dispersant and a solvent; and mixing the quantum dot dispersion with: an initiator; a polymerizable monomer (e.g., an acryl-based monomer); optionally, the thiol compound; optionally, the metal oxide particles, and optionally, the aforementioned additives. Each of the components can be mixed sequentially or simultaneously, but the mixing order is not particularly limited.

[0229] The composition of the embodiment can be used to provide a pattern including a quantum dot complex (e.g., a quantum dot polymer complex). The composition can provide a quantum dot polymer complex via (e.g., free radical) polymerization. In an embodiment, the composition can be a photoresist composition applicable to a photolithography process. In an embodiment, the composition can be an ink composition applicable to an inkjet process (e.g., a droplet discharge method such as inkjet printing).

[0230] In an embodiment, a quantum dot composite (e.g., a quantum dot polymer composite) may include: a (polymer) matrix; and the core-shell quantum dots dispersed in the matrix. The quantum dot composite may further include fine metal oxide particles dispersed in the matrix. The (polymer) matrix may include a cross-linked polymer, a linear polymer, or a combination thereof. The cross-linked polymer may include a thiol-ene polymer, a cross-linked poly(meth)acrylate, a cross-linked polyurethane, a cross-linked epoxy resin, a cross-linked vinyl polymer, a cross-linked silicone resin, or a combination thereof. In an embodiment, the cross-linked polymer may be a polymerization product of the polymerizable monomer and optionally the polythiol compound. The linear polymer may include repeating units derived from carbon-carbon unsaturated bonds (e.g., carbon-carbon double bonds). The repeating unit may include a carboxylic acid group. The linear polymer may include ethylene repeating units.

[0231] The matrix may include the dispersant (e.g., a binder monomer or polymer), a polymerized product (e.g., an insulating polymer) of a polymerizable monomer including a carbon-carbon double bond (at least one / e.g., at least two, at least three, at least four, or at least five), optionally a polymerized product of a polythiol compound including at least two thiol groups (e.g., at the end of the polythiol compound), or a combination thereof. The quantum dot polymer composite may further include fine metal oxide particles. Two or more of the aforementioned components (e.g., dispersant, polymerized product, fine metal oxide particles) may be present.

[0232] The (polymer) matrix may include a cross-linked polymer, a linear polymer, or a combination thereof. The cross-linked polymer may include a thiol-ene polymer, a cross-linked poly (meth) acrylate, or a combination thereof. In an embodiment, the cross-linked polymer may include the polymerizable monomer and optionally the polymerized product of a polythiol compound. The details of the quantum dots, dispersant or binder polymer, polymerizable monomer, and polythiol compound are the same as described above.

[0233] The (patterned) film of the quantum dot polymer composite may have a thickness of, for example, less than or equal to about 30 micrometers (μm), for example, less than or equal to about 25 μm, less than or equal to about 20 μm, less than or equal to about 15 μm, less than or equal to about 10 μm, less than or equal to about 8 μm, less than or equal to about 7 μm and greater than about 2 μm, for example, greater than or equal to about 3 μm, greater than or equal to about 3.5 μm, greater than or equal to about 4 μm, greater than or equal to about 5 μm, or greater than or equal to about 6 μm.

[0234] In an embodiment, the patterned film may include at least one (kind of) repeating segment configured to emit light of a predetermined wavelength. In an embodiment, the repeating segment may include a first segment emitting a first light. The repeating segment may include a second segment emitting a second light having a maximum (photo)luminescence peak wavelength different from the maximum (photo)luminescence peak wavelength of the first light. At least one of the first segment and the second segment may include the quantum dot complex.

[0235] The first light or the second light may be red light having a maximum photoluminescence peak wavelength between about 600 nm and about 650 nm (e.g., about 620 nm to about 650 nm) or green light having a maximum photoluminescence peak wavelength between about 500 nm and about 550 nm (e.g., about 510 nm to about 540 nm). The patterned film may further include a third segment that emits or passes a third light (e.g., blue light) different from the first light and the second light. The third light may have a maximum (photo)luminescence peak wavelength in the range of 380 nm to 480 nm.

[0236] like Figure 1A As shown in, a patterned film of a quantum dot composite can be prepared by using a photoresist composition. In such a method, a composition is applied to a substrate by a suitable method such as spin coating, slit coating, etc. to form a film having a predetermined thickness (step 1). The formed film can be optionally pre-baked (PRB) (step 2). The pre-baking can be performed by selecting appropriate conditions from known conditions such as temperature, time, atmosphere, etc. The selected area of ​​the formed (or optionally pre-baked) film is exposed to light having a predetermined wavelength (e.g., less than or equal to about 400nm) (step 3). The wavelength and intensity of the light can be selected considering the type and amount of the photoinitiator, the type and amount of the core-shell quantum dots, etc.

[0237] The exposed film is treated with an alkaline developing solution (e.g., dip coating or spraying) to dissolve the unexposed area and obtain the desired pattern (step 4). The obtained pattern may be optionally post-baked (POB) to improve the crack resistance and solvent resistance of the pattern, for example, at about 150° C. to about 230° C. for a predetermined time (e.g., greater than or equal to about 10 minutes or greater than or equal to about 20 minutes) (step 5).

[0238] In an embodiment in which the quantum dot polymer composite pattern has multiple (kinds of) repeating segments, a quantum dot polymer composite having a desired pattern can be obtained by preparing multiple compositions including core-shell quantum dots (e.g., quantum dots emitting red light, quantum dots emitting green light, or optionally quantum dots emitting blue light) having desired photoluminescent properties (photoluminescent peak wavelength, etc.) to form each repeating segment, and repeating the formation of the above pattern for each composition an appropriate number of times (e.g., two or more times, or three or more times) (step 6).

[0239] The quantum dot composite pattern may be formed by using an ink composition configured to form a pattern via an inkjet method. Figure 1B The method comprises: preparing an ink composition; obtaining a substrate comprising a pattern, such as an electrode formed by a bank and optionally a pattern of pixel regions; depositing the ink composition on the substrate (or the pixel region) to form a first quantum dot layer (or a first repeating segment); and depositing the ink composition on the substrate (or the pixel region) to form a second quantum dot layer (or a second repeating segment). The formation of the first quantum dot layer and the second quantum dot layer can be performed simultaneously or sequentially.

[0240] The deposition of the ink composition may be carried out using an appropriate droplet discharge system such as an inkjet printer or a nozzle printing system.The deposited ink composition may be heated to remove the solvent and optionally to carry out polymerization and thereby provide a (first or second) quantum dot layer.

[0241] The quantum dot composite pattern can be used as a photoluminescent color filter in a display device.

[0242] In an embodiment, an electronic device may include the core-shell quantum dots. The electronic device may include a display device, a light emitting diode (LED), an organic light emitting diode (OLED), a QD LED, a sensor, a solar cell, an imaging sensor, or a liquid crystal display (LCD), but is not limited thereto. The core-shell quantum dots may be included in an electronic device. The electronic device may include a handheld terminal, a monitor, a laptop computer, a television, an electronic display board, a camera, an autonomous driving vehicle, but is not limited thereto. The electronic device may be a handheld terminal, a monitor, a laptop computer, or a television each including a display device (or a light emitting device) containing quantum dots. The electronic device may be a camera or a handheld terminal each including an image sensor containing quantum dots. The electronic device may be a camera or an autonomous driving vehicle each including a photodetector containing core-shell quantum dots.

[0243] In an embodiment, a display device (or light emitting device) may include a light emitting element and optionally a light source. The light emitting element may include a light emitting layer. The light emitting element may include a substrate, and the light emitting layer may be disposed on the substrate. The light emitting layer may include a film or a patterned film of a quantum dot composite. The light source may be configured to provide incident light to the light emitting element. The incident light may have a peak wavelength of light emission greater than or equal to about 440 nm, for example, greater than or equal to about 450 nm and less than or equal to about 560 nm, less than or equal to about 500 nm, less than or equal to about 480 nm, less than or equal to about 470 nm, or less than or equal to about 460 nm.

[0244] In an embodiment, the light emitting element or the light emitting layer may include a sheet of the quantum dot polymer composite. Figure 2 , the photoluminescent device 400 may include a backlight unit and a liquid crystal panel (LC), and the backlight unit may include a sheet of the quantum dot polymer composite (QD sheet). The backlight unit may have a structure in which a reflector, a light guide plate (LGP) and a blue LED light source (blue LED), a quantum dot-polymer composite sheet (QD sheet), and a variety of optical films such as prisms, double brightness enhancement films (DBEF), etc. are stacked, and the liquid crystal panel is disposed on the backlight unit. Between two polarizers and (pol), liquid crystal and a color filter may be disposed. The quantum dot polymer composite sheet (QD sheet) may include red quantum dots and green quantum dots that absorb light emitted from a light source and emit red and green light, respectively. The blue light provided by the light source passes through the quantum dot polymer composite sheet and is combined with the red and green light emitted from the quantum dots to be converted into white light. The white light may be separated into blue light, green light, and red light by a color filter in the liquid crystal panel, and extracted to the outside according to pixels.

[0245] In an embodiment, the light-emitting layer comprises a patterned film of a quantum dot polymer composite, and the patterned film may include a repeating segment configured to emit light of a predetermined wavelength. The repeating segment may include a first repeating segment that can emit a first light. The first segment may be a segment that emits red light. The repeating segment may include a second repeating segment that can emit a second light. The second segment may be a segment that emits green light. The repeating segment may include a third repeating segment that can emit or transmit a third light. The third segment may be a segment that emits or transmits blue light. Further details of the first, second, and third segments may refer to the above.

[0246] The light source may include an element that emits excitation light. The excitation light may include blue light and optionally green light. The light source may include an LED. The light source may include an organic LED (e.g., an OLED). In an embodiment, a first optical element 160 that cuts off (e.g., absorbs or reflects) blue light and optionally green light is provided on the front side (i.e., the light emitting surface) of the first segment and the second segment. The light source may include an OLED (organic light emitting diode) that emits blue light and an OLED that emits green light, and in this case, an optical element that filters or removes green light is provided on the third segment that emits or transmits blue light.

[0247] The light source may include a plurality of light-emitting units corresponding to the first segment and the second segment, respectively, and each of the light-emitting units 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. The electroluminescent layer may include an organic light-emitting material. For example, each light-emitting unit of the light source may include an electroluminescent device (e.g., an organic light-emitting diode (OLED)) configured to emit light of a predetermined wavelength (e.g., blue light, green light, or a combination thereof). The structure and material of the electroluminescent device, such as the organic light-emitting diode (OLED), are not particularly limited.

[0248] Figure 3A is a schematic cross-sectional view of a display device according to an embodiment, and Figure 3B is a schematic cross-sectional view of a display device according to another embodiment. Figure 3A and 3B The light source includes an organic light emitting diode (OLED) emitting blue light. The organic light emitting diode OLED may include (at least two, for example, three or more) pixel electrodes 90a, 90b, 90c formed on a substrate 100, pixel defining layers 150a, 150b formed between adjacent pixel electrodes 90a, 90b, 90c, organic light emitting layers 140a, 140b, 140c formed on the pixel electrodes 90a, 90b, 90c, and a common electrode layer 130 formed on the organic light emitting layers 140a, 140b, 140c.

[0249] A thin film transistor and a substrate may be disposed under the organic light emitting diode (OLED). Pixel regions of the OLED may be disposed corresponding to first, second, and third sections, respectively, which will be described in detail below.

[0250] A quantum dot complex pattern (e.g., comprising a first repeating segment comprising quantum dots that emit green light, a second repeating segment comprising quantum dots that emit red light, or a combination thereof) can be configured, for example, as a stacked structure that further includes a substrate, for example, configured on (e.g., directly on) a light source or configured above a light source, if the light source is present.

[0251] Light emitted from the light source (e.g., blue light, green light, or a combination thereof) may enter the second segment 21 and the first segment 11 of the pattern 170 to respectively emit (e.g., converted) red light R and green light G. Blue light B emitted from the light source passes through the third segment 31 or is transmitted from the third segment 31.

[0252] An optical element 160 may be disposed above the second segment 21 emitting red light, the first segment 11 emitting green light, or a combination thereof. The optical element may be an excitation light cutoff layer or a first filter that cuts off (e.g., reflects or absorbs) excitation light (e.g., blue light, green light, or a combination thereof). The excitation light cutoff layer or optical element 160 may be disposed on the upper substrate 240, or as shown, the excitation light cutoff layer 160 may be disposed under the upper substrate 240 (e.g., on the bottom surface of the upper substrate 240). The excitation light cutoff layer 160 may be disposed between the upper substrate 240 and the quantum dot polymer composite pattern and above the first segment 11 and the second segment 21, and if desired, above the third segment 31. The details of the excitation light cutoff layer are the same as those described below for the first filter.

[0253] The display device may be obtained by separately manufacturing the stacked structure and the LED or OLED (e.g., emitting blue light) and then assembling them. Alternatively, the display device may be obtained by directly forming a quantum dot polymer composite pattern on the LED or OLED.

[0254] The substrate may be a substrate including an insulating material. The substrate may include: glass; various polymers such as polyester (e.g., polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polymethacrylate, or polyacrylate); polycarbonate; polysiloxane (e.g., polydimethylsiloxane (PDMS)); inorganic materials such as Al 2 O 3 or ZnO; or a combination thereof, but not limited thereto. The thickness of the substrate may be appropriately selected in consideration of the substrate material, but is not particularly limited. The substrate may be flexible. The substrate may have a transmittance of greater than or equal to about 50%, greater than or equal to about 60%, greater than or equal to about 70%, greater than or equal to about 80%, or greater than or equal to about 90% for light emitted from the quantum dots.

[0255] A circuit layer including a thin film transistor and the like is formed on the substrate. The circuit layer may further include a gate line, a sustaining voltage line, a gate insulating layer, a data line, a source electrode, a drain electrode, a semiconductor, a protective layer, and the like. The detailed structure of the circuit layer may be verified according to the implementation. The gate line and the sustaining voltage line are electrically isolated from each other, and the data line is insulated and crosses the gate line and the sustaining voltage line. The gate electrode, the source electrode, and the drain electrode respectively form a control terminal, an input terminal, and an output terminal of the thin film transistor. The drain electrode is electrically connected to a pixel electrode to be described below.

[0256] The pixel electrode can be used as an anode of the display device. The pixel electrode can be formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). The pixel electrode can be formed of a material with light blocking properties such as gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or titanium (Ti). The pixel electrode can have a double-layer structure as follows: wherein the transparent conductive material and the material with light blocking properties are stacked sequentially.

[0257] Between two adjacent pixel electrodes, a pixel defining layer (PDL) may overlap ends of the pixel electrodes to divide the pixel electrodes into pixel units. The pixel defining layer is an insulating layer that may electrically block at least two pixel electrodes.

[0258] The pixel defining layer covers a portion of an upper surface of the pixel electrode, and a remaining area of ​​the pixel electrode not covered by the pixel defining layer may provide an opening. An organic emission layer to be described below may be formed on an area defined by the opening.

[0259] The organic emission layer defines each pixel region through the pixel electrode and the pixel defining layer. In other words, one pixel region may be defined as a region formed by one organic emission unit layer contacting one pixel electrode divided by the pixel defining layer.

[0260] For example, in the display device according to the embodiment, the organic emission layer may be defined as a first pixel region, a second pixel region, and a third pixel region, and the pixel regions are spaced apart from each other by the pixel defining layer, leaving a predetermined interval.

[0261] In an embodiment, the organic emission layer may emit a third light belonging to the visible light region or to the UV region. That is, the first to third pixel regions of the organic emission layer may each emit a third light. In an embodiment, the third light may be light with higher energy in the visible light region, for example, blue light, and optionally green light. When all pixel regions of the organic emission layer are designed to emit the same light, the pixel regions of the organic emission layer may all be formed of the same or similar materials or may exhibit the same or similar properties. The process difficulty of forming the organic emission layer may be reduced, and the display device may be applied to large-scale / large-area processes, for example, formed by large-scale / large-area processes or used in large-scale / large-area processes. However, the organic emission layer according to the embodiment is not necessarily limited thereto, but the organic emission layer may be designed to emit at least two different lights.

[0262] The organic emission layer includes an organic emission unit layer in each pixel area, and each organic emission unit layer may further include an auxiliary layer (e.g., a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL), etc.) in addition to the emission layer.

[0263] The common electrode may be used as a cathode of the display device. The common electrode may be formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). The common electrode may be formed on the organic emission layer and may be integrated therewith.

[0264] A planarization layer or a passivation layer may be formed on the common electrode. The planarization layer may include an (eg, transparent) insulating material for ensuring electrical insulation from the common electrode.

[0265] refer to Figure 4 , a display device (e.g., a liquid crystal display device) may include a lower substrate 210, an optical element (e.g., a polarizer) 300 disposed below the lower substrate 210, and a liquid crystal layer 220 between the stacked structure and the lower substrate 210. The stacked structure may be arranged in such a way that the light-emitting layer (i.e., the quantum dot polymer composite pattern) faces the liquid crystal layer. The display device may further include an optical element (e.g., a polarizer) 300 between the liquid crystal layer 220 and the light-emitting layer. The material and structure of the polarizer 300 are known and are not particularly limited. The light source 110 may further include an LED and optionally a light guide plate 120. As shown, a backlight unit (e.g., emitting blue light) may be disposed below the polarizer 300.

[0266] The stacked structure includes a transparent substrate (or upper substrate) 240 and a light emitting layer (hereinafter, also referred to as a photoluminescent layer) 230 including a pattern including a quantum dot polymer composite.

[0267] The lower substrate 210 (also referred to as an array substrate) may be a transparent insulating material substrate. The substrate is the same as described above. A circuit board 211 is provided on the upper surface of the lower substrate 210. The circuit board 211 may include a plurality of gate lines and data lines defining pixel areas, a thin film transistor disposed adjacent to the intersection area of ​​the gate lines and the data lines, and a pixel electrode for each pixel area, but is not limited thereto. The details of such a circuit board are known and are not particularly limited.

[0268] The liquid crystal layer 220 may be disposed on the circuit board 211. The liquid crystal layer 220 may include an alignment layer 221 on and below the liquid crystal layer 220 to initially align the liquid crystal material included therein. Details of the liquid crystal material and the alignment layer (e.g., liquid crystal material, alignment layer material, method of forming the liquid crystal layer, thickness of the liquid crystal layer, etc.) are known and are not particularly limited.

[0269] An upper optical element or upper polarizer 300 may be provided between the liquid crystal layer 220 and the light emitting layer 230. The polarizer may be any polarizer used in a liquid crystal display device. The polarizer may be TAC (triacetyl cellulose) having a thickness of less than or equal to about 200 μm, but is not limited thereto. In an embodiment, the upper optical element may be a coating for controlling a refractive index without a polarization function.

[0270] The backlight unit includes a light source 110. The light source may emit blue light (shown) or white light. The light source may include a blue (or green) LED, a (white) LED, a (white) OLED, or a combination thereof, but is not limited thereto.

[0271] The backlight unit may further include a light guide plate 120. In an embodiment, the backlight unit may be an edge-type lighting device. For example, the backlight unit may include a reflector, a light guide plate provided on the reflector and providing a planar light source to the liquid crystal panel 200, at least one optical sheet such as a diffuser, a prism sheet, etc. on the light guide plate, or a combination thereof, but is not limited thereto. The backlight unit may not include a light guide plate. In an embodiment, the backlight unit may be a direct lighting device. For example, the backlight unit may have a reflector and may have a plurality of fluorescent lamps arranged at regular intervals on the reflector, or may have a plurality of light-emitting diodes on which an LED operating substrate may be arranged, a diffuser plate thereon, and optionally at least one optical sheet. The details of such a backlight unit (e.g., light-emitting diodes, fluorescent lamps, light guide plates, various optical sheets, and components of the reflector) are known and are not particularly limited.

[0272] The black matrix 241 is provided below the transparent substrate 240 and has an opening and hides the gate lines, data lines, and thin film transistors of the wiring board on the lower substrate. For example, the black matrix 241 may have a lattice shape. The photoluminescent layer 230 is provided in the opening of the black matrix 241 and has a first segment (R) configured to emit a first light (e.g., red light), a second segment (G) configured to emit a second light (e.g., green light), and a quantum dot polymer composite pattern configured to emit / transmit a third segment (B) such as blue light. If desired, the photoluminescent layer may further include at least one fourth segment. The fourth segment may include quantum dots that emit light of a color different from the light emitted from the first to third segments (e.g., cyan, magenta, and yellow light).

[0273] In the light emitting layer 230, segments of a pattern may be repeatedly formed corresponding to a pixel region formed on the lower substrate. A transparent common electrode 231 may be provided on the photoluminescent layer 230 (eg, a photoluminescent color filter layer).

[0274] The third segment (B) configured to emit / transmit blue light may be a transparent color filter that does not change the light emission spectrum of the light source. In this case, the blue light emitted from the backlight unit may enter in a polarized state and may be emitted through the polarizer and the liquid crystal layer. If desired, the third segment may include quantum dots that emit blue light.

[0275] As described above, if desired, the display device or the light emitting device may further include an excitation light blocking layer or a first filter layer (hereinafter referred to as the first filter layer). The first filter layer may be disposed between the bottom surface of the first segment (R) and the second segment (G) and a substrate (e.g., an upper substrate 240) or on a top surface of the substrate (e.g., an upper substrate 240). The first filter layer may include a sheet having an opening corresponding to a pixel area (e.g., a third segment) displaying a blue color. In other words, the first filter layer may be integrally formed as an integral structure at a portion other than a portion overlapping with the third segment, but is not limited thereto. At least two (e.g., three) first filter layers may be spaced apart and disposed at respective positions overlapping with the first and second segments and optionally the third segment. When the light source includes an element emitting green light, a green light cutoff filter layer may be disposed on the third segment.

[0276] In an embodiment, the first filter layer may block light having a portion of a wavelength region in the visible light region. The first filter layer may transmit light having other (visible light) wavelength regions. For example, the first filter layer may block blue light (or green light) and transmit light other than blue (or green) light. For example, the first filter layer may transmit green light, red light, or yellow light as a mixture thereof. The first filter layer may transmit blue light and block green light, and may be disposed on a pixel emitting blue light.

[0277] In an embodiment, the first filter layer may substantially block the excitation light and may transmit light of a desired wavelength. In an embodiment, the first filter layer 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 about 100% for light of a desired wavelength range.

[0278] In an embodiment, a first filter layer that selectively transmits red light may be disposed on a portion overlapping with a segment emitting red light, and a first filter layer that selectively transmits green light may be disposed on a portion overlapping with a segment emitting green light, respectively. In an embodiment, the first filter layer may include a first region, a second region, or a combination thereof, wherein the first region blocks (e.g., absorbs) blue light and red light and transmits a wavelength having a predetermined range (e.g., 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 545 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 530 nm). In an embodiment, the excitation light may include blue light and green light, and the first filter layer may further include a third region that blocks green light and selectively transmits blue light.

[0279] The first region may be disposed at a position overlapping with a segment emitting green light. The second region may be disposed at a position overlapping with a segment emitting red light. The third region may be disposed at a position overlapping with a segment emitting or transmitting blue light.

[0280] The first region, the second region, and optionally the third region may be optically isolated.The first filter layer may help to improve the color purity of the display device.

[0281] The display device may further include a second filter layer 311 (e.g., a red / green light or yellow light recycling layer) disposed between the light emitting layer 230 and the liquid crystal layer 220, and between the light emitting layer 230 (e.g., the quantum dot polymer composite layer) and the upper polarizer 300. The second filter layer 311 may transmit at least a portion of the third light (i.e., the excitation light) and reflect at least a portion of the first light, the second light, or the first light and the second light. The first light may be red light. The second light may be green light. The third light may include blue light. The second filter layer may transmit a third light (B) having a wavelength range of blue light less than or equal to 500 nm. Light having a wavelength range greater than about 500 nm (e.g., red light R, green light G, or yellow light) may not be allowed to pass through the second filter and may be reflected thereby. The reflected green light and red light are then transmitted through the first and second segments and emitted out of the display device.

[0282] In the display device according to the embodiment, the first filter layer, the second filter layer, or the first filter layer and the second filter layer may be formed as an integrated single layer having a substantially flat surface.

[0283] In an embodiment, the first filter layer may include a dye and / or a pigment that absorbs light of a predetermined wavelength to be blocked. For example, the first filter layer, the second filter layer, or the first and second filter layers may include a single layer having a low refractive index, and it may be a transparent thin film having a refractive index of less than or equal to about 1.4, less than or equal to about 1.3, or less than or equal to about 1.2. The first or second filter layer having a low refractive index may be, for example, porous silicon oxide, a porous organic material, a porous organic / inorganic composite, or a combination thereof.

[0284] In an embodiment, the second (or first) filter layer may include a plurality of layers having different refractive indices, for example, the second (or first) filter layer may be formed by alternately stacking two layers having different refractive indices, or for example, the second or first filter layer may be formed by alternately stacking a material having a high refractive index and a material having a low refractive index.

[0285] refer to Figure 5A, the electronic device 10 may include a first electrode 11 and a second electrode 15 each having a surface opposite to the other, and an active layer 13 disposed between the first electrode and the second electrode and including the aforementioned quantum dot composite. The first electrode 11 or the second electrode 15 may be an anode, and the other may be a cathode. In particular, the first electrode 11 is an anode, and the second electrode 15 is a cathode, as discussed further below.

[0286] In an embodiment, the electronic device may be an electroluminescent device. The active layer 13 may be a light emitting layer, which includes the core-shell quantum dots, and the electrons and holes injected from the cathode 15 and the anode 11 are respectively recombined therein to form excitons, and according to the energy of the formed excitons, light with a predetermined wavelength is emitted. In an embodiment, the electronic device including the quantum dots may be a photodetector or a solar cell. The active layer 13 may be a light absorbing layer, and the core-shell quantum dots of the active layer 13 may absorb photons from the outside, which are then separated into holes and electrons and provided to the anode 11 and the cathode 15, respectively.

[0287] In an embodiment, the electronic device may include a hole auxiliary layer 12 between the first electrode (anode) 11 and the active layer 13 and / or an electron auxiliary layer 14 between the second electrode (cathode) 15 and the active layer 13 .

[0288] The light emitting device may further include a substrate (not shown). The substrate may be disposed on one side of the anode 11 or the cathode 15, or on each side of the two electrodes. In an embodiment, the substrate may be disposed at the opposite surface of the first electrode (anode). The substrate may include an insulating material (e.g., an insulating transparent substrate). The substrate may include: glass; polymers such as polyesters (e.g., polyethylene terephthalate (PET), polyethylene naphthalate (PEN)), polycarbonates, polyacrylates, polyimides, poly(amide-imides), polysiloxanes (e.g., PDMS), or combinations thereof; inorganic materials such as Al 2 O 3 , ZnO, or a combination thereof; or a combination comprising at least two of the foregoing, but not limited thereto. The substrate may be made of a silicon wafer. As used herein, the term "transparent" refers to a transmittance of greater than or equal to about 85% of light having a predetermined wavelength (e.g., light emitted from quantum dots), or, for example, 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%, such as about 85%-about 99.99%, or about 90%-about 99.9%. The thickness of the substrate may be appropriately selected in consideration of the substrate material, but is not particularly limited. The transparent substrate may be flexible.

[0289] The first electrode 11 may be made of a conductive material such as a metal, a conductive metal oxide, or a combination thereof. The first electrode 11 may include, for example, a metal or an alloy thereof, the metal including nickel, platinum, vanadium, chromium, copper, zinc, and gold; 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 a metal oxide such as ZnO and Al, or SnO 2 and Sb, but not limited thereto.

[0290] The second electrode 15 may be made of a conductive material such as a metal, a conductive metal oxide, a conductive polymer, or a combination thereof. The second electrode 15 may include, for example, a metal or an alloy thereof such as aluminum, magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, silver, gold, platinum, tin, lead, cesium, or barium; a multilayer structure of a material such as LiF / Al, Li 2 O / Al, 8-hydroxyquinoline lithium / aluminum (Liq / Al), LiF / Ca, or BaF 2 / Ca, but not limited thereto. A combination comprising at least two of the foregoing may also be used. The conductive metal oxide is the same as described above.

[0291] In an embodiment, the work function of the first electrode 11 and the work function of the second electrode 15 are not particularly limited and are appropriately selected. The work function of the first electrode may be higher or lower than the work function of the second electrode.

[0292] At least one of the first electrode 11 and the second electrode 15 may be a light-transmitting electrode, and the light-transmitting electrode may be made of, for example, a conductive oxide such as zinc oxide, indium oxide, tin oxide, indium tin oxide (ITO), indium zinc oxide (IZO), fluorine-doped tin oxide, a metal thin layer including a single layer or multiple layers, or a combination thereof. In the case where either of the first electrode 11 and the second electrode 15 is a non-light-transmitting (e.g., non-transparent) electrode, it may include, for example, an opaque conductive material such as aluminum (Al), silver (Ag), gold (Au), or a combination thereof.

[0293] The thickness of the electrode (first electrode and / or second electrode) is not particularly limited and can be appropriately selected in consideration of device efficiency. For example, the thickness of the electrode may be greater than or equal to about 5 nanometers (nm), for example, greater than or equal to about 50 nm, or greater than or equal to about 1 μm. For example, the thickness of the electrode may be less than or equal to about 100 micrometers (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.

[0294] The active layer 13 includes (e.g., a plurality of) the aforementioned core-shell quantum dots. The active layer may include at least one monolayer of the quantum dots. The active layer 13 may include at least one monolayer of the quantum dots (e.g., at least two monolayers, at least three monolayers, at least four monolayers). The number of monolayers of the quantum dots may be less than or equal to about 20, less than or equal to about 10, less than or equal to about 9, less than or equal to about 8, less than or equal to about 7, or less than or equal to about 6.

[0295] The active layer 13 may have a thickness of about 5 nm or more, such as about 10 nm or more, about 20 nm or more, or about 30 nm or more and about 200 nm or less, such as about 150 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, or about 50 nm or less. The active layer 13 may have a thickness of, for example, about 10 nm to about 150 nm, such as about 20 nm to about 100 nm, or about 30 nm to about 50 nm.

[0296] The light emitting device of the embodiment may further include a hole auxiliary layer 12. In a non-limiting embodiment, the hole auxiliary layer 12 may be disposed between the first electrode 11 and the active layer 13. The hole auxiliary layer 12 may have one layer or two or more layers, and may include, for example, a hole injection layer (HIL), a hole transport layer (HTL), an electron blocking layer, or a combination thereof. The hole auxiliary layer 12 may include a single component layer or a multilayer structure in which adjacent layers include components different from each other.

[0297] The hole assisting layer 12 may have a HOMO energy level that matches the HOMO energy level of the active layer 13 to facilitate the migration of holes from the hole assisting layer 12 into the active layer 13. In an embodiment, the hole assisting layer 12 may include a hole injection layer close to the first electrode 11 and a hole transport layer close to the active layer 13.

[0298] The material included in the hole auxiliary layer 12 (e.g., a hole transport layer or a hole injection layer) is not particularly limited, and may include, for example, poly(9,9-dioctyl-fluorene-co-N-(4-butylphenyl)-diphenylamine) (TFB), polyarylamine (polyarylamine), poly(N-vinylcarbazole), poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), polyaniline, polypyrrole, N,N,N' , N'-tetrakis(4-methoxyphenyl)-benzidine (TPD), 4,4'-di[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), m-MTDATA (4,4',4"-tri[phenyl(m-tolyl)amino]triphenylamine), 4,4',4"-tri(N-carbazolyl)-triphenylamine (TCTA), 1,1-di[(di-4-tolylamino)phenyl]cyclohexane (TAPC), p-type metal oxides (e.g., NiO, WO 3 、MoO 3 etc.), carbon-based materials such as graphene oxide, or combinations thereof, but not limited thereto

[0299] If used, the electron blocking layer (EBL) may include, for example, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), poly(9,9-dioctyl-fluorene-co-N-(4-butylphenyl)-diphenylamine) (TFB), polyarylamine, poly(N-vinylcarbazole), polyaniline, polypyrrole, N,N,N',N'-tetrakis(4-methoxyphenyl)-benzidine (TPD), 4,4'-di[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), m-MTDATA, 4,4',4"-tris(N-carbazolyl)-triphenylamine (TCTA), or a combination thereof, but is not limited thereto.

[0300] In the hole auxiliary layer, the thickness of each layer may be appropriately selected depending on the desired characteristics of each layer. For example, the thickness of each layer may 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, greater than or equal to about 20 nm and less than or equal to about 100 nm, such as 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, less than or equal to about 50 nm, 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.

[0301] In an embodiment, the electron assist layer 14 may be disposed between the active layer 13 and the second electrode 15. The electron assist layer 14 may include, for example, an electron injection layer (EIL) facilitating injection of electrons, an electron transport layer (ETL) facilitating transport of electrons, a hole blocking layer (HBL) blocking movement of holes, or a combination thereof, but is not limited thereto.

[0302] In an embodiment, the EIL may be disposed between the ETL and the cathode. In an embodiment, the HBL may be disposed between the ETL (or EIL) and the emission layer, but is not limited thereto. In an embodiment, the thickness of each layer may be appropriately selected and 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 EIL may be an organic layer (e.g., prepared by vapor deposition). The ETL may include inorganic oxide nanoparticles, an organic layer (e.g., prepared by vapor deposition), or a combination thereof.

[0303] The electron transport layer, the electron injection layer, or a combination thereof may include, for example, 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA), bathocuproine (BCP), tris[3-(3-pyridyl)- yl]borane (3TPYMB), LiF, Alq 3 , Gaq 3 、Inq 3 、Znq 2 、Zn(BTZ) 2 、BeBq 2 , ET204 (8-(4-(4,6-di(naphthalene-2-yl)-1,3,5-triazine-2-yl)phenyl)quinolone), 8-hydroxyquinoline lithium (Liq), n-type metal oxides (e.g., ZnO, HfO 2 etc.), or a combination thereof, but not limited thereto.

[0304] In an embodiment, the electron assist layer 14 may include an electron transport layer. The ETL may include a plurality of nanoparticles.

[0305] The nanoparticles include a metal oxide including zinc.

[0306] The metal oxide may include 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 an embodiment, M may be magnesium (Mg). In an embodiment, x may be greater than or equal to about 0.01 and less than or equal to about 0.3, such as 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.

[0307] The absolute value of the LUMO of the quantum dots included in the emission layer may be lower than the absolute value of the LUMO of the metal oxide. In an embodiment, the absolute value of the LUMO of the quantum dots may be greater than the absolute value of the LUMO of the metal oxide of the ETL. 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.

[0308] The hole blocking layer (HBL) may include, for example, 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA), bathocuproin (BCP), tris[3-(3-pyridyl)- yl]borane (3TPYMB), LiF, Alq 3 , Gaq 3 、Inq 3 、Znq 2 、Zn(BTZ) 2 、BeBq 2 , or a combination thereof, but not limited thereto.

[0309] In embodiments, the thickness of the electron assisting layer 14 (e.g., the thickness of each of the electron injection layer, the electron transport layer, or the hole blocking layer) may be greater than or equal to about 5 nm, greater than or equal to about 6 nm, greater than or equal to about 7 nm, greater than or equal to about 8 nm, greater than or equal to about 9 nm, greater than or equal to about 10 nm, greater than or equal to about 11 nm, greater than or equal to about 12 nm, greater than or equal to about 13 nm, greater than or equal to about 14 nm, greater than or equal to about 15 nm, greater than or equal to about 16 nm, greater than or equal to about 17 nm, greater than or equal to about 18 nm, greater than or equal to about 19 nm, greater than or equal to about 20 nm, greater than or equal to about 21 nm, greater than or equal to about 22 nm, greater than or equal to about 23 nm, greater than or equal to about 24 nm, greater than or equal to about 25 nm, greater than or equal to about 26 nm, greater than or equal to about 27 nm, greater than or equal to about 28 nm, greater than or equal to about 29 nm, greater than or equal to about 30 nm, greater than or equal to about 31 nm, greater than or equal to about 32 nm, greater than or equal to about 33 nm, greater than or equal to about 34 nm, greater than or equal to about 35 nm, greater than or equal to about 36 nm, greater than or equal to about 37 nm, greater than or equal to about 38 nm, greater than or equal to about 39 nm, greater than or equal to about 40 nm, greater than or equal to about 41 nm, greater than or equal to about 42 nm, greater than or equal to about 43 nm, greater than or equal to about 44 nm, greater than or equal to about 45 nm, greater than or equal to about 46 nm, greater than or equal to about 47 nm, or equal to about 17 nm, greater than or equal to about 18 nm, greater than or equal to about 19 nm, or greater than or equal to about 20 nm and less than or equal to about 120 nm, less than or equal to about 110 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, less than or equal to about 50 nm, less than or equal to about 40 nm, less than or equal to about 30 nm, or less than or equal to about 25 nm, but is not limited thereto.

[0310] refer to Figure 5B, the electroluminescent device of the embodiment may have a normal structure. The electroluminescent device 200 may include a transparent substrate 100, an anode 10 disposed on the transparent substrate 100, 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 may include a metal with a relatively low work function. For example, the anode may be an electrode including indium tin oxide (ITO, work functions of about 4.6eV and about 5.1eV), and the cathode may be an electrode including magnesium (Mg, work function of about 3.66eV), aluminum (Al, work function of about 4.28eV), or a combination thereof. In an embodiment, 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 transport layer, a hole injection layer, or a combination thereof. If present, the hole injection layer may be disposed close to the anode 10, and the hole transport layer may be disposed close to the quantum dot active layer. In an embodiment, the electron assisting layer 40 may be disposed between the quantum dot active layer 30 and the cathode 50. The electron assisting 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.

[0311] refer to Figure 5C , the device according to the embodiment may have an inverted structure. The electroluminescent device with an inverted structure may include a cathode 50 disposed on a transparent substrate 100 and an anode 10 facing the cathode. The cathode 50 may include a transparent electrode based on a metal oxide (e.g., ITO), and the anode facing it may include a metal with a relatively high work function. In an embodiment, the anode 50 may be an electrode including indium tin oxide (ITO, work functions of about 4.6eV and about 5.1eV), and the cathode may be an electrode including gold (Au, work function of about 5.1eV), silver (Ag, work function of about 4.26eV), aluminum (Al, work function of about 4.28eV), or a combination thereof.

[0312] In an embodiment, the electron auxiliary layer 40 may be disposed between the cathode 50 and the quantum dot active layer 30. The electron auxiliary layer 40 may include an electron transport layer, an electron injection layer, or a combination thereof. If present, 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. In an embodiment, the electron auxiliary layer 40 may be disposed between the quantum dot active layer 30 and the cathode 50. The electron auxiliary layer 40 (e.g., the electron transport layer) may include a metal oxide such as crystalline Zn oxide or an n-type doped metal oxide. 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 transport layer, a hole injection layer, or a combination thereof. If present, the hole injection layer may be disposed close to the anode 10, and the hole transport layer may be disposed close to the quantum dot active layer. The hole transport layer (HTL) may include TFB, PVK, or a combination thereof, and the hole injection layer (HIL) may include MoO 3 or another p-type metal oxide, or a combination thereof.

[0313] The electroluminescent device can emit light of a predetermined wavelength generated in the active layer 30 through the transparent electrode and the transparent substrate. Figure 5B , the anode 10 includes an indium tin oxide (ITO)-based transparent electrode, and the light generated in the active layer can pass through the anode 10 and the transparent substrate 100 and be emitted outside the device. Figure 5C , the cathode 50 includes an indium tin oxide (ITO)-based transparent electrode, and light generated in the active layer can pass through the cathode 50 and the transparent substrate 100 and be emitted outside the device.

[0314] The device of the embodiment can be prepared in an appropriate manner. In an embodiment, the electroluminescent device can be prepared by forming a charge (e.g., hole or electron) auxiliary layer on a substrate having an electrode thereon, forming an active layer including the quantum dots (e.g., a pattern of the aforementioned quantum dots) thereon, and forming an electrode thereon (optionally together with a charge (e.g., electron or hole) auxiliary layer). The formation of the electrode / hole auxiliary layer / electron auxiliary layer is not particularly limited, and the electrode, hole auxiliary layer, and electron auxiliary layer can each be independently formed in an appropriate manner (e.g., via physical or chemical deposition or coating).

[0315] Hereinafter, the embodiments are described in more detail with reference to Examples. However, they are illustrative examples of the present disclosure, and the present disclosure is not limited thereto.

[0316] Example

[0317] Analytical methods

[0318] 1. Photoluminescence Analysis

[0319] Photoluminescence (PL) spectra of the fabricated nanocrystals were obtained using a Hitachi F-7000 spectrometer at a radiation wavelength of 372 nanometers (nm).

[0320] 2. Ultraviolet (UV) spectroscopy analysis

[0321] UV spectroscopy analysis was performed using an Agilent Cary 5000 spectrometer.

[0322] 3. Inductively coupled plasma (ICP) analysis

[0323] Inductively coupled plasma-atomic emission spectrometry (ICP-AES) analysis was performed using Shimadzu ICPS-8100.

[0324] 4. X-ray Photoelectron Spectroscopy (XPS) Analysis

[0325] X-ray photoelectron spectroscopy analysis was performed using Quantum2000 manufactured by Physical Electronics.

[0326] The synthesis was carried out under an inert gas atmosphere (nitrogen flowing condition) unless otherwise specifically stated.

[0327] Embodiment 1:

[0328] [1] Selenium and tellurium were dispersed in trioctylphosphine (TOP) to obtain a 0.4 molar concentration (M) Se / TOP stock solution and a 0.5 M Te / TOP stock solution. Solutions were prepared from the Te / TOP stock solution, an organic ligand including oleylamine, and lithium aluminum hydride. An acetone solution of zinc chloride (concentration 1 M) was also prepared.

[0329] In a 300 milliliter (mL) reaction flask, 0.9 mmol of zinc acetate was dissolved in octadecene and oleic acid was added. The reaction mixture (flask) was heated at 120° C. under vacuum. After one hour at 120° C., the atmosphere in the flask was replaced with an inert gas (nitrogen) and the reaction flask was heated to 300° C.

[0330] The Se / TOP stock solution was injected into the reaction mixture into the heated reaction flask, and the temperature of the reaction flask was lowered to about 280° C. Then, an acetone solution of dodecanethiol and zinc chloride was added to the reaction flask, and the resulting mixture was stirred. In the reaction mixture, 1 mole of Te was used per 1 mole of the hydride compound.

[0331] The reactor was cooled to room temperature, and acetone was added thereto to promote the formation of a precipitate, which was separated via centrifugation to provide the treated ZnTeSe cores.The treated ZnTeSe cores were then dispersed in toluene.

[0332] [2] Sulfur was dispersed in trioctylphosphine (TOP) to obtain a 1 molar concentration (M) S / TOP stock solution. As a gallium precursor, (oleic acid) Ga was dispersed in TOP and ODE (octadecene) to obtain a 0.4 M gallium stock solution.

[0333] To a 300 mL reaction flask, trioctylamine (TOA), zinc acetate and oleic acid were added and the mixture was heated at 120°C for one hour under vacuum. The atmosphere in the flask was replaced with an inert atmosphere (nitrogen) and the flask was heated to a temperature greater than about 250°C.

[0334] To the heated reaction mixture, the ZnTeSe cores and Se / TOP stock solution prepared above were each added, and the reaction was performed for 10 minutes.

[0335] Then, the gallium precursor (Ga(oleate)) and S / TOP stock solution were added to the reaction flask to form a layer further including gallium and sulfur, and then a zinc precursor and S / TOP stock solution were added to form a ZnS layer.

[0336] After the reaction was completed, the flask was cooled to room temperature, and acetone was added to promote the formation of precipitates, and the ZnTeSe / ZnSe / ZnS core-shell quantum dots containing gallium were separated via centrifugation. The separated core-shell quantum dots were dispersed in toluene.

[0337] During the shell formation, the addition amount of Se and the addition amount of S were about 0.1 mmol and about 0.4 mmol, respectively, and the addition amount of gallium was about 1.2 mmol, relative to about 0.9 mmol of Zn.

[0338] For the as-prepared core and core-shell quantum dots, UV-Vis absorption spectroscopy analysis and photoluminescence spectroscopy analysis were performed, and the results are summarized in Table 1.

[0339] XPS analysis was performed on the core-shell quantum dots and the results are shown in Figure 6 and Table 1.

[0340] For the core-shell quantum dots, ICP-AES analysis was performed and the results are shown in Table 2.

[0341] Comparative Example 1:

[0342] Core-shell quantum dots were prepared in the same manner as in Example 1, except that during core formation, the acetone solution of dodecanethiol and zinc chloride was not used in the reaction preparation. The obtained core and the obtained core-shell quantum dots were dispersed in toluene.

[0343] UV-Vis absorption spectroscopy analysis and photoluminescence spectroscopy analysis were performed, and the results are summarized in Table 1. XPS analysis was performed on the core-shell quantum dots, and the results are shown in Figure 6 and Table 1.

[0344] For the core-shell quantum dots, ICP-AES analysis was performed and the results are shown in Table 2.

[0345] Embodiment 2:

[0346] ZnTeSe / ZnS core-shell quantum dots were prepared in the same manner as in Example 1, except that during core formation, the amount of tellurium relative to zinc of the core or relative to zinc or selenium of the quantum dots was increased as in Table 2, and during shell formation, neither Se / TOP nor gallium precursors were used.

[0347] During the shell formation, about 0.1 mmol of S was added relative to 0.9 mmol of Zn. The obtained core and the obtained core-shell quantum dots were dispersed in toluene.

[0348] For the core and core-shell quantum dots, UV-Vis absorption spectroscopy analysis and photoluminescence spectroscopy analysis were performed, and the results are summarized in Table 1. XPS analysis was performed on the core-shell quantum dots, and the results are shown in Table 1.

[0349] For the core-shell quantum dots, ICP-AES analysis was performed and the results are shown in Table 2.

[0350] Comparative Example 2:

[0351] Core-shell quantum dots were prepared in the same manner as in Example 2, except that during the core formation, the acetone solution of dodecanethiol and zinc chloride was not used. The obtained core and the obtained core-shell quantum dots were dispersed in toluene.

[0352] For the core and core-shell quantum dots as prepared, UV-Vis absorption spectroscopy analysis and photoluminescence spectroscopy analysis were performed, and some of the results are summarized in Table 1. XPS analysis was performed on the core-shell quantum dots thus prepared, and the results are shown in Table 1.

[0353] For the as-prepared core-shell quantum dots, ICP-AES analysis was performed and the results are listed in Table 2.

[0354] Table 1

[0355]

[0356] FWHM: Half Width (nm)

[0357] PL: Photoluminescence

[0358] QY: Quantum efficiency (%)

[0359] The results of Table 1 demonstrate that the quantum dots of Examples 1 and 2 exhibit reduced amounts of tellurium oxide and improved optical properties.

[0360] Table 2

[0361]

[0362]

[0363] While the present disclosure has been described with respect 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, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. Core-shell quantum dots, including: A core comprising a first semiconductor nanocrystal, the first semiconductor nanocrystal comprising zinc, tellurium, and selenium; and a semiconductor nanocrystal shell disposed on the core, the shell comprising zinc chalcogenide, wherein the core-shell quantum dots do not include cadmium, lead, mercury, or a combination thereof, In the X-ray photoelectron spectrum of the core-shell quantum dots, the peak area of ​​Te oxide as an area percentage is 5 / 2 The peak area is less than or equal to 25%, The core-shell quantum dots further include additional metals, and the additional metals include aluminum and lithium.

2. The core-shell quantum dot of claim 1, wherein the core-shell quantum dot has a molar ratio of tellurium to selenium greater than 0.1:

1.

3. The core-shell quantum dot of claim 1, wherein the core-shell quantum dot has a molar ratio of tellurium to selenium of less than or equal to 4:

1.

4. The core-shell quantum dot of claim 1, wherein the peak area of ​​Te oxide as area percentage is relative to Te3d 5 / 2 The peak area is less than or equal to 20%. 5 . The core-shell quantum dot of claim 1 , wherein the core-shell quantum dot has a molar ratio of the additional metal to tellurium greater than or equal to 0.001 and less than or equal to 1.

5. The core-shell quantum dots of claim 1 , wherein the core-shell quantum dots do not include indium phosphide.

7. The core-shell quantum dots of claim 1, wherein the core-shell quantum dots are water-insoluble.

8. The core-shell quantum dot of claim 1, wherein the zinc chalcogenide comprises selenium, sulfur, or a combination thereof.

9. The core-shell quantum dot of claim 1, wherein the core-shell quantum dot has a molar ratio of sulfur to selenium greater than 0:1 and less than or equal to 4:

1.

10. The core-shell quantum dot of claim 1, wherein the core-shell quantum dot has a molar ratio of sulfur to tellurium greater than 0.5:1 and less than or equal to 3:

1. 11 . The core-shell quantum dot according to claim 1 , wherein the maximum luminescence peak wavelength of the core-shell quantum dot is in the range of greater than 450 nanometers and less than or equal to 600 nanometers. 12 . The core-shell quantum dot of claim 1 , wherein the maximum photoluminescence peak of the core-shell quantum dot has a half-width less than or equal to 30 nanometers.

13. The core-shell quantum dot of claim 1, wherein the core-shell quantum dot has a quantum efficiency greater than or equal to 35%.

14. The core-shell quantum dot of claim 1, wherein the core-shell quantum dot comprises an organic ligand, and the organic ligand comprises RCOOH, RNH2, R2NH, R3N, RSH, RH2PO, R2HPO, R3PO, RH2P, R2HP, R3P, ROH, RCOOR', RHPO(OH), RPO(OH)2, R2POOH, a polymer organic ligand, or a combination thereof, wherein R and R' are the same or different and are each independently a substituted or unsubstituted C1-C40 aliphatic hydrocarbon group, a substituted or unsubstituted C6-C40 aromatic hydrocarbon group, or a combination thereof.

15. A method for manufacturing a core-shell quantum dot according to any one of claims 1 to 14, comprising: preparing a core particle by reacting a zinc precursor, a selenium precursor, and a tellurium precursor in the presence of lithium aluminum hydride at a core formation temperature to form a first semiconductor nanocrystal; and adding a treatment agent to a reaction medium including the first semiconductor nanocrystals for post-treatment; wherein the treating agent comprises a combination of an organic thiol compound and a metal compound, the metal compound comprises a metal halide, and the metal compound comprises zinc; and A zinc precursor is reacted with a chalcogen precursor in the presence of a core particle and a shell-forming organic ligand at a shell-forming temperature to form a semiconductor nanocrystalline shell on the core particle.

16. The method of claim 15, wherein the organic thiol compound comprises a compound represented by RSH, wherein R is an unsubstituted C1-C30 hydrocarbon group, and wherein the metal compound comprises zinc chloride.

17. The method of claim 15, wherein the core forming temperature is greater than or equal to 280°C, and the post-treatment is performed at a temperature greater than or equal to 50°C and less than the core forming temperature.

18. A quantum dot composite comprising: matrix; and a plurality of quantum dots dispersed in the matrix, wherein the plurality of quantum dots include the core-shell quantum dots as described in any one of claims 1-14.

19. Display devices, including Light emitting element, The light-emitting element comprises a plurality of core-shell quantum dots, wherein the plurality of quantum dots comprise the core-shell quantum dots as described in any one of claims 1-14.

20. Electronic devices, including: a first electrode and a second electrode, each having a surface opposite to the other, and An active layer is arranged between the first electrode and the second electrode, the active layer comprising a plurality of quantum dots, wherein the plurality of quantum dots comprise the core-shell quantum dots according to any one of claims 1 to 14.

21. A quantum dot composition comprising: The core-shell quantum dots according to any one of claims 1 to 14; and a polymerizable monomer having a carbon-carbon double bond.

22. The quantum dot composition of claim 21, wherein the polymerizable monomer is a photopolymerizable monomer.

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