Quantum dots, quantum dot groups including the same, display devices, quantum dot composites and quantum dot compositions

Abstract

The present invention relates to quantum dots, quantum dot groups including the same, display devices, quantum dot complexes and quantum dot compositions. Cadmium-free quantum dots or groups thereof or devices including the same, wherein the cadmium-free quantum dots include the following and exhibit a quantum efficiency of about 60% or more: a core (or semiconductor nanocrystal particle) including a first semiconductor nanocrystal including a IIB-VI group compound; and a shell (or coating layer) disposed on the core (or the semiconductor nanocrystal particle) including a IIB-V group compound.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefits of Korean Patent Application No. 10-2020-0134705 filed in the Korean Intellectual Property Office on October 16, 2020, and all rights arising therefrom, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] Disclosed are quantum dots, a method for manufacturing the same, and an electronic device (equipment) comprising the quantum dots. Background Art

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

[0005] Embodiments provide environmentally friendly quantum dots that can achieve, for example, exhibiting improved optical properties (eg, luminous efficiency, half-width, or a combination thereof) and, for example, emitting light of a desired wavelength.

[0006] Embodiments provide methods of manufacturing the aforementioned quantum dots.

[0007] An embodiment provides a quantum dot-polymer composite including the quantum dots.

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

[0009] In an embodiment, a quantum dot (or multiple quantum dots, hereinafter referred to as "quantum dots") includes: a core including a first semiconductor nanocrystal, and a semiconductor nanocrystal shell disposed on the core, wherein the first semiconductor nanocrystal includes a IIB-VI group compound and the semiconductor nanocrystal shell includes a IIB-V group compound, and wherein the quantum dot does not include cadmium and the quantum yield of the quantum dot is greater than or equal to about 60%.

[0010] The quantum dots may be configured to emit light (e.g., by excitation), and the maximum luminescence (e.g., photoluminescence) peak wavelength of the light emitted by the quantum dots (or of the quantum dots) may be in the range of greater than or equal to about 480 nanometers (nm) and less than or equal to about 580 nm. The quantum dots may be configured to emit green light, for example, by photoexcitation.

[0011] The quantum dots may not include lead, mercury, or a combination thereof.

[0012] The quantum dots may include zinc, tellurium, selenium, and optionally sulfur. The IIB-VI group compound may include zinc chalcogenide. The semiconductor nanocrystal shell or the IIB-V group compound may include zinc and a group V element. The semiconductor nanocrystal shell may further include a IIB-VI group compound.

[0013] The zinc chalcogenide may include zinc; and a chalcogen element (eg, selenium, sulfur, tellurium, or a combination thereof).

[0014] In the quantum dot, a molar ratio of tellurium to selenium (Te:Se) may be greater than or equal to about 0.1: 1. In the quantum dot, a 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, or greater than or equal to about 0.2: 1.

[0015] In the quantum dots, a molar ratio of tellurium to selenium (Te:Se) may be less than or equal to about 4:1.

[0016] In the quantum dots, a molar ratio of zinc to the sum of Group VI elements may be greater than or equal to about 1.35:1, or greater than or equal to about 1.45:1.

[0017] In the quantum dots, a molar ratio of zinc to a sum of selenium and tellurium may be greater than or equal to about 3.5:1, or greater than or equal to about 4:1.

[0018] In the quantum dots, a molar ratio of the group V element (eg, phosphorus) to tellurium may be greater than or equal to about 0.15:1.

[0019] In the quantum dots, a molar ratio of the group V element (eg, phosphorus) to selenium may be greater than or equal to about 1.3:1, greater than or equal to about 1.5:1, greater than or equal to about 2:1, or greater than or equal to about 2.5:1.

[0020] The Group V element may include nitrogen, phosphorus, arsenic, bismuth, or a combination thereof.

[0021] The Group IIB-V compound may include zinc phosphide.

[0022] In the quantum dots, the molar ratio of the group V element (e.g., phosphorus) to the group IIB metal may be greater than or equal to about 0.1: 1, greater than or equal to about 0.15: 1, or greater than or equal to about 0.18: 1. In the quantum dots, the molar ratio of the group V element to zinc may be less than or equal to about 0.9: 1.

[0023] In an embodiment, the core (or the quantum dot) may not include a semiconductor nanocrystal including a Group III-V compound.

[0024] The quantum dots may be insoluble in water.

[0025] The IIB-VI group compound may include an alloy of zinc and tellurium. The first semiconductor nanocrystal or the IIB-VI group compound 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. In an embodiment, x may be between about 0.6 and about 0.8.

[0026] The quantum dot (or the semiconductor nanocrystal shell) may include selenium and sulfur. In the quantum dot, the molar ratio of sulfur to selenium (S:Se) may be greater than 0:1, greater than or equal to about 0.05:1, or greater than or equal to about 0.1:1. In the quantum dot, 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 semiconductor nanocrystal shell may include a first layer and a second layer disposed on the first layer. The first layer may include nanocrystals of the IIB-VI group compound. The second layer may include a IIB-V group compound. In an embodiment, the crystallinity of the second layer (e.g., the outer layer of the quantum dot) may be lower than that of the first layer and / or the core (e.g., the inner portion of the quantum dot) (e.g., as determined by transmission electron microscopy). The second layer may be the outermost layer of the quantum dot.

[0028] The maximum light emission peak of the quantum dots may have a half width less than or equal to about 45 nm.

[0029] The quantum efficiency (or quantum yield) of the quantum dots may be greater than or equal to about 65%, or greater than or equal to about 70%.

[0030] The quantum dots may include organic ligands (eg, bound to their surface).

[0031] 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, a polymeric organic ligand, or a combination thereof, wherein R and R' are the same or different and are independently a substituted or unsubstituted C1-C40 aliphatic hydrocarbon group or a substituted or unsubstituted C6-C40 aromatic hydrocarbon group, or a combination thereof.

[0032] In an embodiment, the quantum dot group includes the aforementioned quantum dots. The average size of the quantum dots may be greater than or equal to about 7 nanometers.

[0033] In an embodiment, the quantum dot (multiple quantum dots) includes: a semiconductor nanocrystal particle including a IIB-VI group compound and a coating (coating) disposed on the semiconductor nanocrystal particle, wherein the quantum dot does not include cadmium, and the coating includes a material having a lower crystallinity than the semiconductor nanocrystal particle as determined by a transmission electron microscope and including a IIB-V group compound. The quantum dot may be configured to emit light under light excitation, wherein the wavelength of the light emitted by the quantum dot is shorter than the wavelength of the excitation light. The maximum luminescence peak of the light emitted by the quantum dot (or the quantum dot) may have a half-width of less than or equal to about 45nm. The semiconductor nanocrystal particle may include: a first semiconductor nanocrystal layer including zinc, tellurium, and selenium; and a second semiconductor nanocrystal layer disposed on the first semiconductor nanocrystal layer and including zinc, selenium, and optionally tellurium.

[0034] An amount of tellurium in the first semiconductor nanocrystal layer may be greater than an amount of tellurium in the second semiconductor nanocrystal layer.

[0035] The maximum emission peak wavelength of the light (or the quantum dots) may be greater than or equal to about 480 nm and less than or equal to about 580 nm, and the quantum yield of the quantum dots may be greater than or equal to about 65%, or greater than or equal to about 70%.

[0036] In an embodiment, a quantum dot group may include a plurality of the quantum dots. In the group, the quantum dots may have an average size greater than or equal to about 7 nm.

[0037] In an embodiment, a method for manufacturing quantum dots (multiple quantum dots) includes: obtaining a particle including a core, the core including a first semiconductor nanocrystal, the first semiconductor nanocrystal including a Group IIB-VI compound; and reacting a Group IIB metal precursor and a Group V element precursor in a solvent in the presence of the particle to form a coating on the surface of the particle to manufacture the quantum dot, wherein the coating includes: a second layer including a Group IIB-V compound on the particle, wherein the second layer or the Group IIB-V compound has a lower crystallinity than the Group IIB-VI compound or the particle.

[0038] The quantum dot (or the particle) may further include a first layer, the first layer including a second semiconductor nanocrystal, the second semiconductor nanocrystal including a IIB-VI group compound. The first layer may be arranged between the core and the second layer. The first layer may be (directly) arranged on the core.

[0039] In an embodiment, a method of manufacturing the quantum dots comprises:

[0040] A reaction medium comprising a first organic solvent and a first organic ligand is heated; the core, a Group IIB metal precursor, a chalcogen precursor, and a Group V element precursor are provided to the reaction medium and reacted at a shell formation temperature in the presence of the core (or the semiconductor nanocrystal particle) to form the semiconductor nanocrystal shell (or the coating) on ​​the surface of the core (or the semiconductor nanocrystal particle).

[0041] The formation of the semiconductor nanocrystal shell may include

[0042] The IIB group metal precursor is reacted with the chalcogen precursor in the presence of the core (and optionally in the presence of a group V element) to form a first layer of semiconductor nanocrystals on the core, the semiconductor nanocrystals comprising a IIB-VI group compound; and the IIB group metal precursor is reacted with the group V element precursor to form a second layer comprising the IIB-V group compound on the first layer. The second layer may be less than the crystallinity of the first layer and / or the core. The second layer may be non-crystalline, for example, as determined by TEM analysis.

[0043] In an embodiment, the preparation of the core may include: preparing a metal precursor organic solution including a zinc precursor and a second organic ligand in a second organic solvent; and

[0044] While the metal precursor organic solution is heated at a core forming temperature, a selenium precursor, a tellurium precursor, a hydride compound, and a third organic ligand different from the second organic ligand are added thereto.

[0045] In an embodiment, a quantum dot (eg, polymer) composite comprises a (eg, polymer) matrix; and a plurality of quantum dots dispersed in the (polymer) matrix,

[0046] The plurality of quantum dots include the aforementioned quantum dots.

[0047] The matrix may comprise a polymer.

[0048] The matrix may include a cross-linked polymer, a monomer or polymer comprising a carboxylic acid group, or a combination thereof.

[0049] 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.

[0050] The quantum dot composite may further include metal oxide fine particles (eg, dispersed in the polymer matrix).

[0051] In an embodiment, a display device includes a light emitting element, and the light emitting element includes a plurality of the quantum dots.

[0052] In an embodiment, the display device includes a light emitting element (eg, a photoluminescent element), wherein the light emitting element includes the aforementioned quantum dots or the quantum dot-polymer composite. In an embodiment, the display device may further include a light source, wherein the light source is configured to provide incident light to the light emitting element.

[0053] The incident light may have a (luminescence) peak wavelength in the range of about 440 nm to about 560 nm (eg, about 440 nm to about 460 nm, or about 450 nm to about 480 nm, or about 500 nm to about 560 nm).

[0054] The light emitting element may include a sheet of the quantum dot composite.

[0055] The light-emitting element may include a stacked structure including a substrate and a light-emitting layer (e.g., a photoluminescent layer) disposed on the substrate. The light-emitting layer may include a pattern of the quantum dot composite. The pattern may include a repeating segment (portion) (e.g., at least one (kind) or two (kinds) of repeating segments) configured to emit light of a predetermined wavelength.

[0056] The display device may be configured to have a color reproducibility of greater than or equal to about 80% according to the BT2020 standard.

[0057] In an embodiment, the electronic device may include: a first electrode and a second electrode having surfaces facing each other; and an active layer including the quantum dots, for example, disposed between the first and second electrodes.

[0058] The electronic device may further include a charge assisting layer (eg, a hole assisting layer) disposed between the first electrode and the active layer.

[0059] The electronic device may further include a charge assisting layer (eg, an electron assisting layer) disposed between the first electrode and the active layer.

[0060] In embodiments, quantum dots may exhibit improved optical properties (eg, narrowed half-width and enhanced luminous efficiency) at desired wavelengths (greater than about 470 nm or green light region), while they may be substantially free of harmful heavy metals such as cadmium.

[0061] In an embodiment, the quantum dots include semiconductor nanocrystal particles containing zinc, selenium, and tellurium and no harmful heavy metals and a shell or coating layer containing a Group IIB-V compound, achieving an increase in luminous efficiency and a decrease in half-width.

[0062] According to an embodiment, the quantum dots can emit light of a desired wavelength (e.g., green light) with a relatively high level of quantum efficiency and a relatively narrow half-width, and can be included in a quantum dot-based light-emitting device or a display device including the same in various forms (e.g., films, patterns, or tracks), contributing to the realization of, for example, providing a display device with high color reproducibility, high efficiency, and high brightness.

[0063] The quantum dots of the embodiments may also be applied to, for example, bio-labeling (biosensors, bio-imaging), security inks, photodetectors, solar cells, hybrid composites, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] 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:

[0065] Figure 1 is a graph of absorption (arbitrary units (au)) versus wavelength (nm) illustrating the definition of valley depth for the UV-Vis absorption spectrum of quantum dots according to embodiments.

[0066] Figure 2A A process of making a quantum dot composite pattern using a composition according to an embodiment is schematically represented.

[0067] Figure 2B A process for making a quantum dot composite pattern using an ink composition is schematically represented.

[0068] Figure 3 is an exploded view of a display device according to an embodiment.

[0069] Figure 4A is a schematic cross-sectional view of a display device according to an embodiment.

[0070] Figure 4B is a schematic cross-sectional view of a display device according to an embodiment.

[0071] Figure 5 is a schematic cross-sectional view of a display device according to an embodiment.

[0072] Fig. 6A is a schematic cross-sectional view of a light emitting device according to an embodiment.

[0073] Figure 6B A schematic cross-sectional view of a light emitting device according to an embodiment.

[0074] Figure 6C is a schematic cross-sectional view of a light emitting device according to an embodiment.

[0075] Fig. 7A is a graph of intensity (arbitrary units) versus diffraction angle (degrees, 2θ) showing the results of X-ray diffraction (XRD) analysis of the quantum dots synthesized in Example 1.

[0076] Figure 7B A TEM image obtained by transmission electron microscopy analysis of the quantum dots synthesized in Example 1 is shown.

[0077] Figure 7C This is an image of transmission electron microscopy-energy dispersive spectroscopy (TEM-EDX) analysis of the quantum dots synthesized in Example 1.

[0078] Fig. 8A , Figure 8B and Figure 8C Each Figure 7B A magnified image of the inner part of the quantum dot shown in the TEM image.

[0079] Fig.9A , Fig. 9B and Fig. 9C Each Figure 7B A magnified image of the outer portion of the quantum dot shown in the TEM image. DETAILED DESCRIPTION

[0080] The advantages and features of the present disclosure, and methods for achieving the same, will become apparent with reference to the following example embodiments, together with the figures 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.

[0081] Unless otherwise defined, all terms (including technical and scientific terms) used in this article may be used with the meaning commonly understood by people of ordinary knowledge in the art. It will be further understood that terms, such as those defined in common dictionaries, should be interpreted as having a meaning consistent with their meaning 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.

[0082] As used herein, the singular forms "a (kind) (indefinite article) (a, an)" and "the" are intended to include plural forms, including "at least one (kind)", unless the content or context clearly indicates otherwise. "At least one (kind)" will not be interpreted as limited to "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.

[0083] In the accompanying drawings, the thickness of layers, films, panels, regions, etc. is exaggerated for clarity. Throughout the specification, the same reference numerals represent the same elements. 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 may be directly on the other element or there may be an intermediate element. On the contrary, when an element is referred to as being "directly on" another element, there is no intermediate element.

[0084] 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 (part). 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).

[0085] 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 ±10% or ±5% relative to the stated value.

[0086] 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 will be expected. Therefore, the embodiments described herein should not be interpreted as being limited to the specific shapes of the regions as illustrated 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 illustrated 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.

[0087] 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.

[0088] 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 (or, for example, at least one hydrogen atom) from an alkane, alkene, alkyne, or 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.

[0089] As used herein, "alkyl" refers to a straight-chain or branched saturated monovalent hydrocarbon group (methyl, ethyl, hexyl, etc.).

[0090] As used herein, "alkenyl" refers to a straight-chain or branched monovalent hydrocarbon group having a carbon-carbon double bond.

[0091] As used herein, "alkynyl" refers to a straight-chain or branched monovalent hydrocarbon group having a carbon-carbon triple bond.

[0092] As used herein, "aryl" refers to a group formed by removing hydrogen (eg, at least one hydrogen) from an aromatic hydrocarbon (eg, phenyl or naphthyl).

[0093] As used herein, "hetero" refers to one or more heteroatoms (eg, 1-3 heteroatoms) including N, O, S, Si, P, or a combination thereof.

[0094] As used herein, "(meth)acryloyl" refers to acryl, methacryloyl, or a combination thereof.

[0095] As used herein, "Group" refers to a Group of the Periodic Table.

[0096] As used herein, “Group III” may refer to Group IIIA and Group IIIB, and examples of Group III metals may be In, Ga, Tl, or a combination thereof, but are not limited thereto.

[0097] As used herein, "Group V" may include nitrogen, phosphorus, arsenic, antimony, bismuth, or a combination thereof, but is not limited thereto.

[0098] As used herein, "Group VI" may include sulfur, selenium, tellurium, or a combination thereof, but is not limited thereto.

[0099] As used herein, the term "average" (eg, average size of quantum dots) may be a mean or a median. In embodiments, the average may be a "mean" average.

[0100] In embodiments, quantum efficiency (also referred to as quantum yield) can be the ratio of photons emitted from a nanostructure (e.g., quantum dots) or its group to photons absorbed by the nanostructure (e.g., quantum dots) or its group, such as relative amount. In embodiments, quantum efficiency can be measured by any suitable method. Quantum efficiency can be measured by absolute and relative methods. Quantum efficiency (or quantum yield) can be measured in a solution state or a solid state (e.g., in a complex).

[0101] In the absolute method, the quantum yield can be determined by detecting all sample fluorescence using an integrating sphere. In the relative method, the fluorescence intensity of a standard sample (e.g., a standard dye) can be compared with the fluorescence intensity of an unknown sample to calculate the quantum yield of the unknown sample. Coumarin 153, coumarin 545, rhodamine 101 inner salt, anthracene, and rhodamine 6G can be used as standard dyes depending on the photoluminescence wavelength, but are not limited thereto.

[0102] The quantum yield (QY) can be easily and reproducibly determined by using commercially available equipment (eg from Hitachi Co. Ltd or Hamamatsu Co. Ltd) and referring to the instructions provided by the manufacturer.

[0103] The full width at half maximum (FWHM) and the maximum emission peak wavelength can be determined from the (photo)luminescence spectrum obtained by a spectrophotometer (or fluorescence spectrophotometer).

[0104] As used herein, the expression "does not include cadmium (or other harmful heavy metals)" may refer to situations where the concentration of cadmium (or another heavy metal considered to be harmful) 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 1 ppmw, less than or equal to about 0.1 ppmw, less than or equal to about 0.01 ppmw, or about 0. 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 an impurity level thereof.

[0105] Semiconductor nanoparticles (e.g., quantum dots) can absorb energy from an excitation source (e.g., a light source providing incident light or electrodes facing each other) and can emit light corresponding to the band gap energy of the quantum dots. The band gap energy of the quantum dots can vary with the size, composition, or combination thereof of the quantum dots. Semiconductor nanocrystals can be used as luminescent materials in a variety of fields such as display devices, energy devices, or bioluminescent devices.

[0106] Quantum dots with relatively improved photoluminescent properties may include toxic heavy metals such as cadmium (Cd), lead (Pb), mercury (Hg), or a combination thereof. Toxic heavy metals such as cadmium may cause environmental problems, health problems, or a combination thereof, and are one of the restricted elements under the Restriction of Hazardous Substances Directive (RoHS) in many countries. Therefore, the development of environmentally friendly quantum dots with improved luminescent properties at a desired wavelength may be desired (when applied to light-emitting devices such as electroluminescent or photoluminescent devices). Indium phosphide-based quantum dots may be applied, for example, for use in practical devices.

[0107] For applications such as for use in quantum dot display devices (e.g., including a color conversion layer containing quantum dots) and for achieving, for example, providing a display device having relatively high color reproducibility according to a next-generation color standard such as BT2020, quantum dots having a relatively narrow half width (FWHM) may be desirable. For example, in order for the device to achieve an improved, for example, improved color reproducibility according to the BT2020 standard, it may be desirable for the luminescent material used therein to have a reduced level of FWHM, for example, a narrower 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 the change in FWHM depending on the size of the quantum dot may be significant. Therefore, an InP-based quantum dot may not have a reduced level of FWHM, for example, a narrower FWHM, when emitting 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). Additionally, a core including indium and phosphorus may be sensitive to surface oxidation, and a quantum dot including the same may have an increased FWHM when including a shell (eg, a shell coated on the core of the quantum dot), and it may be difficult to achieve a desired level of quantum efficiency and a desired FWHM.

[0108] In the case of tellurium-based zinc selenide nanocrystalline particles as cadmium-free quantum dots, the wavelength difference caused by the particle distribution can be maintained at a desired low level compared to indium phosphide quantum dots or cadmium-based quantum dots. In other words, even if the change in particle size distribution is relatively significant, the change in the emission wavelength may not be significant, which may be beneficial for the resulting quantum dots to show, for example, a reduced level of FWHM, such as a narrower FWHM.

[0109] However, a quantum dot structure including a ZnTeSe-based core and an inorganic shell coated thereon may not exhibit desired dispersion properties (e.g., organic solvent dispersibility) and may not exhibit, for example, desired luminescence properties. While not wishing to be bound by any theory, it is believed that the band gap offset between the core and the shell in a ZnSe core including tellurium and a zinc chalcogenide shell is not sufficiently large, and thus even a physically well-formed shell may not result in a sufficiently and desirably high quantum yield.

[0110] In embodiments, quantum dots based on an alloy core including zinc selenide and tellurium and excluding cadmium have the features described herein and are thus able to exhibit significantly improved optical properties (improved luminous efficiency and narrowed half-width).

[0111] In embodiments, the quantum dots may not include harmful heavy metals such as cadmium, lead, or mercury, and may emit light of a desired wavelength (eg, green light) with improved optical properties.

[0112] In an embodiment, a quantum dot (a plurality of quantum dots) (hereinafter referred to as "quantum dot") comprises: a core comprising a first semiconductor nanocrystal, and a semiconductor nanocrystal shell disposed on the core (e.g., on at least a portion of its surface) and having a composition different from that of the core. The first semiconductor nanocrystal comprises a IIB-VI group compound, and the semiconductor nanocrystal shell may comprise a IIB-V group compound. The IIB-VI group compound may comprise zinc chalcogenide. The semiconductor nanocrystal shell or the IIB-V group compound may comprise zinc and a group V element. The semiconductor nanocrystal shell may further comprise a IIB-VI group compound.

[0113] The quantum dot may include zinc, selenium, tellurium, and optionally sulfur. The core or the first semiconductor nanocrystal may include a zinc chalcogenide (e.g., a crystal of a zinc compound including selenium and tellurium in alloy or doped form). In the core or the quantum dot, the amount of tellurium may be greater than the amount of selenium.

[0114] In the quantum dot of the embodiment, the first semiconductor nanocrystal included in the core may include ZnTe x Se 1-x(where x is 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, greater than or equal to about 0.68, greater than or equal to about 0.69, greater than or equal to about 0.70, greater than or equal to about 0.71, greater than or equal to about 0.72, greater than or equal to about 0.73, greater than or equal to less than or equal to about 0.74, or about 0.75 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 0.74 or less, about 0.75 or less 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 0.74 or less, about 0.73 or less, about 0.72 or less, about 0.71 or less, about 0.70 or less, about 0.69 or less, about 0.68 or less, about 0.67 or less, about 0.66 or less, about 0.65 or less, about 0.6 or less, about 0.5 or less, about 0.4 or less, about 0.3 or less, or about 0.2 or less).

[0115] The amounts of components included in the quantum dots as described herein can be determined by appropriate analytical tools (e.g., inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction photoelectron spectroscopy (XPS), ion chromatography, transmission electron microscopy energy dispersive X-ray spectroscopy (TEM-EDS), etc.).

[0116] In the 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, greater than or equal to about 0.93:1, greater than or equal to about 0.94:1, or greater than or equal to about 0.10:1. 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.

[0117] In the quantum dots of the embodiment, the molar ratio of tellurium to selenium (Te:Se) 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, less than or equal to about 2.4:1, less than or equal to about 2.3:1, less than or equal to about 2.2:1, 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, or less than or equal to about 0.9:1.

[0118] In the quantum dots of the embodiments, the molar ratio of tellurium to zinc (Te:Zn) may be greater than about 0.02:1, greater than or equal to about 0.021:1, greater than or equal to about 0.025:1, greater than or equal to about 0.03:1, greater than or equal to about 0.035:1, greater than or equal to about 0.04:1, greater than or equal to about 0.045:1, or greater than or equal to about 0.05:1 (e.g., as measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES)). In the quantum dots of the embodiments, the molar ratio of tellurium to zinc (Te:Zn) may be (e.g., as measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES)) less than 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, less than or equal to about 0.2:1, or less than or equal to about 0.1:1.

[0119] In the quantum dots of the embodiment, the molar ratio of selenium to zinc (Se:Zn) may be less than or equal to about 0.5:1, less than or equal to about 0.45:1, less than or equal to about 0.4:1, less than or equal to about 0.35:1, less than or equal to about 0.3:1, less than or equal to about 0.28:1, less than or equal to about 0.25:1, or less than or equal to about 0.2: 1. The molar ratio of selenium to zinc (Se:Zn) may be greater than or equal to about 0.01:1, greater than or equal to about 0.015:1, greater than or equal to about 0.02:1, greater than or equal to about 0.025:1, or greater than or equal to about 0.03:1.

[0120] In the quantum dots of the embodiments, the molar ratio of zinc to tellurium (Zn:Te) may be greater than or equal to about 5:1, greater than or equal to about 6:1, greater than or equal to about 7:1, greater than or equal to about 8:1, greater than or equal to about 8.5:1, greater than or equal to about 9:1, greater than or equal to about 9.5:1, greater than or equal to about 10:1, greater than or equal to about 10.5:1, greater than or equal to about 11:1, greater than or equal to about 11.5:1, greater than or equal to about 12:1, greater than or equal to about 13:1, greater than or equal to about 14:1, greater than or equal to about 15:1, greater than or equal to about 16:1, greater than or equal to about 17:1, greater than or equal to about 18:1, greater than or equal to about 19:1, greater than or equal to about 20:1, greater than or equal to about 21:1, greater than or equal to about 22:1, greater than or equal to about 23:1, greater than or equal to about 24:1, greater than or equal to about 25:1, greater than or equal to about 26:1, greater than or equal to about 27:1, greater than or equal to about 28:1, greater than or equal to about 29:1, greater than or equal to about 30:1, greater than or equal to about 31:1, greater than or equal to about 32:1, greater than or equal to about 33:1, greater than or equal to about 34:1, greater than or equal to about 35:1 greater than or equal to about 12.5:1, greater than or equal to about 13:1, greater than or equal to about 13.5:1, greater than or equal to about 14:1, greater than or equal to about 14.5:1, greater than or equal to about 15:1, greater than or equal to about 15.5:1, greater than or equal to about 16:1, greater than or equal to about 16.5:1, greater than or equal to about 17:1, greater than or equal to about 17.5:1, greater than or equal to about 18:1, greater than or equal to about 18.5:1, or greater than or equal to about 19:1. In the quantum dots of the embodiments, the molar ratio of zinc to tellurium (Zn:Te) may be 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 29:1, less than or equal to about 28:1, less than or equal to about 27:1, less than or equal to about 26:1, less than or equal to about 25:1, less than or equal to about 24:1, less than or equal to about 23:1, less than or equal to about 22:1, or less than or equal to about 21:1.

[0121] The quantum dots of the embodiments may further include sulfur, and if present, the molar ratio of sulfur to selenium may be greater than 0:1, 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, greater than or equal to about 2:1, greater than or equal to about 2.4:1, greater than or equal to about 2.5:1, greater than or equal to about 3:1, or greater than or equal to about 3.5:1. In the quantum dots of the embodiments, the molar ratio of sulfur to selenium may be less than or equal to about 8:1, less than or equal to about 7:1, less than or equal to about 6:1, or less than or equal to about 5.5:1.

[0122] In the quantum dots of the embodiments, if present, 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 0.5:1, 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, 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, or greater than or equal to about 5: 1. The molar ratio of sulfur to tellurium (S:Te) may be less than or equal to about 8:1, less than or equal to about 7.8:1, or less than or equal to about 7.7:1. In the quantum dots of the embodiments, the molar ratio of sulfur to tellurium may be, for example, 3.2:1 to about 10:1, about 3.5:1 to about 9.5:1, about 4:1 to about 9:1, about 4.5:1 to about 8.5:1, about 5:1 to about 8:1, about 5.5:1 to about 7.9:1, or about 6:1 to about 7.8:1.

[0123] In the quantum dot of the embodiment or in the core (or the first semiconductor nanocrystal), 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 0.75:1, greater than or equal to about 0.8:1, greater than or equal to about 0.9:1, greater than or equal to about 10:10, greater than or equal to about 11:11, greater than or equal to about 12:13, greater than or equal to about 13:14, greater than or equal to about 14:15, greater than or equal to about 15:16, greater than or equal to about 16:17, greater than or equal to about 17:18, greater than or equal to about 18:19, greater than or equal to about 19:11 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.

[0124] In the quantum dots of the embodiments or in the core (or the first semiconductor nanocrystal), 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 0.8:1, 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.

[0125] In the quantum dots of the embodiment, the molar ratio of zinc to the sum of selenium and sulfur (Zn:S+Se) may be greater than or equal to about 1:1, or greater than or equal to about 1.5:1 and less than or equal to about 30:1, less than or equal to about 29:1, less than or equal to about 28:1, less than or equal to about 27:1, less than or equal to about 26:1, less than or equal to about 25:1, less than or equal to about 23:1, less than or equal to about 22:1, less than or equal to about 21:1, or less than or equal to about 20: 1. The molar ratio of zinc to the sum of selenium and sulfur (Zn:S+Se) may be, for example, 1.8:1 to about 5:1, 1.9:1 to about 4:1, or about 2:1 to about 3.5:1.

[0126] In the quantum dots of the embodiments, the molar ratio of the sum of sulfur and selenium to tellurium ((Se+S):Te) may be greater than or equal to about 2:1, greater than or equal to about 3:1, greater than or equal to about 4:1, greater than or equal to about 5:1, greater than or equal to about 6:1, greater than or equal to about 7:1, greater than or equal to about 8:1, greater than or equal to about 9:1, or greater than or equal to about 10:1. The molar ratio of the sum of sulfur and selenium to tellurium ((Se+S):Te) may be less than or equal to about 16:1, 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, less than or equal to about 3:1, or less than or equal to about 2:1.

[0127] In an embodiment, the quantum dots may not include manganese, copper, or a combination thereof, for example, in the core or in the shell. In an embodiment, the quantum dots may not include a III-V compound. The III-V compound may include indium phosphide, indium zinc phosphide, gallium phosphide, or a combination thereof. The quantum dots may not exhibit a peak attributable to the III-V compound (e.g., indium phosphide or gallium phosphide) in an X-ray diffraction analysis.

[0128] In an embodiment, a cadmium-free quantum dot including a zinc telluride alloy core can emit light of a desired wavelength with increased luminous efficiency. In an embodiment, a quantum dot including tellurium in the aforementioned amount can emit light of a wavelength within a desired range, for example, greater than about 480 nm, or greater than or equal to about 490 nm, greater than or equal to about 500 nm, or greater than or equal to about 510 nm and 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, or less than or equal to about 545 nm. In an embodiment, it may be recommended to provide a shell including zinc selenide on the core to increase the stability of the quantum dot. However, the inventors have surprisingly found that the improvement in the optical properties of the quantum dot may be limited as the thickness of the ZnSe shell increases.

[0129] In the case of the quantum dot of the embodiment, the shell layer provided on the core includes the Group IIB-V compound or a cladding layer including the same is provided, and the quantum dot of the embodiment may show relatively improved luminous efficiency and a desired half width.

[0130] In the quantum dots of the embodiments or in the semiconductor nanocrystal shell, the IIB-V group compound may include zinc and a group V element. The group V element may include nitrogen, phosphorus, arsenic, antimony, bismuth, or a combination thereof. In embodiments, the group V element may include phosphorus. The IIB-V group compound may include zinc phosphide.

[0131] In the quantum dots of the embodiments, the molar ratio of the Group V element (e.g., phosphorus) to the Group IIB metal (e.g., zinc) may be greater than or equal to about 0.015:1, 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, greater than or equal to about 10:10, greater than or equal to about 11:11, greater than or equal to about 12:13, greater than or equal to about 13:14, greater than or equal to about 14:15, greater than or equal to about 16:17, greater than or equal to about 18:19, greater than or equal to about 19:11 about 0.09:1, 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, or greater than or equal to about 0.2:1. In the quantum dots of the embodiments, the molar ratio of the Group V element (e.g., phosphorus) to the Group IIB metal (e.g., zinc) may be 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 0.55:1, less than or equal to about 0.5:1, less than or equal to about 0.45:1, or less than or equal to about 0.4:1.

[0132] In the quantum dots of the embodiments, the molar ratio of the Group V element (e.g., phosphorus) to selenium may be greater than or equal to about 0.1:1, greater than or equal to about 0.2:1, greater than or equal to about 0.25:1, 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 0.6:1, 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, 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 1.6:1, greater than or equal to about 1.8:1, greater than or equal to about 1.9:1, greater than or equal to about 2.0:1, 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, greater than or equal to about 2. 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. In the quantum dots of the embodiments, the molar ratio of the Group V element (e.g., phosphorus) to selenium 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, or less than or equal to about 3.5:1.

[0133] In the quantum dots of the embodiments, the molar ratio of the group V element (e.g., phosphorus) to tellurium 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 1.5:1, 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, or greater than or equal to about 4.5:1. In the quantum dots of the embodiments, the molar ratio of the group V element (e.g., phosphorus) 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, or less than or equal to about 6:1.

[0134] The quantum dots may further include additional metals such as aluminum, lithium, or a combination thereof. In the quantum dots of the embodiments, the molar ratio of the additional metal (e.g., 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, greater than or equal to about 10:1, greater than or equal to about 11:1, greater than or equal to about 12:1, greater than or equal to about 13:1, greater than or equal to about 14:1, greater than or equal to about 15:1, greater than or equal to about 16:1, greater than or equal to about 17:1, greater than or equal to about 18:1, greater than or equal to about 19:1, greater than or equal to about 20:1, greater than or equal to about 21:1, greater than or equal to about 23:1, greater than or equal to about 24:1, greater than or equal to about 25:1, greater than or equal to about 26:1, greater than or equal to about 27:1, greater than or equal to about 28:1, greater than or equal to about 29:1, greater than or equal to about 30:1, greater than or equal to about 31:1, greater than or equal to about 32:1, greater than or equal to about 33:1, greater than or equal to about 34:1, greater than or equal to about 35: .09:1, 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 0.40:1, 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, greater than or equal to about 0.50:1, greater than or equal to about 0.51:1, greater than or equal to about 0.52:1 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. In the quantum dot, the molar ratio of the additional metal 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.

[0135] The shell may be a multilayer shell including a plurality of layers. Among the plurality of layers of the shell, adjacent layers may have different materials (eg, semiconductor nanocrystals, amorphous materials, or a combination thereof).

[0136] The multilayer shell may include a first shell disposed on the core (e.g., directly on it) and a second shell disposed on (e.g., directly on it) or above the first layer. The first shell may include a second semiconductor nanocrystal. The second shell may include a material different from the second semiconductor nanocrystal (e.g., a third semiconductor nanocrystal, an amorphous material, or a combination thereof). The second shell may include a IIB-V group compound (e.g., zinc phosphide). In an embodiment, the second shell may exhibit a lower crystallinity than the first shell (e.g., the crystallinity of the first shell) when measured by an appropriate tool such as (HR) TEM. The second layer may be the outermost layer of the quantum dot.

[0137] In embodiments, the outer or outermost layer of the quantum dot may include a Group IIB-V compound and may show a lower crystallinity than the inner portion of the quantum dot, for example, as determined by (high resolution) TEM analysis. High resolution transmission electron microscopy analysis (HRTEM) is a specialized imaging mode of transmission electron microscopy that allows direct imaging of the atomic structure of a sample. Apparatus for (HR)TEM is commercially available and results may be reproducibly and easily obtained.

[0138] In an embodiment, the inner portion of the quantum dot may include the core. The inner portion of the quantum dot may include a (first) shell layer of a Group IIB-VI compound. In the outer layer or outermost layer of the quantum dot, the regularly spaced lattice arrangement (or crystal pattern) may be less than in the inner portion of the quantum dot, as determined by (high resolution) TEM analysis. In an embodiment, in a (high resolution) TEM analysis, the outer layer or outermost layer of the quantum dot may substantially not show a regularly spaced lattice arrangement.

[0139] In an embodiment, the outer or outermost layer of the quantum dot may have a thickness of about 0.3 nm to about 2.5 nm, about 0.5 nm to about 2 nm, about 0.6 nm to about 1.5 nm, about 0.8 nm to about 1.3 nm, about 0.9 nm to about 1.1 nm, or a combination thereof, measured from the surface of the quantum dot.

[0140] The quantum dots may not show a zinc phosphide crystallization peak (which appears from 2θ (2 theta) of about 39-40°, for example) in an X-ray diffraction analysis.

[0141] In the X-ray diffraction analysis of the quantum dots, a crystal peak attributed to zinc selenide may appear in a 2θ range of greater than or equal to about 25.5°, greater than or equal to about 25.6°, greater than or equal to about 25.7°, greater than or equal to about 25.8°, greater than or equal to about 25.9°, greater than or equal to about 26°, greater than or equal to about 26.1°, greater than or equal to about 26.2°, or greater than or equal to about 26.3° and less than or equal to about 27°, less than or equal to about 26.9°, less than or equal to about 26.8°, less than or equal to about 26.7°, less than or equal to about 26.6°, less than or equal to about 26.5°, less than or equal to about 26.4°, less than or equal to about 26.3°, less than or equal to about 26.2°, less than or equal to about 26.1°, less than or equal to about 26°, or less than or equal to about 25.9°.

[0142] The first shell or the second semiconductor nanocrystal may include zinc, selenium, and optionally sulfur. In an embodiment, the first shell or the second semiconductor nanocrystal may have a concentration that changes in a radial direction. The multilayer shell may further include a third shell between the first shell and the second shell, wherein the third shell may have a fourth semiconductor nanocrystal that is different from the second semiconductor nanocrystal. The fourth semiconductor nanocrystal may include zinc and sulfur. The fourth semiconductor nanocrystal may include or may not include selenium. In an embodiment, the first shell may include ZnSe, ZnSeS, ZnS, or a combination thereof. The third shell may be composed of zinc sulfide (e.g., ZnS).

[0143] In a multilayer shell, the thickness of each layer can be appropriately selected. The thickness of the shell layer (e.g., the first shell layer, the second shell layer, and the third shell layer if present) can each independently 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 layer in the multilayer shell can be selected taking into account the desired composition of the final quantum dot.

[0144] In an embodiment, the shell or each of the shell layers in the multi-layer shell may include a gradient alloy having a composition that changes in a radial direction, such as a radial direction from the core of the quantum dot toward the outermost surface. In the quantum dot of an embodiment, the amount (concentration) of the group V element (e.g., phosphorus) in the shell (e.g., at the outermost layer of the shell or the surface of the quantum dot) may be greater than that in the core (or the shell layer closer to the core). In the shell layer, the change of the group V element (e.g., phosphorus) can be determined by using an appropriate analytical tool such as TEM-EDX.

[0145] In the quantum dots of the embodiments, 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.

[0146] The quantum dots (or a group thereof) may have a particle (average) size of greater than or equal to about 2 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. The size (or average size) of the quantum dots (or a group 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, less than or equal to about 5.5 nm, or less than or equal to about 5 nm. In an embodiment, the size of a quantum dot may refer to a diameter or equivalent diameter (e.g., under the assumption of a circle) obtained from a two-dimensional image analyzed by electron microscopy. In an embodiment, "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 or a group 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 suitable image analysis computer program (e.g., Image J).

[0147] In embodiments, the ultraviolet-visible (UV-Vis) absorption spectrum of a (core or core-shell) quantum dot may include a valley that can be relatively clearly noticed. In the UV-vis absorption spectrum, the quantum dot of the embodiment may have a valley adjacent to the first absorption peak. As used herein, the term "valley" of the UV-Vis absorption spectrum refers to the portion where the slope of the tangent line of the UV-Vis absorption spectrum curve changes from a negative value to a positive value as the wavelength increases (see Figure 1 The valley may exist near the first absorption peak 1 (see Figure 1 ).

[0148] In the UV-vis absorption spectrum of the quantum dot, the depth of the valley adjacent to the first absorption peak (ie, valley depth (VD)) can be defined by the following equation:

[0149] (Abs 第一-Abs 谷 ) / Abs 第一 =VD

[0150] Among them Abs 第一 is the absorption intensity at the wavelength of the first absorption peak, and Abs 谷 is the absorption intensity at the lowest point of the valley.

[0151] As used herein, the term "first absorption peak wavelength" refers to the wavelength of the main exciton peak that first appears from the longest wavelength region of the UV-vis absorption spectrum of the quantum dot (i.e., appears in the lowest energy region in the UV-Vis absorption spectrum).

[0152] The quantum dots of the embodiment may exhibit a valley depth of at least a predetermined value. In the UV-vis absorption spectrum of the quantum dots of the embodiment, the valley or its lowest point may appear at a wavelength lower than, for example, shorter than the wavelength of the first absorption peak. In the UV-vis absorption spectrum of the quantum dots, the intensity of the first absorption peak may be greater than the intensity at the lowest point of the valley adjacent thereto.

[0153] In quantum dots of embodiments, the valley depth defined herein may be greater than or equal to about 0.05, for example, greater than or equal to about 0.1, or greater than or equal to about 0.15.

[0154] The first absorption peak of the quantum dot may be, for example, in the range of about 450 nm to about 530 nm, about 460 nm to about 520 nm, about 465 nm to about 515 nm, about 470 nm to about 510 nm, about 475 nm to about 505 nm, about 480 nm to about 500 nm, or about 490 nm to about 495 nm. The lowest point of the valley in the UV-Vis absorption spectrum of the quantum dot may be, for example, about 450 nm to about 530 nm, about 460 nm to about 520 nm, about 465 nm to about 515 nm, about 470 nm to about 510 nm, about 475 nm to about 505 nm, about 480 nm to about 500 nm, or about 490 nm to about 495 nm.

[0155] The quantum dot may be configured to emit light having a wavelength less than or equal to about 580 nm by energy excitation (e.g., photoexcitation). In an embodiment, the quantum dot may emit green light. The maximum peak wavelength of the quantum dot may be, for example, about 440 nm to about 580 nm, about 450 nm to about 570 nm, about 460 nm to about 565 nm, about 470 nm to about 560 nm, about 475 nm to about 560 nm, about 480 nm to about 555 nm, about 490 nm to about 555 nm, about 495 nm to about 550 nm, about 500 nm to about 545 nm, about 505 nm to about 540 nm, about 510 nm to about 540 nm, about 515 nm to about 540 nm, about 520 nm to about 535 nm.

[0156] Compared to other quantum dots based on Zn, Te, and Se, the quantum dots of the embodiments may exhibit significantly improved quantum efficiency, for example, a quantum efficiency of greater than or equal to about 60%. The quantum efficiency may be the ratio of emitted photons to photons absorbed by the quantum dots. The quantum efficiency may be determined by a comparative method using a well-characterized standard sample with a known quantum yield value, or measured absolutely using an integrating sphere. The measuring equipment for quantum efficiency is commercially available from multiple manufacturers (e.g., Hitachi Co., Ltd., Hammamatsu Co. Ltd.).

[0157] In embodiments, the quantum dots may exhibit a quantum efficiency of greater than or equal to about 60%, greater than or equal to about 65%, greater than or equal to about 70%, greater than or equal to about 75%, or greater than or equal to about 80%.

[0158] In embodiments, the quantum dots may exhibit a half width of 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 when analyzed by photoluminescence spectroscopy.

[0159] The quantum dots may constitute a group of quantum dots.

[0160] In an embodiment, the quantum dot may include an organic ligand, for example, on its surface. The organic ligand may include RCOOH, RNH 2 , R 2 NH, R 3 N, RSH, RH2 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 substituted or unsubstituted C1-C40 (e.g., C3-C30 or C6-C24) aliphatic hydrocarbon groups (e.g., alkyl, alkenyl, or alkynyl) or substituted or unsubstituted C6-C40 aromatic hydrocarbon groups, or combinations thereof. Two or more different organic ligands may be used.

[0161] 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)), etc.; phosphine oxides such as substituted or unsubstituted methyl phosphine oxide (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)), 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)), etc.; 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; or a combination thereof, but are not limited thereto. Two or more different organic ligand compounds may be used.

[0162] In an embodiment, the organic ligand compound may be RCOOH and an amine (eg, RNH 2 , R 2 NH, R 3 In an embodiment, 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.

[0163] In an embodiment, the organic ligand may not include a multifunctional organic compound having a thiol moiety and an amino group, a carboxylic acid group, or a combination thereof. In an embodiment, the organic ligand may not include a glutathione compound. The quantum dots may be water-insoluble.

[0164] When dispersed in water, the quantum dots may exhibit, for example, 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 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 are described herein.

[0165] In an embodiment, the quantum dot comprises: a semiconductor nanocrystal particle comprising a IIB-VI group compound and a coating layer disposed on the semiconductor nanocrystal particle, wherein the quantum dot does not include cadmium, and the coating layer comprises a material having a lower crystallinity than the semiconductor nanocrystal particle as determined by a transmission electron microscope and comprising a IIB-V group compound. The quantum dot is configured to emit light after being excited by an excitation light, wherein the wavelength of the light emitted by the quantum dot is shorter than the wavelength of the excitation light. The maximum luminescence peak of the light emitted by the quantum dot (or the quantum dot) may have a half width less than or equal to about 45 nm. The semiconductor nanocrystal particle may include: a first semiconductor nanocrystal layer comprising zinc, tellurium, and selenium; and a second semiconductor nanocrystal layer disposed on the first semiconductor nanocrystal layer and comprising zinc, selenium, and optionally sulfur.

[0166] The amount of tellurium in the first semiconductor nanocrystal layer may be greater than the amount of tellurium in the second semiconductor nanocrystal layer. The maximum luminescence peak wavelength of the light emitted by the quantum dots (or the quantum dots) may be greater than or equal to about 480 nm and less than or equal to about 580 nm, and the quantum yield of the quantum dots may be greater than or equal to about 65%, or greater than or equal to about 70%.

[0167] In an embodiment, the quantum dot population may include a group of the quantum dots. In the group, the quantum dots may have an average size greater than or equal to about 7 nm, such as greater than or equal to about 7.5 nm, or greater than or equal to about 8 nm. The average size of the quantum dots may be less than or equal to about 12 nm, less than or equal to about 11.5 nm, or less than or equal to about 11 nm.

[0168] The details of the quantum dot with core and semiconductor nanocrystal shell can be applied to the quantum dot with semiconductor nanocrystal particles and coating layer. For example, the first semiconductor nanocrystal layer can correspond to the core in the core-shell quantum dot, and the second semiconductor nanocrystal layer can correspond to the first shell layer and optionally the third shell layer for the quantum dot with core and shell.

[0169] In an embodiment, a method of manufacturing the quantum dots comprises:

[0170] The reaction medium comprising the first organic solvent and the first organic ligand is heated; The core is provided to the reaction medium or comprises the particle of the core, the IIB group metal precursor, the V group element precursor and optionally the chalcogen precursor and reacts under the shell formation temperature to form the semiconductor nanocrystal shell (or the coating) on ​​the surface of the core (or the semiconductor nanocrystal particle) in the presence of the core (or the semiconductor nanocrystal particle). The details of the core and the semiconductor nanocrystal shell are the same as those set forth herein.

[0171] The method may further include preparing the core, the core comprising the first semiconductor nanocrystal, the first semiconductor nanocrystal comprising the IIB-VI group compound. The IIB group metal precursor, the V group element precursor, and optionally the chalcogen precursor may be added to the heated reaction medium simultaneously or in any suitable order.

[0172] In an embodiment, a method for making quantum dots of the present invention, the method comprising:

[0173] obtaining a core, the core comprising a first semiconductor nanocrystal, the first semiconductor nanocrystal comprising a Group IIB-VI compound; and

[0174] heating the core, a Group IIB metal precursor, a chalcogen, and a Group V element precursor in an organic solvent to form a semiconductor nanocrystal shell on the surface of the core to produce the quantum dot,

[0175] Wherein the semiconductor nanocrystal shell comprises:

[0176] a first layer comprising a Group IIB-VI compound on the core, and

[0177] A second layer on the first layer includes a Group IIB-V compound, the Group IIB-V compound having a lower crystallinity than the Group IIB-VI compound.

[0178] In an embodiment, the core or the first semiconductor nanocrystal may include zinc, tellurium, and selenium, and preparing nanocrystals including ZnTeSe may include: preparing a zinc precursor organic solution including a zinc precursor and a second organic ligand in a second organic solvent; and adding a selenium precursor, a tellurium precursor, a hydride compound, and a third organic ligand different from the second organic ligand (e.g., at least one third organic ligand) to the zinc precursor organic solution while heating the zinc precursor organic solution at a core formation temperature.

[0179] The reaction temperature 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 reaction temperature for core formation 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 in consideration of the precursor for core formation, the reaction temperature, the desired size of the core, and the like.

[0180] 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, about 290° C. or more, or about 300° 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 in consideration of the desired shell composition, such as the precursor used, the shell formation temperature, the desired shell thickness, and the like.

[0181] The synthesized core can be separated from the reaction system, for example, before the shell is formed, for example, by using a non-solvent. The separation using a non-solvent can be described in detail herein.

[0182] The details of the composition of the quantum dots and the formation of the shell are the same as described herein.

[0183] 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 / L (molar concentration (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. In an embodiment, the use of a tellurium precursor in the aforementioned concentration range may contribute to improving the reactivity of the tellurium precursor, providing improved quality of the core.

[0184] In an embodiment, during the synthesis of the core, the selenium precursor, tellurium precursor, metal hydride compound, and third organic ligand may be mixed to form a single stock solution (stock solution) at a temperature of less than about 80° C., such as 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., before being added to the zinc precursor organic solution. The temperature may be greater than or equal to about 10° C., greater than or equal to about 20° C., or, for example, about room temperature.

[0185] The third organic ligand may be an aliphatic organic amine compound or a combination thereof.

[0186] 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 (e.g., at least one hydrocarbon group) (e.g., C1-C18 alkyl, C2-C18 alkenyl, or C2-C18 alkynyl) or a C6-C40 aromatic hydrocarbon group, or a combination thereof), an inorganic metal hydride compound, or a combination thereof. The metal hydride compound may include an alkyl lithium hydride; a dialkyl lithium borohydride, wherein each alkyl group may have 1-6 carbon atoms; a lithium aluminum hydride compound, or a combination thereof.

[0187] 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, based on 1 mole of tellurium. 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, based on 1 mole of tellurium.

[0188] During 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.

[0189] During 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.

[0190] During 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, during the preparation of the core, the amount of zinc relative to 1 mol of tellurium may be greater than or equal to about 1 mol, greater than or equal to about 2 mol, greater than or equal to about 3 mol, greater than or equal to about 4 mol, or greater than or equal to about 5 mol. According to an embodiment, during the preparation of the core, the amount of zinc relative to 1 mol of tellurium may be less than or equal to about 20 mol, less than or equal to about 15 mol, less than or equal to about 10 mol, less than or equal to about 9 mol, less than or equal to about 8 mol, less than or equal to about 7 mol, less than or equal to about 6 mol, less than or equal to about 5 mol, less than or equal to about 4 mol, less than or equal to about 3 mol, or less than or equal to about 2 mol.

[0191] In an embodiment, the formation of the shell may include heating the organic ligand in the organic solvent under vacuum at a predetermined temperature (e.g., at a temperature greater than or equal to about 100° C., such as greater than or equal to about 120° C.) (or vacuum heating), changing the atmosphere of the reaction system to an inert gas, and heating it at a predetermined reaction temperature. A Group IIB metal precursor (hereinafter, an embodiment using a zinc precursor may be described, but is not limited thereto) and a chalcogen precursor and a Group V element precursor (hereinafter, an embodiment using a phosphorus precursor may be described, but is not limited thereto) may be added to the heated reaction system when the reaction system is heated to the shell formation temperature.

[0192] For the duration of the reaction, the Group IIB metal precursor and the chalcogen precursor may be added simultaneously or in any suitable order taking into account the desired shell composition. The addition of the shell precursor may be controlled or adjusted to achieve a shell having a desired composition (e.g., a single composition or a gradient or multilayer composition).

[0193] In an embodiment, the formation of the semiconductor nanocrystal shell may include reacting the zinc precursor with the selenium precursor, the sulfur precursor, or a combination thereof. In an embodiment, the zinc precursor may react with the selenium precursor to form a first layer including zinc and selenium, and then react with the sulfur precursor to form a second layer including zinc and sulfur. In an embodiment, the formation of the semiconductor nanocrystal shell may include reacting the zinc precursor with the selenium precursor, and then reacting the zinc precursor with the sulfur precursor. In an embodiment, the zinc precursor may react with selenium and sulfur precursors to form a semiconductor nanocrystal shell (e.g., ZnSeS) including zinc, selenium and sulfur.

[0194] The formation of the semiconductor nanocrystal shell may include reacting the Group IIB metal precursor with the chalcogen precursor in the presence of the core to form a first layer of the semiconductor nanocrystal shell on the core; and reacting the Group IIB metal precursor with the Group V element precursor to form a second layer comprising a non-crystalline material on the first layer, the non-crystalline material comprising the Group IIB-V compound. In an embodiment, the reaction of the Group IIB metal precursor with the chalcogen precursor may be performed in the presence of a Group V element precursor.

[0195] In an embodiment, the formation of the semiconductor nanocrystal shell may include: reacting the Group IIB metal precursor with the chalcogen precursor to form a (first) shell layer (e.g., nanocrystal layer) of nanocrystals including Group IIB-VI compounds on the core, and reacting the Group IIB metal precursor with the Group V element precursor to form a (second shell) layer (or coating layer) on the (first) shell layer that includes Group IIB-V compounds and has a lower crystallinity than the (first) shell layer.

[0196] In an embodiment, the Group IIB metal precursor may include metal powder (Zn powder), metal oxide (e.g., ZnO), alkylated metal compound (e.g., C2-C30 alkyl (e.g., dialkyl) zinc, such as dimethyl zinc, diethyl zinc), metal alkoxide (e.g., metal ethoxide), metal carboxylate (e.g., metal acetate or aliphatic zinc carboxylate such as long-chain aliphatic zinc carboxylate such as zinc oleate), metal nitrate, metal perchlorate, metal sulfate, metal acetylacetonate, metal halide (e.g., metal chloride), metal cyanide, metal hydroxide, metal carbonate, metal peroxide, or a combination thereof. The Group II metal precursor may include zinc. The Group II metal may be zinc. Examples of Group II metal precursors including zinc 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.

[0197] 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.

[0198] 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.

[0199] 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), bis(trimethylsilyl) sulfide, bis(trimethylsilylmethyl) sulfide, ammonium sulfide, sodium sulfide, or a combination thereof.

[0200] The group V element precursor may include a compound in which a given group V element is linked to a ligand group (e.g., an organic ligand group such as a dialkylamine group, a trialkylsilyl group, etc.). In an embodiment, the group V element precursor may include a compound having a tri(dialkylamine) moiety. In an embodiment, the group V element precursor may include a tri(dialkylamine)phosphine compound, a tri(trialkylsilyl)phosphine compound such as TMS. 3 P, a trialkylphosphine such as trioctylphosphine, a trialkylphosphine oxide, or a combination thereof.

[0201] In the formation of the semiconductor nanocrystal shell, the metal precursor may be present simultaneously with the chalcogen precursor and the Group V element precursor. Although not wishing to be bound by any theory, the chalcogen precursor may tend to first participate in the reaction with the metal precursor to form a first shell layer having a relatively high level of crystallinity, after which the Group V element precursor (e.g., a phosphorus precursor) may react with the metal precursor to form an inorganic shell including the IIB-V compound (e.g., having a lower crystallinity than the first shell layer).

[0202] The first organic solvent and the second organic solvent may be the same or different from each other. The first organic solvent and the second organic solvent (hereinafter, simply referred to as organic solvent) may be C6-C22 primary amines such as hexadecylamine, C6-C22 secondary amines such as dioctylamine, C6-C40 tertiary amines such as trioctylamine, nitrogen-containing heterocyclic compounds such as pyridine, C6-C40 olefins such as octadecene, C6-C40 aliphatic hydrocarbons such as hexadecane, octadecane, or squalane, aromatic hydrocarbons substituted with C6-C30 alkyl groups such as phenyldodecane, phenyltetradecane, or phenylhexadecane, primary, secondary, or tertiary phosphine (e.g., trioctylphosphine) substituted with (e.g., at least one) (e.g., 1, 2, or 3) C6-C22 alkyl groups, phosphine oxides (e.g., trioctylphosphine oxide) substituted with (e.g., at least one) (e.g., 1, 2, or 3) C6-C22 alkyl groups, C12-C22 aromatic ethers such as phenyl ether or benzyl ether, or a combination thereof.

[0203] At least two or all of the first organic ligand, the second organic ligand, and the third organic ligand may be the same. At least two or all of the first organic ligand, the second organic ligand, and the third organic ligand may be different. The details of the first and second organic ligands and the third organic ligand are the same as those described herein for the organic ligands.

[0204] In an embodiment, the second organic ligand may include a fatty acid (e.g., an aliphatic hydrocarbon group including C5 or greater, C10 or greater, or C15 or greater), and the third organic ligand may include an aliphatic organic amine (e.g., a primary amine including an aliphatic or aromatic hydrocarbon group including C5 or greater, C10 or greater, or C15 or greater), or a combination thereof. The aliphatic organic amine may be a RNH 2 The compound represented by wherein R is a C5-C40 aliphatic hydrocarbon group such as an alkyl, alkenyl, or alkynyl group or a C6-C40 aryl group. The carbon number of the aliphatic hydrocarbon group may be 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; less than or equal to about 50, less than or equal to about 40, or less than or equal to about 30; or a combination thereof.

[0205] The amount of the second organic ligand and the third organic ligand may be selected in consideration of the type of the organic ligand and the type of the precursor. The amount of the second 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 second 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.

[0206] The molar ratio between the second organic ligand and the third organic ligand (the second organic ligand: the third organic ligand) may be, for example, 1: about 0.1 or greater, 1: about 0.5 or greater, 1: about 0.9 or greater, or 1: about 1 or greater; 1: about 10 or less; 1: about 5 or less, 1: about 2.5 or less, or 1: about 1.5 or less.

[0207] The amount of the group V element precursor added during the shell forming reaction may be appropriately controlled in view of the type of the precursor, the organic solvent, and the like.

[0208] In an embodiment, the amount of the precursor (e.g., the Group V element precursor or the Group IV element precursor) may be greater than or equal to about 0.001 millimole (mmol), greater than or equal to about 0.005 mmol, greater than or equal to about 0.01 mmol, greater than or equal to about 0.05 mmol, or greater than or equal to about 0.1 mmol, and less than or equal to about 1 mmol, less than or equal to about 0.6 mmol, less than or equal to about 0.55 mmol, less than or equal to about 0.5 mmol, less than or equal to about 0.45 mmol, less than or equal to about 0.4 mmol, or less than or equal to about 0.35 mmol, based on 10 milliliters (mL) of the reaction solvent.

[0209] In an embodiment, the selenium precursor, tellurium precursor, and 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.

[0210] 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 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, such as a molar ratio). The composition of the final quantum dots can be determined by appropriate analytical tools such as inductively coupled plasma atomic emission spectroscopy.

[0211] After the formation of the core, shell, or its combination, a non-solvent is added to the reaction product, and the nanocrystal particles that are coordinated with the ligand compound, for example, bound to the ligand compound, can be separated. The non-solvent can be a polar solvent that is miscible with the solvent used in the core formation reaction, the shell formation reaction, or its combination and that the produced nanocrystals cannot be dispersed therein. 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 the nanocrystal particles can include centrifugation, sedimentation, chromatography, or distillation. If desired, the separated nanocrystal particles can be added to a washing (or dispersion) solvent and washed (or dispersed). The type of the washing (or dispersion) solvent is not particularly limited, and a solvent with a solubility parameter similar to the solubility parameter of the ligand can be used, and examples thereof can include hexane, heptane, octane, chloroform, toluene, benzene, etc.

[0212] In an embodiment, the organic ligand may not include a multifunctional organic compound having a thiol moiety and an amino group, a carboxylic acid group, or a combination thereof. In an embodiment, the organic ligand may not include a glutathione compound.

[0213] The quantum dots may be insoluble in water. When dispersed in water, the quantum dots may exhibit, for example, 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.

[0214] When dispersed in an organic solvent (e.g., toluene, octane, etc.), the quantum dots can be configured to form an organic solution having an average particle size of less than or equal to about 500 nm, less than or equal to about 400 nm, less than or equal to about 300 nm, less than or equal to about 200 nm, less than or equal to about 100 nm, or less than or equal to about 90 nm as determined by DLS analysis. Examples of the organic solvents are described herein.

[0215] In an embodiment, a quantum dot composition includes: the aforementioned (eg, multiple) quantum dots; an organic solvent, a liquid vehicle (carrier), or a combination thereof; and optionally a monomer, a dispersant, or a combination thereof. The dispersant can disperse the quantum dots.

[0216] The dispersant may include a compound (e.g., a monomer or a polymer) containing a carboxylic acid group. The composition may include a (photo)polymerizable monomer having (e.g., at least one) carbon-carbon double bond, a (photo or thermal) initiator, or a combination thereof. The composition may be a photosensitive composition.

[0217] The details of the quantum dots in the composition are as described herein. The amount of the quantum dots in the composition (or the composite as described herein) can be appropriately adjusted taking into account the components of the composition (or the composite) and the desired end use (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 may 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 solid content of the composition. The weight percentage of the component relative to the total solid content in the composition may represent the content of the component in the composite to be described herein.

[0218] In the composition according to the embodiment, the dispersant can ensure the dispersion of the quantum dots. In an embodiment, the dispersant can be a binder (or a binder polymer). The binder can include an organic compound (e.g., a monomer or a polymer) that optionally includes a carboxylic acid group (e.g., in a repeating unit). The binder can be an insulating polymer.

[0219] The organic compound comprising a carboxylic acid group may comprise a copolymer of a monomer mixture comprising: a first monomer comprising a carboxylic acid group and a carbon-carbon double bond, a second monomer comprising a carbon-carbon double bond and a hydrophobic moiety and not comprising a carboxylic acid group, and optionally a third monomer comprising a carbon-carbon double bond and a hydrophilic moiety and not comprising a carboxylic acid group;

[0220] A polymer containing a plurality of aromatic rings (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 containing a carboxylic acid group (—COOH); or

[0221] Its combination.

[0222] The dispersant may include the first monomer, the second monomer, the third monomer, or a combination thereof.

[0223] In the composition, the amount of the dispersant or the binder polymer may be greater than or equal to about 0.5 wt %, for example, 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 dispersant or the binder polymer may be less than or equal to about 35 wt %, for example, 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. The amount of the dispersant or the binder polymer may be from about 0.5 wt % to about 55 wt %, based on the total weight or total solid content of the composition.

[0224] In the composition, the polymerizable (e.g., photopolymerizable) monomer containing a carbon-carbon double bond (hereinafter, may be referred to as "monomer") may include a (e.g., photopolymerizable) (meth)acryloyl-based (i.e., (meth)acryloyl-containing) monomer. The monomer may be a precursor for an insulating polymer.

[0225] The amount of the monomer can 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 of the composition. The amount of the monomer can 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 of the composition.

[0226] The (photo)initiator included in the composition is a compound that initiates the (photo)polymerization of the aforementioned monomers in the composition. An 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). The initiator may be a thermal initiator or a photoinitiator. The initiator is not particularly limited and may be appropriately selected.

[0227] In the composition, the amount of the initiator may be appropriately adjusted in consideration of the type and amount of the polymerizable monomer. In an embodiment, the amount of the initiator may be greater than or equal to about 0.01 wt %, such as greater than or equal to about 1 wt % and less than or equal to about 10 wt %, such as 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 weight of the solid content) of the composition, but is not limited thereto.

[0228] The composition (or the composite to be described herein) may further include a (multi- or monofunctional) thiol compound having (eg, at least one) thiol group at the end, metal oxide particles, or a combination thereof.

[0229] The metal oxide particles may include TiO 2 、SiO 2 、BaTiO 3 , Ba 2 TiO 4 , ZnO, or a combination thereof. In the composition, the amount of the metal oxide particles may be greater than or equal to about 1 wt %, greater than or equal to about 5 wt %, or greater than or equal to about 10 wt % and less than or equal to about 50 wt %, less than or equal to about 40 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 %, or less than or equal to about 5 wt %, based on the total weight (or solid content) of the composition. The metal oxide particles may be non-emissive (e.g., do not emit light). The metal oxide may include an oxide of a metal or a metalloid.

[0230] The metal oxide particles may have an appropriately selected diameter without particular limitation. The diameter of the metal oxide particles may 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.

[0231] The polythiol compound may be a dithiol compound, a trithiol compound, a tetrathiol compound, or a combination thereof. For example, the thiol compound may be ethylene glycol di-3-mercaptopropionate, ethylene glycol dithioacetate, 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.

[0232] The amount of the thiol compound may be less than or equal to about 50 wt%, less than or equal to about 40 wt%, less than or equal to about 30 wt%, less than or equal to about 20 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%, or greater than or equal to about 15 wt%, based on the total weight or total solid content of the composition.

[0233] The composition may further include an organic solvent (or liquid vehicle, hereinafter referred to as a solvent). The type of the organic solvent that can be used is not particularly limited. Examples of the solvent may include, but are not limited to: ethyl 3-ethoxypropionate; ethylene glycol series (class) such as ethylene glycol, diethylene glycol, or polyethylene glycol; glycol ether series 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 acetate series 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 series such as propylene glycol; propylene glycol ether series 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 acetate series such as propylene Glycol monomethyl ether acetate or dipropylene glycol monoethyl ether acetate; amide series such as N-methylpyrrolidone, dimethylformamide, or dimethylacetamide; ketone series such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), or cyclohexanone; petroleum products such as toluene, xylene, or solvent naphtha; ester series such as ethyl acetate, propyl acetate, butyl acetate, cyclohexyl 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 a combination thereof.

[0234] The type and amount of the solvent can be appropriately selected by taking into account the aforementioned main components (i.e., the quantum dots, dispersant, photopolymerizable monomer, initiator, and thiol compound if used) and the types and amounts of additives to be described herein. The composition can include the solvent in an amount other than the desired amount of the solid content (non-volatile component).

[0235] 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.

[0236] If the composition is used in an inkjet process, the composition can be discharged onto a substrate at room temperature and can form a quantum dot polymer composite or a pattern of quantum dot polymer composites, for example, by heating. Using the disclosed viscosities, the ink composition can have a viscosity greater than or equal to about 21 millinewtons per 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. N / m, or a surface tension of about 31 mN / m or more and about 40 mN / m or less, about 39 mN / m or less, about 38 mN / m or less, about 37 mN / m or less, about 36 mN / m or less, about 35 mN / m or less, about 34 mN / m or less, about 33 mN / m or less, or about 32 mN / m or less at 23° C. The surface tension of the ink composition may be about 31 mN / m or less, about 30 mN / m or less, about 29 mN / m or less, or about 28 mN / m or less.

[0237] If desired, the composition may further include various additives such as a light diffusing agent (light diffuser), a leveling agent, or a coupling agent in addition to the aforementioned components.

[0238] The components (binder, monomer, solvent, additive, thiol compound, cardo binder, etc.) included in the composition of the embodiment (eg, photoresist composition) may be appropriately selected as described in, for example, US-2017-0052444-A1.

[0239] The composition according to the embodiment can be prepared by a method including: preparing a quantum dot dispersion including the aforementioned quantum dots, a dispersant, and a solvent; and mixing the quantum dot dispersion with the initiator, the polymerizable monomer (e.g., an acryl-based (i.e., acryl-containing) monomer), optionally the thiol compound, optionally the metal oxide particles, and optionally the aforementioned additives. The aforementioned components can each be mixed sequentially or simultaneously, but the mixing order is not particularly limited.

[0240] The composition according to the embodiment can be used to provide a quantum dot composite pattern (e.g., a patterned quantum dot polymer composite). The composition can provide a quantum dot-polymer composite by (e.g., free radical) polymerization. The composition according to the embodiment can be a photoresist composition including quantum dots suitable for photolithography. The composition according to the embodiment can be an ink composition that can provide a pattern by printing (e.g., a droplet discharge method such as inkjet printing).

[0241] In an embodiment, the quantum dot (polymer) complex comprises: a matrix (e.g., a polymer matrix); and the aforementioned quantum dots dispersed in the matrix. The quantum dot matrix may further include metal oxide particles dispersed in the matrix. The (polymer) matrix may include a linear polymer, a cross-linked polymer, or a combination thereof. The cross-linked polymer may include a thiol-ene resin, 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. 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.

[0242] The matrix may include a dispersant (e.g., a binder monomer or polymer comprising a carboxylic acid group), a polymerization product (e.g., an insulating polymer) of a polymerizable monomer having a carbon-carbon double bond (e.g., at least one, such as at least two, at least three, at least four, or at least five), optionally a polymerization product of the polymerizable monomer and a thiol compound (e.g., a polythiol compound having at least two thiol groups, such as at the ends thereof), or a combination thereof.

[0243] The cross-linked polymer may include a thiol-ene resin, a cross-linked poly (meth) acrylate, or a combination thereof. In an embodiment, the cross-linked polymer may be a polymerization product of the polymerizable monomer and a polythiol compound (e.g., at its end) optionally having at least two thiol groups. The quantum dots, dispersants, or binder polymers, polymerizable monomers, and polythiol compounds may be the same as described herein.

[0244] The film of the quantum dot-polymer composite (or a pattern thereof as described herein) 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, or less than or equal to about 7 μm and greater than or equal to 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.

[0245] In an embodiment, the patterned film of the quantum dot complex may include a repeating segment (e.g., at least one (kind of) repeating segment) configured to emit a predetermined light. In an embodiment, the repeating segment may include a first segment configured to emit a first light. The repeating segment may further include a second segment that emits a second light having a wavelength different from the first light. The first segment, the second segment, or a combination thereof may include the aforementioned quantum dot (polymer) complex. The first light or the second light may be red light having a maximum photoluminescence peak wavelength between about 600nm and about 650nm (e.g., about 620nm-about 650nm), or green light having a maximum photoluminescence peak wavelength between about 500nm and about 550nm (e.g., about 510nm-about 540nm). The patterned film may further include a third segment that may pass or emit a third light (e.g., blue light) different from the first light and the second light. The third light may include excitation light. The third light (or the excitation light) may include blue light having a maximum peak wavelength in the range of about 380 nm to about 480 nm and optionally green light.

[0246] In an embodiment, a patterned quantum dot composite film may be manufactured by a method using the photoresist composition. The method may include:

[0247] forming a film of the composition on a substrate (S1);

[0248] optionally prebaking the film (S2);

[0249] exposing selected areas of the film to light (e.g., a wavelength of less than or equal to about 400 nm) (S3); and

[0250] The exposed film is developed with an alkaline developing solution to obtain a pattern including the quantum dot-polymer composite (S4).

[0251] refer to Figure 2A A non-limiting method of forming a pattern is described.

[0252] The composition can be coated on the substrate by a suitable method such as spin coating or slit coating to a predetermined thickness (S1). The formed film can be optionally pre-baked (PRB) (S2). The pre-baking can be performed by selecting appropriate conditions such as temperature, time, atmosphere, etc.

[0253] The formed (or optionally pre-baked) film may be exposed to light having a predetermined wavelength under a mask having a predetermined pattern (e.g., a photomask used in a photolithography process) (S3). The wavelength and intensity of the light may be selected by taking into account the initiator (e.g., photoinitiator), the amount of the initiator (e.g., photoinitiator), the quantum dots, the amount of the quantum dots, etc. Figure 2A In FIG. 1 , BM represents a black matrix.

[0254] The exposed film may be treated with an alkaline developing solution (e.g., by dipping or spraying) to dissolve the unexposed area and obtain the desired pattern (S4). 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) (S5).

[0255] In the embodiment where 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 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.) for forming each repeating segment, and repeating the pattern formation (S6) for an appropriate number of times (e.g., two or more times, or three or more times) for each composition. For example, the quantum dot-polymer composite may have a pattern including at least two (kinds) of repeating color segments (e.g., RGB segments), for example, provided as a pattern including at least two (kinds) of repeating color segments (e.g., RGB segments). The quantum dot-polymer composite pattern can be used as a photoluminescent color filter in a display device.

[0256] The quantum dot composite pattern may be formed by using an ink composition configured to form a pattern via an inkjet method. Figure 2B 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.

[0257] The deposition of the ink composition can be carried out using an appropriate droplet discharge system such as an inkjet printer or a nozzle printing system (e.g., having an ink reservoir and (e.g., at least one) printing head). The deposited ink composition can be heated to remove the solvent and optionally to carry out polymerization, and thereby provide a (first or second) quantum dot layer. The method can provide a highly precise quantum dot-polymer composite film or pattern in a relatively short period of time in a relatively simple manner.

[0258] The aforementioned quantum dots or quantum dot complexes (patterns) may be included in electronic devices. Such electronic devices may include display devices, light emitting diodes (LEDs), organic light emitting diodes (OLEDs), quantum dot LEDs, sensors, solar cells, imaging sensors, photodetectors, or liquid crystal display devices, but are not limited thereto. The aforementioned quantum dots may be included in electronic devices. Such electronic devices may include portable (handheld) terminal equipment, monitors, notebook personal computers (PCs), televisions, electronic displays, cameras, cars, etc., but are not limited thereto. The electronic device may be a portable terminal device, monitor, notebook PC, or television including a display device (or light emitting device) containing quantum dots. The electronic device may be a camera or portable terminal device including an image sensor including quantum dots. The electronic device may be a camera or vehicle including a photodetector including quantum dots.

[0259] The device (display device or light-emitting device) may further include a light-emitting element, such as a light-emitting element, and optionally a light source. The light-emitting element may include a light-emitting layer. The light-emitting element may further include a substrate, and the light-emitting layer may be disposed on one surface of the substrate. The light-emitting layer may include a film or a patterned film of the quantum dot composite. The light source may be configured to provide incident light to the light-emitting element. The incident light may have a photoluminescence peak wavelength in the range of greater than or equal to about 440 nm, such as greater than or equal to about 450 nm and less than or equal to about 500 nm, such as 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.

[0260] In an embodiment, the light emitting element or the light emitting layer may include a sheet of the quantum dot composite. Figure 3, the photoluminescent device 400 includes a backlight unit and a liquid crystal panel, and the backlight unit may include a quantum dot polymer composite sheet (QD sheet). For example, the backlight unit may include a reflector, a light guide plate (LGP), a light source (blue LED, etc.), a quantum dot polymer composite sheet (QD sheet), and an optical film (prism, double brightness enhancement film (DBEF), etc.), etc. The liquid crystal panel may be arranged on the backlight unit, and may have a structure including a thin film transistor (TFT), a liquid crystal (LC), and a color filter between two polarizers (Pol). The quantum dot polymer composite sheet (QD sheet) may include quantum dots that emit red light by absorbing light from a light source and quantum dots that emit green light. The blue light from the light source may pass through the quantum dot polymer composite sheet, and the red light and green light from the quantum dots and be converted into white light. The white light may be separated into blue light, green light, and red light by the color filter in the liquid crystal panel, and may be emitted to the outside in each pixel.

[0261] In an embodiment, the light-emitting layer may be provided on a front surface (e.g., a light extraction surface) of a device (light-emitting device or display device) in the form of a film patterned with quantum dots (or a composite thereof). The patterned film may include a repeating segment configured to emit the desired light. The repeating segment may include a first segment. The first segment may be a segment that emits red light. The repeating segment may include a second segment. The second segment may include a segment that emits green light. The repeating segment may include a third segment. The third segment may be a segment that emits or transmits blue light. The details of the first, second, and third segments are as described herein.

[0262] The light source may be an element that can provide incident light, emit excitation light, or a combination thereof to the light-emitting layer. The incident or 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 (OLED). On the front surface (light-emitting surface) of the first segment and the second segment, an optical element for blocking (e.g., reflecting or absorbing) blue light (and optionally green light) described herein, such as a blue light (and optionally green light) blocking layer or a first filter, may be provided. When the light source includes an organic light-emitting diode for emitting blue light and an organic light-emitting diode for emitting green light, a green light removal filter may be further provided on a third segment through which the blue light is transmitted.

[0263] The light source may include a plurality of light-emitting units corresponding to the first segment and the second segment, respectively, and the light-emitting units may include a first electrode and a second electrode facing each other and an (organic) electroluminescent layer 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 and the organic light-emitting diode (OLED) are not particularly limited.

[0264] Figure 4A is a schematic cross-sectional view of a display device according to an embodiment, and Figure 4B is a schematic cross-sectional view of a display device according to an embodiment. Figure 4A and 4B , the light source includes an organic light emitting diode (OLED) emitting blue (B) light (and optionally green light). The organic light emitting diode (OLED) may include at least two 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 each pixel electrode 90a, 90b, 90c, and a common electrode layer 130 formed on the organic light emitting layers 140a, 140b, 140c. A thin film transistor and a substrate may be disposed below the organic light emitting diode (OLED). The pixel regions of the OLED may correspond to the first, second, and third segments, respectively.

[0265] A stacked structure including a quantum dot composite pattern 170 (e.g., a first segment 11 or R including quantum dots emitting red light, a second segment 21 or G including quantum dots emitting green light, and a third segment 31 or B including or not including quantum dots, such as quantum dots emitting blue light) pattern and a substrate 240 may be disposed on the light source. Blue light emitted from the light source enters the first segment and the second segment and may emit red light and green light, respectively. Blue light emitted from the light source may pass through the third segment. If desired, an element configured to block the excitation light (a first filter 160 or an excitation light blocking layer) may be disposed between the quantum dot composite layers R and G and the substrate. When the excitation light includes blue light and green light, a green light blocking filter may be added to the third segment. The first filter or the excitation light blocking layer will be described in more detail herein.

[0266] Such a (display) device can be manufactured by separately manufacturing the aforementioned stacked structure and an LED or OLED (e.g., emitting blue light), and then combining the stacked structure and the LED or OLED. The (display) device can be manufactured by directly forming the quantum dot composite pattern on the LED or OLED.

[0267] The substrate may be a substrate including an insulating material. The substrate may include: glass; various polymers such as polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate, and polyacrylate; 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.

[0268] 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 vary depending on 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 form a control terminal, an input terminal, and an output terminal of the thin film transistor, respectively. The drain electrode is electrically connected to a pixel electrode to be described herein.

[0269] The pixel electrode may be used as an electrode (e.g., an anode) of the display device. The pixel electrode may be formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). The pixel electrode may be formed of a material having a light blocking property 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 may have a double-layer structure as follows: wherein the transparent conductive material and the material having a light blocking property are sequentially stacked.

[0270] 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.

[0271] The pixel defining layer covers a portion of the 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 light emitting layer to be described herein may be formed in an area defined by the opening.

[0272] The organic light-emitting layer defines each pixel region through the aforementioned pixel electrode and the pixel defining layer. In other words, one pixel region may be defined as a region formed by one organic light-emitting unit layer in contact with one pixel electrode divided by the pixel defining layer. In a display device according to an embodiment, the organic light-emitting layer may be defined as a first pixel region, a second pixel region, and a third pixel region, and each pixel region is spaced apart from each other by the pixel defining layer, leaving a predetermined interval.

[0273] In an embodiment, the organic light emitting layer may emit a third light belonging to the visible light region or to the ultraviolet (UV) region. The first to third pixel regions of the organic light emitting layer may each emit a third light. In an embodiment, the third light may be light having the highest energy in the visible light region, for example, blue light (and optionally green light). When all pixel regions of the organic light emitting layer are designed to emit the same light, the pixel regions of the organic light emitting layer may all be formed of the same or similar materials, or may exhibit, for example, the same or similar properties. Therefore, the process of forming the organic light emitting layer may be simplified, and the display device may be easily applied to large-scale / large-area processes, for example, manufactured by large-scale / large-area processes. However, the organic light emitting layer according to the embodiment is not necessarily limited thereto, but the organic light emitting layer may be designed to emit at least two different lights, for example, at least two different colored lights.

[0274] The organic light emitting layer includes an organic light emitting unit layer in each pixel region, and each organic light emitting unit layer may further include an auxiliary layer (eg, a hole injection layer, a hole transport layer, an electron transport layer, etc.) in addition to the light emitting layer.

[0275] 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 light emitting layer and may be integrated therewith.

[0276] A planarization layer or a passivation layer (not shown) 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.

[0277] In an embodiment, the display device may further include a lower substrate, a polarizer disposed below the lower substrate, and a liquid crystal layer disposed between the stacked structure and the lower substrate, and in the stacked structure, the photoluminescent layer (i.e., the light emitting layer) may be disposed to face the liquid crystal layer. The display device may further include a polarizer between the liquid crystal layer and the light emitting layer. The light source may further include an LED, and if desired, a light guide plate.

[0278] Non-limiting examples of display devices (eg, liquid crystal display devices) according to embodiments are described with reference to the accompanying drawings. Figure 5 2 is a schematic cross-sectional view showing a liquid crystal display according to an embodiment. Figure 5 The display device of the embodiment includes a liquid crystal panel 200 , a polarizing plate 300 disposed under the liquid crystal panel 200 , and a backlight unit disposed under the polarizing plate 300 .

[0279] The liquid crystal panel 200 includes a lower substrate 210, a stacked structure, and a liquid crystal layer 220 disposed between the stacked structure and the lower substrate. The stacked structure includes a transparent substrate 240, a first filter layer 310, a photoluminescent layer 230 including a pattern of a quantum dot polymer composite, and a second filter layer 311.

[0280] The lower substrate 210, referred to as an array substrate, may be a transparent insulating material substrate. The substrate is the same as described herein. A wiring board 211 is provided on the upper surface of the lower substrate 210. The wiring board 211 may include a plurality of gate lines (not shown) and data lines (not shown) defining pixel regions, a thin film transistor disposed adjacent to the intersection region of the gate lines and the data lines, and a pixel electrode for each pixel region, but is not limited thereto. The details of such a wiring board are not particularly limited.

[0281] The liquid crystal panel may be provided on the circuit board 211. The liquid crystal panel 200 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 layer 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 not particularly limited.

[0282] The lower polarizer 300 is provided below the lower substrate 210. The material and structure of the polarizer 300 are not particularly limited. A backlight unit (e.g., emitting blue light) may be provided below the polarizer 300. An upper optical element or polarizer 300 may be provided between the liquid crystal layer 220 and the transparent substrate 240, but is not limited thereto. For example, the upper polarizer may be provided between the liquid crystal layer 220 and the photoluminescent layer 230. The polarizer may be any suitable 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.

[0283] The backlight unit includes a light source 110. The light source 110 may emit blue light or white light. The light source 110 may include a blue LED, a white LED, a white OLED, or a combination thereof, but is not limited thereto.

[0284] 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 (not shown), a light guide plate (not shown) provided on the reflector and providing a planar light source to the liquid crystal panel 200, (e.g., at least one) optical sheet (not shown) on the light guide plate, such as a diffuser, a prism sheet, etc., 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 (not shown) 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 (e.g., at least one) optical sheet. The details of such a backlight unit (e.g., light-emitting diodes, fluorescent lamps, light guide plates, a variety of optical sheets, and components of a reflector) are not particularly limited.

[0285] 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 quantum dot composite pattern including 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 third segment (B) configured to emit / transmit, for example, blue light. If desired, the photoluminescent layer 230 may further include (e.g., at least one) fourth segment. The fourth segment may include quantum dots that emit light of a different color (e.g., cyan, magenta, and yellow light) than the light emitted from the first to third segments.

[0286] In the photoluminescent layer 230, segments of a pattern may be repeatedly formed corresponding to a pixel region formed on the lower substrate 210. A transparent common electrode 231 may be provided on the photoluminescent color filter layer.

[0287] The third segment (B) configured to emit / transmit blue light may be a transparent color filter that does not change the emission spectrum of the light source. The blue light emitted from the backlight unit may enter in a polarized state and may be emitted as is through the polarizer and the liquid crystal layer. If desired, the third segment may include quantum dots that emit blue light.

[0288] As described herein, if desired, the display device or light-emitting device of the embodiment may further have 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 surfaces of the first segment (R) and the second segment (G) and the substrate (e.g., the upper substrate 240), or on the upper surface of the substrate. The first filter layer 310 may be a sheet having an opening in a region corresponding to a pixel region (third segment) displaying blue and thus formed in a region corresponding to the first and second segments. The first filter layer may be disposed at a position other than a position overlapping with the third segment and integrally therewith, such as Figure 4A , 4B and Figure 5 As shown in, but not limited to this. For example, at least two first filter layers may be arranged at respective positions overlapping the first and second segments leaving space. When the light source includes an element emitting green light, a green light blocking layer may be arranged on the third segment.

[0289] The first filter layer may block (e.g., absorb) or substantially block light having, for example, a predetermined wavelength region in the visible light region, and may transmit light in other wavelength regions, and for example, the first filter layer may block blue light (or green light) and may transmit light other than the blue light (or green light). The first filter layer may transmit, for example, green light, red light, and / or yellow light as a mixed color thereof.

[0290] The first filter layer can substantially block the excitation light and transmit the light in the desired wavelength range. The transmittance of the first filter layer for the light in the desired wavelength range can be greater than or equal to about 70%, greater than or equal to about 80%, greater than or equal to about 90%, or even about 100%.

[0291] A first filter layer configured to selectively transmit red light may be disposed at a position overlapping the red light emission segment, and a first filter layer configured to selectively transmit green light may be disposed at a position overlapping the green light emission segment. The first filter layer may include a first region that blocks (e.g., absorbs) blue light and red light and selectively transmits light in 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 520 nm); a second region that blocks (e.g., absorbs) blue light and green light and selectively transmits light in a predetermined range (e.g., greater than or equal to about 600 nm, greater than or equal to about 610 nm, or greater than or equal to about 615 nm and less than or equal to about 650 nm, less than or equal to about 645 nm, less than or equal to about 640 nm, less than or equal to about 635 nm, less than or equal to about 630 nm, less than or equal to about 625 nm, or less than or equal to about 620 nm); or a combination thereof. When the light source emits blue and green mixed light, the first optical filter may further include a third region that selectively transmits blue light and blocks green light.

[0292] The first region may be disposed at a position overlapping the segment emitting green light. The second region may be disposed at a position overlapping the segment emitting red light. The third region may be disposed at a position overlapping the segment emitting blue light.

[0293] The first region, the second region, and optionally the third region may be optically isolated.Such a first filter layer may contribute to an improvement in the color purity of the display device.

[0294] The display device may further include a second filter layer (e.g., a red / green or yellow light recycling layer) 311 disposed between the photoluminescent layer and the liquid crystal layer (e.g., the photoluminescent layer and an upper polarizing plate such as a polarizer), which transmits at least a portion of the third light (excitation light) and reflects a portion (e.g., at least a portion) of the first light, a portion (e.g., at least a portion) of the second light, or a portion (e.g., at least a portion) of each of the first light and the second light. The first light may be red light, the second light may be green light, and the third light may be blue light. For example, the second filter layer may transmit only the third light (B) in the blue light wavelength region having a wavelength region less than or equal to about 500 nm, and light in a wavelength region greater than about 500 nm as green light (G), yellow light, red light (R), etc. may not pass through the second filter layer and be reflected. The reflected green light and red light may pass through the first and second segments and be emitted to the outside of the display device.

[0295] The second filter layer or the first filter layer may be formed as an integrated layer having a relatively flat surface.

[0296] The first filter layer may include a polymer film including a dye that absorbs light of a wavelength to be blocked, a pigment that absorbs light of a wavelength to be blocked, or a combination thereof. The second filter layer and the first filter layer may include a single layer having a low refractive index, and may be, for example, a transparent 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 second filter layer or the first 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.

[0297] The first filter layer or the second filter layer may include a plurality of layers having different refractive indices. The first filter layer or the second filter layer may be formed by laminating two layers having different refractive indices. For example, the first / second filter layer may be formed by alternately laminating a material having a high refractive index and a material having a low refractive index.

[0298] refer to Fig. 6A The electronic device 10 includes: a first electrode 11 and a second electrode 15 facing each other, and an active layer 13 disposed between the first electrode 11 and the second electrode 15 and including the aforementioned quantum dots.

[0299] In an embodiment, the electronic device including the quantum dots may be an electroluminescent device. The quantum dots of the active layer 13 may be a light-emitting layer in which electrons and holes injected from the first electrode 11 and the second electrode 15 are recombined to form excitons, and light of a constant wavelength by the energy of the formed excitons may be emitted. In addition, the electronic device including the quantum dots may be a photodetector or a solar cell. For example, the active layer 13 may be a light-absorbing layer in which the quantum dots absorb external photons and separate the external photons into electrons and holes to provide the electrons and holes to the first electrode 11 and the second electrode 15.

[0300] The hole auxiliary layer 12 may be disposed between the first electrode 11 and the active layer 13 , and the electron auxiliary layer 14 may be disposed between the second electrode 15 and the active layer 13 .

[0301] The electronic device 10 may further include a substrate (not shown). The substrate may be disposed on the side of the first electrode 11 or the second electrode 15. The substrate may be a substrate including an insulating material (e.g., an insulating transparent substrate). In addition, the substrate may include glass, various polymers such as polyesters (e.g., polyethylene terephthalate (PET), polyethylene naphthalate (PEN)), polycarbonate, polyacrylate, polyimide, polyamide-imide, etc., inorganic materials such as polysiloxane (e.g., PDMS), Al 2 O 3 , ZnO, etc., or a combination thereof, or may be made of a silicon wafer. Here, "transparent" may mean that the transmittance of a certain wavelength of light (e.g., light emitted from quantum dots) passing therethrough is greater than or equal to about 85%, greater than or equal to about 88%, greater than or equal to about 90%, greater than or equal to about 95%, greater than or equal to about 97%, or greater than or equal to about 99%. The thickness of the substrate may be appropriately selected in consideration of the substrate material, etc., but is not particularly limited. The transparent substrate may be flexible.

[0302] One of the first electrode 11 and the second electrode 15 may be an anode and the other may be a cathode. For example, the first electrode 11 may be an anode and the second electrode 15 may be a cathode.

[0303] The first electrode 11 may be made of a conductor such as a metal, a conductive metal oxide, or a combination thereof. The first electrode 11 may be made of, for example, a metal such as nickel, platinum, vanadium, chromium, copper, zinc, and gold, or an alloy thereof, a conductive metal oxide such as zinc oxide, indium oxide, tin oxide, indium tin oxide (ITO), indium zinc oxide (IZO), or fluorine-doped tin oxide, or a combination of a metal and an oxide such as ZnO and Al, or SnO 2and Sb, but not limited thereto. The second electrode 15 may be made of a conductor such as a metal, a conductive metal oxide, a conductive polymer, or a combination thereof. The second electrode 15 may be made of, for example, a metal such as aluminum, magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, silver, gold, platinum, tin, lead, cesium, and barium, or an alloy thereof, a multilayer structure material such as LiF / Al, lithium oxide (Li 2 O) / Al, 8-hydroxyquinoline lithium (Liq) / Al, LiF / Ca, and BaF 2 / Ca, but not limited thereto. The conductive metal oxide is the same as described herein.

[0304] The work functions of the first electrode 11 and the second electrode are not particularly limited and may be appropriately selected. The work function of the first electrode 11 may be higher or lower than the work function of the second electrode 15.

[0305] The first electrode 11, the second electrode 15, or a combination thereof may be a light-transmitting electrode, and the light-transmitting electrode may be made, for example, of a conductive oxide such as zinc oxide, indium oxide, tin oxide, indium tin oxide (ITO), indium zinc oxide (IZO), or fluorine-doped tin oxide, or a single or multiple metal thin layer. When one of the first electrode 11 and the second electrode 15 is a non-light-transmitting electrode, the non-light-transmitting electrode may be made, for example, of an opaque conductor such as aluminum (Al), silver (Ag), or gold (Au).

[0306] The thickness of the first electrode, the second electrode, or each of the first and second electrodes is not particularly limited and can be appropriately selected in consideration of device efficiency. For example, the thickness of the electrode can be greater than or equal to about 5 nm, for example, greater than or equal to about 50 nm and less than or equal to about 100 μm, for example, less than or equal to about 10 μm, less than or equal to about 1 μm, less than or equal to about 900 nm, less than or equal to about 500 nm, or less than or equal to about 100 nm.

[0307] The active layer 13 includes quantum dots described herein. The active layer 13 may include a single layer or multiple single layers of quantum dot layers. The multiple single layers may be two layers or more, three layers or more, or four layers or more and 20 layers or less, 10 layers or less, 9 layers or less, 8 layers or less, 7 layers or less, or 6 layers or less. The active layer 13 may have a thickness greater than or equal to about 5 nm, such as greater than or equal to about 10 nm, greater than or equal to about 20 nm, or greater than or equal to about 30 nm and less than or equal to about 200 nm, such as less than or equal to about 150 nm, less than or equal to about 100 nm, less than or equal to about 90 nm, less than or equal to about 80 nm, less than or equal to about 70 nm, less than or equal to about 60 nm, or less than or equal to about 50 nm. The active layer 13 may have a thickness of about 10 nm-about 150 nm, about 10 nm-about 100 nm, or about 10 nm-about 50 nm.

[0308] The electronic device 10 may further include a hole auxiliary layer 12. The hole auxiliary layer 12 is disposed between the first electrode 11 and the active layer 13. The hole auxiliary layer 12 may include a hole injection layer (HIL), a hole transport layer (HTL), an electron blocking layer (EBL), or a combination thereof. The hole auxiliary layer 12 may be a single component layer or a multilayer structure in which adjacent layers include different components.

[0309] The highest occupied molecular orbital (HOMO) energy level of the hole assisting layer 12 may have a HOMO energy level that can match the HOMO energy level of the active layer 13 to improve the mobility of holes transferred from the hole assisting layer 12 to the active layer 13. For example, 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.

[0310] The material included in the hole auxiliary layer 12 (e.g., a hole transport layer or a hole injection layer) is not particularly limited, but may include, for example, poly(9,9-dioctyl-fluorene-co-N-(4-butylphenyl)-diphenylamine) (TFB), polyarylamine (polyarylamine), poly(N-vinylcarbazole) (PVK), poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), polyaniline, polypyrrole, N,N, N',N'-tetrakis(4-methoxyphenyl)-benzidine (TPD), 4,4'-di[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), 4,4',4"-tri[phenyl(m-tolyl)amino]triphenylamine (m-MTDATA), 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 are not limited thereto.

[0311] When an electron blocking layer (EBL) is used, the electron blocking layer (EBL) may include, for example, poly(3,4-ethylenedioxythiophene):poly(styrene 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.

[0312] In the hole auxiliary layer, the thickness of each layer can be appropriately selected. For example, the thickness of each layer can be greater than or equal to about 5 nm, greater than or equal to about 10 nm, greater than or equal to about 15 nm, or greater than or equal to about 20 nm and less than or equal to about 50 nm, such as less than or equal to about 40 nm, less than or equal to about 35 nm, or less than or equal to about 30 nm, but is not limited thereto.

[0313] The electron auxiliary layer 14 may be disposed between the active layer 13 and the second electrode 15. The electron auxiliary layer 14 may include, for example, an electron injection layer (EIL) that promotes the injection of electrons, an electron transport layer (ETL) that promotes electron transport, a hole blocking layer (HBL) that blocks the movement of holes, or a combination thereof. For example, the electron injection layer may be disposed between the electron transport layer and the cathode. For example, the hole blocking layer (HBL) may be disposed between the active layer and the electron transport (injection) layer, but is not limited thereto. For example, the thickness of each layer may be greater than or equal to about 1 nm and less than or equal to about 500 nm, but is not limited thereto. The electron injection layer may be an organic layer formed by vapor deposition, and the electron transport layer may include inorganic oxide nanoparticles.

[0314] The electron transport layer (ETL) may include, for example, 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA), bathocuproine (BCP), tris[3-(3-pyridyl)- yl] borane (3TPYMB), LiF, tris(8-hydroxyquinoline)aluminum (Alq 3 ), tris(8-hydroxyquinoline)gallium (Gaq 3 ), tris(8-hydroxyquinoline)indium (Inq 3 ), bis(8-hydroxyquinoline)zinc (Znq 2), bis(2-(2-hydroxyphenyl)benzothiazole)zinc (Zn(BTZ) 2 ), bis(10-hydroxybenzo[h]quinolinolato)beryllium (BeBq 2 ), 8-(4-(4,6-di(naphthalene-2-yl)-1,3,5-triazine-2-yl)phenyl)quinolone (ET204), 8-hydroxyquinoline lithium (Liq), n-type metal oxides (e.g., ZnO, HfO 2 etc.), or a combination thereof, but not limited thereto.

[0315] In addition, the electron transport layer (ETL) may include a plurality of nanoparticles. The nanoparticles may include a metal oxide including zinc, such as zinc oxide, zinc magnesium oxide, or a combination thereof. The metal oxide may include Zn 1-x M x O (wherein M is Mg, Ca, Zr, W, Li, Ti, Y, Al, or a combination thereof, and 0≤x≤0.5). In the chemical formula, x may be greater than or equal to about 0.01 and less than or equal to about 0.3, for example, less than or equal to about 0.25, less than or equal to about 0.2, or less than or equal to about 0.15. The absolute value of the lowest unoccupied molecular orbital (LUMO) of the aforementioned quantum dots included in the active layer may be less than the absolute value of the LUMO of the metal oxide. The average size of the nanoparticles may be greater than or equal to about 1 nm, for example, greater than or equal to about 1.5 nm, greater than or equal to about 2 nm, greater than or equal to about 2.5 nm, or greater than or equal to about 3 nm and less than or equal to about 10 nm, less than or equal to about 9 nm, less than or equal to about 8 nm, less than or equal to about 7 nm, less than or equal to about 6 nm, or less than or equal to about 5 nm.

[0316] 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.

[0317] The thickness of each of the electron auxiliary layer 14 (e.g., 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, or greater than or equal to about 18 nm. 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.

[0318] refer to Figure 6B , the device according to the embodiment may have a normal structure. The electroluminescent device 200 may include an anode 10 disposed on a 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 10 may include a conductive metal with a low work function. For example, the anode may include an indium tin oxide (ITO, a work function of about 4.6 electron volts (eV)-about 5.1eV) electrode, and the cathode 50 may include an electrode containing magnesium (Mg, a work function of about 3.66eV), aluminum (Al, a work function of about 4.28eV), or a combination thereof. In addition, the hole auxiliary layer 20 may be disposed between the anode 10 and the quantum dot active layer 30. The hole auxiliary layer 20 may include a hole injection layer, a hole transport layer, or a combination thereof. The hole injection layer may be disposed near the anode 10 and the hole transport layer may be disposed near the quantum dot active layer. In addition, the electron auxiliary 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, an electron transport layer, or a combination thereof. 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 .

[0319] refer to Figure 6C, the device according to the embodiment may have an inverted structure. The inverted electroluminescent device 300 may include a cathode 50 disposed on a transparent substrate 100 and an anode 10 facing the cathode 50. The cathode 50 may include a transparent electrode based on a metal oxide, and the anode 10 facing the cathode 50 may include a conductive metal with a high work function. For example, the cathode 50 may be an indium tin oxide (ITO, a work function of about 4.6eV-5.1eV) electrode, and the anode 10 may be an electrode including gold (Au, a work function of about 5.1eV), silver (Ag, a work function of about 4.26), aluminum (Al, a work function of 4.28eV), or a combination thereof. In addition, the electron auxiliary layer 40 may be disposed between the quantum dot active layer 30 and the cathode 50. The electron auxiliary layer 40 may include an electron injection layer, an electron transport layer, or a combination thereof. The electron injection layer may be disposed close to the cathode 50 and the electron transport layer may be disposed close to the quantum dot active layer 30. The electron auxiliary layer 40 may include, for example, a metal oxide in the electron transport layer, such as a crystalline Zn oxide or an n-type doped metal oxide. In addition, the hole auxiliary layer 20 may be disposed between the anode 10 and the quantum dot active layer 30. The hole auxiliary layer 20 may include a hole injection layer, a hole transport layer, or a combination thereof. The hole injection layer may be disposed near the anode 10, and the hole transport layer may be disposed near the quantum dot active layer 30. The hole transport layer may include TFB, PVK, or a combination thereof, and the hole injection layer may include MoO 3 or other p-type metal oxides.

[0320] In the electroluminescent device, light of a certain wavelength generated in the active layer 30 is emitted to the outside through the light-transmitting electrode and the transparent substrate. Figure 6B or Figure 6C When a metal oxide-based transparent electrode (eg, indium tin oxide (ITO)) as a light-transmitting electrode is applied to the anode 10, light formed in the active layer is emitted to the outside through the anode 10 and the transparent substrate 100. Figure 6B or Figure 6C When a metal oxide-based transparent electrode (eg, indium tin oxide (ITO)) as a light-transmitting electrode is applied to the cathode 50, light formed in the active layer is emitted to the outside through the cathode 50 and the transparent substrate 100.

[0321] The aforementioned electronic device can be manufactured by a suitable method. For example, the electroluminescent device can be manufactured by forming a hole auxiliary layer (or an electron auxiliary layer) on a substrate on which an electrode is formed, forming an active layer including quantum dots (for example, a pattern of the aforementioned quantum dots), and forming an electron auxiliary layer (or a hole auxiliary layer) and an electrode. The electrode, the hole auxiliary layer, and the electron auxiliary layer can each be independently formed by a suitable method, and can be formed, for example, by vapor deposition or coating, but is not particularly limited.

[0322] 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.

[0323] Example

[0324] Analytical methods

[0325] 1. Photoluminescence Analysis

[0326] Photoluminescence (PL) spectra of the fabricated nanocrystals were obtained using a Hitachi F-7000 spectrometer at a radiation wavelength of 458 nanometers (nm).

[0327] 2. Ultraviolet (UV) spectroscopy analysis

[0328] UV spectroscopy analysis was performed using an Agilent Cary 5000 spectrometer.

[0329] 3. Inductively coupled plasma (ICP) analysis

[0330] Inductively coupled plasma-atomic emission spectrometry (ICP-AES) analysis was performed using Shimadzu ICPS-8100.

[0331] 4. Transmission electron microscopy analysis, transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDX) analysis

[0332] TEM analysis and TEM-EDX analysis were performed by using a UT F30 Tecnai electron microscope.

[0333] High-resolution transmission electron microscopy images were also obtained using a UT F30 Tecnai electron microscope.

[0334] 5. X-ray diffraction (XRD) analysis

[0335] XRD analysis was performed using a Bruker In-plane XRD D8 Discover.

[0336] Embodiment 1:

[0337] 1. Selenium and tellurium are dispersed in trioctylphosphine (TOP) to obtain 0.4 molar concentration (M) Se / TOP stock solution and 2 M Te / TOP stock solution, respectively. Then, a mixed solution containing the Te / TOP stock solution, an organic ligand including oleylamine, and lithium aluminum hydride is prepared.

[0338] In a 100 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 1 hour at 120° C., the atmosphere in the flask was replaced with an inert gas and the reaction flask was heated to 280° C.

[0339] The Se / TOP stock solution and the mixed solution were injected into the heated reaction flask to perform a core formation reaction. The reaction time for core formation was about 4 minutes.

[0340] The reaction mixture was cooled to room temperature, and then acetone was added to promote the formation of a precipitate, which was separated via centrifugation to provide ZnTeSe cores (average diameter: about 4.5 nm).The ZnTeSe cores were then dispersed in toluene.

[0341] Zinc acetate was heated in trioctylamine (TOA) in the presence of oleic acid to prepare a zinc precursor. Se / TOP stock solution was prepared as disclosed. As a Group V element precursor (eg, phosphorus precursor), tri(diethylamino)phosphine was prepared.

[0342] Octadecene was placed in a 300 mL reaction flask and heated at 120° C. for 1 hour under vacuum. The atmosphere in the flask was replaced with an inert gas (nitrogen), and during the time when the flask was heated to the shell formation temperature (260° C.), the prepared ZnTeSe core, the zinc precursor, the Se / TOP stock solution, and the phosphorus precursor were added, and the reaction was carried out to form a (ZnSe / zinc phosphide) shell. The reaction time was about 240 minutes.

[0343] After the reaction was completed, the flask was cooled to room temperature, acetone was added to promote the formation of precipitates, and the ZnTeSe / ZnSe / ZnP quantum dots were separated via centrifugation. The separated quantum dots were dispersed in toluene. The average size of the quantum dots was 8.17±0.09 nm.

[0344] During the shell formation, the amount of the selenium precursor and the amount of the phosphorus precursor were 0.6 mmol and 0.4 mmol, respectively, based on 10 mL of the reaction solvent.

[0345] 2. Analysis

[0346] With respect to the as-prepared quantum dots, UV-Vis absorption spectroscopy analysis and photoluminescence spectroscopy analysis were performed, and the results are summarized in Table 1. With respect to the quantum dots, ICP-AES analysis was performed, and the results are shown in Table 2.

[0347] For the as-synthesized quantum dots, high-resolution transmission electron microscopy analysis was performed and the results are shown in Figure 7B middle.

[0348] Figure 7B Shown are TEM images of the obtained quantum dots (right) and a HR TEM image of one of them (left).

[0349] According to the HR TEM image, the inner portion of the quantum dot has much more well-oriented lattice arrangement than the outer layer (i.e., ZnP layer or ZnP coating layer) of the quantum dot. According to the HR TEM image, the inner portion of the quantum dot has a regularly spaced lattice arrangement. In contrast, the outer portion of the quantum dot does not substantially have a regularly spaced lattice arrangement.

[0350] Therefore, the results of HR TEM clearly show that, in the quantum dot, the layer including the Group IIB-V compound (or the outer cladding layer of the quantum dot) has lower crystallinity than the inner part (eg, the core and the layer of the Group IIB-VI compound).

[0351] Fig. 8A , Figure 8B and Figure 8C Display each separately Figure 7B An enlarged image of an inner portion (eg, including the center) of a quantum dot shown in the TEM image. Fig.9A , Fig. 9B and Fig. 9C Each shows an enlarged image of an outer layer (ie, ZnP layer or ZnP coating layer) of the quantum dot shown in the TEM image.

[0352] In TEM images, crystals show a pattern determined by the arrangement of bright spots.

[0353] like Fig. 8A and Figure 8B As clearly shown in FIG. 1 , the inner portion of the quantum dot shows an arrangement of three bright spots, which indicates that a crystal pattern (eg, including three straight lines inclined clockwise) is well formed in the quantum dot. Figure 8C As clearly shown in FIG. 1 , the inner portion of the quantum dot has an arrangement of three bright spots, which indicates that a crystalline pattern (eg, including three vertical lines) is formed in the quantum dot.

[0354] On the contrary, Fig.9A , Fig. 9B and Fig. 9C As clearly shown in , no arrangement of bright spots is observed for the outer layer, which indicates that the outer layer of the quantum dots has substantially no crystalline pattern.

[0355] The results show that a layer of ZnP having a relatively low crystallinity (the outer layer of the quantum dots) is formed on or around particles having a relatively high crystallinity (ie, ZnTeSe / ZnSe particles).

[0356] Depend on Fig. 8A , 8B and 8C and Fig.9A , 9B From the results of FIGS. 9A and 9C , it is clearly understood that, in the quantum dot thus obtained, the layer including the Group IIB-V compound (the outer cladding layer of the quantum dot) has a lower crystallinity than the inner portion of the quantum dot.

[0357] For the quantum dots as synthesized, X-ray diffraction analysis was performed and the results are shown in Fig. 7A The results show that the quantum dots do not show a peak attributable to zinc phosphide (eg, 2θ, 39-40°). The peak at 2θ of 26.3° is a peak attributable to ZnSe.

[0358] For the as-synthesized quantum dots, TEM-EDX analysis was performed and the results are shown in Figure 7C The results of TEM-EDX showed that zinc was disposed over the entire surface of the particle and phosphorus was present on the outer layer of relatively low crystallinity.

[0359] Comparative Example 1:

[0360] ZnTeSe / ZnSe quantum dots were prepared in the same manner as in Example 1, except that no phosphorus precursor was used during shell formation.

[0361] With respect to the as-prepared quantum dots, UV-Vis absorption spectroscopy analysis and photoluminescence spectroscopy analysis were performed, and the results are summarized in Table 1. With respect to the quantum dots, ICP-AES analysis was performed, and the results are shown in Table 2.

[0362] Table 1

[0363]

[0364] The results in Table 1 demonstrate that the quantum dots of Example 1 exhibit improved optical properties compared to the quantum dots of Comparative Example 1.

[0365] Table 2

[0366]

[0367] Example 2-1 and Example 2-2:

[0368] Sulfur was dispersed in trioctylphosphine (TOP) to obtain a 1 MS / TOP stock solution.

[0369] Quantum dots were prepared in the same manner as in Example 1, except that in a shell-forming reaction medium including a zinc precursor and a phosphorus precursor, a Se / TOP stock solution was added to form a ZnSe shell layer (Example 2-1), and then an S / TOP stock solution was added to form a ZnS shell layer (Example 2-2). In Example 2-1, the quantum dots had a structure of ZnTeSe / ZnSe / ZnP, and in Example 2-2, the quantum dots had a structure of ZnTeSe / ZnSe / ZnS / ZnP.

[0370] The average size of the quantum dots of Example 2-2 is 7.72±0.1 nm.

[0371] During the shell formation, the amount of the selenium precursor, the amount of the sulfur precursor, and the amount of phosphorus were 0.2 mmol, 0.3 mmol, and 0.25 mmol, respectively, based on 10 mL of the reaction solvent.

[0372] With respect to the as-prepared quantum dots, UV-Vis absorption spectroscopy analysis and photoluminescence spectroscopy analysis were performed, and the results are summarized in Table 3. With respect to the quantum dots, ICP-AES analysis was performed, and the results are shown in Table 4.

[0373] Comparative Example 2-1 and Comparative Example 2-2:

[0374] Quantum dots were prepared in the same manner as in Examples 2-1 and 2-2, except that no phosphorus precursor was used during shell formation.

[0375] With respect to the as-prepared quantum dots, UV-Vis absorption spectroscopy analysis and photoluminescence spectroscopy analysis were performed, and the results are summarized in Table 3. With respect to the quantum dots, ICP-AES analysis was performed, and the results are shown in Table 4.

[0376] Table 3

[0377]

[0378] Table 4

[0379]

[0380]

[0381] Experimental Example 1:

[0382] The quantum dots prepared in Example 1 and the quantum dots prepared in Comparative Example 1 were washed with acetone and redispersed in toluene, and then their photoluminescence quantum efficiencies were measured, respectively.

[0383] The quantum dots of Example 1 showed a significantly smaller decrease compared to the quantum dots of Comparative Example 1, and after redispersion, the quantum efficiency of the quantum dots of Example 1 was 2.47 times greater than that of the quantum dots of Comparative Example 1.

[0384] 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. Quantum dots, including: a core comprising a first semiconductor nanocrystal; and a shell disposed on the core, in the first semiconductor nanocrystal comprises a Group IIB-VI compound and the shell comprises a Group IIB-V compound, The quantum dots do not include cadmium, and The quantum efficiency of the quantum dots is greater than or equal to 60%, The IIB-VI Group compound includes zinc chalcogenide, and the zinc chalcogenide includes zinc, selenium and tellurium, The shell includes a first shell layer and a second shell layer disposed on the first shell layer, the first shell layer including zinc, selenium, and optionally sulfur, and the second shell layer including a Group IIB-V compound, the Group IIB-V compound including zinc and a Group V element, and the Group V element including nitrogen, phosphorus, arsenic, antimony, bismuth, or a combination thereof.

2. The quantum dot of claim 1, wherein the quantum dot is configured to emit light by excitation, and a maximum luminescence peak wavelength of the light emitted by the quantum dot exists in a range greater than or equal to 480 nanometers and less than or equal to 580 nanometers.

3. The quantum dot of claim 1, wherein the quantum dot further comprises sulfur. 4 . The quantum dot of claim 3 , wherein in the quantum dot, a molar ratio of tellurium to selenium is greater than or equal to 0.1:

1. 5 . The quantum dot of claim 1 , wherein the quantum dot comprises zinc, and in the quantum dot, a molar ratio of zinc to the sum of Group VI elements is greater than or equal to 1.35:

1. 6 . The quantum dot of claim 1 , wherein the quantum dot comprises selenium, and in the quantum dot, a molar ratio of the group V element to selenium is greater than or equal to 1.3:

1.

7. The quantum dot of claim 1, wherein the shell further comprises a third shell between the first shell and the second shell, and the third shell comprises semiconductor nanocrystals comprising zinc and sulfur.

8. The quantum dot of claim 1, wherein in the quantum dot, a molar ratio of the Group V element to the Group IIB metal is greater than or equal to 0.1:

1. 9 . The quantum dot of claim 1 , wherein the quantum dot comprises tellurium, and in the quantum dot, a molar ratio of the group V element to tellurium is greater than or equal to 0.15:

1.

10. The quantum dot of claim 1, wherein the first shell comprises ZnSe, ZnSeS, or a combination thereof.

11. The quantum dot according to claim 1, wherein The crystallinity of the second shell layer is lower than that of the first shell layer as determined by transmission electron microscopy.

12. The quantum dot of claim 1, wherein the second shell is the outermost shell of the quantum dot.

13. The quantum dot of claim 1, wherein the maximum luminescence peak of the quantum dot has a half-width less than or equal to 40 nanometers.

14. Quantum dots, including Semiconductor nanocrystalline particles comprising Group IIB-VI compounds; and A coating layer is provided on the semiconductor nanocrystal particles, in The quantum dots do not include cadmium, The coating layer includes a material having a lower crystallinity than the semiconductor nanocrystal particles as measured by transmission electron microscopy, the material including a Group IIB-V compound, and The quantum dots are configured to emit light after being excited by excitation light, The semiconductor nanocrystal particles include a first semiconductor nanocrystal layer comprising zinc, tellurium, and selenium, and a second semiconductor nanocrystal layer disposed on the first semiconductor nanocrystal layer and comprising zinc, selenium, and optionally sulfur, The Group IIB-V compound includes zinc and a Group V element, and the Group V element includes nitrogen, phosphorus, arsenic, antimony, bismuth, or a combination thereof.

15. The quantum dot of claim 14, wherein the amount of tellurium in the first semiconductor nanocrystal is greater than the amount of tellurium in the second semiconductor nanocrystal.

16. The quantum dot of claim 14, wherein The maximum luminescence peak of the light emitted by the quantum dots is greater than or equal to 480 nanometers and less than or equal to 580 nanometers, and The quantum efficiency of the quantum dots is greater than or equal to 65%.

17. Quantum dot groups, including A plurality of quantum dots according to any one of claims 1 to 16, The average size of the quantum dots is greater than or equal to 7 nanometers.

18. Display devices, including Light emitting element, The light-emitting element comprises a plurality of quantum dots as described in any one of claims 1 to 16.

19. Quantum dot complex, comprising: matrix; and a plurality of quantum dots according to any one of claims 1 to 16 dispersed in the matrix.

20. A quantum dot composition comprising: The quantum dot according to any one of claims 1 to 16; an organic solvent, a liquid medium, or a combination thereof; and optionally a monomer, a dispersant, or a combination thereof.

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