Method for manufacturing semiconductor nanoparticles, semiconductor nanoparticles, electroluminescent device including semiconductor nanoparticles, and display device

Abstract

A method of manufacturing a semiconductor nanoparticle, a semiconductor nanoparticle, an electroluminescent device including the semiconductor nanoparticle, and a display device. In an embodiment, a method of an embodiment includes: preparing a first semiconductor nanocrystal including zinc, tellurium, and selenium, where the preparation of the first semiconductor nanocrystal includes heating a first solution including a first zinc precursor, a first selenium precursor, and a tellurium precursor in a first organic solvent at a reaction temperature to form a heated solution; and adding an additive to the heated first solution to produce the first semiconductor nanocrystal, where the additive includes a second selenium precursor and the additive does not include tellurium, and the semiconductor nanoparticles are configured to emit blue light.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority and all benefits arising therefrom to Korean Patent Application No. 10 - 2024 - 0013461, filed on January 29, 2024, with the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference. Technical field

[0003] The present disclosure relates to a method for manufacturing semiconductor nanoparticles, semiconductor nanoparticles, and an electroluminescent device including the semiconductor nanoparticles. Background art

[0004] Semiconductor nanoparticles having nanoscale dimensions (e.g., quantum dots) can exhibit luminescent properties. For example, quantum dots including semiconductor nanocrystals can exhibit a quantum confinement effect. When electrons in an excited state, for example, by photoexcitation or voltage application, transition from the conduction band to the valence band, light emission of the semiconductor nanoparticles can occur. The semiconductor nanoparticles can be configured to emit light in a desired wavelength region by controlling their size, their composition, or a combination thereof. The semiconductor nanoparticles can be used in various light - emitting devices (e.g., electroluminescent devices) and display devices. Summary of the invention

[0005] Embodiments relate to a method for manufacturing blue - emitting semiconductor nanoparticles, which can exhibit improved stability and luminescent properties.

[0006] Embodiments relate to semiconductor nanoparticles manufactured by the above - mentioned method.

[0007] Embodiments relate to a light - emitting device that emits light itself when a voltage is applied to the above - mentioned semiconductor nanoparticles (e.g., quantum dots).

[0008] Embodiments relate to a display device (e.g., a quantum dot (QD) - light - emitting diode (LED) display) that includes nanocrystal particles (e.g., quantum dots) as a light - emitting material in red / green / blue pixels.

[0009] In an embodiment, the method for manufacturing semiconductor nanoparticles includes:

[0010] Preparing a first semiconductor nanocrystal containing zinc, tellurium, and selenium; wherein the preparation of the first semiconductor nanocrystal includes:

[0011] Heating a first solution including a first zinc precursor, a first selenium precursor, and a tellurium precursor in a first organic solvent and optionally a first organic ligand at a reaction temperature (e.g., for a first period of time) to form a heated first solution; and

[0012] Further add an additive to the heated first solution (to fabricate the first semiconductor nanocrystals),

[0013] wherein the additive includes a second selenium precursor and the additive does not include tellurium, and

[0014] the semiconductor nanoparticles are configured to emit blue light.

[0015] The additive may further include a zinc compound, hydrofluoric acid, or a combination thereof.

[0016] The method may further include heating a second zinc precursor and a chalcogen precursor in a second organic solvent in the presence of the first semiconductor nanocrystals and a second organic ligand to obtain semiconductor nanoparticles (e.g., second semiconductor nanocrystals on the first semiconductor nanocrystals).

[0017] The second selenium precursor may be the same as or different from the first selenium precursor.

[0018] In the method, based on 1 mole of the first selenium precursor, the amount of the second selenium precursor may be about 0.1 to about 10 moles. Based on 1 mole of the first selenium precursor, the amount of the second selenium precursor may be greater than or equal to about 0.1 mole, greater than or equal to about 0.12 mole, greater than or equal to about 0.125 mole, greater than or equal to about 0.14 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, or greater than or equal to about 0.5 mole. Based on each 1 mole of the first selenium precursor, the amount of the second selenium precursor may be less than or equal to about 8 moles, less than or equal to about 4 moles, or less than or equal to about 1 mole.

[0019] The zinc compound may be the same as or different from the zinc precursor.

[0020] The zinc compound may include zinc carboxylate, zinc acetylacetonate, zinc halide, or a combination thereof.

[0021] The zinc compound may be two or more types.

[0022] The zinc compound may include zinc carboxylate and zinc halide.

[0023] The zinc halide may include zinc chloride.

[0024] The zinc precursor may include dialkylzinc.

[0025] The additive may be added once or multiple times, or two or more times.

[0026] In the method, based on 1 mole of the tellurium precursor, the total amount of the first selenium precursor and the second selenium precursor may be greater than or equal to about 10 moles, greater than or equal to about 15 moles, or greater than or equal to about 20 moles.

[0027] In the method, based on 1 mole of tellurium precursor, the total amount of the first selenium precursor and the second selenium precursor may be less than or equal to about 60 moles, less than or equal to about 55 moles, less than or equal to about 50 moles, less than or equal to about 40 moles, less than or equal to about 28 moles, or less than or equal to about 21 moles.

[0028] In the first semiconductor nanocrystal, the molar ratio of tellurium to selenium may be greater than or equal to about 0.0001:1 and less than or equal to about 0.08:1, less than or equal to about 0.07:1, less than or equal to about 0.053:1, or less than or equal to about 0.052:1.

[0029] In the first semiconductor nanocrystal, the molar ratio of tellurium to selenium may be less than or equal to about 0.033:1, or less than or equal to about 0.025:1.

[0030] In the first semiconductor nanocrystal, the molar ratio of zinc to the total amount of tellurium and selenium may be greater than or equal to about 1:1, or greater than or equal to about 1.1:1, or greater than or equal to about 1.2:1. In the first semiconductor nanocrystal, the molar ratio of zinc to the total amount of tellurium and selenium may be less than or equal to about 2.5:1, or less than or equal to about 1.3:1.

[0031] In the semiconductor nanoparticle, the molar ratio of tellurium to selenium may be greater than or equal to about 0.0005:1, or greater than or equal to about 0.001:1 and less than about 0.01:1, less than or equal to about 0.008:1, or less than or equal to about 0.007:1.

[0032] In the semiconductor nanoparticle, the molar ratio of the sum of sulfur and selenium to zinc ((S + Se):Zn) may be greater than or equal to about 0.8:1 and less than about 0.86:1.

[0033] In the semiconductor nanoparticle, the molar ratio of the sum of sulfur and selenium to zinc ((S + Se):Zn) may be in the range of about 0.87:1 to about 0.9:1.

[0034] The semiconductor nanoparticle may be configured to emit a first light when a voltage is applied, and the peak wavelength of the first light or the electroluminescence of the semiconductor nanoparticle may be greater than or equal to about 455 nanometers (nm), greater than or equal to about 457 nm, greater than or equal to about 460 nm, or greater than or equal to about 461 nm and less than or equal to about 490 nm.

[0035] The semiconductor nanoparticle may have a ratio of the intensity at the trap emission wavelength (e.g., 500 nm or peak emission wavelength + 50 nm) to the intensity at the peak emission wavelength in the emission spectrum as follows: less than or equal to about 0.25:1, less than or equal to about 0.2:1, less than or equal to about 0.15:1, or less than or equal to about 0.12:1.

[0036] In an embodiment, the semiconductor nanoparticles comprise

[0037] zinc, tellurium, selenium, and sulfur;

[0038] the semiconductor nanoparticles do not include cadmium,

[0039] in the semiconductor nanoparticles, the molar ratio of tellurium to selenium is greater than or equal to about 0.0005:1 and less than or equal to about 0.008:1,

[0040] the semiconductor nanoparticles have a particle size or average particle size less than about 10.3 nm, or less than or equal to about 10.2 nm, and

[0041] the semiconductor nanoparticles have an absolute quantum efficiency greater than or equal to about 90%.

[0042] the semiconductor nanoparticles may have a size or average size less than or equal to about 10.1 nm, less than or equal to about 10 nm, less than or equal to about 9.9 nm, less than or equal to about 9.7 nm, less than or equal to about 9.6 nm, less than or equal to about 9.4 nm, less than or equal to about 9.2 nm, less than or equal to about 9 nm, less than or equal to about 8.8 nm, or less than or equal to about 8.4 nm (hereinafter, may be simply referred to as "size").

[0043] the semiconductor nanoparticles may have an absolute quantum efficiency greater than or equal to about 93%, greater than or equal to about 94%, greater than or equal to about 95%, or greater than or equal to about 96%.

[0044] In an embodiment, the electroluminescent device includes a first electrode and a second electrode spaced apart from each other, and a light-emitting layer disposed between the first electrode and the second electrode, the light-emitting layer including semiconductor nanoparticles,

[0045] wherein the semiconductor nanoparticles contain zinc, tellurium, selenium, and sulfur,

[0046] the semiconductor nanoparticles do not include cadmium,

[0047] in the semiconductor nanoparticles, the molar ratio of tellurium to selenium is greater than or equal to about 0.0005:1 and less than or equal to about 0.008:1, and

[0048] the light-emitting layer is configured to emit a first light upon voltage application, and the first light or the electroluminescence peak wavelength of the semiconductor nanoparticles is greater than about 460 nm and less than or equal to about 490 nm.

[0049] The semiconductor nanoparticles may have a ratio of the intensity at the trap emission wavelength (e.g., 500 nm or peak emission wavelength + 50 nm) to the intensity at the peak emission wavelength in the emission spectrum of less than or equal to about 0.25:1, less than or equal to about 0.2:1, less than or equal to about 0.13:1, or less than or equal to about 0.12:1.

[0050] In the semiconductor nanoparticles, the molar ratio of tellurium to selenium may be less than or equal to about 0.007:1.

[0051] In the semiconductor nanoparticles, the molar ratio of tellurium to selenium may be less than or equal to about 0.003:1.

[0052] The peak emission wavelength of the first light may be greater than or equal to about 462 nm, greater than or equal to about 465 nm, or greater than or equal to about 467 nm.

[0053] The first light may have a full width at half maximum of less than or equal to about 45 nm.

[0054] In the semiconductor nanoparticles, the molar ratio of the sum of sulfur and selenium to zinc ((S + Se):Zn) may be greater than or equal to about 0.8:1 and less than about 0.86:1.

[0055] In the semiconductor nanoparticles, the molar ratio of the sum of sulfur and selenium to zinc ((S + Se):Zn) may be in the range of about 0.87:1 to about 0.9:1.

[0056] The electroluminescent device may have a maximum external quantum efficiency of greater than or equal to about 10%.

[0057] The electroluminescent device may have a maximum brightness of greater than or equal to about 75,000 cd / m 2 2.

[0058] When measured at 650 nits, the electroluminescent device may have a T90 of greater than or equal to about 10 hours. When measured at 650 nits, the electroluminescent device may have a T50 of greater than or equal to about 100 hours.

[0059] When measured at 146 nits, the electroluminescent device may have a T90 of greater than or equal to about 20 hours. When measured at 146 nits, the electroluminescent device may have a T50 of greater than or equal to about 150 hours.

[0060] In an embodiment, the display device or the electronic device may include the electroluminescent device or the semiconductor nanoparticles.

[0061] The display device or the electronic device may include a virtual reality device, an augmented reality device, a portable terminal, a monitor, a laptop computer, a television, an electronic board, a camera, or an electrical component.

[0062] In an embodiment, the semiconductor nanoparticles include: a core comprising a first semiconductor nanocrystal, the first semiconductor nanocrystal comprising zinc, tellurium, and selenium; and an additional semiconductor nanocrystal (e.g., a third semiconductor nanocrystal) on the core, the additional semiconductor nanocrystal comprising zinc and sulfur, wherein the core has a decreasing tellurium concentration gradient in a direction from the center of the core to the additional semiconductor nanocrystal.

[0063] According to the manufacturing method of the embodiment, surface oxidation of the first semiconductor nanocrystal can be effectively suppressed, and the semiconductor nanoparticles thus manufactured can emit relatively long-wavelength blue light when applied to, for example, an electroluminescent device. The semiconductor nanoparticles of the embodiment can exhibit a relatively reduced level of trap emission, as confirmed in the emission spectrum, and an electroluminescent device including the same can exhibit improved efficiency and lifetime characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The above and other advantages and features of the present disclosure will become more apparent by referring to the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings, wherein:

[0065] Figure 1 is a schematic cross-sectional view of an embodiment of a QD-LED device;

[0066] Figure 2 is a schematic cross-sectional view of an embodiment of a QD-LED device;

[0067] Figure 3 is a schematic cross-sectional view of an embodiment of a QD-LED device;

[0068] Figure 4 is a schematic cross-sectional view of an embodiment of a QD-LED device;

[0069] Figure 5A 、 Figure 5B and Figure 5C are diagrams showing the schematic structures of the first semiconductor nanocrystal and the semiconductor nanoparticles formed thereby during the synthesis process, wherein the distributions of tellurium in the first semiconductor nanocrystal and the semiconductor nanoparticles during formation are shown respectively;

[0070] Figure 6 is a schematic cross-sectional view of a light-emitting device (red-green-blue (RGB) pixel) according to an embodiment;

[0071] Figure 7 is a schematic front view of a display panel according to an embodiment;

[0072] Figure 8 is taken along line IV-IVFigure 7 Schematic cross-sectional view of a display panel;

[0073] Figure 9 Is a graph of arbitrary units (A.U.) versus wavelength (nm), showing the results of ultraviolet (UV)-visible (Vis) absorption spectrometry of a sample collected from a reaction solution after the first reaction in Preparation Example 1;

[0074] Figure 10 Is a graph of arbitrary units versus wavelength, showing the photoluminescence spectrum of semiconductor nanoparticles fabricated in Preparation Example 1;

[0075] Figure 11 Is a transmission electron microscopy (TEM) image of semiconductor nanoparticles fabricated in Preparation Example 1; and

[0076] Figure 12 Is a TEM image of semiconductor nanoparticles fabricated in Comparative Preparation Example 1. Detailed Description of the Invention

[0077] Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings, so that those of ordinary skill in the art can easily implement the present disclosure. The present disclosure may be embodied in many different forms and is not limited to the embodiments described herein.

[0078] To clearly explain the present disclosure, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar elements throughout the specification.

[0079] For better understanding and convenience of description, the sizes and thicknesses of the respective components shown in the drawings are randomly shown, and the present disclosure is not necessarily limited to those shown. In the drawings, for clarity, the thicknesses of layers, films, panels, regions, etc. are exaggerated. Also, in the drawings, for convenience of description, the thicknesses of some layers and regions are exaggerated.

[0080] In addition, it will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or there can also be intervening elements. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements. Further, being "on" a reference part means being disposed above or below the reference part and does not necessarily mean "above" in the opposite direction of gravity.

[0081] In this document, relative terms such as "lower" or "bottom" and "upper" or "top" may be used to describe the relationship of one element to another as shown in the figures. It will be understood that relative terms are intended to cover different orientations of the device in addition to the orientation shown in the figures. For example, if the device in one of the figures is flipped, an element described as being on the "lower" side of another element will be oriented on the "upper" side of the other element. Thus, the exemplary term "lower" can include both the "lower" and "upper" orientations, depending on the specific orientation of the figure. Similarly, if the device in one of the figures is flipped, an element described as "beneath" or "under" another element will be oriented "above" the other element. Thus, the exemplary terms "beneath" or "under" can include both the orientation above and the orientation below.

[0082] 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 sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, without departing from the teachings herein, the "first element", "component", "region", "layer", or "section" discussed below may be referred to as a second element, component, region, layer, or section.

[0083] Furthermore, unless explicitly described to the contrary, the word "comprising" and variations such as "including" will be understood to mean including the stated elements but not excluding any other elements.

[0084] In the specification, a "cross-section" may mean a cross-section viewed from the side of a target portion cut substantially perpendicularly (e.g., substantially perpendicular to the bottom surface).

[0085] In addition, unless otherwise specified, the singular includes the plural.

[0086] The terms used in this specification are for the purpose of describing particular embodiments only and are not intended to be limiting. As used herein, unless the context clearly dictates otherwise, the indefinite articles "a," "an," the definite article "the," and "at least one" do not denote a limitation of quantity and are intended to include both the singular and the plural. For example, unless the context clearly dictates otherwise, the term "an element" has the same meaning as "at least one element." Thus, a reference to "an" element in a claim followed by a reference to "the" element encompasses one element and a plurality of elements. "At least one" is not to be construed as limiting "one." "Or" means "and / or." As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0087] In the drawings, for the sake of clarity, the thicknesses of layers, films, panels, regions, etc. are exaggerated. Throughout the specification, like reference numerals denote like elements.

[0088] Exemplary embodiments are described herein with reference to cross-sectional views that are schematic illustrations of idealized embodiments. As such, variations in the shapes of the illustrations due to, for example, manufacturing techniques and / or tolerances are to be expected. Thus, the embodiments described herein are not to be construed as limited to the particular shapes of regions shown herein but include, for example, deviations in shapes due to manufacturing. For example, regions shown or described as flat may typically have rough and / or non-linear features. Additionally, sharp corners shown may be rounded. Thus, the regions shown in the figures are schematic in nature and their shapes are not intended to illustrate the exact shape of a region and are not intended to limit the scope of the claims.

[0089] Hereinafter, the value of the work function or the (highest occupied molecular orbital (HOMO) or lowest unoccupied molecular orbital (LUMO)) energy level is represented as an absolute value from the vacuum level. Additionally, a deep, high, or large work function or energy level means that the absolute value is large when the vacuum level is set to "0 eV," and a shallow, low, or small work function or energy level means that the absolute value is small when the vacuum level is set to "0 eV."

[0090] In an embodiment, the work function may refer to the minimum energy required to remove an electron from a solid metal (e.g., the metal surface) to a vacuum (e.g., the portion just outside the solid surface).

[0091] An average (value) may be a mean or a median. In an embodiment, the average (value) is a mean.

[0092] As used herein, the term "peak emission wavelength" refers to the wavelength at which a given emission spectrum of light reaches its maximum value.

[0093] The first absorption peak refers to the main exciton peak that first appears starting from the lowest wavelength region in the UV-Vis absorption spectrum, and the wavelength of the first absorption peak refers to the wavelength at which the first absorption peak exhibits the maximum intensity.

[0094] In this specification, "group" means a group of the periodic table of elements.

[0095] "Group III" may include Group IIIA and Group IIIB, and examples of Group III metals include, but are not limited to, Al, In, Ga, and Tl.

[0096] "Group V" includes Group VA and includes, but is not limited to, nitrogen, phosphorus, arsenic, antimony, and bismuth.

[0097] As used herein, when no other definition is provided, "substituted" means that a hydrogen, such as at least one hydrogen, of a compound or the corresponding moiety is replaced by a substituent selected from the group consisting of a C1-C30 alkyl, a C2-C30 alkenyl, a C2-C30 alkynyl, a C6-C30 aryl, a C7-C30 alkylaryl, a C1-C30 alkoxy, a C1-C30 heteroalkyl, a C3-C30 heteroaryl, 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 (-NO2), a cyano (-CN), an amino (-NRR', where R and R' are each independently hydrogen or a C1-C6 alkyl), an azide (-N3), an amidino (-C(=NH)NH2), a hydrazino (-NHNH2), a hydrazono (=N(NH2)), an aldehyde (-C(=O)H), a carbamoyl (-C(O)NH2), a mercapto (-SH), an ester group (-C(=O)OR, where R is a C1-C6 alkyl or a C6-C12 aryl), a carboxyl (-COOH) or its salt (-C(=O)OM, where M is an organic or inorganic cation), a sulfonic acid group (-SO3H) or its salt (-SO3M, where M is an organic or inorganic cation), a phosphoric acid group (-PO3H2) or its salt (-PO3MH or -PO3M2, where M is an organic or inorganic cation), or a combination thereof.

[0098] As used herein, unless otherwise defined, a "hydrocarbon group" refers to a group containing carbon and hydrogen (e.g., an aliphatic group such as an alkyl, alkenyl, or alkynyl group, or an aromatic group such as an aryl group). A hydrocarbon group can be a monovalent or higher-valent group formed by removing one or more hydrogen atoms from an alkane, alkene, alkyne, or aromatic hydrocarbon. In the hydrocarbon group, a methylene group, such as at least one methylene group, can be replaced by an oxide (oxygen) moiety, a carbonyl moiety, an ester moiety, -NH-, or a combination thereof. Unless otherwise stated to the contrary, a hydrocarbon (alkyl, alkenyl, alkynyl, or aryl) group can have 1 to 60, 2 to 32, 3 to 24, or 4 to 12 carbon atoms.

[0099] As used herein, unless otherwise defined, an "alkyl" refers to a straight-chain or branched-chain saturated monovalent hydrocarbon group (such as methyl, ethyl, hexyl, etc.).

[0100] As used herein, unless otherwise defined, an "alkenyl" refers to a straight-chain or branched-chain monovalent hydrocarbon group having one or more carbon-carbon double bonds.

[0101] As used herein, unless otherwise defined, an "alkynyl" refers to a straight-chain or branched-chain monovalent hydrocarbon group having one or more carbon-carbon triple bonds.

[0102] As used herein, unless otherwise defined, an "aryl" refers to a group formed by removing hydrogen, such as at least one hydrogen, from an aromatic hydrocarbon (e.g., phenyl or naphthyl).

[0103] As used herein, unless otherwise defined, "hetero" refers to including 1 to 3 heteroatoms of N, O, S, Si, P, or a combination thereof.

[0104] As used herein, unless otherwise defined, an "alkoxy" refers to an alkyl group connected via oxygen (i.e., alkyl-O-), such as methoxy, ethoxy, or sec-butoxy.

[0105] As used herein, unless otherwise defined, an "amino group" can be -NRR', where R and R' are each independently hydrogen, a C1 to C12 alkyl group, a C7 to C20 alkylaryl group, a C7 to C20 arylalkyl group, or a C6 to C18 aryl group.

[0106] A description of being free of cadmium (or other toxic heavy metals) can refer to a concentration of cadmium (or the corresponding heavy metal) that is 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, nearly zero or zero (e.g., undetectable by current methods). In an embodiment, cadmium, its salts, (or other heavy metals) are substantially absent, or if present, are in an amount or impurity level below the detection limit of a given detection device. As used herein, "substantially" or "about" or "approximately" means not only the stated value, but also within an acceptable deviation range taking into account the errors associated with the corresponding measurement and the measurement of the measured value. For example, "substantially" or "about" or "approximately" can mean within ±10%, 5%, 3%, or 1% of the stated value or within the standard deviation.

[0107] A nanoparticle refers to a structure having at least one region or characteristic scale with a nanoscale dimension. In an embodiment, the size of the nanoparticle can be less than or equal to about 300 nm, less than or equal to about 250 nm, less than or equal to about 150 nm, less than or equal to about 100 nm, less than or equal to about 50 nm, or less than or equal to about 30 nm. Such nanoparticles can have any suitable shape.

[0108] The nanoparticles can have any suitable shape, such as nanowires, nanorods, nanotubes, a multi-legged shape having two or more legs, nanodots (or quantum dots), etc., and there is no particular limitation. The nanoparticles can be, for example, substantially crystalline, substantially single-crystalline, polycrystalline, amorphous (non-crystalline), or a combination thereof.

[0109] For example, semiconductor nanoparticles such as quantum dots can exhibit quantum confinement or exciton confinement. In this specification, unless otherwise specifically defined, the term "nanoparticle or quantum dot" has no limitation in its shape. Semiconductor nanoparticles such as quantum dots can have a size smaller than the diameter of the Bohr excitation in the bulk crystal of the same material and can exhibit a quantum confinement effect. By controlling the size of the nanocrystal as the emission center, the quantum dots can emit light corresponding to their bandgap energy.

[0110] T50 refers to the time it takes for the brightness of a given device to decrease to 50% based on an initial brightness of 100% when the device is driven at a predetermined brightness (e.g., 650 nits or 146 nits).

[0111] T90 refers to the time it takes for the brightness of a given device to decrease to 90% based on an initial brightness of 100% when the device is driven at a predetermined brightness (e.g., 650 nits or 146 nits).

[0112] In this document, the external quantum efficiency refers to the ratio of the number of photons emitted from a light-emitting diode (LED) to the number of electrons passing through the device. The external quantum efficiency (EQE) can be a criterion (judgment criterion) for how effectively a light-emitting diode converts electrons into photons and allows them to escape. In an embodiment, the EQE can be determined based on the following equation:

[0113] EQE = (Injection efficiency) × (Solid-state quantum yield) × (Extraction efficiency)

[0114] Injection efficiency = the proportion of electrons passing through the device that are injected into the active region;

[0115] Solid-state quantum yield = the proportion of all radiative electron-hole recombinations in the active region that thus produce photons; and

[0116] Extraction efficiency = the proportion of photons generated in the active region that escape from the device.

[0117] The maximum external quantum efficiency refers to the maximum value of the external quantum efficiency.

[0118] The maximum brightness refers to the maximum value of the brightness that the device can achieve.

[0119] Quantum efficiency is a term that can be used interchangeably with quantum yield. The quantum efficiency (or quantum yield) can be measured in solution or in the solid state (in a complex). In an embodiment, the quantum efficiency (or quantum yield) is the ratio of the photons emitted by a nanostructure or a group thereof to the photons absorbed. In an embodiment, the quantum efficiency can be measured by any suitable method. For example, for fluorescence quantum yield or efficiency, there can be two methods: an absolute method and a relative method.

[0120] In the absolute method, the quantum efficiency is obtained by detecting the fluorescence of all samples via an integrating sphere. In the relative method, the quantum efficiency of an unknown sample is calculated by comparing the fluorescence intensity of a standard dye (standard sample) with the fluorescence intensity of the unknown sample. Coumarin 153, Coumarin 545, Rhodamine 101 inner salt, Anthracene, and Rhodamine 6G can be used as standard dyes according to their photoluminescence (PL) wavelengths, but the present disclosure is not limited thereto.

[0121] Unless otherwise specified, the numerical ranges described herein are inclusive. Unless otherwise mentioned, the numerical ranges described herein include any real number within the endpoints of the stated range and include the endpoints. In this specification, numerical endpoints or upper or lower limit values (e.g., described as "described, any real number within the endpoints and including the endpoints. In this specification, described as described, any within the endpoints) can be used to form a numerical range for a given feature. In other words, the upper and lower endpoints stated for each numerical value can be independently combined to provide a range.

[0122] The bandgap energy of semiconductor nanoparticles can be changed according to the size, structure, and composition of the nanocrystals. For example, as the size of the quantum dots increases, the quantum dots can have a narrow bandgap energy and an increased emission wavelength. Semiconductor nanocrystals have attracted attention as luminescent materials in various fields such as display devices, energy devices, and bioluminescent devices.

[0123] Semiconductor nanoparticles having electroluminescent properties at a practically applicable level may include harmful heavy metals such as cadmium (Cd), lead, mercury, or a combination thereof. It is desirable to provide semiconductor nanoparticles that emit light of a desired wavelength (e.g., relatively low-energy blue light) while substantially not containing harmful heavy metals. Additionally, from an environmental perspective, it is desirable to provide a light-emitting device or a display device (e.g., emitting blue light) having a light-emitting layer based on semiconductor nanoparticles that does not include cadmium (a harmful heavy metal).

[0124] The semiconductor nanoparticles according to an embodiment are environmentally friendly, can emit blue light of a desired wavelength with improved luminous efficiency, and can exhibit improved stability in an external environment. The electroluminescent device according to an embodiment is a self-emitting light-emitting device that includes semiconductor nanoparticles and is configured to emit desired light by voltage application with or without a separate light source. The light-emitting device and the display device of the embodiment are desirable from an environmental perspective.

[0125] In an embodiment, the semiconductor nanoparticles include zinc, tellurium, selenium, and sulfur, the semiconductor nanoparticles do not include cadmium, the molar ratio of tellurium to selenium in the semiconductor nanoparticles is greater than or equal to about 0.0005:1 and less than or equal to about 0.008:1, and the semiconductor nanoparticles are configured to emit light having a peak emission wavelength greater than about 460 nm, e.g., greater than or equal to about 461 nm and less than or equal to about 490 nm, when a voltage is applied. In the semiconductor nanoparticles, the molar ratio of tellurium to selenium can be less than or equal to about 0.007:1, or less than or equal to about 0.003:1. The embodiment relates to an electronic device (e.g., an electroluminescent device) including the semiconductor nanoparticles (e.g., in a light-emitting layer).

[0126] In an embodiment, the electroluminescent device includes: a first electrode 1 and a second electrode 5 spaced apart (e.g., facing each other); and a light-emitting layer 3 disposed between the first electrode and the second electrode and including semiconductor nanoparticles and not including cadmium (see Figure 1 ). The first electrode may include an anode, and the second electrode may include a cathode. Alternatively, the first electrode may include a cathode, and the second electrode may include an anode. The electroluminescent device may further include a hole assisting layer 2 between the light-emitting layer and the first electrode. The electroluminescent device may further include an electron assisting layer 4 between the light-emitting layer and the second electrode.

[0127] In an electroluminescent device, the first electrode 10 or the second electrode 20 may be disposed on a (transparent) substrate 100. The transparent substrate may be a light extraction surface. (Reference: Figure 2 and Figure 3 )

[0128] Referring to Figure 2 and 3 , the light-emitting layer 30 may be disposed between the first electrode (e.g., anode) 10 and the second electrode (e.g., cathode) 50. The second electrode or cathode 50 may include an electron injection conductor. The first electrode or anode 10 may include a hole injection conductor. The work functions of the electron / hole injection conductors included in the second electrode and the first electrode may be appropriately adjusted and are not particularly limited. For example, the second electrode may have a small work function, and the first electrode may have a relatively large work function, or vice versa.

[0129] The electron / hole injection conductor may include a metal-based material (e.g., metal, metal compound, alloy, or a combination thereof) (aluminum, magnesium, tungsten, nickel, cobalt, platinum, palladium, calcium, LiF, etc.), a metal oxide such as indium gallium oxide or indium tin oxide (ITO), or a conductive polymer (e.g., having a relatively high work function) such as polyethylenedioxythiophene, but is not limited thereto.

[0130] The first electrode, the second electrode, or a combination thereof may be a light-transmissive electrode or a transparent electrode. In an embodiment, both the first electrode and the second electrode may be light-transmissive electrodes. The electrodes may be patterned. The first electrode, the second electrode, or a combination thereof may be disposed on a (e.g., insulating) substrate 100. The substrate 100 may be optically transparent (e.g., may have a light 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%, greater than or equal to about 85%, or greater than or equal to about 90% and, for example, less than or equal to about 99%, or less than or equal to about 95%). The substrate may further include a region for blue pixels, a region for red pixels, a region for green pixels, or a combination thereof. A thin-film transistor may be disposed in each region of the substrate, and one of the source electrode and the drain electrode of the thin-film transistor may be electrically connected to the first electrode or the second electrode.

[0131] The light-transmissive electrode may be disposed on a (e.g., insulating) transparent substrate. The substrate may be rigid or flexible. The substrate may be plastic, glass, or metal.

[0132] The light-transmissive electrode may have a light transmittance as follows: 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%, e.g., in the range of about 80% to about 100%, about 85% to about 95%, or a combination thereof.

[0133] The light-transmitting electrode may include, for example, a transparent conductor such as indium tin oxide (ITO) or indium zinc oxide (IZO), indium gallium tin oxide, indium tin zinc oxide, titanium nitride, polyaniline, LiF / Mg:Ag, etc., or a single-layer or multi-layer metal thin film, but is not limited thereto. The first electrode, the second electrode, or a combination thereof may include silver, aluminum (Al), lithium aluminum (Li:Al) alloy, magnesium-silver alloy (Mg:Ag), lithium fluoride-aluminum (LiF:Al), etc. In the alloy electrode, the ratio between the respective materials may be appropriately controlled, for example, within the range of about 1:0.1 to about 1:10, about 1:0.2 to about 1:5, about 1:0.3 to about 1:3, or a combination thereof.

[0134] In an embodiment, the first electrode or the second electrode may be a multi-layer electrode. In an embodiment, the first electrode (or anode) may be a multi-layer electrode including two or more layers, three or more layers and ten or fewer layers, or five or fewer layers of electrode materials. In an embodiment, the second electrode (or cathode) may be a multi-layer electrode including two or more layers, three or more layers and ten or fewer layers, or five or fewer layers of electrode materials.

[0135] The multi-layer electrode may include, for example, a light-transmitting conductive material such as indium tin oxide, an opaque conductive material (or reflective electrode material) such as aluminum, or a combination thereof. In an embodiment, the electrode (e.g., anode or cathode) may have a structure in which the opaque conductive material (or reflective electrode material layer) is disposed between the transparent conductive materials (e.g., layers of transparent conductive materials). In an embodiment, the electrode (anode or cathode) may have a structure in which the light-transmitting conductive material (e.g., layer of light-transmitting conductive material) is disposed between the opaque conductive materials (or reflective electrode materials).

[0136] When a voltage is applied between the first electrode and the second electrode, the light-emitting layer may emit light upward and downward through the electric field, and the light traveling to the reflective electrode may be reflected and emitted in the opposite direction.

[0137] In an embodiment, the light may be emitted toward the cathode. In an embodiment, the light may be emitted toward the anode.

[0138] The thickness of the electrode (the first electrode, the second electrode, or a combination thereof) 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, such as greater than or equal to about 10 nm, greater than or equal to about 20 nm, greater than or equal to about 30 nm, greater than or equal to about 40 nm, or greater than or equal to about 50 nm. For example, the thickness of the electrode can be less than or equal to about 100 micrometers (μm), such as less than or equal to about 90 μm, less than or equal to about 80 μm, less than or equal to about 70 μm, less than or equal to about 60 μm, less than or equal to about 50 μm, less than or equal to about 40 μm, less than or equal to about 30 μm, less than or equal to about 20 μm, 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, 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, or less than or equal to about 60 nm.

[0139] The method of forming the electrode is not particularly limited and can be appropriately selected depending on the material. In an embodiment, the electrode can be formed by (but not limited to) deposition, coating, or a combination thereof.

[0140] The light-emitting layer 3 or 30 is disposed between the first electrode 1 and the second electrode 5 (e.g., the anode 10 and the cathode 50). The light-emitting layer includes semiconductor nanoparticles (e.g., blue light-emitting nanoparticles, red light-emitting nanoparticles, or green light-emitting nanoparticles). The light-emitting layer can include a single layer of one or more (e.g., 2 or more or 3 or more and 10 or less) nanoparticles.

[0141] The light-emitting layer can be patterned. In an embodiment, the patterned light-emitting layer can include a blue light-emitting layer (e.g., disposed within a blue pixel in a display device described later), a red light-emitting layer (e.g., disposed within a red pixel in a display device described later), a green light-emitting layer (e.g., disposed within a green pixel in a display device described later), or a combination thereof. Each light-emitting layer can be (optically) separated from an adjacent light-emitting layer by a partition wall. In an embodiment, a partition wall or a bank such as a black matrix or a pixel defining layer (PDL) can be disposed between the red light-emitting layer, the green light-emitting layer, and the blue light-emitting layer (refer to Figure 4 and 6 ). In an embodiment, the red light-emitting layer, the green light-emitting layer, and the blue light-emitting layer can be each optically substantially isolated.

[0142] In an embodiment, the light-emitting layer does not include cadmium. In an embodiment, the light-emitting layer or the semiconductor nanoparticles can be free of mercury, lead, or a combination thereof.

[0143] The semiconductor nanoparticles included in the light-emitting layer 3 or 30 may include zinc, tellurium, and selenium. The semiconductor nanoparticles may further include sulfur. Embodiments relate to the semiconductor nanoparticles or a group thereof.

[0144] The semiconductor nanoparticles may include a first semiconductor nanocrystal containing zinc, tellurium, and selenium (a first zinc chalcogenide including zinc, tellurium, and selenium), or a core including the same. The semiconductor nanoparticles may include a semiconductor nanocrystal containing zinc, selenium, sulfur, or a combination thereof (a zinc chalcogenide including zinc, selenium, sulfur, or a combination thereof), or a shell including the same. In an embodiment, the semiconductor nanoparticles may not include a group III-V compound containing indium and phosphorus. In an embodiment, the semiconductor nanoparticles may not include indium phosphide, indium gallium phosphide, indium zinc phosphide, or a combination thereof. The semiconductor nanoparticles may exhibit an emission peak wavelength, such as a photoluminescence peak wavelength or an electroluminescence peak wavelength, in the range of greater than or equal to about 420 nm, greater than or equal to about 430 nm, greater than or equal to about 440 nm, greater than or equal to about 445 nm, greater than or equal to about 448 nm, greater than or equal to about 450 nm, greater than or equal to about 452 nm, greater than or equal to about 453 nm, greater than or equal to about 454 nm, greater than or equal to about 455 nm, greater than or equal to about 457 nm, greater than or equal to about 459 nm, or greater than or equal to about 461 nm and less than or equal to about 480 nm, less than or equal to about 475 nm, less than or equal to about 470 nm, less than or equal to about 465 nm, or less than or equal to about 462 nm. The semiconductor nanoparticles may be configured to exhibit an absolute quantum yield of greater than or equal to about 80%, greater than or equal to about 90%, greater than or equal to about 92%, greater than or equal to about 93%, greater than or equal to about 94%, greater than or equal to about 95%, or greater than or equal to about 96% in photoluminescence spectroscopy. The semiconductor nanoparticles may be configured to exhibit a full width at half maximum (FWHM) of less than or equal to about 55 nm, less than or equal to about 52 nm, less than or equal to about 50 nm, less than or equal to about 49 nm, less than or equal to about 48 nm, less than or equal to about 45 nm, or less than or equal to about 43 nm.

[0145] Cadmium-free semiconductor nanocrystals based on zinc, selenium, and tellurium (e.g., containing) or semiconductor nanoparticles including the same are capable of emitting blue light. The composition of the semiconductor nanoparticles can be altered to provide emission of blue light at a desired wavelength. For example, the semiconductor nanoparticles can emit blue light having a relatively long wavelength. The present inventors have found that when cadmium-free semiconductor nanoparticles based on zinc, selenium, and tellurium emit blue light having a relatively long wavelength, a significant degree of trap emission can occur in the trap emission wavelength region (e.g., greater than 500 nm). Without wishing to be bound by any theory, it is believed that in semiconductor nanoparticles emitting blue light having a relatively long wavelength, tellurium, which is prone to oxidation, can be present on the surface of the ZnTeSe semiconductor nanocrystal (or core), resulting in an increase in core surface oxidation and core-shell interface defects. The semiconductor nanoparticles can cause an undesirable decrease in quantum efficiency and stability in an electroluminescent device.

[0146] Surprisingly, the present inventors have found that the semiconductor nanoparticles of the embodiments can be synthesized by the methods described herein and exhibit the characteristics described herein, and can exhibit enhanced luminescence efficiency and enhanced stability at a desired emission peak wavelength. Without intending to be bound by a particular theory, it is believed that in semiconductor nanoparticles obtained by the manufacturing method of the exemplary embodiments, the internal concentration of tellurium in the first semiconductor nanocrystal can be increased, thereby reducing the occurrence of core surface oxidation and core / shell interface defects due to tellurium exposure. In addition, when applied to an electroluminescent device including the semiconductor nanoparticles as a luminescent material in a light-emitting layer, the semiconductor nanoparticles of the embodiments can contribute to improving device efficiency and extending the lifetime.

[0147] In an embodiment, the semiconductor nanoparticles can have a core-shell structure. The core-shell structure can include: a core including a first semiconductor nanocrystal, and a shell disposed on the core and including a semiconductor nanocrystal.

[0148] In an embodiment, the first semiconductor nanocrystal or core can include a first zinc chalcogenide including zinc, selenium, and tellurium. The size or average size (hereinafter, abbreviated as "size") of the core can be 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 of the core can be less than or equal to about 6 nm, for example, less than or equal to about 5 nm. The size of the core can be from about 2 nm to about 6 nm, or from about 2.5 nm to about 5 nm. The first semiconductor nanocrystal can include ZnTe x Se 1-x(Wherein, x is greater than 0, greater than or equal to about 0.0001, greater than or equal to about 0.001, greater than or equal to about 0.003, greater than or equal to about 0.005, greater than or equal to about 0.007, greater than or equal to about 0.009, greater than or equal to about 0.01, greater than or equal to about 0.03, greater than or equal to about 0.05, greater than or equal to about 0.09 and less than or equal to about 0.1, less than or equal to about 0.05, less than or equal to about 0.04, less than or equal to about 0.03, less than or equal to about 0.02, less than or equal to about 0.01, or less than or equal to about 0.08). The approval may further include or may not further include sulfur.

[0149] In an embodiment, in the first semiconductor nanocrystal or core, the distribution of Te element may be concentrated at the center of the particle, and such a structure can be obtained, for example, by the synthesis methods described herein. In an embodiment, the difference in reactivity between the tellurium precursor and the selenium precursor can be utilized. In an embodiment, the method of separately (i.e., in batches) adding multiple precursors (e.g., selenium precursor) or additives to the reaction system in a separate (individual) addition can contribute to providing a core with a concentration gradient of tellurium element. In the first semiconductor nanocrystal or core obtained in this way, surface oxidation caused by the exposure of tellurium can be inhibited, and the occurrence frequency of core-shell interface defects in the subsequent shell formation reaction can be reduced. Additionally, compared with the particles manufactured according to conventional techniques, the trap emission of the semiconductor nanoparticles of the embodiment can be reduced. When included in an electroluminescent device, the semiconductor nanoparticles of the embodiment can contribute to improving the efficiency of the device and extending the lifespan of the device.

[0150] The first semiconductor nanocrystal or core of the embodiment has a concentration gradient of tellurium. For example, it may exhibit a difference in the concentration of tellurium between the central part A and the adjacent surface part C. Figure 5A Schematically shows the distribution of tellurium atoms in the core of the semiconductor nanoparticle in the embodiment. Referring to Figure 5A , when the composition at the core central part A is ZnTe a Se 1-a (where a is a number representing the relative molar ratio between tellurium and selenium, greater than 0 and less than 1) and the composition of the first semiconductor nanocrystal is ZnTe b Se 1-b (where b is a number representing the relative molar ratio between tellurium and selenium, greater than 0 and less than 1), a can be greater than b. For example, the relative molar ratio between tellurium and selenium can be represented by the following equations respectively:

[0151] Moles of tellurium / (moles of tellurium + moles of selenium)

[0152] In an embodiment, the first semiconductor nanocrystal may have a tellurium distribution index (%) represented by (b / a) x 100 as follows: less than or equal to about 95%, less than or equal to about 90%, less than or equal to about 85%, less than or equal to about 80%, less than or equal to about 75%, less than or equal to about 70%, less than or equal to about 65%, less than or equal to about 60%, less than or equal to about 55%, less than or equal to about 50%, less than or equal to about 45%, or less than or equal to about 40%.

[0153] In the semiconductor nanoparticles of the embodiment, the first semiconductor nanocrystal may have a Te element concentrated at the central portion. In an embodiment, the tellurium distribution index may represent the uniformity of the distribution of tellurium, and a smaller distribution index value may indicate a higher concentration of tellurium at the central portion. In the first semiconductor nanocrystal, the tellurium distribution index (percentage) may be in the range of about 1% to about 95%, about 5% to about 87%, about 9% to about 83%, about 11% to about 79%, about 14% to about 77%, about 18% to about 73%, about 21% to about 63%, about 29% to about 45%, about 32% to about 41%, or a combination of the upper and lower limits described herein.

[0154] In the first semiconductor nanocrystal of the embodiment, the central portion A may have a diameter greater than or equal to about 1.5 nm, greater than or equal to about 2 nm, or greater than or equal to about 2.5 nm and less than or equal to about 4 nm, or less than or equal to about 3.5 nm.

[0155] In the first semiconductor nanocrystal, the molar ratio of tellurium to selenium can be greater than or equal to about 0.0001:1, greater than or equal to about 0.0005:1, greater than or equal to about 0.001:1, greater than or equal to about 0.005:1, 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 0.022:1, greater than or equal to about 0.025:1, greater than or equal to about 0.03:1, greater than or equal to about 0.031:1, 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, greater than or equal to about 0.05:1, greater than or equal to about 0.051:1, greater than or equal to about 0.065:1, greater than or equal to about 0.07:1, greater than or equal to about 0.074:1, or greater than or equal to about 0.078:1. In the first semiconductor nanocrystal, the molar ratio of tellurium to selenium can be less than or equal to about 0.08:1, less than or equal to about 0.079:1, less than or equal to about 0.077:1, less than or equal to about 0.073:1, less than or equal to about 0.071:1, less than or equal to about 0.069:1, less than or equal to about 0.06:1, less than or equal to about 0.055:1, less than or equal to about 0.053:1, less than or equal to about 0.052:1, less than or equal to about 0.051:1, less than or equal to about 0.05:1, less than or equal to about 0.048:1, less than or equal to about 0.047:1, less than or equal to about 0.046:1, less than or equal to about 0.045:1, less than or equal to about 0.044:1, less than or equal to about 0.043:1, less than or equal to about 0.042:1, less than or equal to about 0.041:1, less than or equal to about 0.040:1, less than or equal to about 0.039:1, less than or equal to about 0.038:1, less than or equal to about 0.037:1, less than or equal to about 0.036:1, less than or equal to about 0.035:1, less than or equal to about 0.034:1, less than or equal to about 0.033:1, less than or equal to about 0.032:1, less than or equal to about 0.031:1, less than or equal to about 0.030:1, less than or equal to about 0.029:1, less than or equal to about 0.028:1, less than or equal to about 0.027:1, less than or equal to about 0.026:1, less than or equal to about 0.025:1, less than or equal to about 0.024:1, less than or equal to about 0.023:1, less than or equal to about 0.022:1, less than or equal to about 0.021:1, or less than or equal to about 0.02:1.

[0156] In the first semiconductor nanocrystal, the molar ratio of zinc to the total amount of tellurium and selenium can be greater than or equal to about 1:1, greater than or equal to about 1.1:1, greater than or equal to about 1.15:1, greater than or equal to about 1.16:1, greater than or equal to about 1.2:1, greater than or equal to about 1.22:1, greater than or equal to about 1.23:1, greater than or equal to about 1.25:1, or greater than or equal to about 1.28:1. In the first semiconductor nanocrystal, the molar ratio of zinc to the sum of tellurium and selenium can be less than or equal to about 2.5:1, less than or equal to about 2.1:1, less than or equal to about 2:1, 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 1.29:1, or less than or equal to about 1.21:1.

[0157] In the semiconductor nanoparticles of an embodiment, the shell or the semiconductor nanocrystals included therein (hereinafter referred to as the semiconductor nanocrystal shell) can have a composition different from that of the first semiconductor nanocrystal. (Refer to Figure 5B )

[0158] In the semiconductor nanoparticles, the shell or the semiconductor nanocrystals included therein can include zinc, selenium, and sulfur (or a zinc chalcogenide including zinc, selenium, and sulfur). In an embodiment, the shell can include or not include tellurium. The shell (or each layer of the multi-layer shell described herein) can be a gradient alloy having a composition that varies in the radial direction. In an embodiment, the amount of sulfur in the semiconductor nanocrystal shell can increase towards the surface of the semiconductor nanoparticles. For example, in the shell, the amount of sulfur can have a concentration gradient that increases with the distance from the core.

[0159] The shell can be a multi-layer shell including multiple layers. In the multi-layer shell, adjacent layers can include semiconductor materials with different compositions. The multi-layer shell can include an intermediate shell layer on the core (e.g., directly on the core) and an outer shell layer on the intermediate shell layer. In other words, the second semiconductor nanocrystal (or the intermediate shell layer) can be disposed between the first semiconductor nanocrystal (or the core) and the third semiconductor nanocrystal (or the outer layer). (Refer to Figure 5C )

[0160] In an embodiment, the semiconductor nanocrystal shell can include a second semiconductor nanocrystal (or an intermediate shell layer including it) and a third semiconductor nanocrystal (or an outer layer including it), the second semiconductor nanocrystal includes a second zinc chalcogenide containing zinc and selenium, and the third semiconductor nanocrystal includes a third zinc chalcogenide containing zinc and sulfur. The second zinc chalcogenide can have a composition different from that of the third zinc chalcogenide.

[0161] The intermediate shell or second semiconductor nanocrystal may include zinc, selenium and optionally sulfur. The second zinc chalcogenide may further include or may not further include sulfur. The intermediate shell or second semiconductor nanocrystal may include ZnSe, ZnSeS or a combination thereof. The outer shell or third semiconductor nanocrystal may include zinc, sulfur and optionally selenium. The outer shell or third semiconductor nanocrystal may include ZnS, ZnSSe or a combination thereof. The third zinc chalcogenide may further include or may not further include selenium. The outer shell may be the outermost layer of the semiconductor nanoparticle.

[0162] In the semiconductor nanoparticles of an embodiment, the thickness of the second semiconductor nanocrystal (or intermediate shell) may be 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, greater than or equal to about 2.6 nm, greater than or equal to about 2.7 nm, greater than or equal to about 2.8 nm, greater than or equal to about 2.9 nm, greater than or equal to about 3 nm, greater than or equal to about 3.1 nm, greater than or equal to about 3.2 nm, greater than or equal to about 3.3 nm, greater than or equal to about 3.4 nm, greater than or equal to about 3.5 nm, greater than or equal to about 3.6 nm, greater than or equal to about 3.7 nm, greater than or equal to about 3.8 nm, greater than or equal to about 3.8 nm, greater than or equal to about 4 nm, greater than or equal to about 4.1 nm, greater than or equal to about 4.2 nm, greater than or equal to about 4.3 nm, greater than or equal to about 4.4 nm, greater than or equal to about 4.5 nm, greater than or equal to about 4.6 nm, greater than or equal to about 4.7 nm, greater than or equal to about 4.8 nm, greater than or equal to about 4.9 nm, greater than or equal to about 5 nm, greater than or equal to about 5.1 nm, or greater than or equal to about 5.1 nm. The thickness of the second semiconductor nanocrystal (or intermediate shell) may be less than or equal to about 6.5 nm, less than or equal to about 6 nm, less than or equal to about 5.9 nm, less than or equal to about 5.8 nm, less than or equal to about 5.7 nm, less than or equal to about 5.6 nm, less than or equal to about 5.5 nm, less than or equal to about 5.4 nm, less than or equal to about 5.3 nm, less than or equal to about 5.2 nm, less than or equal to about 5.1 nm, less than or equal to about 5 nm, less than or equal to about 4.9 nm, less than or equal to about 4.8 nm, less than or equal to about 4.7 nm, less than or equal to about 4.6 nm, less than or equal to about 4.5 nm, less than or equal to about 4.4 nm, less than or equal to about 4.3 nm, less than or equal to about 4.2 nm, less than or equal to about 4 nm, less than or equal to about 3.4 nm, less than or equal to about 3.1 nm, less than or equal to about 2.8 nm, less than or equal to about 2.6 nm, or less than or equal to about 2.3 nm.

[0163] In the semiconductor nanoparticles of the embodiments, the thickness of the third semiconductor nanocrystal can be greater than or equal to about 0.2 nm, greater than or equal to about 0.23 nm, greater than or equal to about 0.25 nm, greater than or equal to about 0.27 nm, greater than or equal to about 0.31 nm, greater than or equal to about 0.33 nm, greater than or equal to about 0.35 nm, greater than or equal to about 0.37 nm, greater than or equal to about 0.39 nm, greater than or equal to about 0.41 nm, greater than or equal to about 0.43 nm, greater than or equal to about 0.45 nm, greater than or equal to about 0.47 nm, greater than or equal to about 0.49 nm, or greater than or equal to about 0.5 nm. The thickness of the third semiconductor nanocrystal (or outer layer) can be less than or equal to about 3 nm, less than or equal to about 2.5 nm, less than or equal to about 1.2 nm, less than or equal to about 1.1 nm, less than or equal to about 1 nm, less than or equal to about 0.9 nm, or less than or equal to about 0.8 nm.

[0164] In the semiconductor nanoparticles of the embodiments, the thickness of the semiconductor nanocrystal shell can be 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, greater than or equal to about 3 nm, greater than or equal to about 3.5 nm, greater than or equal to about 3.8 nm, greater than or equal to about 3.9 nm, greater than or equal to about 4 nm, greater than or equal to about 4.2 nm, greater than or equal to about 4.5 nm, greater than or equal to about 4.8 nm, greater than or equal to about 5 nm, greater than or equal to about 5.2 nm, greater than or equal to about 5.4 nm, or greater than or equal to about 5.5 nm. The thickness of the semiconductor nanocrystal shell can be less than or equal to about 20 nm, less than or equal to about 15 nm, less than or equal to about 10 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 5.7 nm, less than or equal to about 5.5 nm, less than or equal to about 5 nm, or less than or equal to about 4.5 nm.

[0165] In the semiconductor nanoparticles of the embodiments, the molar ratio of selenium to the sum of selenium and sulfur (Se:(Se + S)) can be greater than or equal to about 0.55:1, greater than or equal to about 0.56:1, greater than or equal to about 0.565:1, greater than or equal to about 0.57:1, greater than or equal to about 0.575:1, greater than or equal to about 0.58:1, greater than or equal to about 0.585:1, greater than or equal to about 0.59:1, greater than or equal to about 0.595:1, greater than or equal to about 0.6:1, greater than or equal to about 0.61:1, greater than or equal to about 0.62:1, greater than or equal to about 0.63:1, greater than or equal to about 0.64:1, or greater than or equal to about 0.65:1. The molar ratio of selenium to the sum of selenium and sulfur (Se:(Se + S)) can be less than or equal to about 0.99:1, less than or equal to about 0.97:1, less than or equal to about 0.95:1, less than or equal to about 0.94:1, less than or equal to about 0.92:1, less than or equal to about 0.88:1, less than or equal to about 0.86:1, less than or equal to about 0.84:1, less than or equal to about 0.82:1, less than or equal to about 0.78:1, less than or equal to about 0.76:1, less than or equal to about 0.74:1, less than or equal to about 0.72:1, less than or equal to about 0.7:1, less than or equal to about 0.68:1, less than or equal to about 0.66:1, less than or equal to about 0.64:1, less than or equal to about 0.62:1, less than or equal to about 0.61:1, less than or equal to about 0.6:1, less than or equal to about 0.58:1, or less than or equal to about 0.56:1.

[0166] In the semiconductor nanoparticles, the molar ratio of tellurium to sulfur (Te:S) can be greater than or equal to about 0.005:1, greater than or equal to about 0.0056:1, greater than or equal to about 0.0059:1, greater than or equal to about 0.006:1, greater than or equal to about 0.007:1, greater than or equal to about 0.008:1, greater than or equal to about 0.009:1, or greater than or equal to about 0.01:1. The molar ratio of tellurium to sulfur (Te:S) can be less than or equal to about 0.1:1, less than or equal to about 0.09:1, less than or equal to about 0.08:1, less than or equal to about 0.07:1, less than or equal to about 0.06:1, less than or equal to about 0.05:1, less than or equal to about 0.04:1, less than or equal to about 0.03:1, less than or equal to about 0.02:1, less than or equal to about 0.015:1, less than or equal to about 0.013:1, less than or equal to about 0.012:1, less than or equal to about 0.011:1, or less than or equal to about 0.01:1.

[0167] In the semiconductor nanoparticles, the molar ratio of tellurium to selenium (Te:Se) can be less than or equal to about 0.01:1, less than or equal to about 0.009:1, less than or equal to about 0.008:1, less than or equal to about 0.007:1, less than or equal to about 0.006:1, less than or equal to about 0.005:1, less than or equal to about 0.004:1, less than or equal to about 0.003:1, or less than or equal to about 0.002:1. The molar ratio of tellurium to selenium (Te:Se) can be greater than or equal to about 0.0001:1, greater than or equal to about 0.00015:1, greater than or equal to about 0.0002:1, greater than or equal to about 0.00025:1, greater than or equal to about 0.0003:1, greater than or equal to about 0.00035:1, greater than or equal to about 0.0004:1, greater than or equal to about 0.00045:1, greater than or equal to about 0.0005:1, greater than or equal to about 0.00055:1, greater than or equal to about 0.006:1, greater than or equal to about 0.00065:1, greater than or equal to about 0.0007:1, greater than or equal to about 0.00075:1, greater than or equal to about 0.0008:1, greater than or equal to about 0.00085:1, greater than or equal to about 0.0009:1, greater than or equal to about 0.00095:1, greater than or equal to about 0.001:1, greater than or equal to about 0.0015:1, greater than or equal to about 0.002:1, greater than or equal to about 0.0025:1, greater than or equal to about 0.003:1, greater than or equal to about 0.0035:1, greater than or equal to about 0.004:1, greater than or equal to about 0.0045:1, greater than or equal to about 0.005:1, greater than or equal to about 0.0055:1, greater than or equal to about 0.006:1, greater than or equal to about 0.0065:1, or greater than or equal to about 0.007:1. In the semiconductor nanoparticles of an embodiment, the molar ratio of tellurium to selenium (Te:Se) can be from about 0.001:1 to about 0.009:1, from about 0.002:1 to about 0.008:1, from about 0.003:1 to about 0.007:1, from about 0.004:1 to about 0.006:1, from about 0.0045:1 to about 0.0055:1, or a combination thereof.

[0168] In semiconductor nanoparticles, the molar ratio of tellurium to zinc (Te:Zn) can be less than or equal to about 0.009:1, less than or equal to about 0.0085:1, less than or equal to about 0.008:1, less than or equal to about 0.0075:1, less than or equal to about 0.007:1, less than or equal to about 0.0065:1, less than or equal to about 0.006:1, less than or equal to about 0.0055:1, less than or equal to about 0.005:1, less than or equal to about 0.0045:1, or less than or equal to about 0.004:1. The molar ratio of tellurium to zinc (Te:Zn) can be greater than or equal to about 0.0001:1, greater than or equal to about 0.0003:1, greater than or equal to about 0.0005:1, greater than or equal to about 0.0007:1, greater than or equal to about 0.0009:1, greater than or equal to about 0.001:1, greater than or equal to about 0.0012:1, greater than or equal to about 0.0014:1, greater than or equal to about 0.0016:1, greater than or equal to about 0.0018:1, greater than or equal to about 0.0019:1, greater than or equal to about 0.002:1, greater than or equal to about 0.0021:1, greater than or equal to about 0.0022:1, greater than or equal to about 0.0023:1, greater than or equal to about 0.0024:1, greater than or equal to about 0.0025:1, greater than or equal to about 0.0026:1, greater than or equal to about 0.0027:1, greater than or equal to about 0.0028:1, greater than or equal to about 0.0029:b1, greater than or equal to about 0.003:1, greater than or equal to about 0.0031:1, greater than or equal to about 0.0032:1, greater than or equal to about 0.0033:1, greater than or equal to about 0.0034:1, greater than or equal to about 0.0035:1, greater than or equal to about 0.0036:1, greater than or equal to about 0.0037:1, greater than or equal to about 0.0038:1, greater than or equal to about 0.0039:1, or greater than or equal to about 0.004:1.

[0169] In semiconductor nanoparticles, the molar ratio of Se to Zn (Se:Zn) can be less than about 1:1, such as less than or equal to about 0.7:1, less than or equal to about 0.6:1, less than or equal to about 0.55:1, 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. The molar ratio of Se to Zn (Se:Zn) can be greater than or equal to about 0.1:1, such as greater than or equal to about 0.2:1, greater than or equal to about 0.3:1, greater than or equal to about 0.4:1, greater than or equal to about 0.45:1, greater than or equal to about 0.46:1, greater than or equal to about 0.48:1, greater than or equal to about 0.5:1, greater than or equal to about 0.51:1, greater than or equal to about 0.52:1, greater than or equal to about 0.53:1, greater than or equal to about 0.54:1, greater than or equal to about 0.55:1, greater than or equal to about 0.56:1, greater than or equal to about 0.57:1, greater than or equal to about 0.58:1, greater than or equal to about 0.59:1, or greater than or equal to about 0.6:1.

[0170] In semiconductor nanoparticles, the molar ratio of Se + S to zinc ((S + Se):Zn) can be 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 0.81:1, greater than or equal to about 0.82:1, greater than or equal to about 0.83:1, greater than or equal to about 0.84:1, greater than or equal to about 0.85:1, greater than or equal to about 0.86:1, greater than or equal to about 0.87:1, greater than or equal to about 0.88:1, greater than or equal to about 0.89:1, greater than or equal to about 0.9:1, greater than or equal to about 0.91:1, greater than or equal to about 0.92:1, greater than or equal to about 0.93:1, greater than or equal to about 0.94:1, greater than or equal to about 0.95:1, greater than or equal to about 0.96:1, greater than or equal to about 0.97:1, greater than or equal to about 0.98:1, greater than or equal to about 0.99:1, or greater than or equal to about 1:1. In semiconductor nanoparticles, the molar ratio of Se + S to zinc ((S + Se):Zn) can be less than or equal to about 1.5:1, less than or equal to about 1.2:1, less than or equal to about 1:1, less than or equal to about 0.95:1, less than or equal to about 0.92:1, less than or equal to about 0.87:1, less than or equal to about 0.86:1, less than or equal to about 0.85:1, or less than or equal to about 0.83:1.

[0171] In the semiconductor nanoparticles, the molar ratio of sulfur to selenium (S:Se) can be less than or equal to about 0.8:1, less than or equal to about 0.77:1, less than or equal to about 0.75:1, less than or equal to about 0.73:1, less than or equal to about 0.7:1, less than or equal to about 0.69:1, less than or equal to about 0.68:1, less than or equal to about 0.67:1, less than or equal to about 0.66:1, less than or equal to about 0.65:1, less than or equal to about 0.64:1, less than or equal to about 0.63:1, less than or equal to about 0.62:1, or less than or equal to about 0.61:1. In the semiconductor nanoparticles of an embodiment, the molar ratio of sulfur to selenium (S:Se) can be 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 0.59:1, greater than or equal to about 0.6:1, greater than or equal to about 0.62:1, greater than or equal to about 0.64:1, greater than or equal to about 0.65:1, greater than or equal to about 0.67:1, greater than or equal to about 0.7:1, greater than or equal to about 0.74:1, or greater than or equal to about 0.76:1.

[0172] In the present specification, the molar ratio between elements can be confirmed by appropriate analysis methods (e.g., inductively coupled plasma-atomic emission spectrometry (ICP-AES), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy-energy dispersive spectrometry (TEM-EDX), scanning electron microscopy-energy dispersive spectrometry (SEM-EDX), X-ray fluorescence (XRF), etc.).

[0173] The semiconductor nanoparticles of the embodiments may have the particle sizes described herein. The particle size may be a diameter or an equivalent diameter calculated assuming a spherical shape. The particle size of the semiconductor nanoparticles can be confirmed by analysis using appropriate analytical methods such as electron microscopy. The (average) size of the above-mentioned semiconductor nanoparticles may be 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 11.5 nm, greater than or equal to about 12 nm, greater than or equal to about 12.5 nm, greater than or equal to about 12.8 nm, greater than or equal to about 13 nm, greater than or equal to about 13.5 nm, greater than or equal to about 14 nm, or greater than or equal to about 14.2 nm. The (average) size of the nanoparticles may be 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, 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, 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 17.5 nm, less than or equal to about 17 nm, less than or equal to about 16.5 nm, less than or equal to about 16 nm, less than or equal to about 15.5 nm, less than or equal to about 15 nm, less than or equal to about 14.5 nm, less than or equal to about 14 nm, less than or equal to about 13.5 nm, less than or equal to about 13 nm, less than or equal to about 12.5 nm, less than or equal to about 12 nm, or less than or equal to about 11.5 nm. The average (value) may be a mean value. The average (value) may be a median value. The numerical values set forth in this specification may include approximate values.

[0174] Semiconductor nanoparticles fabricated by the methods of the embodiments can exhibit improved luminescent properties (e.g., a quantum efficiency or absolute quantum efficiency of greater than or equal to about 90%, greater than or equal to about 92%, greater than or equal to about 94%, greater than or equal to about 96%, greater than or equal to about 97%, greater than or equal to about 98%, greater than or equal to about 99%, or greater than or equal to about 99.5%), while having a further reduced size by including a first semiconductor nanocrystal synthesized according to the methods described herein. The semiconductor nanoparticles of the embodiments can have an (average) particle size of less than or equal to about 10.9 nm, less than or equal to about 10.7 nm, less than or equal to about 10.5 nm, less than or equal to about 10.3 nm, less than or equal to about 10.1 nm, less than or equal to about 9.9 nm, less than or equal to about 9.7 nm, less than or equal to about 9.5 nm, less than or equal to about 9.3 nm, less than or equal to about 9.1 nm, less than or equal to about 9 nm, less than or equal to about 8.9 nm, less than or equal to about 8.8 nm, or less than or equal to about 8.7 nm. The semiconductor nanoparticles of the embodiments can have a particle size distribution (or standard deviation of particle size) of less than or equal to about 15%, less than or equal to about 14%, less than or equal to about 13%, less than or equal to about 12%, or less than or equal to about 11%. The particle size distribution can be greater than or equal to about 1%, greater than or equal to about 5%, or greater than or equal to about 7%.

[0175] The size of the particles can be easily and reproducibly determined from photographs of the particles (according to the manuals provided by the manufacturers, etc.) obtained by analyzing with electron microscopy (e.g., scanning electron microscopy or transmission electron microscopy) using known or commercially available image analysis tools (e.g., Image J). The image analysis tools and measurement conditions are not particularly limited.

[0176] In an embodiment, the semiconductor nanoparticles, the light-emitting layer including the semiconductor nanoparticles, or the electroluminescent device can be configured to emit blue light. For example, the semiconductor nanoparticles can emit blue light upon optical excitation or voltage application. The peak emission wavelength (maximum electroluminescent peak wavelength or maximum photoluminescent peak wavelength) of the blue light or the semiconductor nanoparticles can be in the range of greater than or equal to about 450 nm, greater than or equal to about 452 nm, greater than or equal to about 455 nm, greater than or equal to about 457 nm, greater than or equal to about 460 nm, greater than or equal to about 465 nm, greater than or equal to about 470 nm, or greater than or equal to about 477 nm and less than or equal to about 480 nm (e.g., less than or equal to about 470 nm, less than or equal to about 465 nm, less than or equal to about 460 nm, or less than or equal to about 455 nm).

[0177] The photoluminescence peak wavelength or electroluminescence peak wavelength of the semiconductor nanoparticles or the light-emitting layer can be greater than or equal to about 455 nm, greater than or equal to about 456 nm, greater than or equal to about 457 nm, greater than or equal to about 458 nm, greater than or equal to about 459 nm, greater than or equal to about 460 nm, greater than or equal to about 461 nm, greater than or equal to about 462 nm, greater than or equal to about 463 nm, greater than or equal to about 464 nm, greater than or equal to about 465 nm, greater than or equal to about 466 nm, greater than or equal to about 467 nm, greater than or equal to about 468 nm, greater than or equal to about 469 nm, or greater than or equal to about 470 nm. The (photo)luminescence peak wavelength of the semiconductor nanoparticles or the blue light can be less than or equal to about 480 nm, less than or equal to about 479 nm, less than or equal to about 478 nm, less than or equal to about 477 nm, less than or equal to about 476 nm, less than or equal to about 475 nm, less than or equal to about 474 nm, less than or equal to about 473 nm, less than or equal to about 471 nm, or less than or equal to about 470 nm. The photoluminescence peak wavelength is the peak emission wavelength of the light emitted by the semiconductor nanoparticles or the light-emitting layer including the same upon photoexcitation. The electroluminescence peak wavelength is the peak emission wavelength of the light emitted by the semiconductor nanoparticles or the light-emitting layer including the same when a voltage is applied.

[0178] When irradiated with light in a solution state or when fabricated as a light-emitting film, the semiconductor nanoparticles of the above-described embodiments can exhibit a quantum yield (e.g., absolute quantum yield) as follows: greater than about 75%, for example, greater than or equal to about 76%, greater than or equal to about 77%, greater than or equal to about 78%, greater than or equal to about 79%, greater than or equal to about 80%, greater than or equal to about 81%, greater than or equal to about 82%, greater than or equal to about 83%, greater than or equal to about 84%, greater than or equal to about 85%, greater than or equal to about 86%, greater than or equal to about 87%, greater than or equal to about 88%, or greater than or equal to about 89%. The semiconductor nanoparticles can exhibit a quantum yield in the range of about 76% to about 100%, about 80% to about 99%, about 84% to about 97%, about 86% to about 96%, about 87% to about 95%, about 88% to about 94%, about 89% to about 93%, about 90% to about 92%, or a combination thereof. The quantum yield can be an absolute quantum yield or a relative quantum yield.

[0179] When a voltage is applied or when excited by light, the semiconductor nanoparticles of the embodiments can exhibit a (maximum) luminescence peak with a full width at half maximum (FWHM) at a desired level. The FWHM can be in the range of about 5 nm to about 55 nm, about 8 nm to about 54 nm, about 9 nm to about 53 nm, about 10 nm to about 52 nm, about 11 nm to about 51 nm, about 12 nm to about 50 nm, about 13 nm to about 49 nm, about 14 nm to about 48 nm, about 15 nm to about 47 nm, about 16 nm to about 46 nm, about 17 nm to about 45 nm, about 18 nm to about 44 nm, about 19 nm to about 43 nm, about 20 nm to about 42 nm, about 21 nm to about 41 nm, about 22 nm to about 40 nm, about 25 nm to about 35 nm, about 28 nm to about 32 nm, or a combination thereof.

[0180] The semiconductor nanoparticles are configured to emit a first light when a voltage is applied, and the peak wavelength of the first light or the electroluminescence of the semiconductor nanoparticles can be greater than or equal to about 460 nm, or greater than or equal to about 461 nm and less than or equal to about 490 nm.

[0181] The core or the semiconductor nanoparticles can exhibit a reduced level of trap emission. In an embodiment, the core or the semiconductor nanoparticles can have a ratio of the intensity at the trap emission wavelength to the intensity at the peak emission wavelength in the photoluminescence spectrum that is less than or equal to about 0.24:1, less than or equal to about 0.23:1, less than or equal to about 0.19:1, less than or equal to about 0.18:1, less than or equal to about 0.15:1, less than or equal to about 0.14:1, less than or equal to about 0.13:1, or less than or equal to about 0.12:1. The trap emission wavelength can be 500 nm or (peak emission wavelength + 50 nm).

[0182] In an embodiment, the semiconductor nanoparticles can further include a halogen (e.g., fluorine, chlorine, or a combination thereof).

[0183] In an embodiment, the semiconductor nanoparticles can be manufactured according to the methods described herein. In an embodiment, the method of manufacturing semiconductor nanoparticles includes,

[0184] preparing a first semiconductor nanocrystal including zinc, tellurium, and selenium; and

[0185] heating a second zinc precursor and a chalcogen precursor in a second organic solvent in the presence of the first semiconductor nanocrystal and an organic ligand (e.g., a second organic ligand) to obtain semiconductor nanoparticles (e.g., including the first semiconductor nanocrystal and the second semiconductor nanocrystal),

[0186] The preparation of the first semiconductor nanocrystal includes:

[0187] Heating a first solution including a first zinc precursor, a first selenium precursor, a tellurium precursor, and optionally a first ligand in a first organic solvent at a reaction temperature, for example, for a first period of time; and

[0188] Further adding an additive to the heated first solution,

[0189] wherein the additive includes a second selenium precursor and the additive does not include tellurium. The additive may include a zinc compound, hydrofluoric acid (HF), or a combination thereof. Details of the semiconductor nanoparticles and the first semiconductor nanocrystal are as described herein.

[0190] By the method of the embodiment, the first semiconductor nanocrystal may have a tellurium distribution concentrated in the central portion as defined herein, and including the first semiconductor nanocrystal manufactured thereby (e.g., as a core) may reduce trap emission and improve the luminescence efficiency and lifetime characteristics in the EL device.

[0191] In an embodiment, the fabrication of the first semiconductor nanocrystal can be accomplished by: taking advantage of the difference in reactivity between the Te and Se precursors, controlling the distribution of Te by separate (batch) injection of some precursors, or a combination thereof. According to the method of the embodiment, the core (center) (or central portion) of the first semiconductor nanocrystal can be formed by heating a first solution including a first zinc precursor, a first selenium precursor, and a tellurium precursor in a first organic solvent at a reaction temperature for a first period of time (e.g., the nucleation time). During the formation of the core of these first semiconductor nanocrystals, the reaction system includes a Zn precursor, a Te precursor, and a Se precursor, thereby providing a ZnTeSe core (e.g., Figure 5A the core or central portion A having the composition of ZnTe a Se 1-a ) with a desired (e.g., relatively high) amount of Te. When confirmed by UV-Vis absorption spectroscopy analysis, these ZnTeSe cores may exhibit a first absorption peak of less than or equal to about 380 nm. Additionally, the UV-Vis absorption spectrum of these ZnTeSe cores may have a valley depth (VD) of greater than or equal to about 0.01, or greater than or equal to about 0.05, or greater than or equal to about 0.09, or greater than or equal to about 0.1, as defined by the following equation:

[0192] 1 - (Abs 谷 / Abs 第一 ) = VD

[0193] where Abs 第一 is the absorption at the first absorption peak, Abs 谷is the absorption at the lowest point of the valley adjacent to the first absorption peak.

[0194] The valley depth can be less than or equal to about 0.3, less than or equal to about 0.2, or less than or equal to about 0.15.

[0195] The first time period can be in the range of less than or equal to about 45 minutes, less than or equal to about 40 minutes, less than or equal to about 35 minutes, about 1 minute to about 30 minutes, about 2 minutes to about 25 minutes, about 3 minutes to about 20 minutes, about 4 minutes to about 18 minutes, about 5 minutes to about 15 minutes, about 6 minutes to about 14 minutes, about 7 minutes to about 13 minutes, about 8 minutes to about 12 minutes, about 9 minutes to about 12 minutes, about 10 minutes to about 11 minutes, or a combination thereof.

[0196] In an embodiment, a mixture comprising a first selenium precursor and a tellurium precursor can be added to a reaction medium comprising a zinc precursor to form a first solution. The mixture can further comprise, for example, additional organic ligands (e.g., arylphosphine compounds such as diphenylphosphine).

[0197] The heated first solution can comprise a ZnTeSe core (e.g., a ZnTeSe core with a high amount of Te or Figure 5A a core or central portion having ZnTe a Se 1-a composition), and an additive can be added thereto. After the addition of the additive, the first solution can be further heated at the reaction temperature for an additional time period. The additive comprises a second selenium precursor and optionally a zinc compound, hydrofluoric acid, or a combination thereof, wherein the additive does not contain tellurium.

[0198] According to the method of an embodiment, additional Se precursor (and optionally Zn precursor) is injected to grow the first semiconductor nanocrystal to a desired core size, and the first semiconductor nanocrystal thus fabricated can have an elemental concentration distribution (e.g., the tellurium distribution index (%) as described herein), wherein the amount of Te in the central portion (i.e., the ZnTeSe) core is higher than the amount of Te in the adjacent surface portion, and thus the Te:Se molar ratio in the entire first semiconductor nanocrystal can be lower than the Te:Se molar ratio in the ZnSeTe core. (Refer to Figure 5A )

[0199] Without wishing to be bound by a particular theory, it is believed that, as in the case of the first semiconductor nanocrystals in the present embodiment, the concentration of Te inside the crystal can contribute to reducing the oxidation of the core surface due to Te exposure and the occurrence of interface defects in the core / shell structure. The semiconductor nanoparticles manufactured according to the manufacturing method of the embodiment can exhibit optical properties at the molar ratios described herein. Semiconductor nanoparticles having a core with an increased internal Te concentration as in the present embodiment can exhibit improved performance (EQE, lifetime) in an electroluminescent device.

[0200] In manufacturing the first semiconductor nanocrystals according to the embodiment, the second selenium precursor can be the same as or different from the first selenium precursor.

[0201] In the method, per 1 mole of the first selenium precursor, the amount of the second selenium precursor can be greater than or equal to about 0.05 mole, greater than or equal to about 0.06 mole, greater than or equal to about 0.07 mole, greater than or equal to about 0.08 mole, greater than or equal to about 0.09 mole, greater than or equal to about 0.1 mole, greater than or equal to about 0.2 mole, greater than or equal to about 0.25 mole, greater than or equal to about 0.27 mole, greater than or equal to about 0.3 mole, greater than or equal to about 0.35 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 1.3 mole, greater than or equal to about 1.5 mole, greater than or equal to about 1.7 mole, greater than or equal to about 1.9 mole, greater than or equal to about 2 moles, greater than or equal to about 2.5 moles, greater than or equal to about 3 moles, greater than or equal to about 3.5 moles, greater than or equal to about 4 moles, greater than or equal to about 4.5 moles, greater than or equal to about 5 moles, greater than or equal to about 5.5 moles, greater than or equal to about 6 moles, greater than or equal to about 6.5 moles, greater than or equal to about 7 moles, greater than or equal to about 7.5 moles, greater than or equal to about 8 moles, greater than or equal to about 8.5 moles, greater than or equal to about 9 moles, or greater than or equal to about 9.5 moles. In the method, per 1 mole of the first selenium precursor, the amount of the second selenium precursor can be less than or equal to about 20 moles, less than or equal to about 18 moles, less than or equal to about 16 moles, less than or equal to about 14 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, less than or equal to about 1 mole, less than or equal to about 0.9 mole, less than or equal to about 0.7 mole, less than or equal to about 0.5 mole, less than or equal to about 0.3 mole, or less than or equal to about 0.1 mole.

[0202] In an embodiment, the amount of the first selenium precursor may be greater than the amount of the second selenium precursor. For example, it may be greater than or equal to about 10% or greater than or equal to about 20%. The second selenium precursor may be added one or more times, such as two, three, four or more times.

[0203] In an embodiment, the zinc compound added as an additive may be the same as or different from the zinc precursor. The zinc compound may be different from the zinc precursor. In an embodiment, the zinc compound may include zinc carboxylates such as zinc acetate, zinc oleate, zinc myristate, zinc stearate, etc., zinc acetylacetonate, zinc halides such as zinc chloride, zinc bromide, zinc iodide, zinc fluoride, etc., or a combination thereof. The zinc compound may be two or more types. For specific examples of other zinc compounds, reference may be made to the zinc precursors described herein.

[0204] In an embodiment, the zinc precursor may include dialkyl zinc. The zinc compound may include zinc carboxylate and zinc halide. The zinc halide may include zinc chloride. The additives may each be added one or more times, or two or more times. In an embodiment, the additives may include the second selenium precursor; and a zinc compound, hydrofluoric acid, or a combination thereof, which may be added as a mixture or separately. The second selenium precursor may be added in one go or injected in multiple separate portions.

[0205] In an embodiment, the additive (e.g., a zinc compound, hydrofluoric acid, or a combination thereof) may be added to the reaction system before or after adding the second selenium precursor. When the addition of the second selenium precursor is carried out two or more times, it may be added after the initial or first addition of the second selenium precursor, for example, before or together with the subsequent addition of the second selenium precursor.

[0206] In the method, per 1 mole of tellurium precursor, the total amount of the first selenium precursor and the second selenium precursor can be greater than or equal to about 5 moles, greater than or equal to about 10 moles, greater than or equal to about 11 moles, greater than or equal to about 12 moles, greater than or equal to about 13 moles, greater than or equal to about 15 moles, greater than or equal to about 17 moles, greater than or equal to about 20 moles, greater than or equal to about 23 moles, greater than or equal to about 25 moles, greater than or equal to about 28 moles, greater than or equal to about 29 moles, greater than or equal to about 30 moles, greater than or equal to about 35 moles, greater than or equal to about 39 moles, greater than or equal to about 43 moles, greater than or equal to about 44 moles, greater than or equal to about 48 moles, greater than or equal to about 49 moles, greater than or equal to about 50 moles, greater than or equal to about 52 moles, greater than or equal to about 54 moles, greater than or equal to about 55 moles, greater than or equal to about 57 moles, greater than or equal to about 58 moles, greater than or equal to about 59 moles, or greater than or equal to about 60 moles. In the method, per 1 mole of tellurium precursor, the total amount of the first selenium precursor and the second selenium precursor can be less than or equal to about 65 moles, less than or equal to about 63 moles, less than or equal to about 62 moles, less than or equal to about 60 moles, less than or equal to about 58 moles, less than or equal to about 55 moles, less than or equal to about 52 moles, less than or equal to about 50 moles, less than or equal to about 47 moles, less than or equal to about 42 moles, less than or equal to about 32 moles, less than or equal to about 29 moles, less than or equal to about 27 moles, less than or equal to about 24 moles, 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 16 moles, less than or equal to about 14 moles, or less than or equal to about 12 moles. In the method, per 1 mole of tellurium precursor, the total amount of the first selenium precursor and the second selenium precursor can be any suitable combination of the molar amounts described herein.

[0207] In the method of an embodiment, if added, the amount of the zinc compound can be appropriately adjusted in view of the desired composition and structure of the core. In an embodiment, per 1 mole of the second selenium precursor, the zinc compound can be present in an amount greater than or equal to about 0.05 moles, greater than or equal to about 0.1 moles, greater than or equal to about 0.3 moles, greater than or equal to about 0.5 moles, greater than or equal to about 0.7 moles, greater than or equal to about 0.9 moles, greater than or equal to about 1 mole, greater than or equal to about 1.1 moles, greater than or equal to about 1.2 moles, greater than or equal to about 1.3 moles, greater than or equal to about 1.4 moles, or greater than or equal to about 1.5 moles. In an embodiment, per 1 mole of the second selenium precursor, the zinc compound can be present in an amount less than or equal to about 10 moles, less than or equal to about 5 moles, less than or equal to about 3 moles, less than or equal to about 2 moles, less than or equal to about 1 mole, less than or equal to about 0.8 moles, or less than or equal to about 0.7 moles.

[0208] In an embodiment, when in use, based on 1 mole of the second selenium precursor, the amount of hydrofluoric acid may be greater than or equal to about 0.001 mole, greater than or equal to about 0.005 mole, 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, or greater than or equal to about 0.5 mole. In an embodiment, when in use, based on 1 mole of the second selenium precursor, the amount of hydrofluoric acid may be less than or equal to about 10 moles, less than or equal to about 5 moles, less than or equal to about 3 moles, less than or equal to about 2 moles, less than or equal to about 1 mole, less than or equal to about 0.8 mole, less than or equal to about 0.7 mole, less than or equal to about 0.4 mole, less than or equal to about 0.2 mole, less than or equal to about 0.1 mole, less than or equal to about 0.05 mole, or less than or equal to about 0.03 mole.

[0209] In the first semiconductor nanocrystal or core formation reaction, the ratio between the respective precursors (e.g., the molar ratio of a tellurium or selenium precursor to a zinc precursor) or the total reaction time can be appropriately selected in consideration of the emission wavelength of the final semiconductor nanoparticles, the reactivity of the precursors, the reaction temperature, etc. The reaction temperature for forming the first semiconductor nanocrystal can be appropriately selected. The first semiconductor nanocrystal formation reaction temperature may be greater than or equal to about 200 °C, greater than or equal to about 220 °C, greater than or equal to about 230 °C, greater than or equal to about 240 °C, greater than or equal to about 250 °C, greater than or equal to about 280 °C, or greater than or equal to about 290 °C. The reaction temperature for forming the first semiconductor nanocrystal can be in the range of less than or equal to about 350 °C, from about 210 °C to about 340 °C, such as from about 220 °C to about 330 °C, from about 230 °C to about 300 °C, from about 240 °C to about 290 °C, or a combination thereof. The total reaction time for forming the first semiconductor nanocrystal can be controlled by considering the desired core size and the reactivity of the precursors. For example, the total reaction time may be greater than or equal to about 5 minutes, greater than or equal to about 30 minutes, or greater than or equal to about 50 minutes, but is not limited thereto. For example, the reaction time may be less than or equal to about 2 hours, but is not limited thereto. The formed core may or may not be separated from the reaction system (e.g., by non-solvent precipitation). The separated core can be optionally washed and added to the subsequent reaction.

[0210] The method of the embodiment includes forming a semiconductor nanocrystal shell on the first semiconductor nanocrystal by reacting a zinc precursor and a chalcogen precursor in the presence of the first semiconductor nanocrystal manufactured, thereby obtaining the semiconductor nanoparticles of the embodiment. In an embodiment, the second zinc precursor and the chalcogen precursor can be heated in a second organic solvent in the presence of the first semiconductor nanocrystal and a second organic ligand.

[0211] Chalcogen precursors (e.g., for forming a semiconductor nanocrystal shell) can include selenium precursors, sulfur precursors, tellurium precursors, or combinations thereof. The chalcogen precursor can include a selenium precursor and a sulfur precursor. When the chalcogen precursor includes two or more precursors, each precursor can be added to the reaction system taking into account the composition of the final semiconductor nanoparticles.

[0212] In the method of an embodiment, a zinc precursor, a solvent, and optionally an organic ligand can be heated (or vacuum treated) under vacuum to a predetermined temperature (e.g., 100 °C or higher and 180 °C or lower), and the reaction system is heated to a reaction temperature for shell formation by changing to an inert gas atmosphere. A first semiconductor nanocrystal and a chalcogen precursor can be added to the reaction system. Reaction conditions for shell formation such as reaction temperature and time can be appropriately selected taking into account the desired shell composition.

[0213] Taking into account the final composition, the chalcogen precursor can be introduced simultaneously or sequentially to form a shell of a desired composition (e.g., having a gradient or multiple layers). In an embodiment, the zinc precursor and the selenium precursor can react to form a first shell layer (e.g., an intermediate shell layer), and then the zinc precursor and the sulfur precursor can react to form a second shell layer (e.g., an outer shell layer). In an embodiment, the zinc precursor, the selenium precursor, and the sulfur precursor can react together.

[0214] In an embodiment, reacting the zinc precursor and the chalcogen precursor can include reacting the zinc precursor and the selenium precursor to form a second semiconductor nanocrystal (or an intermediate shell layer), and reacting the zinc precursor and the sulfur precursor to form a third semiconductor nanocrystal (or an outer shell layer) (e.g., on the intermediate shell layer).

[0215] In the formation of a semiconductor nanocrystal shell, the amount of selenium precursor used per 1 mole of zinc precursor can be greater than or equal to about 0.1 mole, greater than or equal to about 0.3 mole, greater than or equal to about 0.5 mole, greater than or equal to about 0.65 mole, greater than or equal to about 0.7 mole, greater than or equal to about 0.9 mole, greater than or equal to about 1 mole, greater than or equal to about 1.5 moles, or greater than or equal to about 2 moles and 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, but is not limited thereto. In the formation of a semiconductor nanocrystal shell, the amount of sulfur precursor used per 1 mole of zinc precursor can be greater than or equal to about 0.1 mole, greater than or equal to about 0.3 mole, greater than or equal to about 0.5 mole, greater than or equal to about 0.7 mole, greater than or equal to about 0.9 mole, greater than or equal to about 1 mole, greater than or equal to about 1.3 moles, greater than or equal to about 1.5 moles, or greater than or equal to about 2 moles and 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, but is not limited thereto.

[0216] When two or more chalcogen precursors are used for the formation of the semiconductor nanocrystal shell, the amounts of the respective precursors used can be appropriately selected to control the thickness of each shell layer and the ratio therebetween as disclosed herein.

[0217] In the method of an embodiment, the amount of sulfur precursor used per 1 mole of selenium precursor can be greater than or equal to about 0.1 mole, greater than or equal to about 0.5 mole, greater than or equal to about 0.65 mole, greater than or equal to about 0.7 mole, greater than or equal to about 0.9 mole, greater than or equal to about 1 mole, greater than or equal to about 1.1 mole, greater than or equal to about 1.3 mole, greater than or equal to about 1.5 mole, greater than or equal to about 1.7 mole, or greater than or equal to about 2 moles. In the method, the amount of sulfur precursor used per 1 mole of selenium precursor can be less than or equal to about 3 moles, less than or equal to about 2.5 moles, less than or equal to about 2 moles, less than or equal to about 1.8 moles, less than or equal to about 1.6 moles, less than or equal to about 1.4 moles, less than or equal to about 1.2 moles, less than or equal to about 0.8 mole, or less than or equal to about 0.6 mole.

[0218] The addition of the chalcogen precursor (e.g., selenium precursor or sulfur precursor) can be carried out in one go or in a batchwise manner. In the method of an embodiment, the selenium precursor can be injected into the reaction system in batches (i.e., intermittently), and injected two or more times (three or more times, four or more times, five or more times, six or more times, seven or more times, eight or more times, or nine or more times) in equal or different aliquots. In the method, the sulfur precursor can be injected into the reaction system in one go, or can be injected in two or more portions (e.g., three or more times, four or more times, five or more times) in batches, optionally together with the zinc precursor. The selenium precursor and the sulfur precursor can be injected separately. The selenium precursor and the sulfur precursor can be injected without mixing. In an embodiment, the batchwise injection of the sulfur precursor can be started after the injection of a predetermined amount of the selenium precursor is completed.

[0219] The reaction temperature for shell formation can be greater than or equal to about 300 °C, greater than or equal to about 320 °C, greater than or equal to about 330 °C, greater than or equal to about 340 °C, greater than or equal to about 342 °C, greater than or equal to about 345 °C, greater than or equal to about 350 °C, greater than or equal to about 355 °C, or greater than or equal to about 360 °C. The reaction temperature for shell formation can be less than or equal to about 380 °C, less than or equal to about 370 °C, less than or equal to about 360 °C, less than or equal to about 355 °C, or less than or equal to about 350 °C.

[0220] The zinc precursor or zinc compound may include Zn metal powder, ZnO, alkylated Zn compounds (e.g., (C2 to C30 dialkyl) zinc such as diethyl zinc), Zn alkoxides (e.g., zinc ethoxide), Zn carboxylates (e.g., zinc acetate), Zn nitrate, Zn perchlorate, Zn sulfate, Zn acetylacetonate, Zn halides (e.g., zinc chloride), Zn cyanide, Zn hydroxide, zinc carbonate, zinc peroxide, or a combination thereof. Examples of zinc precursors 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.

[0221] The selenium precursor (or first selenium precursor, second selenium precursor, or a combination thereof) may include, but is not limited to, selenium - trioctylphosphine (Se - TOP), selenium - tributylphosphine (Se - TBP), selenium - triphenylphosphine (Se - TPP), selenium - diphenylphosphine (Se - DPP), or a combination thereof.

[0222] The tellurium precursor may include, but is not limited to, tellurium - tributylphosphine (Te - TBP), tellurium - triphenylphosphine (Te - TPP), tellurium - diphenylphosphine (Te - DPP), or a combination thereof.

[0223] The sulfur precursor may include hexanethiol, octanethiol, decanethiol, dodecanethiol, hexadecanethiol, mercaptopropylsilane, sulfur - trioctylphosphine (S - TOP), sulfur - tributylphosphine (S - TBP), sulfur - triphenylphosphine (S - TPP), sulfur - trioctylamine (S - TOA), bis(trialkylsilyl) sulfide, bis(trialkylsilylalkyl) sulfide (e.g., bis(trimethylsilylmethyl) sulfide), ammonium sulfide, sodium sulfide, or a combination thereof.

[0224] The organic solvent (first organic solvent, second organic solvent, or a combination thereof) may include: C6 - C22 primary amines such as oleylamine or cetylamine; 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 phosphines (e.g., trioctylphosphine) substituted with C6 to C22 alkyl groups, for example at least one (e.g., 1, 2, or 3) C6 to C22 alkyl groups; primary, secondary, or tertiary phosphine oxides (e.g., trioctylphosphine oxide) substituted with (e.g., 1, 2, or 3) C6 to C22 alkyl groups; C12 - C22 aromatic ethers such as phenyl ether or benzyl ether; or a combination thereof.

[0225] The semiconductor nanoparticles may include, for example, organic ligands (second organic ligands) on the surface. The organic ligands coordinate to the surface of the fabricated nanocrystals and can not only enable the nanocrystals to be well-dispersed in the solution phase but also affect the luminescent and electrical properties. The organic ligands (e.g., first organic ligand and / or second organic ligand) may include RCOOH, RNH2, R2NH, R3N, RSH, RH2PO, R2HPO, R3PO, RH2P, R2HP, R3P, ROH, RCOOR', RPO(OH)2, R2PO(OH) or a combination thereof (wherein R and R' each independently include a substituted or unsubstituted C1 to C40 (or C3 to C24) aliphatic hydrocarbon group, or a substituted or unsubstituted C6 to C40 (or C6 to C24) aromatic hydrocarbon group, or a combination thereof). The ligands may be used alone or as a mixture of two or more compounds.

[0226] Specific examples of the organic ligand compounds may include: methanethiol, ethanethiol, propanethiol, butanethiol, pentanethiol, hexanethiol, octanethiol, dodecanethiol, hexadecanethiol, octadecanethiol, benzyl mercaptan; methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, octylamine, dodecylamine, hexadecylamine, oleylamine, octadecylamine, dimethylamine, diethylamine, dipropylamine; formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, dodecanoic acid, hexadecanoic acid, octadecanoic acid, oleic acid, benzoic acid, palmitic acid, stearic acid; phosphines such as methylphosphine, ethylphosphine, propylphosphine, butylphosphine, pentylphosphine, tributylphosphine or trioctylphosphine; phosphine oxides such as methylphosphine oxide, ethylphosphine oxide, propylphosphine oxide, butylphosphine oxide or trioctylphosphine oxide; diphenylphosphine or triphenylphosphine compounds, or their oxide compounds; phosphonic acids, etc., but are not limited thereto. The organic ligand compounds may be used alone or as a mixture of two or more compounds. In an embodiment, the organic ligand compound may be a combination of RCOOH and an amine (e.g., RNH2, R2NH, R3N or a combination thereof).

[0227] After the reaction is completed, when a non-solvent is added to the reaction product, nanocrystal particles coordinated with a 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 a combination thereof and cannot dissolve the prepared nanocrystals. The non-solvent can be selected depending on the solvent used in the reaction and can include, for example, acetone, ethanol, butanol, isopropanol, ethylene glycol, water, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), diethyl ether, formaldehyde, acetaldehyde, solvents having solubility parameters similar to the foregoing non-solvents, or a combination thereof. The semiconductor nanocrystal particles can be separated by centrifugation, sedimentation, chromatography, or distillation. If desired, the separated nanocrystal particles can be added to a washing solvent and washed. The washing solvent is not particularly limited and can be insoluble in the nanocrystalline particles and can have a solubility parameter similar to that of the ligand and can include, for example, hexane, heptane, octane, chloroform, toluene, benzene, etc.

[0228] The semiconductor nanoparticles of the embodiment can be undispersible or insoluble in water, the foregoing non-solvent, or a combination thereof.

[0229] The semiconductor nanoparticles of the embodiment can be dispersed in the foregoing organic solvents. In an embodiment, the foregoing semiconductor nanoparticles can be dispersed in a substituted or unsubstituted C6 to C40 aliphatic hydrocarbon, a substituted or unsubstituted C6 to C40 aromatic hydrocarbon, or a combination thereof.

[0230] In the light-emitting device, the thickness of the light-emitting layer can be appropriately selected. In an embodiment, the light-emitting layer can include a single layer of nanoparticles. In an embodiment, the emission layer can include one or more single layers of nanoparticles, such as two or more layers, three or more layers, or four or more layers 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 light-emitting layer can have a thickness as follows: 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 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 light-emitting layer can have a thickness of, for example, about 10 nm to about 150 nm, about 20 nm to about 100 nm, or about 30 nm to about 50 nm.

[0231] The formation of the light-emitting layer can be carried out by: obtaining a composition including nanoparticles (configured to emit desired light), and applying or depositing it on a substrate or a charge assisting layer by an appropriate method (for example, by spin coating, inkjet printing, etc.).

[0232] In an embodiment, the light-emitting layer may include: a first layer including the above-described semiconductor nanoparticles (hereinafter referred to as first semiconductor nanoparticles), and a second layer adjacent to the first layer and including second semiconductor nanoparticles. Adjacent layers in the multi-layer light-emitting layer (e.g., the first light-emitting layer and the second light-emitting layer) may be configured to emit the same color (e.g., blue light). In an embodiment, the second semiconductor nanoparticles may include zinc chalcogenide, wherein the zinc chalcogenide may include zinc, selenium, and sulfur, and the semiconductor particles may not include cadmium and may emit blue light.

[0233] The formation of the multi-layer light-emitting layer may include: forming a layer of semiconductor nanoparticles, and contacting the formed layer with an organic solution (e.g., an alcohol solution) of a metal halide (e.g., zinc chloride) to exchange the ligands of the particles included in the formed layer. Alternatively, the formation of the multi-layer light-emitting layer may include: dispersing semiconductor nanoparticles in an organic solvent, adding an organic solution (e.g., an alcohol solution) of a metal halide (e.g., zinc chloride) thereto to obtain ligand-exchanged particles, and forming the first layer (or the second layer) therefrom. On the ligand-exchanged layer, a layer of semiconductor nanoparticles may be further provided. Thus, in the multi-layer structure, adjacent layers (e.g., the first light-emitting layer and the second light-emitting layer) may have the same or different compositions, ligands, or a combination thereof. In an embodiment, the light-emitting layer or the multi-layer light-emitting layer including two or more layers may have a varying amount of halogen in the thickness direction. In the (multi-layer) light-emitting layer according to an embodiment, the amount of halogen may increase toward the electron assisting layer. In the (multi-layer) light-emitting layer according to an embodiment, the amount of organic ligand may decrease toward the electron assisting layer. In the light-emitting layer according to an embodiment, the amount of halogen may decrease toward the electron assisting layer. In the (multi-layer) light-emitting layer according to an embodiment, the amount of organic ligand may increase toward the electron assisting layer.

[0234] The electroluminescent device may include a charge (hole or electron) assisting layer between a first electrode and a second electrode (e.g., an anode and a cathode). For example, the electroluminescent device may include a hole assisting layer 20 or an electron assisting layer 40 between the first electrode 10 and the light-emitting layer 30, between the second electrode 50 and the light-emitting layer 30, or a combination thereof. (Refer to Figure 2 and 3 )

[0235] The light-emitting device according to an embodiment may further include a hole assisting layer. The hole assisting layer 20 is located between the first electrode 10 and the light-emitting layer 30. The hole assisting layer 20 may include a hole injection layer, a hole transport layer (HTL), an electron blocking layer, or a combination thereof. The hole assisting layer 20 may be a single-component layer or a multi-layer structure in which adjacent layers include different components.

[0236] The hole auxiliary layer 20 may have a HOMO energy level that can match the HOMO energy level of the light-emitting layer 30 to enhance the mobility of holes transferred from the hole auxiliary layer 20 to the light-emitting layer 30. In an embodiment, the hole auxiliary layer 20 may include a hole injection layer near the first electrode 10 and a hole transport layer near the light-emitting layer 30.

[0237] The materials included in the hole auxiliary layer 20 (e.g., hole transport layer, hole injection layer, or electron blocking layer) are not particularly limited and may include, for example, poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)-diphenylamine) (TFB), polyarylamine (polyaryl amine), poly(N-vinylcarbazole), poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), polyaniline, polypyrrole, N,N,N',N'-tetrakis(4-methoxyphenyl)-benzidine (TPD), 4,4'-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), m-MTDATA (4,4',4''-tris[phenyl(m-tolyl)amino]triphenylamine), 4,4',4''-tris(N-carbazolyl)-triphenylamine (TCTA), 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), p-type metal oxides (e.g., NiO, WO3, MoO3, etc.), carbon-based materials such as graphene oxide, or a combination thereof, but are not limited thereto.

[0238] 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 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, for example, 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.

[0239] The electron auxiliary layer 40 is located between the light-emitting layer 30 and the second electrode 50. The electron auxiliary layer 40 may include, for example, an electron injection layer, an electron transport layer, a hole blocking layer, or a combination thereof. The electron auxiliary layer may include, for example, an electron injection layer (EIL) that promotes electron injection, an electron transport layer (ETL) that promotes electron transport, a hole blocking layer (HBL) that inhibits hole transport, or a combination thereof.

[0240] In an embodiment, an electron injection layer may be disposed between the electron transport layer and the second electrode. For example, a hole blocking layer may be disposed between the emission layer and the electron transport (injection) layer, but is not limited thereto. The thickness of each layer may be appropriately selected. For example, the thickness of each layer may be greater than or equal to about 1 nm and less than or equal to about 500 nm, but is not limited thereto. The electron injection layer may be an organic layer formed by deposition. The electron transport layer may include inorganic oxide nanoparticles or may be an organic layer formed by deposition.

[0241] The electron transport layer (ETL), the electron injection layer (EIL), the hole blocking layer, or a combination thereof may include, for example, 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA), bathocuproine (BCP), tris[3-(3-pyridyl)-mesityl]borane (3TPYMB), LiF, tris(8-hydroxyquinoline)aluminum (Alq3), tris(8-hydroxyquinoline)gallium (Gaq3), tris-(8-hydroxyquinoline)indium (Inq3), bis(8-hydroxyquinoline)zinc (Znq2), bis(2-(2-hydroxyphenyl)benzothiazole)zinc (Zn(BTZ)2), bis(10-hydroxybenzo[h]quinoline)beryllium (BeBq2), 8-(4-(4,6-bis(naphthalen-2-yl)-1,3,5-triazin-2-yl)phenyl)quinolone (ET204), lithium 8-hydroxyquinolate (Liq), n-type metal oxides (such as ZnO, HfO2, etc.), or a combination thereof, but is not limited thereto.

[0242] The electron assisting layer 40 may include an electron transport layer. The electron transport layer may include a plurality of nanoparticles. The plurality of nanoparticles may include a metal oxide containing zinc.

[0243] The metal oxide may include zinc oxide, zinc magnesium oxide, or a combination thereof. The metal oxide may include Zn 1- x M x O (where M is Mg, Ca, Zr, W, Li, Ti, Y, Al, or a combination thereof and 0 ≤ x ≤ 0.5). In an embodiment, Zn 1-x M x In M in O may be magnesium (Mg). In an embodiment, Zn 1-x M x In x in O may be greater than or equal to about 0.01 and less than or equal to about 0.3, such as less than or equal to about 0.25, less than or equal to about 0.2, or less than or equal to about 0.15.

[0244] The absolute value of the LUMO of the above-described nanoparticles included in the light-emitting layer may be greater than or 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, such as 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.

[0245] In an embodiment, the thickness of each of the electron assisting layers 40 (e.g., an electron injection layer, an electron transport layer, or a hole blocking layer) may be greater than or equal to about 5 nm, greater than or equal to about 6 nm, greater than or equal to about 7 nm, greater than or equal to about 8 nm, greater than or equal to about 9 nm, greater than or equal to about 10 nm, greater than or equal to about 11 nm, greater than or equal to about 12 nm, greater than or equal to about 13 nm, greater than or equal to about 14 nm, greater than or equal to about 15 nm, greater than or equal to about 16 nm, greater than or equal to about 17 nm, greater than or equal to about 18 nm, greater than or equal to about 19 nm, 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 40nm, less than or equal to about 30 nm, or less than or equal to about 25 nm, but is not limited thereto.

[0246] The device according to the embodiment may have a normal structure. In an embodiment, in the device, the first electrode 10 disposed on the transparent substrate 100 may include a transparent electrode based on a metal oxide (e.g., an ITO electrode), and the second electrode (cathode) 50 facing the first electrode 10 may include a conductive metal (e.g., having a relatively low work function, such as Mg, Al, etc.). A hole assisting layer 20 (e.g., a hole injection layer such as PEDOT:PSS, a p-type metal oxide, or a combination thereof; a hole transport layer such as TFB, polyvinylcarbazole (PVK), or a combination thereof; or a combination thereof) may be provided between the transparent electrode 10 and the light-emitting layer 30. The hole injection layer may be disposed adjacent to the transparent electrode, and the hole transport layer may be disposed adjacent to the light-emitting layer. An electron assisting layer 40 such as an electron injection / transport layer may be disposed between the light-emitting layer 30 and the second electrode 50. (Refer to Figure 2 )

[0247] The device according to an embodiment may have an inverted structure. The second electrode 50 disposed on the transparent substrate 100 may include a metal oxide-based transparent electrode (e.g., ITO), and the first electrode 10 facing the second electrode 50 may include a metal (e.g., having a relatively high work function, such as Au, Ag, etc.). For example, an (optionally doped) n-type metal oxide (crystalline Zn metal oxide) etc. may be provided as the electron assisting layer 40 (e.g., electron transport layer) between the transparent electrode 50 and the light emitting layer 30. A hole assisting layer 20 (e.g., a hole transport layer including TFB, PVK or a combination thereof; a hole injection layer including MoO3 or other p-type metal oxides; or a combination thereof) may be provided between the metal first electrode 10 and the light emitting layer 30. (Reference Figure 3 )

[0248] The foregoing device may be manufactured by an appropriate method. For example, an electroluminescent device may be manufactured as follows: forming a hole assisting layer (e.g., by deposition or coating) on a substrate on which an electrode is optionally formed, forming a light emitting layer including nanoparticles (e.g., a pattern of the foregoing semiconductor nanoparticles), and forming an electrode (e.g., by vapor deposition or coating) on the light emitting layer. The method of forming the electrode / hole assisting layer / electron assisting layer may be appropriately selected and is not particularly limited.

[0249] The electroluminescent device may be configured to emit blue light. The wavelength range of the blue light is as described above.

[0250] The electroluminescent device may have a maximum external quantum efficiency as follows: greater than or equal to about 4%, greater than or equal to about 5%, greater than or equal to about 6%, greater than or equal to about 7%, greater than or equal to about 8%, greater than or equal to about 9%, greater than or equal to about 10%, greater than or equal to about 10.5%, greater than or equal to about 11%, greater than or equal to about 11.5%, greater than or equal to about 12%, greater than or equal to about 12.5%, greater than or equal to about 13%, greater than or equal to about 13.5%, or greater than or equal to about 14%. The electroluminescent device may have a maximum external quantum efficiency as follows: less than or equal to about 50%, less than or equal to about 40%, less than or equal to about 30%, or less than or equal to about 20%.

[0251] The electroluminescent device may have a luminance greater than or equal to about 40,000 nits (cd / m 2) The maximum brightness is greater than or equal to about 50,000 nits, greater than or equal to about 60,000 nits, greater than or equal to about 70,000 nits, greater than or equal to about 80,000 nits, greater than or equal to about 90,000 nits, greater than or equal to about 95,000 nits, greater than or equal to about 100,000 nits, greater than or equal to about 105,000 nits, greater than or equal to about 110,000 nits, greater than or equal to about 115,000 nits, greater than or equal to about 120,000 nits, or greater than or equal to about 125,000 nits. The maximum brightness can be from about 3,000 nits to about 500,000 nits.

[0252] The electroluminescent device can exhibit an improved lifespan. In an embodiment, the lifespan of the electroluminescent device can be measured when driven at a predetermined initial brightness (e.g., about 146 nits or about 650 nits).

[0253] The lifespan T50 of the electroluminescent device can be greater than or equal to about 10 hours, greater than or equal to about 50 hours, greater than or equal to about 80 hours, greater than or equal to about 100 hours, greater than or equal to about 150 hours, greater than or equal to about 300 hours, greater than or equal to about 310 hours, greater than or equal to about 350 hours, greater than or equal to about 380 hours, greater than or equal to about 400 hours, greater than or equal to about 450 hours, or greater than or equal to about 500 hours, and T90 can be greater than or equal to about 10 hours, greater than or equal to about 15 hours, greater than or equal to about 20 hours, greater than or equal to about 25 hours, greater than or equal to about 30 hours, greater than or equal to about 35 hours, greater than or equal to about 40 hours, greater than or equal to about 50 hours, greater than or equal to about 75 hours, greater than or equal to about 100 hours, greater than or equal to about 125 hours, greater than or equal to about 150 hours, greater than or equal to about 175 hours, or greater than or equal to about 200 hours.

[0254] In an embodiment, T50 can be from about 150 hours to about 5,000 hours, from about 400 hours to about 4,000 hours, from about 500 hours to about 3,500 hours, from about 750 hours to about 2,000 hours, from about 1,000 hours to about 1,500 hours, or a combination thereof.

[0255] In an embodiment, T90 can be from about 13 hours to about 2,000 hours, from about 15 hours to about 1,800 hours, from about 18 hours to about 1,200 hours, from about 22 hours to about 1,000 hours, from about 31 hours to about 800 hours, from about 50 hours to about 700 hours, from about 60 hours to about 500 hours, from about 80 hours to about 400 hours, or a combination thereof.

[0256] Embodiments relate to a display device (e.g., a display panel) including an electroluminescent device according to an embodiment.

[0257] The display device (e.g., a display panel) may include a first pixel and a second pixel configured to emit light of a different color from the first pixel. In an embodiment, first light from a light-emitting layer may be extracted through a second electrode (e.g., in the Z direction) (refer to Figure 4 ). In an embodiment, the first light may be extracted through a (transparent) first electrode and an optional substrate 100 (refer to Figure 3 ). The light-emitting layer may be disposed within a pixel (or sub-pixel) in the display device (display panel) described later.

[0258] Figure 6 is a schematic cross-sectional view of a light-emitting device (RGB pixel). The light-emitting device includes a driving circuit and a substrate, a transparent electrode 10, a pixel defining layer PDL, a hole assisting layer 20, a red light-emitting layer 30R, a green light-emitting layer 30G, a blue light-emitting layer 30B, an electron assisting layer 40, and a second electrode 50.

[0259] Refer to Figure 7 , according to an embodiment, the display panel 1000 may include a display area 1000D for displaying an image and an optional non-display area 1000P located around the display area 1000D and having an adhesive material disposed thereon.

[0260] The display area 1000D may include a plurality of pixels PX arranged along rows (e.g., in the x direction), columns (e.g., in the y direction), or a combination thereof, and each pixel PX may include a plurality of sub-pixels PX1, PX2, and PX3 that display different colors. As an example, a configuration in which three sub-pixels PX1, PX2, and PX3 form one pixel is shown, but the present disclosure is not limited thereto, and may further include additional sub-pixels such as white sub-pixels, or may further include one or more sub-pixels that display the same color. The plurality of sub-pixels PX may be arranged, for example, in a Bayer matrix, a PenTile matrix, a diamond matrix, or a combination thereof, but is not limited thereto.

[0261] Each of the sub-pixels PX1, PX2, and PX3 may display the following colors: the primary colors or a combination of the primary colors, such as red, green, blue, or a combination thereof. For example, the first sub-pixel PX1 may display red, the second sub-pixel PX2 may display green, and the third sub-pixel PX3 may display blue.

[0262] Although the accompanying drawings illustrate examples in which all sub-pixels have the same size, the present disclosure is not limited thereto, and a sub-pixel (e.g., at least one of the sub-pixels) may be larger or smaller than other sub-pixels. Although the accompanying drawings illustrate examples in which all sub-pixels have the same shape, the present disclosure is not limited thereto, and a sub-pixel (e.g., at least one of the sub-pixels) may have a shape different from that of other sub-pixels.

[0263] In an embodiment, the display panel may include a light-emitting panel 100, and the light-emitting panel 100 includes a substrate 110, a buffer layer 111, thin film transistors (TFTs), and light-emitting devices 180. The display panel may include circuit elements for switching (turning on and off) each light-emitting device, driving each light-emitting device, or a combination thereof.

[0264] Reference Figure 8 , in the light-emitting panel, the light-emitting devices 180 may be disposed in the respective sub-pixels PX1, PX2, and PX3, and the light-emitting devices 180 disposed in the sub-pixels PX1, PX2, and PX3 may be independently driven. The sub-pixels may include blue sub-pixels, red sub-pixels, or green sub-pixels. The light-emitting device 180 (e.g., at least one of the light-emitting devices 180) may be an electroluminescent device according to an embodiment.

[0265] The substrate 110 is as described above. The buffer layer 111 may include an organic, inorganic, or organic-inorganic material, and may include, for example, an oxide, a nitride, or a oxynitride, and may include, for example, silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof, but is not limited thereto. The buffer layer 111 may have one layer or two or more layers, and may cover the entire surface of the lower substrate 110. The buffer layer 111 may be omitted.

[0266] The thin film transistor TFT may be a three-terminal device for switching the light-emitting device 180, driving the light-emitting device 180, or a combination thereof, and one or more may be included for each sub-pixel. The thin film transistor TFT includes a gate electrode 124, a semiconductor layer 154 overlapping the gate electrode 124, a gate insulating film 140 between the gate electrode 124 and the semiconductor layer 154, and a source electrode 173 and a drain electrode 175 electrically connected to the semiconductor layer 154. The accompanying drawings show a coplanar top-gate structure as an example, but are not limited thereto, and may have different structures.

[0267] The gate electrode 124 is electrically connected to a gate line (not shown), and may include a low-resistance metal such as aluminum (Al), molybdenum (Mo), copper (Cu), titanium (Ti), silver (Ag), gold (Au), an alloy thereof, or a combination thereof, but is not limited thereto.

[0268] The semiconductor layer 154 may be an inorganic semiconductor such as amorphous silicon, polycrystalline silicon, an oxide semiconductor; an organic semiconductor; an organic-inorganic semiconductor; or a combination thereof. For example, the semiconductor layer 154 may include an oxide semiconductor containing indium (In), zinc (Zn), tin (Sn), gallium (Ga), or a combination thereof, and the oxide semiconductor may include, for example, indium-gallium-zinc oxide, zinc-tin oxide, or a combination thereof, but is not limited thereto. The semiconductor layer 154 may include a channel region and doped regions, and the doped regions are disposed on both sides of the channel region and are electrically connected to the source electrode 173 and the drain electrode 175, respectively.

[0269] The gate insulating film 140 may include an organic, inorganic, or organic-inorganic material, and may include, for example, an oxide, a nitride, or a oxynitride, and may include, for example, silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof, but is not limited thereto. The drawings show an example where the gate insulating film 140 is formed on the entire surface of the lower substrate 110, but is not limited thereto, and may be selectively formed between the gate electrode 124 and the semiconductor 154. The gate insulating film 140 may have one layer or two or more layers.

[0270] The source electrode 173 and the drain electrode 175 may include a low-resistance metal such as aluminum (Al), molybdenum (Mo), copper (Cu), titanium (Ti), silver (Ag), gold (Au), an alloy thereof, or a combination thereof, but is not limited thereto. The source electrode 173 and the drain electrode 175 may each be electrically connected to the doped region of the semiconductor layer 154. The source electrode 173 is electrically connected to a data line (not shown), and the drain electrode 175 is electrically connected to the light-emitting device 180 described above.

[0271] An interlayer insulating film 145 is additionally formed between the gate electrode 124 and the source / drain electrodes 173 and 175. The interlayer insulating film 145 may include an organic, inorganic, or organic-inorganic material, and may include, for example, an oxide, a nitride, or a oxynitride, and may include, for example, silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof, but is not limited thereto. The interlayer insulating film 145 may have one layer or two or more layers.

[0272] In an embodiment, the protective film 160 may be formed on the thin-film transistor TFT. The protective film 160 may be, for example, a passivation film, but is not limited thereto. The protective film 160 may include an organic, inorganic, or organic-inorganic material, and may include polyacrylic acid, polyimide, polyamide, polyamideimide, or a combination thereof, but is not limited thereto. The protective film 160 may have one or more layers.

[0273] In an embodiment, one of the first electrodes 1 and 10 and the second electrodes 5 and 50 may be a pixel electrode connected to the TFT, and the other may be a common electrode.

[0274] The electroluminescent device of the embodiment or the display device including the same may be used in a top emission mode, a bottom emission mode, a double-sided emission mode, or a combination thereof.

[0275] In an embodiment, the first electrode 10 may be a light-transmissive electrode, and the second electrode 50 may be a reflective electrode, and the display panel may be a bottom emission type display panel that emits light toward the first electrode 10 and the substrate 110 if present. In an embodiment, the first electrode 10 may be a reflective electrode, and the second electrode 50 may be a light-transmissive electrode, and the display panel may be a top emission type display panel that emits light opposite to the first electrode 10 and the substrate 100 if present. In an embodiment, both the first electrode and the second electrode may be light-transmissive electrodes, and the display panel 1000 may be a double-sided emission type display panel that emits light toward the substrate 110 side and the opposite side of the substrate 110.

[0276] The display device may include a VR / AR device, a portable terminal device, a monitor, a laptop computer, a television, an electronic board, a camera, or an electrical component (e.g., for an automobile).

[0277] Hereinafter, specific examples are shown. However, these examples are exemplary, and the present disclosure is not limited thereto.

[0278] Examples

[0279] Analysis method

[0280] 1. Photoluminescence and UV-Vis absorption analysis

[0281] (1) At room temperature, use a Hitachi F-7000 spectrophotometer or a Hamamatsu QY instrument (Quantaurus-QY absolute PL quantum yield spectrophotometer C11347-11) to obtain the photoluminescence spectrum and the absolute quantum yield (QY) of the nanoparticles at an irradiation wavelength of 372 nanometers (nm).

[0282] (2) Use an Agilent Cary 5000 spectrophotometer to perform UV spectral analysis to obtain a UV-visible absorption spectrum.

[0283] 2. Transmission electron microscopy analysis

[0284] Use a UT F30 Tecnai electron microscope to obtain a transmission electron microscopy image of the fabricated nanoparticles.

[0285] 3. Inductively coupled plasma (ICP) analysis

[0286] Perform inductively coupled plasma atomic emission spectrometry (ICP-AES) using a Shimadzu ICPS-8100.

[0287] 4. Electroluminescence property analysis and lifetime measurement

[0288] When a voltage is applied, the current according to the voltage is measured using a Keithley 2635B source meter, and the EL emission brightness is measured using a CS2000 spectrometer.

[0289] T90 (h): The time (hours) taken for the brightness to reach 90% based on the initial brightness of 100% when driven at a predetermined brightness (e.g., 650 nits) is measured.

[0290] T50 (h): The time (hours) taken for the brightness to reach 50% based on the initial brightness of 100% when driven at a predetermined brightness (e.g., 650 nits) is measured.

[0291] The following syntheses are carried out under an inert gas atmosphere (under nitrogen flow conditions) unless otherwise stated. The precursor amounts are in molar content unless otherwise stated.

[0292] Reference Example: Synthesis of ZnMgO nanoparticles

[0293] Zinc acetate dihydrate and magnesium acetate tetrahydrate are added to a reactor containing dimethyl sulfoxide and heated in air at 60 °C. Subsequently, an ethanol solution of tetramethylammonium hydroxide pentahydrate is added to the reactor. After stirring the mixture for 1 hour, a precipitate is formed and separated from the reaction mixture using a centrifuge. The precipitate is dispersed in ethanol to obtain Zn 1- x Mg x O nanoparticles (x = 0.15). The obtained nanoparticles are subjected to transmission electron microscopy analysis. The particles have an average size of about 3 nm.

[0294] Preparation Example 1:

[0295] 1. Selenium (Se), sulfur (S), and tellurium (Te) are dispersed in trioctylphosphine (TOP) to obtain 2M Se / TOP stock solution, 1M S / TOP stock solution, and 0.1 molar concentration (M) Te / TOP stock solution.

[0296] Oleic acid and oleylamine are placed in a reaction flask including trioctylamine and heated under vacuum at 120 °C, and after 15 minutes, the atmosphere inside the reactor is changed to nitrogen.

[0297] Heat the reaction flask to 240 °C, inject 9 millimoles (mmol) of diethylzinc, and then immediately add a mixture of Se / TOP stock solution (the first selenium precursor) (3.5 mmol), Te / TOP stock solution (0.225 mmol), and DPP (4.5 mmol), and conduct the first reaction for 10 minutes. Then, add the second selenium precursor (1.0 mmol). After 30 minutes, quickly cool the reaction flask to room temperature, add ethanol to the reaction flask, and obtain the first ZnSeTe semiconductor nanocrystals by centrifugation. Disperse the first semiconductor nanocrystals in hexane to obtain the first semiconductor nanocrystal solution.

[0298] According to 1 mole of the Te precursor, the total amount of the second selenium precursor and the first selenium precursor is 20 moles, and the molar ratio between the first selenium precursor and the second selenium precursor is 7:2.

[0299] After the first reaction, collect samples from the reaction solution, and undergo UV-Vis absorption spectrometry, and the results are shown in Figure 9 . From Figure 9 the results, the ZnTeSe core in the reaction solution has a valley depth (VD) of 0.1 or higher in the UV-Vis absorption spectrum.

[0300] Perform ICP analysis and photoluminescence spectrometry analysis on the fabricated first semiconductor nanocrystals, and the results are summarized in Table 4.

[0301] 2. Add zinc acetate (4.8 mmol) and oleic acid (9.6 mmol) to a reaction flask containing 80 milliliters (mL) of trioctylamine (TOA) and conduct vacuum treatment at 120 °C. Replace the inside of the flask with nitrogen (N2), heat the reaction flask to 280 °C, and then cool it to 240 °C. Quickly add the first semiconductor nanocrystal solution to the reaction flask, then inject an HF aqueous solution diluted with acetone (10 weight percent (wt%), 0.44 mL) and ZnCl2 (0.09 mmol), and heat the flask to 340 °C. Then, add a zinc precursor (ZnOA2, zinc oleate, 12 mmol) and Se / TOP stock solution (8 mmol) and conduct the reaction for 30 minutes. Subsequently, add the S / TOP stock solution (11.2 mmol) together with an additional zinc precursor (16.8 mmol), and continue the reaction for 90 minutes.

[0302] The amount of the selenium precursor used according to 1 mole of the zinc precursor is 0.48 mole, and for the formation of the ZnS shell, the amount of the sulfur precursor used according to 1 mole of the zinc precursor is 0.67 mole.

[0303] After the reaction is completed, the reactor is cooled to room temperature and ethanol is added to the reaction solution to precipitate the fabricated nanoparticles. The precipitate is collected by centrifugation, and the obtained nanoparticles are dispersed in octane.

[0304] 3. ICP analysis was performed on the fabricated semiconductor nanoparticles, and the results are summarized in Table 1.

[0305] Photoluminescence analysis was performed on the fabricated semiconductor nanoparticles, and the results are shown in Figure 10 . The photoluminescence peak wavelength of the semiconductor nanoparticles of Example 1 was 457 nm, and the full width at half maximum was 38 nm. In Figure 10 , the x-axis represents the peak emission wavelength as 0 nm, 50 nm is the trap emission wavelength, and the y-axis is normalized based on the intensity at the maximum emission peak wavelength. Transmission electron microscopy (TEM) analysis was performed on the fabricated semiconductor nanoparticles, and the results are shown in Figure 11 .

[0306] Preparation of Comparative Example 1:

[0307] 1. The first semiconductor nanocrystal was fabricated in the same manner as in Preparation of Example 1, except that 4.5 mmol of the first selenium precursor was used instead of the second selenium precursor. ICP analysis and photoluminescence spectrometry analysis were performed on the fabricated first semiconductor nanocrystal, and the results are summarized in Table 4.

[0308] 2. Semiconductor nanoparticles were obtained in the same manner as in Preparation of Example 1, except that the above-obtained first semiconductor nanocrystal was used.

[0309] 3. ICP analysis was performed on the fabricated semiconductor nanoparticles, and the results are summarized in Table 1. TEM analysis was performed on the fabricated semiconductor nanoparticles, and the results are shown in Table 2 and Figure 12 . Photoluminescence analysis was performed on the fabricated semiconductor nanoparticles, and the results are summarized in Table 2. The photoluminescence peak wavelength of the semiconductor nanoparticles of Comparative Example 1 was 459 nm and the full width at half maximum was about 40 nm.

[0310] Preparation of Example 2:

[0311] 1. Selenium (Se), sulfur (S), and tellurium (Te) were dispersed in trioctylphosphine (TOP) to obtain 2M Se / TOP stock solution, 1M S / TOP stock solution, and 0.1 M Te / TOP stock solution. Zinc acetate and oleic acid were placed together in a 300 mL reaction flask containing TOA and treated under vacuum at 120 °C to obtain zinc oleate.

[0312] Oleic acid (13.5 mmol) and oleylamine (9 mmol) were added to a reaction flask containing 50 mL of trioctylamine and heated under vacuum at 120 °C. After 15 minutes, the atmosphere inside the reactor was changed to nitrogen. The reaction flask was heated to 240 °C, 9 mmol of diethylzinc was injected, and then a mixture of Se / TOP stock solution (first selenium precursor) (3.5 mmol), Te / TOP stock solution (0.225 mmol), and DPP (4.5 mmol) was added immediately, and the first reaction was carried out for 10 minutes. Then, a second selenium precursor (1.0 mmol) was added and the reaction was continued for an additional 20 minutes.

[0313] Then, a zinc compound (zinc oleate) (3.75 mmol) and a second selenium precursor (2.5 mmol) were added, and the reaction flask was heated to 340 °C. After 10 minutes, the reaction flask was rapidly cooled to room temperature, ethanol was added to the reaction flask, and ZnSeTe first semiconductor nanocrystals were obtained by centrifugation. The first semiconductor nanocrystals were dispersed in hexane to obtain a first semiconductor nanocrystal solution.

[0314] The fabricated first semiconductor nanocrystals were subjected to ICP analysis and photoluminescence spectrometry analysis, and the results are summarized in Table 4.

[0315] 2. Semiconductor nanoparticles were obtained in the same manner as in Preparation Example 1, except that the first semiconductor nanocrystals obtained above were used and the shell formation conditions (precursor content) were partially adjusted to obtain the composition set forth in Table 1.

[0316] 3. The fabricated semiconductor nanoparticles were subjected to ICP analysis, and the results are summarized in Table 1.

[0317] Preparation Example 3:

[0318] 1. The first semiconductor nanocrystals were prepared in the same manner as in Preparation Example 2, except that zinc oleate and zinc chloride were added as zinc compounds. The fabricated first semiconductor nanocrystals were subjected to ICP analysis and photoluminescence spectrometry analysis, and the results are summarized in Table 4.

[0319] 2. Semiconductor nanoparticles were obtained in the same manner as in Preparation Example 2, except that the first semiconductor nanocrystals obtained above were used.

[0320] 3. The fabricated semiconductor nanoparticles were subjected to ICP analysis, and the results are summarized in Table 1.

[0321] Table 1

[0322]

[0323] Table 2

[0324]

[0325] PLQY: Absolute quantum efficiency (photoluminescence quantum yield)

[0326] PWL: Peak emission wavelength

[0327] Table 4

[0328]

[0329] PWL: Peak emission wavelength

[0330] As can be seen from Table 4, in the case of the first semiconductor nanocrystals formed in the preparation examples, the Te:Se molar ratio is less than that in the preparation comparative examples, but the peak emission wavelength is longer than that in the preparation comparative examples.

[0331] Example 1

[0332] Using the semiconductor nanoparticles fabricated in Preparation Example 1, a light-emitting device having the following structure was fabricated using the following method: indium tin oxide (ITO) / poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) (300 Å) / poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)-diphenylamine) (TFB) (250 Å) / semiconductor nanoparticle emission layer (360 Å) / ZnMgO (240 Å) / Al, and the electroluminescence properties were measured:

[0333] On a glass substrate on which an ITO electrode (first electrode) was deposited, PEDOT:PSS and TFB layers were formed as a hole injection layer and a hole transport layer by spin coating. A light-emitting layer was formed by spin coating the semiconductor nanoparticle solution prepared in Preparation Example 1 on the formed TFB layer (25 nm). A zinc oxide magnesium nanoparticle layer was formed as an electron assisting layer on the light-emitting layer, and then an Al electrode was formed by deposition to fabricate a light-emitting device.

[0334] The electroluminescence properties and lifetime of the fabricated device were measured. It was confirmed that the EQE and T90 of the device were greater than or equal to 13% and 18 hours. The electroluminescence properties are summarized in Table 3.

[0335] Comparative Example 1

[0336] An electroluminescent device was fabricated in the same manner as in Example 1, except that the semiconductor nanoparticles fabricated in Preparation Comparative Example 1 were used.

[0337] The electroluminescence properties and lifetime of the fabricated device were measured. The electroluminescence properties are summarized in Table 3.

[0338] Table 3

[0339]

[0340] Relative maximum EQE: Maximum external quantum efficiency of a given device / Maximum external quantum efficiency of the device in Comparative Example 1

[0341] Relative maximum luminance: Maximum luminance of a given device / Maximum luminance of the device in Comparative Example 1

[0342] EL maximum at 650 nits: Peak wavelength of electroluminescence at 650 nits

[0343] Relative T90: T90 (hours) of a given device / T90 (hours) of the device in Comparative Example 1

[0344] Relative T50: T50 (hours) of a given device / T50 (hours) of the device in Comparative Example 1

[0345] From the results in Table 3, compared with the device of Comparative Example 1, the device of Example 1 can exhibit improved electroluminescent properties and increased lifetime.

[0346] Although the present disclosure has been described in connection with the content of presently considered practical example embodiments, it will be understood that the present invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A method for manufacturing semiconductor nanoparticles, comprising preparing a first semiconductor nanocrystal comprising zinc, tellurium, and selenium, wherein the preparation of the first semiconductor nanocrystal comprises: heating a first solution comprising a first zinc precursor, a first selenium precursor, and a tellurium precursor in a first organic solvent at a reaction temperature to form a heated first solution; and adding an additive to the heated first solution, wherein the additive comprises a second selenium precursor and the additive does not comprise tellurium, and the semiconductor nanoparticles are configured to emit blue light.

2. The method according to claim 1, wherein the method further comprises heating a second zinc precursor and a chalcogen precursor in a second organic solvent in the presence of the first semiconductor nanocrystal and an organic ligand to obtain semiconductor nanoparticles.

3. The method according to claim 1, wherein the additive further comprises a zinc compound, hydrofluoric acid, or a combination thereof.

4. The method according to claim 1, wherein based on 1 mole of the first selenium precursor, the amount of the second selenium precursor is 0.1 to 10 moles.

5. The method according to claim 1, wherein the additive comprises the second selenium precursor and a zinc compound, the first selenium precursor is the same as or different from the second selenium precursor, the first zinc precursor is different from the zinc compound, and the zinc compound comprises zinc carboxylate, zinc halide, or a combination thereof.

6. The method according to claim 5, wherein the first zinc precursor comprises dialkylzinc, and the zinc compound comprises zinc carboxylate and optionally zinc chloride.

7. The method according to claim 1, wherein based on 1 mole of the tellurium precursor, the total amount of the first selenium precursor and the second selenium precursor is greater than or equal to 10 moles and less than or equal to 55 moles, and the molar ratio between the first selenium precursor and the second selenium precursor is 1:0.1 to 1:0.

5.

8. The method according to claim 1, wherein in the semiconductor nanoparticles, the molar ratio of tellurium to selenium is greater than or equal to 0.0005:1 and less than or equal to 0.008:

1.

9. The method according to claim 1, wherein in the semiconductor nanoparticles, the molar ratio of selenium to the sum of sulfur and selenium is 0.55:1 to 0.65:1, or the molar ratio of tellurium to sulfur is 0.005:1 to 0.05:1, or the molar ratio of selenium to zinc is 0.5:1 to 0.6:

1.

10. The method according to claim 1, wherein the semiconductor nanoparticles are configured to emit a first light when a voltage is applied, and the electroluminescence peak wavelength of the first light is greater than 460 nm and less than or equal to 490 nm.

11. Semiconductor nanoparticles, comprising zinc, tellurium, selenium, and sulfur, wherein the semiconductor nanoparticles do not comprise cadmium, in the semiconductor nanoparticles, the molar ratio of tellurium to selenium is greater than or equal to 0.0005:1 and less than or equal to 0.008:1, the semiconductor nanoparticles have an average particle size of less than 10.3 nm, and the semiconductor nanoparticles have an absolute quantum efficiency of greater than or equal to 90%.

12. The semiconductor nanoparticles according to claim 11, wherein The semiconductor nanoparticles have an average particle size of less than 10 nanometers and an absolute quantum efficiency of greater than or equal to 93%.

13. The semiconductor nanoparticles according to claim 11, wherein in the emission spectrum, the semiconductor nanoparticles exhibit a ratio of the intensity at peak emission wavelength +50 nanometers to the intensity at the peak emission wavelength of less than or equal to 0.12:

1.

14. The semiconductor nanoparticles according to claim 11, wherein the semiconductor nanoparticles are manufactured by the method according to any one of claims 1-10.

15. An electroluminescent device, comprising: a first electrode and a second electrode spaced apart from each other, and a light-emitting layer disposed between the first electrode and the second electrode, the light-emitting layer comprising the semiconductor nanoparticles according to any one of claims 11-14.

16. The electroluminescent device according to claim 15, wherein the semiconductor nanoparticles exhibit a ratio of the intensity at peak emission wavelength +50 nanometers to the intensity at the peak emission wavelength in the emission spectrum of less than or equal to 0.25:

1.

17. The electroluminescent device according to claim 15, wherein in the semiconductor nanoparticles, the molar ratio of tellurium to selenium is less than or equal to 0.007:1, and the peak emission wavelength of the first light is less than or equal to 462 nanometers.

18. The electroluminescent device according to claim 15, wherein the electroluminescent device has a T90 of greater than or equal to 15 hours at the start at 650 nits, and a maximum external quantum efficiency of greater than or equal to 7%.

19. The electroluminescent device according to claim 15, wherein, in the semiconductor nanoparticles, the molar ratio of selenium to the sum of sulfur and selenium is 0.55:1 to 0.65:1, or the molar ratio of tellurium to sulfur is 0.005:1 to 0.05:1, or the molar ratio of selenium to zinc is 0.5:1 to 0.6:

1.

20. A display device, comprising the electroluminescent device according to any one of claims 15-19.

21. The display device according to claim 20, wherein the display device includes a virtual reality device, an augmented reality device, a portable terminal, a monitor, a laptop computer, a television, an electronic board, a camera, or an electrical component.

22. Semiconductor nanoparticles, comprising: a core including a first semiconductor nanocrystal, the first semiconductor nanocrystal including zinc, tellurium, and selenium; and an additional semiconductor nanocrystal on the core, the additional semiconductor nanocrystal including zinc and sulfur, wherein the core has a decreasing tellurium concentration gradient in the direction from the center of the core to the additional semiconductor nanocrystal.

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