Semiconductor nanoparticles, methods of making semiconductor nanoparticles, electroluminescent devices, and display devices

Abstract

Semiconductor nanoparticles, methods for preparing semiconductor nanoparticles, electroluminescent devices, and display devices are provided. The semiconductor nanoparticles comprise: a first semiconductor nanocrystal comprising zinc, selenium, and optionally tellurium; and a semiconductor nanocrystal shell disposed on the first semiconductor nanocrystal and comprising zinc and sulfur. The semiconductor nanoparticles further comprise organic ligands containing N-H bonds, and in Fourier transform infrared spectroscopy, the semiconductor nanoparticles exhibit a first relative N-H absorbance value greater than or equal to 0.85 and less than or equal to 8 according to the following equation: First relative N-H absorbance value = First transmittance / Second transmittance, where the first transmittance is at 3190 cm⁻¹. ‑1 Up to 3270cm ‑1 The minimum transmittance of the first peak within the range, and the second transmittance at 1520 cm⁻¹. ‑1 Up to 1575cm ‑1 The minimum transmittance of the second peak within the range.

Description

[0001] This application claims priority to and all benefits arising therefrom of Korean Patent Application No. 10-2025-0016189, filed on February 7, 2025, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to semiconductor nanoparticles, methods for manufacturing semiconductor nanoparticles, and apparatus or devices (including electroluminescent devices and display devices) that include semiconductor nanoparticles. Background Technology

[0003] Semiconductor nanoparticles (e.g., semiconductor nanocrystal particles) can emit light. For example, quantum dots comprising semiconductor nanocrystals can exhibit quantum confinement effects, thereby exhibiting luminescent properties. Light emission from semiconductor nanoparticles can occur, for example, when electrons excited by photoexcitation or by the application of a voltage transition from the conduction band to the valence band. By controlling the size, composition, or combinations thereof, semiconductor nanoparticles can be configured to emit light in a desired wavelength region.

[0004] Nanoparticles can be used in light-emitting devices (e.g., electroluminescent devices) and display devices that include nanoparticles. Summary of the Invention

[0005] The embodiments provide a semiconductor nanoparticle that can exhibit improved properties (e.g., electroluminescent properties and / or longer device lifetime).

[0006] The embodiments relate to a method for manufacturing semiconductor nanoparticles.

[0007] An embodiment provides a light-emitting device that can emit light, for example, by applying a voltage to semiconductor nanoparticles (e.g., quantum dots).

[0008] An embodiment provides a display device (e.g., a quantum dot light-emitting diode (“QD-LED”) display) that includes nanoparticles as light-emitting materials in its blue pixels, red pixels, green pixels, or any two or three of these pixels.

[0009] In this embodiment, the semiconductor nanoparticles include:

[0010] First semiconductor nanocrystals, comprising zinc, selenium, and optionally tellurium; and

[0011] A semiconductor nanocrystal shell is disposed on a first semiconductor nanocrystal, and the semiconductor nanocrystal shell comprises zinc and sulfur.

[0012] The semiconductor nanoparticles do not include cadmium.

[0013] The semiconductor nanoparticles also include organic ligands containing NH bonds, and in Fourier transform infrared (FTIR) spectroscopy, the semiconductor nanoparticles exhibit a first relative NH absorbance value greater than or equal to about 0.85 and less than or equal to about 8 according to the following equation:

[0014] First relative NH absorption rate = First transmittance / Second transmittance

[0015] The first transmittance is greater than or equal to approximately 3190 cm⁻¹. -1 to less than or equal to approximately 3270cm -1 (For example, approximately 3230cm) -1 The minimum transmittance of the first peak within the range of ), and

[0016] The second transmittance is at or above approximately 1520 cm⁻¹ -1 to less than or equal to approximately 1575cm -1 (For example, approximately 1550cm) -1 The minimum transmittance of the second peak within the range of ).

[0017] In an embodiment, the semiconductor nanoparticles may have a second relative NH absorbance value of less than or equal to about 5, less than or equal to about 4.5, or less than or equal to about 3.48 in the FTIR spectrum according to the following equation:

[0018] Second relative NH absorption rate = First transmittance / Third transmittance

[0019] The first transmittance is greater than or equal to approximately 3190 cm⁻¹. -1 to less than or equal to approximately 3270cm -1 (For example, approximately 3230cm) -1 The minimum transmittance of the first peak within the range of ), and

[0020] The third transmittance is greater than or equal to approximately 2890 cm⁻¹. -1 to less than or equal to approximately 2970cm -1 (For example, approximately 2927cm) -1 The minimum transmittance of the third peak within the range of ).

[0021] The first peak in the FTIR spectrum can be an NH peak (e.g., an NH vibrational peak). The semiconductor nanoparticles can exhibit an NH peak (e.g., an NH vibrational peak) in the infrared spectrum.

[0022] The second peak in the FTIR spectrum can be a carboxylate peak (e.g., a COO (vibrational) peak). The second peak can also be a vibrational peak of the carbonyl moiety. The semiconductor nanoparticles can exhibit a carboxylate peak (e.g., a COO vibrational peak) in the infrared spectrum.

[0023] The third peak in the FTIR spectrum can be a CH (vibrational) peak. The semiconductor nanoparticles can exhibit a CH peak in the infrared spectrum.

[0024] The minimum transmittance of the first peak or the first peak can be greater than or equal to approximately 3190 cm⁻¹. -1 to less than or equal to approximately 3250cm -1 Or greater than or equal to approximately 3190cm -1 to less than or equal to approximately 3235cm -1 Within the range.

[0025] The minimum transmittance of the second peak or the second peak can be greater than or equal to approximately 1530 cm⁻¹. -1 to less than or equal to approximately 1572cm -1 Within the range. The minimum transmittance of the second peak or the second peak can be greater than or equal to approximately 1540 cm⁻¹. -1 to less than or equal to approximately 1565cm -1 Within the range. The minimum transmittance of the second peak or the second peak can be greater than or equal to approximately 1545 cm⁻¹. -1 to less than or equal to approximately 1560cm -1 Within the range.

[0026] The minimum transmittance of the third peak or the third peak can be greater than or equal to approximately 2920 cm⁻¹. -1 to less than or equal to approximately 2940cm -1 Or greater than or equal to approximately 2925cm -1 to less than or equal to approximately 2935cm -1 Or greater than or equal to approximately 2927cm -1 to less than or equal to approximately 2932cm -1 Within the range.

[0027] The first relative NH absorption rate value may be greater than or equal to about 0.9, greater than or equal to about 1, or greater than or equal to about 1.2.

[0028] The first relative NH absorption rate value may be less than or equal to about 5.5, less than or equal to about 5, or less than or equal to about 4.5.

[0029] The second relative NH absorption rate value may be less than or equal to about 3, less than or equal to about 2.8, or less than or equal to about 2.6.

[0030] The second relative NH absorption rate value can be greater than or equal to about 0.1, greater than or equal to about 0.5, or greater than or equal to about 1.

[0031] In an embodiment, the semiconductor nanoparticles can be larger than or equal to about 800 cm⁻¹ in the FTIR spectrum. -1 to less than or equal to approximately 900cm -1 The peaks within the range of NH groups are attributed to NH groups.

[0032] In an embodiment, the semiconductor nanoparticle may further include a first organic ligand having a carboxylate group, a second organic ligand having a carboxylate group, or a combination thereof, wherein the first organic ligand may have a total carbon number greater than or equal to about 3 and less than or equal to about 15, and the second organic ligand may have a total carbon number greater than about 15.

[0033] The second organic ligand may have a total carbon number of less than or equal to about 25.

[0034] The semiconductor nanoparticles may further include chlorine. In the semiconductor nanoparticles, the molar ratio of chlorine to zinc may be greater than or equal to about 0.01:1, greater than or equal to about 0.05:1, greater than or equal to about 0.1:1, greater than or equal to about 0.15:1, or greater than or equal to about 0.2:1. In the semiconductor nanoparticles, the molar ratio of chlorine to zinc may be less than or equal to about 1:1, less than or equal to about 0.9:1, less than or equal to about 0.7:1, or less than or equal to about 0.5:1.

[0035] In the semiconductor nanoparticles, the atomic ratio of fluorine to zinc may be less than about 0.13:1, less than or equal to about 0.1:1, less than or equal to about 0.05:1, or less than or equal to about 0.04:1.

[0036] In the semiconductor nanoparticles, the amount of fluorine may be less than about 1.9 atomic% or less than about 1 atomic% (e.g., based on the total amount of elements in the semiconductor nanoparticles).

[0037] In this embodiment, the semiconductor nanoparticles do not exhibit fluorine peaks in X-ray photoelectron spectroscopy (XPS) analysis.

[0038] The semiconductor nanocrystal shell may include: a first shell layer; and a second shell layer disposed on the first shell layer. The first shell layer may include zinc and selenium (second semiconductor nanocrystals). The first shell layer or the second semiconductor nanocrystal may include zinc selenide, zinc telluride selenide, zinc sulfide selenide, or combinations thereof. The second shell layer may include zinc and sulfur (third semiconductor nanocrystals). The second shell layer or the third semiconductor nanocrystal may include zinc sulfide selenide, zinc sulfide, or combinations thereof.

[0039] The first light can exhibit a red light emission spectrum, a green light emission spectrum, or a blue light emission spectrum.

[0040] In an embodiment, the first light may be blue light. The peak emission wavelength of the first light or blue light may be greater than or equal to about 440 nm, or greater than or equal to about 460 nm and less than or equal to about 480 nm.

[0041] In an embodiment, the first light may be green light. The peak emission wavelength of the first light or green light may be greater than or equal to about 500 nm and less than or equal to about 580 nm.

[0042] In an embodiment, the first light may be red light. The peak emission wavelength of the first light or red light may be greater than or equal to about 600 nm and less than or equal to about 680 nm.

[0043] The full width at half maximum (FWHM) of the peak emission of the first light can be greater than or equal to about 1 nm, or greater than or equal to about 20 nm and less than or equal to about 50 nm, or less than or equal to about 45 nm.

[0044] The semiconductor nanoparticles may have a quantum yield of about 80% or greater than or equal to about 89%.

[0045] In one embodiment, a method for preparing semiconductor nanoparticles includes:

[0046] A third semiconductor nanocrystal comprising zinc and sulfur is formed by contacting (e.g., reacting) a zinc precursor and a sulfur precursor in a reaction medium comprising an organic solvent and an optional organic ligand at a reaction temperature in the presence of particles comprising a first semiconductor nanocrystal and optionally a second semiconductor nanocrystal; and

[0047] An organic compound comprising an NH bond (hereinafter referred to as an additive) is added to the reaction medium. The additive may include C3 to C30 primary amine compounds, carbamic acids, or combinations thereof.

[0048] The contact (or reaction) between zinc precursors and sulfur precursors can be carried out in the presence of additives.

[0049] The reaction temperature may be greater than or equal to about 220°C (e.g., greater than or equal to about 280°C) and less than or equal to about 350°C, and the additive may be added at a first temperature below the reaction temperature. The first temperature may be greater than or equal to about 200°C and less than or equal to about 300°C, greater than or equal to about 210°C and less than or equal to about 260°C, greater than or equal to about 220°C and less than or equal to about 250°C, or a combination thereof.

[0050] The additive may be present in the reaction system before the formation of the third semiconductor nanocrystal begins. Alternatively, the additive may be added to the reaction medium after the formation of the third semiconductor nanocrystal begins.

[0051] The method may further include adding a metal halide (e.g., a metal chloride) to the reaction medium. The metal halide may include zinc chloride. The contact (or reaction) between the zinc precursor and the sulfur precursor may be carried out in the presence of additives and the metal halide.

[0052] In the method, the zinc precursor may include a first zinc precursor comprising a first organic ligand and zinc ions, and a second zinc precursor comprising a second organic ligand and zinc ions. The first organic ligand and the second organic ligand may have different carbon numbers. The second organic ligand may have a larger carbon number than the first organic ligand. The second organic ligand may have a larger molecular weight than the first organic ligand.

[0053] The first organic ligand may include a hexanoate group, a methylbutyrate group, a butyloctanoate group, or a combination thereof.

[0054] The first organic ligand may include a hexanoate moiety substituted with C1 to C3 alkyl, a butanoate moiety substituted with C1 to C3 alkyl, a valerate moiety substituted with C1 to C3 alkyl, an octanoate moiety substituted with C1 to C4 alkyl, or a combination thereof.

[0055] In embodiments, the second organic ligand may include a straight-chain or branched aliphatic hydrocarbon group of C13 to C25, C14 to C23, C15 to C22, C16 to C21, C17 to C20, or C18 to C19 (e.g., the straight-chain or branched aliphatic hydrocarbon group may be alkyl, alkenyl, or alkynyl). The second organic ligand may include an aliphatic hydrocarbon group having a carbon number greater than or equal to about 17.

[0056] The second organic ligand may include, for example, one or more, or two or more, carbon-carbon double bonds in the aliphatic hydrocarbon group chain.

[0057] The first organic ligand may include a branched alkyl group, and the second organic ligand may include a straight-chain alkenyl group.

[0058] In one embodiment, an electroluminescent device includes: a first electrode and a second electrode spaced apart from each other; and an emitting layer disposed between the first electrode and the second electrode, wherein the emitting layer comprises the semiconductor nanoparticles described above. Details regarding the semiconductor nanoparticles are as described herein.

[0059] The emitting layer can be configured to emit first light upon the application of a voltage.

[0060] Details about the first light are as described here.

[0061] In an embodiment, the peak emission wavelength of the first light or semiconductor nanoparticle (electroluminescence or photoluminescence) may be greater than or equal to about 440 nm, or greater than or equal to about 460 nm and less than or equal to about 480 nm, or less than or equal to about 470 nm.

[0062] In an embodiment, the peak emission wavelength of the first optical or semiconductor nanoparticle may be greater than or equal to about 500 nm, or greater than or equal to about 510 nm and less than or equal to about 580 nm, or less than or equal to about 540 nm.

[0063] In an embodiment, the peak emission wavelength of the first optical or semiconductor nanoparticle may be greater than or equal to about 600 nm, or greater than or equal to about 610 nm and less than or equal to about 680 nm, or less than or equal to about 635 nm.

[0064] The first electrode can be an anode, and the second electrode can be a cathode.

[0065] The electroluminescent device may further include a charge-assisted layer between the emitting layer and the first electrode, between the emitting layer and the second electrode, or between the two.

[0066] The electroluminescent device may further include a hole-assisted layer between the emitting layer and the first electrode. The electroluminescent device may further include an electron-assisted layer between the emitting layer and the second electrode.

[0067] The charge-assisted layer may include a hole-assisted layer containing organic compounds, an electron-assisted layer containing metal oxide nanoparticles, or a combination thereof.

[0068] The electroluminescent device may have a density greater than or equal to approximately 10,000 candela per square meter (cd / m²). 2 ), greater than or equal to approximately 30,000 cd / m 2 Or greater than or equal to approximately 50,000 cd / m³ 2 Maximum brightness.

[0069] The electroluminescent device may have a maximum external quantum efficiency of about 3%, about 5%, or about 7%.

[0070] When measured, for example, at an initial brightness of about 146 nits (e.g., at about 650 nits or about 1000 nits), the electroluminescent device may have a T90 of about 30 hours.

[0071] The embodiments relate to an electronic device or display device, which includes an electroluminescent device.

[0072] The display device or the electronic device may include a virtual reality display device, an augmented reality display device, a portable terminal device, a monitor, a laptop computer, a television, an electronic bulletin board, a camera, or an automotive electronic component.

[0073] According to embodiments, the semiconductor nanoparticles, when applied to, for example, electroluminescent devices, can achieve improved optical properties and lifetime characteristics, and can exhibit dispersibility suitable for use as an ink composition. Attached Figure Description

[0074] The above and other advantages and features of this disclosure will become clearer by describing exemplary embodiments of the disclosure in more detail with reference to the accompanying drawings.

[0075] Figure 1 This is a schematic cross-sectional view of an embodiment of a quantum dot light-emitting diode (“QD-LED”) device.

[0076] Figure 2 This is a schematic cross-sectional view of an embodiment of a QD-LED device.

[0077] Figure 3 This is a schematic cross-sectional view of an embodiment of a QD-LED device.

[0078] Figure 4 This is a schematic cross-sectional view of a QD-LED device according to an embodiment.

[0079] Figure 5 This is a schematic cross-sectional view of a light-emitting device (RGB pixel) according to an embodiment.

[0080] Figure 6 This is a schematic front view of the display panel according to an embodiment.

[0081] Figure 7 yes Figure 6 A schematic cross-sectional view of the display panel taken along line IV-IV.

[0082] Figure 8 A portion of the FTIR spectra of the semiconductor nanoparticles prepared in Preparation Example 1 and Comparative Preparation Example 1 are shown.

[0083] Figure 9 A portion of the FTIR spectra of the semiconductor nanoparticles prepared in Preparation Example 1 and Comparative Preparation Example 1 are shown.

[0084] Figure 10 A portion of the gas chromatography (GC) of the semiconductor nanoparticles prepared in Preparation Example 1 is shown. Detailed Implementation

[0085] And its associated appendices Figure 1 The advantages and features of this disclosure, as well as the methods for implementing these advantages and features, will become clear from the following exemplary embodiments. However, the invention can be embodied in many different forms, and the embodiments should not be construed as limited to those set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The same reference numerals throughout denote the same elements.

[0086] To clearly explain this disclosure, parts irrelevant to the description have been omitted, and throughout the specification, the same reference numerals belong to the same or similar elements. In the drawings, the thickness of layers, films, panels, regions, etc., is exaggerated for clarity. Furthermore, in the drawings, the thickness of some layers and regions is exaggerated for ease of description. Therefore, the embodiments described herein should not be construed as limited to the specific shapes of the regions shown herein, but rather include deviations in shape, for example, due to manufacturing processes. For example, regions shown or described as flat may generally have rough and / or non-linear characteristics. Additionally, acute angles (sharp corners) shown may be rounded (rounded). Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to show the precise shapes of the regions, nor are they intended to limit the scope of the present claims.

[0087] Furthermore, it will be understood that when an element (such as a layer, film, region, or substrate) is referred to as being "on" another element, the element may be directly on the other element, or there may be intermediate elements present. Conversely, when an element is referred to as being "directly on" another element, there are no intermediate elements present. Additionally, setting "on" a reference portion means setting it above or below the reference portion, not necessarily "above".

[0088] It will be understood that while the terms “first,” “second,” “third,” etc., may be used herein to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or part from another. Therefore, without departing from the teaching herein, “first element,” “first component,” “first region,” “first layer,” or “first part” discussed below may be referred to as a second element, second component, second region, second layer, or second part.

[0089] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms containing “at least one,” unless the content clearly indicates otherwise. “At least one” will not be construed as limited to “a” or “an.” “Or” means “and / or.”

[0090] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms “comprising” and / or “including” or “containing” or “comprises” as used in this specification indicate the presence of the stated features, areas, integrals, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, areas, integrals, steps, operations, elements, components, and / or groups thereof.

[0091] As used herein, the term “section” means a cross-section of a given object, for example, cut in a generally vertical direction and viewed from the side.

[0092] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms such as those defined in commonly used (e.g., non-technical) dictionaries shall be interpreted as having a meaning consistent with their meaning in the relevant field and in the context of this disclosure, and shall not be interpreted in an idealized or overly formal sense, unless expressly defined herein.

[0093] As used herein, the values ​​of the work function, conduction band, or lowest unoccupied molecular orbital (LUMO) (or valence band or highest occupied molecular orbital (HOMO)) energy levels are expressed as absolute values ​​from the vacuum level. Furthermore, when the work function or energy level is referred to as “deep,” “high,” or “large,” the work function or energy level has a large absolute value of “0 electron volts (eV)” based on the vacuum level, while when the work function or energy level is referred to as “shallow,” “low,” or “small,” the work function or energy level has a small absolute value of “0 electron volts (eV)” based on the vacuum level. In one aspect, the work function herein refers to the minimum energy required to remove an electron from, for example, a solid metal (e.g., a metal surface) to a vacuum (e.g., a vacuum immediately outside the solid surface).

[0094] As used herein, the term "first absorption peak" refers to the principal exciton peak that first appears in the longest wavelength region of the ultraviolet-visible (UV-Vis) absorption spectrum (i.e., in the lowest energy region of the UV-Vis absorption spectrum), and the term "wavelength of the first absorption peak" or "wavelength of the first absorption peak" refers to the wavelength at which the first absorption peak reaches its maximum intensity.

[0095] As used herein, the mean (average) can be the mean or the median. In this embodiment, the mean (average) can be the mean.

[0096] As used herein, the term "peak emission wavelength" is the wavelength at which a given emission spectrum of light reaches its maximum value.

[0097] As used herein, the term "group" may refer to a group in the periodic table (the periodic table of elements).

[0098] As used herein, “family I” refers to families IA and IB, and examples may include, but are not limited to, Li, Na, K, Rb and Cs.

[0099] As used herein, “Group II” refers to Group IIA and Group IIB, and examples of Group II metals can be Cd, Zn, Hg, and Mg, but are not limited thereto.

[0100] As used herein, “Group III” refers to Group IIIA and Group IIIB, and examples of Group IIIA metals may be Al, In, Ga, and Tl, and examples of Group IIIB metals may be scandium, yttrium, etc., but are not limited thereto.

[0101] As used herein, “Group IV” refers to Group IVA and Group IVB, and examples of Group IVA metals may be Si, Ge and Sn, and examples of Group IVB metals may be titanium, zirconium, hafnium, etc., but are not limited thereto.

[0102] As used herein, “group V” includes group VA and includes, but is not limited to, nitrogen, phosphorus, arsenic, antimony and bismuth.

[0103] As used herein, “Group VI” includes Group VIA and includes, but is not limited to, sulfur, selenium and tellurium.

[0104] As used herein, “metal” includes half-metals (such as, Si).

[0105] As used herein, the number of carbon atoms in a group or molecule may be indicated by a subscript (e.g., C). 6-50 (or referred to as C6 to C50.)

[0106] As used herein, unless otherwise defined, “substituted” means that at least one hydrogen atom of a compound or group is replaced by a corresponding substituent, which includes C1 to C30 alkyl, C2 to C30 alkenyl, C2 to C30 alkynyl, C6 to C30 aryl, C7 to C30 alkylaryl, C1 to C30 alkoxy, C1 to C30 heteroalkyl, C3 to C30 heteroaryl, C3 to C30 cycloalkyl, C3 to C15 cycloalkenyl, C6 to C30 cycloalkynyl, C2 to C30 heterocycloalkyl, halogen (-F, -Cl, -Br or -I), hydroxyl (-OH), nitro (-NO2), cyano (-CN), amino (-NRR', where R and R' are each independently hydrogen or C1 to C6 alkyl), azide, etc. The following groups are used: α-N3, α-amidinyl (-C(=NH)NH2), hydrazine (-NHNH2), hydrazone (=N(NH2)), aldehyde (-C(=O)H), carbamoyl (-C(O)NH2), thiol (-SH), ester (-C(=O)OR, where R is a C1 to C6 alkyl or a C6 to C12 aryl), carboxyl (-COOH) or a salt thereof (-C(=O)OM, where M is an organic or inorganic cation), sulfonic acid (-SO3H) or a salt thereof (-SO3M, where M is an organic or inorganic cation), phosphate (-PO3H2) or a salt thereof (-PO3MH or -PO3M2, where M is an organic or inorganic cation) or combinations thereof.

[0107] As used herein, unless otherwise defined, "hydrocarbon" or "hydrocarbon group" means a compound or group comprising carbon and hydrogen (e.g., alkyl, alkenyl, alkynyl, or aryl). A hydrocarbon group can be a monovalent group or a group having a valence greater than one, formed by removing one or more hydrogen atoms from an alkane group, alkenyl group, alkynyl group, or aromatic group. In a hydrocarbon or hydrocarbon group, at least one methylene group may be replaced by an oxide moiety, a carbonyl moiety, an ester moiety, -NH-, or a combination thereof. Unless otherwise stated to the contrary, a hydrocarbon or hydrocarbon group (alkyl, alkenyl, alkynyl, or aryl) may have 1 to 60, 2 to 32, 3 to 24, or 4 to 12 carbon atoms.

[0108] As used herein, unless otherwise defined, "alkyl" refers to a straight-chain or branched saturated monovalent hydrocarbon group (methyl, ethylhexyl, etc.). In the embodiments, the alkyl group may have 1 to 50 carbon atoms, or 1 to 18 carbon atoms, or 1 to 12 carbon atoms.

[0109] As used herein, unless otherwise defined, "alkenyl" refers to a straight-chain or branched monovalent hydrocarbon group having a carbon-carbon double bond. In embodiments, an alkenyl group may have 2 to 50 carbon atoms, or 2 to 18 carbon atoms, or 2 to 12 carbon atoms.

[0110] As used herein, unless otherwise defined, "alkynyl" refers to a straight-chain or branched monovalent hydrocarbon group having a carbon-carbon triple bond. In the embodiments, the alkenyl group may have 2 to 50 carbon atoms, or 2 to 18 carbon atoms, or 2 to 12 carbon atoms.

[0111] As used herein, unless otherwise defined, "aryl" refers to a group having a carbocyclic aromatic system. When an aryl group comprises multiple rings, the rings may be fused together. Examples include phenyl and naphthyl. In embodiments, the aryl group may have 6 to 50 carbon atoms, 6 to 18 carbon atoms, or 6 to 12 carbon atoms.

[0112] As used herein, unless otherwise defined, “heterogeneous” means including one to three heteroatoms (e.g., N, O, P, Si, B, Se, Ge, Te, S, or combinations thereof).

[0113] As used herein, "heteroaryl" refers to an aromatic system having at least one N, O, P, Si, B, Se, Ge, Te, S, or a combination thereof as a cyclic atom. Examples of heteroaryl groups include pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazinyl, quinolinyl, and isoquinolinyl. When a heteroaryl group comprises multiple rings, the rings may be fused together. In embodiments, the heteroaryl group may have 3 to 50 carbon atoms, 6 to 18 carbon atoms, or 6 to 12 carbon atoms.

[0114] As used herein, unless otherwise defined, "alkoxy" means an alkyl group attached to an oxygen (e.g., alkyl-O-) (e.g., methoxy, ethoxy, or sec-butoxy).

[0115] As used herein, the term "cycloalkyl" refers to a monovalent monocyclic saturated hydrocarbon group. Examples include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl. In embodiments, the cycloalkyl group may have 3 to 50 carbon atoms, 3 to 18 carbon atoms, or 3 to 12 carbon atoms.

[0116] As used herein, the term "heterocyclic alkyl" refers to a monovalent monocyclic group that includes at least one N, O, P, Si, B, Se, Ge, Te, S, or a combination thereof as a cyclic atom in addition to the carbon atom that forms the cyclic atom. Examples include tetrahydrofuranyl and tetrahydrothiophenyl. In embodiments, the heterocyclic alkyl group may have 2 to 50 carbon atoms, 2 to 18 carbon atoms, or 2 to 12 carbon atoms.

[0117] As used herein, the term "cycloalkenyl" refers to a monovalent monocyclic hydrocarbon group having at least one carbon-carbon double bond in its ring, wherein the overall molecular structure is non-aromatic. Examples include cyclopentenyl, cyclohexenyl, and cycloheptenyl. In embodiments, the cycloalkenyl group may have 3 to 50 carbon atoms, 3 to 18 carbon atoms, or 3 to 12 carbon atoms.

[0118] As used herein, the term "heterocyclic alkenyl" refers to a monovalent monocyclic group comprising at least one N, O, P, Si, B, Se, Ge, Te, S, or a combination thereof as cyclic atoms and at least one double bond in its ring, wherein the overall molecular structure is non-aromatic. Examples of heterocyclic alkenyl groups include 2,3-dihydrofuranyl and 2,3-dihydrothiophenylyl. In embodiments, the heterocyclic alkenyl group may have 2 to 50 carbon atoms, or 2 to 18 carbon atoms, or 2 to 12 carbon atoms.

[0119] The term "arylalkyl" refers to an alkyl group that has been substituted with an aryl group. An example of an arylalkyl group is a benzyl group (i.e., -CH2-phenyl).

[0120] The term "alkylaryl" refers to an aryl group that has been substituted with an alkyl group. An example of an alkylaryl group is tolyl.

[0121] As used herein, unless otherwise defined, “amino” is a compound represented by -NR2, wherein each R is independently hydrogen, C1 to C12 alkyl, C7 to C20 alkylaryl, C7 to C20 arylalkyl, or C6 to C18 aryl.

[0122] As used herein, the expression "excluding cadmium (or other hazardous heavy metals)" means that the concentration of cadmium (or another heavy metal considered hazardous) may be less than or equal to about 100 parts per million by weight (ppmw), less than or equal to about 50 ppmw, less than or equal to about 10 ppmw, less than or equal to about 1 ppmw, less than or equal to about 0.1 ppmw, less than or equal to about 0.01 ppmw, or zero. In embodiments, the amount of cadmium (or other toxic heavy metals) may be substantially absent, or if present, the amount of cadmium (or other heavy metals) may be less than or equal to the detection limit or the same as the impurity level of a given analytical instrument (e.g., inductively coupled plasma atomic emission spectrometry).

[0123] Unless otherwise stated, the numerical ranges described herein are inclusive. Unless otherwise stated, the numerical ranges described herein include any real number within and including the endpoints of the stated range. In this specification, numerical endpoints, or upper or lower limits (e.g., stated as "greater than or equal to a value," "at least a value," or "less than or equal to a value," or stated using "from" or "to") may be used to form a numerical range for a given characteristic. In other words, the upper and lower endpoints described for various numerical values ​​may be independently combined to provide a range.

[0124] As used herein, “about” includes the stated value and means within an acceptable range of deviation from the particular value, as determined by a person skilled in the art taking into account the measurement in question and the error associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “about” may mean within one or more standard deviations, or within ±10%, ±5%, ±3%, or ±1% of the stated value.

[0125] As used herein, nanoparticles are structures having at least one region or characteristic dimension (feature size) having a nanoscale size. In embodiments, the size (or average size) of the nanostructure is less than or equal to about 500 nanometers (nm), 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, and may be greater than about 0.1 nm or greater than about 1 nm. In embodiments, nanoparticles may have any suitable shape. Nanoparticles (e.g., semiconductor nanoparticles or metal oxide nanoparticles) may include, but are not limited to, nanowires, nanorods, nanotubes, branched nanostructures, nanotetrapods, nanotripods, nanobipods, nanodots, multi-legged shapes (e.g., at least two legs), etc. Nanoparticles may be, for example, substantially crystalline, substantially single-crystal, polycrystalline, (e.g., at least partially) amorphous, or combinations thereof.

[0126] In embodiments, semiconductor nanoparticles (such as quantum dots) may exhibit quantum confinement or exciton confinement. As used herein, unless otherwise defined, the terms "quantum dot" or "semiconductor nanostructure" are not limited in shape. Semiconductor nanoparticles or quantum dots may have a size smaller than the Bohr excitation diameter for a bulk crystalline material of equivalent composition and may exhibit quantum confinement effects. Semiconductor nanoparticles or quantum dots can emit light corresponding to their bandgap energy by controlling the size of the nanocrystal used as the emission center.

[0127] As used herein, the term "T50" is the time (in hours, h) taken until the brightness (e.g., illuminance) of a given device decreases to 50% of its initial brightness (100%) when the device is started to drive (e.g., operate) at a predetermined initial brightness (e.g., 650 nits).

[0128] As used herein, the term "T90" is the time (h) taken from when a given device is started to be driven at a predetermined initial brightness (e.g., 650 nits) until the brightness (e.g., illuminance) of the given device decreases to 90% of the initial brightness (100%).

[0129] As used herein, the phrase “external quantum efficiency (EQE)” is the ratio of the number of photons emitted from a light-emitting diode (LED) to the number of electrons passing through the device, and can be used as a measure of how efficiently a given device converts electrons into photons and allows photons to escape. EQE can be determined by the following equation:

[0130] EQE = (Injection Efficiency) × ((Solid-State) Quantum Yield) × (Extraction Efficiency)

[0131] The injection efficiency is the proportion of electrons injected into the active region of the device, the quantum yield is the proportion of all electron-hole complexes that radiate and generate photons in the active region, and the extraction efficiency is the proportion of photons generated in the active region that escape from a given device.

[0132] As used here, maximum EQE is the maximum value of EQE.

[0133] As used herein, maximum brightness is the highest value of the brightness of a given device.

[0134] As used herein, the phrase "quantum efficiency" may be used interchangeably with the phrase "quantum yield." In embodiments, quantum efficiency may be a relative quantum yield or an absolute quantum yield, which, for example, can be readily measured by any suitable (e.g., commercially available) device. Quantum efficiency (or quantum yield) may be measured in solution or in a solid state (in a composite). In embodiments, "quantum yield (or quantum efficiency)" may be, for example, the ratio of emitted photons to absorbed photons via a nanostructure or a group of nanostructures. In embodiments, quantum efficiency may be determined by any suitable method. For example, two methods may exist for measuring fluorescence quantum yield or efficiency: absolute methods and relative methods.

[0135] The absolute method directly obtains the quantum yield by detecting the fluorescence of all samples using an integrating sphere. In the relative method, the fluorescence intensity of a standard sample (e.g., a standard dye) is compared with the fluorescence intensity of an unknown sample to calculate the quantum yield of the unknown sample. Coumarin 153, coumarin 545, rhodamine 101 inner salt, anthracene, and rhodamine 6G can be used as standard dyes according to their photoluminescence (PL) wavelengths, but are not limited thereto.

[0136] As used herein, the term "dispersion" refers to a dispersion in which the dispersed phase is a solid, and the continuous medium includes a liquid or a solid different from the dispersed phase. In embodiments, the ink composition may be in the form of a dispersion. Here, "dispersion" may be a colloidal dispersion in which the dispersed phase has a size greater than or equal to about 1 nm (e.g., greater than or equal to about 2 nm, greater than or equal to about 3 nm, or greater than or equal to about 4 nm) to a few micrometers (μm) or smaller (e.g., less than or equal to about 2 μm, less than or equal to about 1 μm, less than or equal to about 900 nm, less than or equal to about 800 nm, less than or equal to about 700 nm, less than or equal to about 600 nm, or less than or equal to about 500 nm).

[0137] The band gap energy of semiconductor nanoparticles can vary with the size and composition of the nanocrystals. For example, as the size of semiconductor nanoparticles increases, their band gap energy can become smaller (e.g., narrower), and they can emit light with a longer wavelength. Semiconductor nanocrystals can be used as luminescent materials in various fields, such as display devices, power devices, or bioluminescent devices.

[0138] In the emissive layer, quantum dots capable of exhibiting electroluminescent properties at a practically applicable level may include harmful heavy metals (such as cadmium (Cd), lead, mercury, or combinations thereof). Therefore, it is desirable to provide light-emitting devices or display devices with an emissive layer that is substantially free of harmful heavy metals. In QD-LEDs, satisfactory electroluminescent properties can be based on cadmium-based (i.e., cadmium-containing) LEDs, and there is room for improvement in QD-LED devices that use environmentally friendly quantum dots that do not contain cadmium or other harmful heavy metals and, for example, emit blue light.

[0139] The semiconductor nanoparticles according to the embodiments are environmentally friendly, capable of emitting light of a desired wavelength (e.g., blue light) with improved luminous efficiency, and exhibiting improved stability to the external environment. The electroluminescent device according to the embodiments includes semiconductor nanoparticles and is a self-emitting light-emitting device configured to emit desired light by applying a voltage, with or without a separate light source. The light-emitting device and display apparatus of the embodiments are desirable from an environmental perspective.

[0140] In this embodiment, the semiconductor nanoparticles include zinc, sulfur, and selenium, and optionally tellurium. The semiconductor nanoparticles may include a first semiconductor nanocrystal and a semiconductor nanocrystal shell disposed on the first semiconductor nanocrystal. The first semiconductor nanocrystal may include zinc, selenium, and optionally tellurium. The semiconductor nanocrystal shell may include zinc and sulfur. The semiconductor nanoparticles may not include cadmium.

[0141] Semiconductor nanoparticles may include organic ligands comprising NH bonds or organic ligand systems comprising NH bonds. Semiconductor nanoparticles or organic ligand systems may also include additional ligands comprising a carboxyl group or a portion derived from a carboxyl group (e.g., a carboxylate group). For example, semiconductor nanoparticles may include a first organic ligand, a second organic ligand, or a combination thereof.

[0142] In Fourier transform infrared (FTIR) spectroscopy analysis, the semiconductor nanoparticles exhibit a first relative NH absorbance value greater than or equal to about 0.85 and less than or equal to about 8 according to the following equation:

[0143] First relative NH absorption rate = First transmittance / Second transmittance

[0144] The first transmittance (or "transmittance") is at or above approximately 3190 cm⁻¹. -1 to less than or equal to approximately 3270cm -1 The minimum transmittance of the first peak within the range, and

[0145] The second transmittance is at or above approximately 1520 cm⁻¹ -1 to less than or equal to approximately 1575cm -1 The minimum transmittance of the second peak within the range.

[0146] The additional ligand may also include a first organic ligand having a carboxylate moiety and a second organic ligand having a carboxylate moiety. The second organic ligand may have a larger molecular weight than the first organic ligand, or may have a larger number of carbons than the first organic ligand.

[0147] Semiconductor nanoparticles can exhibit a first peak attributed to a first organic ligand and a second peak attributed to a second organic ligand in gas chromatography (GC) analysis. The percentage of the area of ​​the first peak relative to the second peak can be greater than or equal to about 0.5%, greater than or equal to about 1%, greater than or equal to about 3%, greater than or equal to about 5%, greater than or equal to about 7%, greater than or equal to about 9%, greater than or equal to about 10%, greater than or equal to about 11%, greater than or equal to about 12%, greater than or equal to about 13%, greater than or equal to about 14%, greater than or equal to about 15%, greater than or equal to about 17%, greater than or equal to about 20%, or greater than or equal to about 25% and / or less than or equal to about 300%, less than or equal to about 150%, less than or equal to about 130%, less than or equal to about 99%, less than or equal to about 90%, 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%, or less than or equal to about 45%.

[0148] The embodiments relate to electronic devices or apparatuses (electroluminescent devices) that include semiconductor nanoparticles (e.g., semiconductor nanoparticles contained in an emitting layer).

[0149] In an embodiment, the electroluminescent device includes a first electrode 1 and a second electrode 5 spaced apart (e.g., facing each other) and an emitting layer 3 disposed between the first electrode and the second electrode (see [link to embodiment]). Figure 1 The emitting layer comprises semiconductor nanoparticles. The emitting layer or semiconductor nanoparticles may not include cadmium. The first electrode may include an anode, and the second electrode may include a cathode. Optionally, the first electrode may include a cathode, and the second electrode may include an anode. The electroluminescent device may also include a hole-assisted layer 2 between the emitting layer and the first electrode. The electroluminescent device may also include an electron-assisted layer 4 between the emitting layer and the second electrode.

[0150] In an electroluminescent device, the first electrode 10 or the second electrode 50 may be disposed on a (transparent) substrate 100. The transparent substrate may be a light-extracting surface (see...). Figure 2 and Figure 3 ).

[0151] Reference Figure 2 and Figure 3 In the electroluminescent device of this embodiment, the emitting layer 30 may be disposed between a first electrode (e.g., an anode) 10 and a second electrode (e.g., a cathode) 50. The cathode 50 may include an electron injection conductor. The anode 10 may include a hole injection conductor. The work function of the electron / hole injection conductors included in the cathode and anode can be appropriately adjusted and is not particularly limited. For example, the cathode may have a small work function, and the anode may have a relatively large work function, or vice versa.

[0152] Electron / hole injection conductors may include, but are not limited to, metal-based materials (e.g., metals, metal compounds, alloys, or combinations thereof) (e.g., aluminum, magnesium, tungsten, nickel, cobalt, platinum, palladium, calcium, LiF, etc.), metal oxides (such as indium gallium oxide or indium tin oxide (ITO)), or (e.g., conductive polymers with relatively high work function) (such as polyethylene dioxythiophene).

[0153] The first electrode, the second electrode, or a combination thereof can be a light-transmitting electrode or a transparent electrode. In an embodiment, both the first electrode and the second electrode can be light-transmitting electrodes. One or more electrodes can be patterned. The first electrode, the second electrode, or a combination thereof can be disposed on a substrate (e.g., an insulating substrate). The substrate can be optically transparent (e.g., having a transmittance 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 include regions for blue pixels, regions for red pixels, regions for green pixels, or combinations thereof. Thin-film transistors can be disposed in each region of the substrate, and one of the source and drain electrodes of the thin-film transistor can be electrically connected to the first electrode or the second electrode.

[0154] The transparent electrode can be disposed on a transparent substrate (e.g., an insulating one). The substrate can be rigid or flexible. The substrate can include plastic or organic materials (such as polymers), inorganic materials (such as glass), or metals.

[0155] The light-transmitting electrode may have a transmittance of about 50%, about 60%, about 70%, about 80%, or about 90% (e.g., about 80% to about 100%, about 85% to about 95%, or combinations thereof).

[0156] The transparent electrode may be made of, for example, a transparent conductor (such as indium tin oxide (ITO) or indium zinc oxide (“IZO”), gallium indium tin oxide, zinc indium tin oxide, titanium nitride, polyaniline, LiF / Mg:Ag, etc.) or a single or multiple layers of metal thin film, but is not limited thereto. If one of the first and second electrodes is an opaque electrode, the opaque electrode may be made of an opaque conductor (such as aluminum (Al), lithium-aluminum (Li:Al) alloy, magnesium-silver (Mg:Ag) alloy, or lithium-aluminum fluoride (LiF:Al) compound). In the case of alloy electrodes, the ratio between the materials may be appropriately adjusted (e.g., 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 combinations thereof).

[0157] In an embodiment, the first electrode or the second electrode may be a multilayer electrode. In an embodiment, the first electrode (or anode) may be a multilayer electrode comprising about 2 layers, about 3 layers and less than or equal to about 10 layers, or less than or equal to about 5 layers of electrode material. In an embodiment, the second electrode (or cathode) may be a multilayer electrode comprising about 2 layers, about 3 layers and less than or equal to about 10 layers, or less than or equal to about 5 layers of electrode material.

[0158] Multilayer electrodes may include, for example, a semi-transparent conductive material (such as indium tin oxide), an opaque conductive material (or a reflective electrode material) (such as aluminum), or a combination thereof. In embodiments, the electrode (e.g., an anode or cathode) may have a structure in which layers of opaque conductive material (or reflective electrode material) are disposed between layers of semi-transparent conductive material (e.g., layers of semi-transparent conductive material). In embodiments, the electrode (anode or cathode) may have a structure in which layers of semi-transparent conductive material (e.g., layers of semi-transparent conductive material) are disposed between layers of opaque conductive material (or reflective electrode material).

[0159] When a voltage is applied between the first and second electrodes, the emitting layer can emit light upward, downward, or a combination of both through the electric field, and the light traveling to the reflecting electrode can be reflected and emitted in the opposite direction.

[0160] In one embodiment, light may be emitted toward the cathode. In another embodiment, light may be emitted toward the anode.

[0161] There is no particular limitation on the thickness of each of the electrodes (the first electrode, the second electrode, or each of the first electrode and the second electrode) and it can be appropriately selected with regard to device efficiency. For example, the thickness of the electrodes can be greater than or equal to about 5 nm, 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), 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.

[0162] There are no particular limitations on the method of forming the electrode, and it can be appropriately selected depending on the material. In the embodiments, the electrode can be formed by vapor deposition, coating, or a combination thereof, but is not limited thereto.

[0163] The emitting layer 3 or 30 disposed between the first electrode 1 and the second electrode 5 (e.g., anode 10 and cathode 50) may include semiconductor nanoparticles (e.g., nanoparticles emitting blue light, nanoparticles emitting red light, nanoparticles emitting green light, or combinations thereof). The emitting layer may include one or more (e.g., two or more, or three or more, and ten or fewer) monolayers of multiple nanostructures.

[0164] The emission layer can be patterned. In an embodiment, the patterned emission layer 30 may include a blue emission layer 30B disposed in blue pixels, a red emission layer 30R disposed in red pixels, a green emission layer 30G disposed in green pixels, or a combination thereof. See [link to documentation]. Figure 4 and Figure 5 Each of the light-emitting layers (e.g., a red, green, or blue light-emitting layer) can be separated from the adjacent light-emitting layer (e.g., optically) by a partition wall. In an embodiment, the partition wall (such as a black matrix or a pixel-defined layer (PDL)) may be disposed between one or more red light-emitting layers, one or more green light-emitting layers, and one or more blue light-emitting layers. The red, green, and blue light-emitting layers may be optically isolated from each other.

[0165] The emitter layer or semiconductor nanoparticles may not include cadmium. The emitter layer or semiconductor nanoparticles may not include lead, mercury, or combinations thereof. The semiconductor nanoparticles may also include or may not include copper, manganese, or combinations thereof.

[0166] Semiconductor nanoparticles include zinc, selenium, and sulfur. Semiconductor nanoparticles may have a core-shell structure. A semiconductor nanoparticle or core-shell structure includes: a first semiconductor nanocrystal; and a semiconductor nanocrystal shell disposed on the first semiconductor nanocrystal and comprising zinc and sulfur (including a third semiconductor nanocrystal).

[0167] The core may include a first zinc chalcogenide (or a first semiconductor nanocrystal). In embodiments, the first semiconductor nanocrystal or core may include a first zinc chalcogenide comprising zinc, selenium, and tellurium. The size or average size of the core (hereinafter referred to as size) may 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 may be less than or equal to about 6 nm (e.g., less than or equal to about 5 nm). The size of the core may be from about 2 nm to about 6 nm or from about 2.5 nm to about 5 nm.

[0168] The first semiconductor nanocrystal may include ZnTe x Se 1-x(Where x is greater than 0, 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, or 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 nucleus may or may not include sulfur.

[0169] The semiconductor nanocrystal shell differs from the first semiconductor nanocrystal and may include zinc and sulfur. The semiconductor nanocrystal shell may also include selenium. In the semiconductor nanoparticle, the shell, or the semiconductor nanocrystal included therein, may include zinc and at least one of selenium and sulfur (or a zinc chalcogenide containing at least one of selenium and sulfur). The shell may include tellurium or may not include tellurium. The shell (or each layer in a multi-shell configuration described herein) may be a gradient alloy having a composition that changes in the radial direction. In embodiments, the amount of sulfur in the semiconductor nanocrystal shell may increase toward the surface of the semiconductor nanoparticle. For example, in the shell, the amount of sulfur may have a concentration gradient that increases with distance from the core.

[0170] The semiconductor nanocrystal shell may include: a first shell layer (including a second semiconductor nanocrystal); and a second shell layer disposed on the first shell layer and including, for example, a third semiconductor nanocrystal. The first shell layer or the second semiconductor nanocrystal may include zinc selenide, zinc telluride selenide, zinc sulfide selenide, or combinations thereof. The second shell layer or the third semiconductor nanocrystal may include zinc sulfide selenide, zinc sulfide, or combinations thereof. In embodiments, core-shell semiconductor nanoparticles may include a semiconductor nanocrystal shell on a first semiconductor nanocrystal (or including a core of the first semiconductor nanocrystal). Depending on the composition of the first semiconductor nanocrystal and the semiconductor nanocrystal shell, the semiconductor nanoparticles may have type I, type II, or quasi-type II energy band alignment and may be configured to emit light with a desired wavelength upon application of a voltage.

[0171] In this embodiment, the semiconductor nanoparticles may have a core-shell structure, and an alloyed intermediate layer may or may not be present at the interface between the core and the shell. The alloyed intermediate layer may comprise a homogeneous alloy or may have a concentration gradient. The gradient alloy may have a concentration gradient, wherein the concentration of the elements in the shell varies radially (e.g., decreasing or increasing in the direction toward the core).

[0172] In embodiments, the shell may have a composition that varies in the radial direction. In embodiments, the shell may be a multilayer shell comprising two or more layers. In a multilayer shell, two adjacent layers may have different compositions from each other. In a multilayer shell, a layer (e.g., at least one layer) may independently comprise semiconductor nanocrystals having a single composition. In a multilayer shell, a layer (e.g., at least one layer) may independently have alloyed semiconductor nanocrystals. In a multilayer shell, a layer (e.g., at least one layer) may have a concentration gradient that varies radially with respect to the composition of the semiconductor nanocrystals.

[0173] In embodiments, in semiconductor nanoparticles with a core-shell structure, the shell material may have a band gap energy greater than that of the core. Alternatively, the shell material may have a band gap energy smaller than that of the core. In the case of multilayer shells, the band gap energy of the outermost shell material may be greater than that of the core and the inner shell materials (layers closer to the core). In the case of multilayer shells, the semiconductor nanocrystals in each layer are selected to have an appropriate band gap, thereby effectively exhibiting a quantum confinement effect.

[0174] The absorption or emission wavelength of semiconductor nanoparticles can be controlled by adjusting the composition, particle size, or a combination of composition and particle size of the semiconductor nanoparticles. The semiconductor nanoparticles included in the emitting layer can emit light of a desired color. The semiconductor nanoparticles may include semiconductor nanoparticles that emit blue light, green light, or red light. In embodiments, the emitting layer may be configured to emit blue, green, or red light, and the wavelengths of the blue, green, and red light are as described herein.

[0175] In embodiments, the peak emission wavelength of the semiconductor nanoparticles or the light-emitting layer (or the light emitted from the electroluminescent device) may be in the wavelength range from ultraviolet to infrared. In embodiments, the peak emission wavelength of the semiconductor nanoparticles or the light-emitting layer (or the light emitted from the electroluminescent device) may be greater than or equal to about 300 nm, greater than or equal to about 500 nm, greater than or equal to about 510 nm, greater than or equal to about 520 nm, greater than or equal to about 530 nm, greater than or equal to about 540 nm, greater than or equal to about 550 nm, greater than or equal to about 560 nm, greater than or equal to about 570 nm, greater than or equal to about 580 nm, greater than or equal to about 590 nm, greater than or equal to about 600 nm, or greater than or equal to about 610 nm. The peak emission wavelength can be less than or equal to about 800 nm, less than or equal to about 650 nm, less than or equal to about 640 nm, less than or equal to about 630 nm, less than or equal to about 620 nm, less than or equal to about 610 nm, less than or equal to about 600 nm, less than or equal to about 590 nm, less than or equal to about 580 nm, less than or equal to about 570 nm, less than or equal to about 560 nm, less than or equal to about 550 nm, or less than or equal to about 540 nm. The peak emission wavelength can be from about 500 nm to about 650 nm.

[0176] Semiconductor nanoparticles, light-emitting layers, or electroluminescent devices may emit green light (e.g., by the application of voltage or by illumination with light), and their peak emission wavelength may be in the range of greater than or equal to about 500 nm (e.g., greater than or equal to about 510 nm, or greater than or equal to about 515 nm) and less than or equal to about 560 nm (e.g., less than or equal to about 540 nm, or less than or equal to about 530 nm). Semiconductor nanoparticles, light-emitting layers, or electroluminescent devices may emit red light (e.g., by the application of voltage or by illumination with light), and their peak emission wavelength may be in the range of greater than or equal to about 600 nm (e.g., greater than or equal to about 610 nm) and less than or equal to about 650 nm, or less than or equal to about 640 nm. Semiconductor nanoparticles, emitting layers, or electroluminescent devices emit blue light, and the peak emission wavelength may be greater than or equal to about 440 nm (e.g., greater than or equal to about 445 nm, greater than or equal to about 450 nm, greater than or equal to about 455 nm, greater than or equal to about 460 nm, greater than or equal to about 462 nm, or greater than or equal to about 465 nm) and less than or equal to about 480 nm (e.g., 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 463 nm).

[0177] In embodiments, the semiconductor nanoparticles, light-emitting layer, or electroluminescent device may exhibit an emission spectrum (e.g., photoluminescence spectrum or electroluminescence spectrum) with a relatively narrow full width at half maximum (FWHM). In embodiments, in the photoluminescence spectrum or electroluminescence spectrum, the semiconductor nanoparticles, light-emitting layer, or electroluminescent device may exhibit a FWHM less than or equal to about 50 nm, less than or equal to about 45 nm, less than or equal to about 44 nm, less than or equal to about 43 nm, less than or equal to about 42 nm, less than or equal to about 41 nm, less than or equal to about 40 nm, less than or equal to about 39 nm, less than or equal to about 38 nm, less than or equal to about 37 nm, less than or equal to about 36 nm, or less than or equal to about 35 nm. This FWHM may be greater than or equal to about 10 nm, greater than or equal to about 15 nm, greater than or equal to about 20 nm, or greater than or equal to about 25 nm.

[0178] The quantum yield of the semiconductor nanoparticles can be greater than or equal to about 10%, for example, greater than or equal to about 20%, greater than or equal to about 30%, greater than or equal to about 40%, 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 90%, or even about 100% (e.g., configured to achieve this). In embodiments, the semiconductor nanoparticles may have a quantum yield (or absolute quantum yield) greater than or equal to about 91%, 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%, greater than or equal to about 96%, or greater than or equal to about 97%.

[0179] Semiconductor nanoparticles may have a size or average size (hereinafter referred to simply as "size") greater than or equal to about 1 nm and less than or equal to about 100 nm. This size may be the diameter or equivalent diameter obtained from an electron microscope image when it is not spherical by converting it to an assumed spherical shape. This size may be calculated from the results of inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis. In embodiments, semiconductor nanoparticles may have a size of about 1 nm to about 50 nm (e.g., about 2 nm (or about 3 nm) to about 35 nm). In embodiments, the size (or average size) of the semiconductor nanoparticles may be greater than or equal to about 1 nm, greater than or equal to about 2 nm, greater than or equal to about 3 nm, greater than or equal to about 4 nm, greater than or equal to about 5 nm, greater than or equal to about 6 nm, greater than or equal to about 7 nm, greater than or equal to about 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, or greater than or equal to about 14 nm. In the embodiments, the size of the semiconductor nanoparticles may be less than or equal to about 50 nm, less than or equal to about 40 nm, less than or equal to about 30 nm, less than or equal to about 25 nm, less than or equal to about 20 nm, less than or equal to about 19 nm, less than or equal to about 18 nm, less than or equal to about 17 nm, less than or equal to about 16 nm, less than or equal to about 15 nm, less than or equal to about 14 nm, less than or equal to about 13 nm, or less than or equal to about 12 nm.

[0180] There are no particular limitations on the shape of semiconductor nanoparticles or semiconductor nanostructures. For example, the shape of semiconductor nanoparticles may include (but is not limited to) spheres, polyhedra, cones, multi-legged shapes, hexahedrons, cubes, cuboids, nanotubes, nanorods, nanowires, or nanosheets.

[0181] Due to the availability of luminescent materials, there is growing interest in electroluminescent devices comprising inorganic-based semiconductor nanoparticles. Semiconductor nanoparticle-based electroluminescent devices (e.g., QD light-emitting diodes, QD-LEDs) utilize the electroluminescence of semiconductor nanoparticles (such as quantum dots) through the injection and recombination of electrons and holes, and hold high potential for use in various electronic devices (e.g., display devices). Semiconductor nanoparticle-based electroluminescent devices may not require a separate backlight and can be provided in thin structures. Therefore, there is active research in various fields to modify semiconductor nanoparticles to improve the performance of electroluminescent devices. For example, research is underway on electroluminescent devices comprising cadmium-free quantum dots that do not contain harmful heavy metals (such as cadmium). One area of ​​interest is core-shell semiconductor nanoparticles having a core comprising a first semiconductor nanocrystal and a shell of semiconductor nanocrystals disposed on the core. Furthermore, research is underway on providing such QD-LED devices through cost-effective solution processes (such as inkjet printing methods).

[0182] The inventors have discovered that, in the prior art, the Zn precursor used during the growth of the shell (e.g., the outermost shell comprising zinc sulfide) can affect not only the shell coating quality of the resulting semiconductor nanoparticles but also the composition of the organic ligands in the semiconductor nanoparticles. Without wishing to be bound by any theory, it is believed that with Zn precursors according to the prior art, it is difficult to achieve the desired level of coating speed, and relatively high lattice strain can exist at the growth interface. Furthermore, the Zn precursors used in the formation of the outermost layer in the prior art can include relatively long organic chains, which can affect the electroluminescent properties of QD-LED devices and hinder improvements in device lifetime.

[0183] Regarding the composition of organic ligands, short-chain organic ligands or inorganic ligands (e.g., halides) can be used to replace organic ligands with relatively long organic chains. However, existing methods inevitably involve additional processes (e.g., separate ligand exchange processes) for controlling the ligand composition of semiconductor nanoparticles, which not only increases manufacturing costs but also has technical disadvantages (i.e., adversely affects the luminescent properties of the resulting semiconductor nanoparticles).

[0184] Furthermore, the inventors have also discovered that organic ligands with relatively long organic chains disposed on the surface of semiconductor nanoparticles can (e.g., in the presence of halides) benefit the dispersion properties of the particles, but when included in a device, they are likely to adversely affect the device properties (such as lifetime). For example, the inventors have found that when ZnTeSe core-based semiconductor nanoparticles prepared according to the prior art have a composition of long-chain organic ligands based on carboxylic acids and are applied to the emitting layer of an electroluminescent device, it is difficult to maintain the initial current efficiency for a sufficiently long period of time due to surface oxidation and shedding of the organic ligands during actuation.

[0185] For example, attempts have been made to address the aforementioned problems through ligand exchange for synthesized semiconductor nanoparticles. However, the inventors have found that in the case of semiconductor nanoparticles comprising compositions that do not contain cadmium (e.g., a ZnTeSe-based core), the luminescence properties of semiconductor nanoparticles having surfaces replaced by such ligand substitution are significantly degraded. Without wishing to be bound by any theory, these results are considered to indicate that whether or not the core contains cadmium can have a significant impact on the properties of semiconductor nanoparticles based on ligand exchange.

[0186] In the embodiments, the semiconductor nanoparticles have a core comprising Zn, Se, and optionally Te, and exhibit significantly improved lifetime when applied to electroluminescent devices by having the surface ligand composition described herein. The surface ligand composition of the semiconductor nanoparticles according to the embodiments can exhibit aspects different from those achieved after synthesis via known ligand exchange reactions. The semiconductor nanoparticles of the embodiments can exhibit surface ligand aspects different from those known in the prior art during their synthesis process (e.g., during the synthesis process of semiconductor nanocrystal layers comprising zinc and sulfur) by using additives described herein. Therefore, the semiconductor nanoparticles of the embodiments are convenient in that they do not require additional ligand exchange in terms of their preparation method.

[0187] In embodiments, the semiconductor nanoparticles include (e.g., on the surface of the nanoparticles) an organic ligand comprising an NH bond (hereinafter referred to as an NH ligand) or a ligand system comprising an NH bond. The nitrogen of the ligand may coordinate to the surface of the nanoparticle. The semiconductor nanoparticles or ligand system may also include additional ligands having a carboxylic acid residue or a residue derived from a carboxylic acid (e.g., a carboxyl group) (hereinafter abbreviated as carboxylic acid group). The additional ligands may include a first organic ligand having a carboxyl group moiety and a second organic ligand different from the first organic ligand and having a carboxyl group moiety. In embodiments, the first organic ligand may be derived from a first zinc precursor (as described herein). The second organic ligand may be derived from a second zinc precursor (as described herein). The first and second organic ligands will be described in detail below.

[0188] The semiconductor nanoparticles of the embodiment exhibit a first relative NH absorbance greater than or equal to about 0.85 and less than or equal to about 8 in the FTIR spectrum, and the first relative NH absorbance can be defined according to the following equation:

[0189] First relative NH absorption rate = First transmittance / Second transmittance

[0190] The first transmittance is greater than or equal to approximately 3190 cm⁻¹ -1 And less than or equal to approximately 3270cm -1 The minimum transmittance of the first peak within the range, and

[0191] The second transmittance is at or above approximately 1520 cm⁻¹ -1 And less than or equal to approximately 1575cm -1 The minimum transmittance of the second peak within the range.

[0192] The term "minimum transmittance" refers to the minimum transmittance value of the peak under discussion.

[0193] The first peak can be an NH peak (e.g., an NH vibrational peak). Semiconductor nanoparticles may exhibit an NH peak (e.g., an NH vibrational peak) in the infrared spectrum. The presence of the first peak indicates the presence of NH ligands. The second peak can be a carboxylate peak (e.g., a COO vibrational peak). Semiconductor nanoparticles may exhibit a carboxylate peak (e.g., a COO vibrational peak) in the infrared spectrum. The second peak can also be a vibrational peak of the carbonyl moiety. The presence of the second peak indicates the presence of additional organic ligands described herein.

[0194] The first peak (or the minimum transmittance of the first peak) can be within the following range: greater than or equal to approximately 3190 cm⁻¹. -1 ≥3193cm -1 ≥3195cm -1≥3197cm -1 ≥3199cm -1 ≥3200cm -1 ≥3203cm -1 ≥3206cm -1 ≥3209cm -1 ≥3210cm -1 ≥3213cm -1 ≥3216cm -1 ≥3219cm -1 ≥3220cm -1 ≥3223cm -1 ≥3226cm -1 ≥3229cm -1 ≥3230cm -1 ≥3233cm -1 ≥3236cm -1 ≥3239cm -1 ≥3240cm -1 ≥3243cm -1 ≥3246cm -1 ≥3249cm -1 Or greater than or equal to approximately 3250cm -1 Less than or equal to approximately 3270cm -1 Less than or equal to approximately 3265cm -1 Less than or equal to approximately 3260cm -1 Less than or equal to approximately 3255cm -1 Less than or equal to approximately 3250cm -1 Less than or equal to approximately 3245cm -1 Less than or equal to approximately 3240cm -1 Or less than or equal to approximately 3235cm -1 Or any combination of wavenumber peak values ​​greater than and less than the aforementioned wavenumber peak values.

[0195] The second peak (or the minimum transmittance of the second peak) can be within the following range: greater than or equal to approximately 1530 cm⁻¹. -1 1531cm or greater -1 1533cm or greater -1 1536cm or greater -11539cm or greater -1 1540cm or greater -1 ≥1541cm -1 1543cm or greater -1 1546cm or greater -1 1549cm or greater -1 1550cm or greater -1 ≥1551cm -1 1553cm or greater -1 1556cm or greater -1 1559cm or greater -1 1560cm or greater -1 ≥1561cm -1 1563cm or greater -1 1566cm or greater -1 Or greater than or equal to approximately 1569cm -1 Less than or equal to approximately 1575cm -1 Less than or equal to approximately 1574cm -1 Less than or equal to approximately 1572cm -1 Less than or equal to approximately 1570cm -1 Less than or equal to approximately 1568cm -1 Less than or equal to approximately 1566cm -1 Less than or equal to approximately 1564cm -1 Less than or equal to approximately 1562cm -1 Or less than or equal to approximately 1560cm -1 Or any combination of wavenumber peak values ​​greater than and less than the aforementioned wavenumber peak values.

[0196] The first relative NH absorption rate defined by the above equation can be greater than or equal to about 0.9, greater than or equal to about 0.95, greater than or equal to about 1, greater than or equal to about 1.05, greater than or equal to about 1.1, greater than or equal to about 1.15, greater than or equal to about 1.2, greater than or equal to about 1.25, greater than or equal to about 1.3, greater than or equal to about 1.35, greater than or equal to about 1.4, greater than or equal to about 1.45, greater than or equal to about 1.50, greater than or equal to about 1.55, greater than or equal to about 1.60, greater than or equal to about 1.65, greater than or equal to about 1.70, greater than or equal to about 1.75, greater than or equal to about 1.80, greater than or equal to about 1.85, greater than or equal to about 1.90, greater than or equal to about 1. .95, greater than or equal to about 2.00, greater than or equal to about 2.05, greater than or equal to about 2.10, greater than or equal to about 2.15, greater than or equal to about 2.20, greater than or equal to about 2.25, greater than or equal to about 2.30, greater than or equal to about 2.35, greater than or equal to about 2.40, greater than or equal to about 2.45, greater than or equal to about 2.50, greater than or equal to about 2.55, greater than or equal to about 2.60, greater than or equal to about 2.65, greater than or equal to about 2.70, greater than or equal to about 2.75, greater than or equal to about 2.80, greater than or equal to about 2.85, greater than or equal to about 2.90, greater than or equal to about 2.95, greater than or equal to about 3.00, greater than or equal to about 3.05, greater than or equal to Approximately 3.10, greater than or equal to approximately 3.15, greater than or equal to approximately 3.20, greater than or equal to approximately 3.25, greater than or equal to approximately 3.30, greater than or equal to approximately 3.35, greater than or equal to approximately 3.40, greater than or equal to approximately 3.45, greater than or equal to approximately 3.50, greater than or equal to approximately 3.55, greater than or equal to approximately 3.60, greater than or equal to approximately 3.65, greater than or equal to approximately 3.70, greater than or equal to approximately 3.75, greater than or equal to approximately 3.80, greater than or equal to approximately 3.85, greater than or equal to approximately 3.90, greater than or equal to approximately 3.95, greater than or equal to approximately 4.00, greater than or equal to approximately 4.05, greater than or equal to approximately 4.10, greater than or equal to approximately 4.15, greater than or equal to approximately 4.20. Greater than or equal to approximately 4.25, greater than or equal to approximately 4.30, greater than or equal to approximately 4.35, greater than or equal to approximately 4.40, greater than or equal to approximately 4.45, greater than or equal to approximately 4.50, greater than or equal to approximately 4.55, greater than or equal to approximately 4.60, greater than or equal to approximately 4.65, greater than or equal to approximately 4.70, greater than or equal to approximately 4.75, greater than or equal to approximately 4.80, greater than or equal to approximately 4.85, greater than or equal to approximately 4.90, greater than or equal to approximately 4.95, greater than or equal to approximately 5.00, greater than or equal to approximately 5.05, greater than or equal to approximately 5.10, greater than or equal to approximately 5.15, greater than or equal to approximately 5.20, greater than or equal to approximately 5.25, greater than or equal to approximately 5.30, greater than or equal to approximately 5.35. Greater than or equal to approximately 5.40, greater than or equal to approximately 5.45, greater than or equal to approximately 5.50, greater than or equal to approximately 5.55, greater than or equal to approximately 5.60, greater than or equal to approximately 5.65, greater than or equal to approximately 5.70, greater than or equal to approximately 5.75, greater than or equal to approximately 5.80, greater than or equal to approximately 5.85, greater than or equal to approximately 5.90, greater than or equal to approximately 5.95, or greater than or equal to approximately 6.00.

[0197] The first relative NH absorption rate defined by the above equation may be less than or equal to about 8.00, less than or equal to about 7.95, less than or equal to about 7.90, less than or equal to about 7.85, less than or equal to about 7.80, less than or equal to about 7.75, less than or equal to about 7.70, less than or equal to about 7.65, less than or equal to about 7.60, less than or equal to about 7.55, less than or equal to about 7.50, less than or equal to about 7.45, less than or equal to about 7.40, less than or equal to about 7.35, less than or equal to about 7.30, less than or equal to about 7.25, less than or equal to about 7.20, less than or equal to about 7.15, less than Or equal to approximately 7.10, less than or equal to approximately 7.05, less than or equal to approximately 7.00, less than or equal to approximately 6.95, less than or equal to approximately 6.90, less than or equal to approximately 6.85, less than or equal to approximately 6.80, less than or equal to approximately 6.75, less than or equal to approximately 6.70, less than or equal to approximately 6.65, less than or equal to approximately 6.60, less than or equal to approximately 6.55, less than or equal to approximately 6.50, less than or equal to approximately 6.45, less than or equal to approximately 6.40, less than or equal to approximately 6.35, less than or equal to approximately 6.30, less than or equal to approximately 6.25, less than or equal to approximately 6.20, less than or equal to approximately 6.15, less than Or equal to approximately 6.10, less than or equal to approximately 6.05, less than or equal to approximately 6.00, less than or equal to approximately 5.95, less than or equal to approximately 5.90, less than or equal to approximately 5.85, less than or equal to approximately 5.80, less than or equal to approximately 5.75, less than or equal to approximately 5.70, less than or equal to approximately 5.65, less than or equal to approximately 5.60, less than or equal to approximately 5.55, less than or equal to approximately 5.50, less than or equal to approximately 5.45, less than or equal to approximately 5.40, less than or equal to approximately 5.35, less than or equal to approximately 5.30, less than or equal to approximately 5.25, less than or equal to approximately 5.20, less than or equal to approximately 5.15, less than Or equal to about 5.10, less than or equal to about 5.05, less than or equal to about 5.00, less than or equal to about 4.95, less than or equal to about 4.90, less than or equal to about 4.85, less than or equal to about 4.80, less than or equal to about 4.75, less than or equal to about 4.70, less than or equal to about 4.65, less than or equal to about 4.60, less than or equal to about 4.55, less than or equal to about 4.50, less than or equal to about 4.45, less than or equal to about 4.40, less than or equal to about 4.35, less than or equal to about 4.30, less than or equal to about 4.25, less than or equal to about 4.20, or less than or equal to about 4.15. Semiconductor nanoparticles can exhibit a second relative NH absorbance of less than or equal to about 5 in FTIR spectra according to the following equation:

[0198] Second relative NH absorption rate = First transmittance / Third transmittance

[0199] The first transmittance is greater than or equal to approximately 3190 cm⁻¹ -1 And less than or equal to approximately 3270cm -1 The minimum transmittance of the first peak within the range, and

[0200] The third transmittance is greater than or equal to approximately 2890 cm⁻¹. -1 And less than or equal to approximately 2970cm -1 The minimum transmittance of the third peak within the range.

[0201] The third peak can be the CH peak. Semiconductor nanoparticles can exhibit the CH peak (CH vibration peak) in infrared spectroscopy.

[0202] The minimum transmittance of the third peak or the third peak can be within the following range: greater than or equal to approximately 2891 cm⁻¹. -1 ≥2893cm -1 ≥2895cm -1 ≥2897cm -1 ≥2899cm -1 ≥2900cm -1 ≥2905cm -1 ≥2910cm -1 ≥2915cm -1 ≥2920cm -1 ≥2925cm -1 ≥2927cm -1 Or greater than or equal to approximately 2929cm -1 Less than or equal to approximately 2970cm -1 Less than or equal to approximately 2965cm -1 Less than or equal to approximately 2960cm -1 Less than or equal to approximately 2955cm -1 Less than or equal to approximately 2950cm -1 Less than or equal to approximately 2945cm -1 Less than or equal to approximately 2940cm -1 Less than or equal to approximately 2935cm -1 Or less than or equal to approximately 2932cm -1 Or any combination of wavenumber peak values ​​greater than the above-mentioned peak value and less than the peak value of the wavenumber.

[0203] The second relative NH absorption rate can be within the following ranges: less than or equal to about 4.95, less than or equal to about 4.90, less than or equal to about 4.85, less than or equal to about 4.80, less than or equal to about 4.75, less than or equal to about 4.70, less than or equal to about 4.65, less than or equal to about 4.60, less than or equal to about 4.55, less than or equal to about 4.50, less than or equal to about 4.45, less than or equal to about 4.40, less than or equal to about 4.35, less than or equal to about 4.30, less than or equal to about 4.25, less than or equal to about 4.20, less than or equal to about 4.15, less than or equal to about 4.10, less than or equal to about 4.05, less than or equal to about 4.00, less than Or equal to approximately 3.95, less than or equal to approximately 3.90, less than or equal to approximately 3.85, less than or equal to approximately 3.80, less than or equal to approximately 3.75, less than or equal to approximately 3.70, less than or equal to approximately 3.65, less than or equal to approximately 3.60, less than or equal to approximately 3.55, less than or equal to approximately 3.50, less than or equal to approximately 3.48, less than or equal to approximately 3.45, less than or equal to approximately 3.40, less than or equal to approximately 3.35, less than or equal to approximately 3.30, less than or equal to approximately 3.25, less than or equal to approximately 3.20, less than or equal to approximately 3.15, less than or equal to approximately 3.10, less than or equal to approximately 3.05, less than or equal to approximately 3.00, less than or equal to approximately 2.95, Less than or equal to about 2.90, less than or equal to about 2.85, less than or equal to about 2.80, less than or equal to about 2.75, less than or equal to about 2.70, less than or equal to about 2.65, less than or equal to about 2.60, less than or equal to about 2.55, less than or equal to about 2.50, less than or equal to about 2.45, less than or equal to about 2.40, less than or equal to about 2.35, less than or equal to about 2.30, less than or equal to about 2.25, less than or equal to about 2.20, less than or equal to about 2.15, less than or equal to about 2.10, less than or equal to about 2.05, less than or equal to about 2.00, less than or equal to about 1.95, less than or equal to about 1.90, less than or equal to about 1.8 5. Less than or equal to about 1.80, less than or equal to about 1.75, less than or equal to about 1.70, less than or equal to about 1.65, less than or equal to about 1.60, less than or equal to about 1.55, less than or equal to about 1.50, less than or equal to about 1.45, less than or equal to about 1.40, less than or equal to about 1.35, less than or equal to about 1.30, less than or equal to about 1.25, less than or equal to about 1.20, less than or equal to about 1.15, less than or equal to about 1.10, less than or equal to about 1.05, or less than or equal to about 1.00; greater than or equal to about 0.1, greater than or equal to about 0.5, or greater than or equal to about 1; or any combination greater than and less than the above values.

[0204] The semiconductor nanoparticles in the embodiment exhibit a wavelength greater than or equal to about 800 cm⁻¹ in the FTIR spectrum. -1 ≥810cm -1 ≥820cm -1 Or greater than or equal to approximately 825cm -1 And less than or equal to approximately 900cm -1 Less than or equal to approximately 890cm -1 Less than or equal to approximately 880cm -1 Less than or equal to approximately 870cm -1 Less than or equal to approximately 850cm -1 Or less than or equal to approximately 845cm -1 The peaks within the range caused by NH swing.

[0205] The semiconductor nanoparticles may further include a first organic ligand having a carboxylate group and / or a second organic ligand having a carboxylate group. The first organic ligand may have a total carbon number greater than or equal to about 3 and less than or equal to about 15, and the second organic ligand may have a total carbon number greater than about 15. The second organic ligand may have a total carbon number less than or equal to about 25.

[0206] In the embodiments, the molecular weight (or number of carbons) of the second organic ligand may be greater than the molecular weight (or number of carbons) of the first organic ligand.

[0207] The first organic ligand may have a molecular weight greater than or equal to about 90 g / mol, greater than or equal to about 100 g / mol, greater than or equal to about 105 g / mol, greater than or equal to about 110 g / mol, greater than or equal to about 115 g / mol, greater than or equal to about 120 g / mol, greater than or equal to about 125 g / mol, greater than or equal to about 130 g / mol, greater than or equal to about 140 g / mol, greater than or equal to about 150 g / mol, greater than or equal to about 160 g / mol, greater than or equal to about 170 g / mol, greater than or equal to about 180 g / mol, greater than or equal to about 190 g / mol, or greater than or equal to about 200 g / mol. The first organic ligand may have a molecular weight of less than or equal to about 257 g / mol, less than or equal to about 230 g / mol, less than or equal to about 225 g / mol, less than or equal to about 220 g / mol, less than or equal to about 215 g / mol, less than or equal to about 210 g / mol, less than or equal to about 200 g / mol, less than or equal to about 190 g / mol, less than or equal to about 180 g / mol, less than or equal to about 170 g / mol, less than or equal to about 160 g / mol, less than or equal to about 155 g / mol, less than or equal to about 150 g / mol, less than or equal to about 145 g / mol, less than or equal to about 140 g / mol, or less than or equal to about 130 g / mol.

[0208] The first organic ligand may include an aliphatic, aromatic, or alicyclic hydrocarbon group. The hydrocarbon group of the first organic ligand may include a substituted or unsubstituted C6 to C18 aromatic hydrocarbon group, or a substituted or unsubstituted C2 to C16, C2 to C14, C3 to C12, C4 to C10, C5 to C9, C4 to C8, or C6 to C7 straight-chain or branched aliphatic hydrocarbon group (e.g., alkyl, alkenyl, or alkynyl). The first organic ligand may include a branched alkyl group. The first organic ligand may include a propionate moiety, an isopropionate moiety, a butyrate moiety, a butyrate moiety having one or more C1 to C3 alkyl groups (e.g., the carboxylate of methylbutyric acid or the carboxylate of ethylbutyric acid), a valerate (or the carboxylate of valerate) moiety, a valerate moiety substituted with one or more C1 to C4 alkyl groups (e.g., the carboxylate of methylvalerate or the carboxylate of propylvalerate), a hexanoate moiety, a hexanoate moiety substituted with one or more C1 to C5 alkyl groups (e.g., the carboxylate of ethylhexanoate), an octanoate moiety, an octanoate moiety substituted with C1 to C6 alkyl groups (e.g., the carboxylate of butyloctanoate), or a combination thereof.

[0209] The first organic ligand comprises a carboxylate moiety (e.g., a carboxylate anion) represented by the following chemical formula 1, and the total number of carbons included in the first organic ligand is about 3 to about 15, or about 4 to about 13, or about 5 to about 11, or about 6 to about 10:

[0210] Chemical Formula 1

[0211]

[0212] In this formula, each R is the same or different, and each is independently hydrogen, or C1 to C6 alkyl, or C2 to C4 alkyl, or C3 to C5 alkyl (e.g., methyl, ethyl, propyl, butyl, pentyl or hexyl), and n is an integer from 1 to 14, or 2 to 12, or 3 to 10, or 4 to 8.

[0213] The second organic ligand may have a larger molecular weight than the first organic ligand, or may have a larger number of carbon atoms than the first organic ligand. The difference between the molecular weight of the second organic ligand and the molecular weight of the first organic ligand may be greater than or equal to about 50 g / mol, greater than or equal to about 75 g / mol, greater than or equal to about 80 g / mol, greater than or equal to about 90 g / mol, greater than or equal to about 100 g / mol, greater than or equal to about 120 g / mol, greater than or equal to about 130 g / mol, or greater than or equal to about 150 g / mol. The difference between the molecular weight of the second organic ligand and the molecular weight of the first organic ligand may be less than or equal to about 240 g / mol, less than or equal to about 220 g / mol, less than or equal to about 200 g / mol, less than or equal to about 180 g / mol, less than or equal to about 160 g / mol, less than or equal to about 150 g / mol, less than or equal to about 140 g / mol, less than or equal to about 130 g / mol, less than or equal to about 120 g / mol, less than or equal to about 100 g / mol, or less than or equal to about 90 g / mol.

[0214] The second organic ligand may have a molecular weight greater than about 200 g / mol, greater than or equal to about 210 g / mol, greater than or equal to about 215 g / mol, greater than or equal to about 220 g / mol, greater than or equal to about 225 g / mol, greater than or equal to about 230 g / mol, greater than or equal to about 235 g / mol, greater than or equal to about 240 g / mol, greater than or equal to about 245 g / mol, greater than or equal to about 250 g / mol, greater than or equal to about 255 g / mol, greater than or equal to about 260 g / mol, greater than or equal to about 265 g / mol, greater than or equal to about 270 g / mol, or greater than or equal to about 280 g / mol. The second organic ligand may have a molecular weight of less than or equal to about 500 g / mol, less than or equal to about 450 g / mol, less than or equal to about 440 g / mol, less than or equal to about 430 g / mol, less than or equal to about 420 g / mol, less than or equal to about 410 g / mol, less than or equal to about 400 g / mol, less than or equal to about 390 g / mol, less than or equal to about 380 g / mol, less than or equal to about 370 g / mol, less than or equal to about 360 g / mol, less than or equal to about 350 g / mol, less than or equal to about 340 g / mol, or less than or equal to about 250 g / mol.

[0215] The second organic ligand may include a straight-chain or branched aliphatic hydrocarbon group (e.g., alkyl, alkenyl, or alkynyl) of C12 to C25, C13 to C23, C14 to C22, C16 to C21, C17 to C20, or C18 to C19. The second organic ligand may include tetradecyl, tetradecenyl, pentadecyl, pentadecenyl, hexadecyl, hexadecenyl, heptadecanyl, heptadecanenyl, octadecyl, octadecenyl, octadecadienyl, octadectrienyl, or combinations thereof.

[0216] The second organic ligand may, for example, include one or more carbon-carbon double bonds, or two or more carbon-carbon double bonds, within an aliphatic hydrocarbon group chain. The second organic ligand may include a linoleic acid moiety, a linoleic acid moiety, an oleic acid moiety, a transoleic acid moiety, a stearate moiety, a palmitic acid moiety, a myristate moiety, or a combination thereof.

[0217] In the embodiments, the first organic ligand may include a branched alkyl group, and the second organic ligand may include a straight-chain alkenyl group.

[0218] In the embodiments, the semiconductor nanoparticles comprise a first organic ligand and a second organic ligand together, and exhibit a first peak attributable to the first organic ligand and a second peak attributable to the second organic ligand in gas chromatography (GC) analysis (e.g., in a chromatogram obtained by gas chromatography). In the semiconductor nanoparticles of the embodiments, the area percentage of the first peak relative to the second peak may be greater than or equal to about 1%, or greater than or equal to about 3% and less than or equal to about 400% (e.g., less than or equal to about 200%), or less than or equal to about 99%. For example, the percentage of the area of ​​the first peak relative to the second peak can be greater than or equal to about 5%, greater than or equal to about 7%, greater than or equal to about 10%, greater than or equal to about 15%, greater than or equal to about 17%, greater than or equal to about 19%, greater than or equal to about 20%, greater than or equal to about 21%, greater than or equal to about 23%, greater than or equal to about 25%, greater than or equal to about 27%, greater than or equal to about 29%, greater than or equal to about 30%, greater than or equal to about 31%, greater than or equal to about 31.4%, greater than or equal to about 33%, greater than or equal to about 35%, greater than or equal to about 37%, greater than or equal to about 39%, greater than or equal to about 40%, greater than or equal to about 41%, greater than or equal to about 43%, greater than or equal to about 45%, greater than or equal to about 47%, greater than or equal to about 49%, greater than or equal to about 50%, greater than or equal to about 51%, greater than or equal to about 53%, greater than or equal to about 55%, and greater than or equal to about 57%. Greater than or equal to about 59%, greater than or equal to about 60%, greater than or equal to about 61%, greater than or equal to about 63%, greater than or equal to about 65%, greater than or equal to about 67%, greater than or equal to about 69%, greater than or equal to about 70%, greater than or equal to about 71%, greater than or equal to about 73%, greater than or equal to about 75%, greater than or equal to about 77%, greater than or equal to about 79%, greater than or equal to about 81%, greater than or equal to about 83%, greater than or equal to about 85%, greater than or equal to about 87%, greater than or equal to about 89%, greater than or equal to about 90%, greater than or equal to about 91%, greater than or equal to about 93%, greater than or equal to about 95%, greater than or equal to about 97%, greater than or equal to about 99%, greater than or equal to about 100%, greater than or equal to about 101%, greater than or equal to about 103%, greater than or equal to about 105%, greater than or equal to about 107%, greater than or equal to about 109%, or greater than or equal to about 110%.The percentage of the area of ​​the first peak relative to the second peak may be less than or equal to about 400%, less than or equal to about 350%, less than or equal to about 300%, less than or equal to about 250%, less than or equal to about 200%, less than or equal to about 190%, less than or equal to about 180%, less than or equal to about 170%, less than or equal to about 160%, less than or equal to about 150%, less than or equal to about 140%, less than or equal to about 130%, less than or equal to about 120%, less than or equal to about 110%, less than or equal to about 98%, or less than or equal to about 97%.

[0219] The retention time of the second peak may be longer than that of the first peak. The ratio of the retention time of the first peak (elution time of the first organic ligand) to the retention time of the second peak (elution time of the second organic ligand) may be greater than or equal to about 0.1, greater than or equal to about 0.2, greater than or equal to about 0.3, greater than or equal to about 0.4, greater than or equal to about 0.5, greater than or equal to about 0.6, or greater than or equal to about 0.7. The ratio between retention times may be less than or equal to about 1, less than or equal to about 0.9, less than or equal to about 0.8, or less than or equal to about 0.7.

[0220] The difference in retention time between the second peak and the first peak may be greater than or equal to approximately 2 minutes, greater than or equal to approximately 3 minutes, greater than or equal to approximately 4 minutes, greater than or equal to approximately 5 minutes, greater than or equal to approximately 6 minutes, greater than or equal to approximately 10 minutes, greater than or equal to approximately 8 minutes, or greater than or equal to approximately 9 minutes. The difference in retention time between the second peak and the first peak may be less than or equal to approximately 15 minutes, less than or equal to approximately 13 minutes, less than or equal to approximately 12 minutes, less than or equal to approximately 11 minutes, less than or equal to approximately 10 minutes, less than or equal to approximately 9 minutes, less than or equal to approximately 7 minutes, or less than or equal to approximately 2 minutes.

[0221] GC analysis can be performed using techniques and knowledge known to those skilled in the art. Gas chromatography (GC) is an analytical technique that can be used to separate, identify, and quantify individual chemical components in complex mixtures. In GC, a gas carrying the sample passes through a GC instrument. In embodiments, there are no particular limitations on the carrier gas or mobile phase, and it can be high-purity helium, hydrogen, or nitrogen. In embodiments, the gas chromatographic analysis device may include, but is not limited to, an injector (e.g., a split / splitless (SSL) injector), a column (e.g., a wall-coated open-tube (WCOT) capillary column comprising a thin layer of dimethylpolysiloxane stationary phase), and a detector (e.g., a flame ionization detector (FID) or mass spectrometry (MS)). In embodiments, the GC column may be a capillary column, and may be a fused silica capillary comprising a polymer outer coating. In chromatograms obtained by GC, the x-axis represents retention time (typically in minutes), and the y-axis represents detector response. In embodiments, the GC device may be a py-GC / MS. In a GC, the temperature of the pyrolyzer can be from about 400°C to about 600°C or from about 450°C to about 550°C. GC equipment may include a capillary column. The capillary column may include a stationary phase of a polysiloxane (e.g., dimethyl polysiloxane, 5% to 65% diphenyldimethyl polysiloxane, polyethylene glycol, etc.), and the polarity may be suitably selected.

[0222] The flow rate of the mobile phase (gas) can be appropriately selected and can be in the range of 0.5 mL / min to 10 mL / min, or 1 mL / min to 5 mL / min, or 1.5 mL / min to 3 mL / min. The inlet temperature of the GC apparatus can be appropriately selected and can be in the range of 100°C to 400°C, 150°C to 300°C, or 200°C to 250°C. The GC oven temperature can be appropriately controlled. The analyzer can be a quadrupole type (range: mass-to-charge ratio (m / z) of 10 to 550).

[0223] As confirmed by thermogravimetric analysis, the semiconductor nanoparticles of the embodiments may exhibit a relatively reduced organic content, but still exhibit the desired level of dispersibility in organic solvents (e.g., aliphatic hydrocarbon solvents such as octane). In thermogravimetric analysis, the semiconductor nanoparticles of the embodiments may exhibit a weight loss (or mass loss) of less than or equal to about 13 wt%, less than or equal to about 12 wt%, less than or equal to about 11.5 wt%, less than or equal to about 11 wt%, less than or equal to about 10.5 wt%, less than or equal to about 10 wt%, less than or equal to about 9.5 wt%, or less than or equal to about 8 wt% in the range of 200°C to 550°C, based on the total weight of the semiconductor nanoparticles. In thermogravimetric analysis, the semiconductor nanoparticles may exhibit a weight loss of greater than or equal to about 1 wt%, greater than or equal to about 3 wt%, greater than or equal to about 5 wt%, or greater than or equal to about 7 wt% in the range of 200°C to 550°C, based on the total weight of the semiconductor nanoparticles.

[0224] In thermogravimetric analysis, semiconductor nanoparticles may have a residual content of about 80 wt%, about 83 wt%, about 87 wt%, or about 88 wt%, or about 90 wt%, or about 91 wt% and less than or equal to about 99 wt%, or less than or equal to about 97 wt%, or less than or equal to about 92 wt%, or less than or equal to about 90 wt% at a temperature of about 550 °C or higher, based on the total weight of the semiconductor nanoparticles.

[0225] Semiconductor nanoparticles can exhibit improved dispersibility in organic solvents, such as aliphatic hydrocarbon solvents (e.g., octane). In examples, the semiconductor nanoparticles, when dispersed in octane and measured by dynamic light scattering (DLS) analysis, can exhibit a DLS particle diameter of less than about 300 nm. DLS particle diameters can be less than or equal to about 200 nm, less than or equal to about 100 nm, less than or equal to about 80 nm, less than or equal to about 60 nm, less than or equal to about 50 nm, less than or equal to about 40 nm, less than or equal to about 30 nm, or less than or equal to about 20 nm. DLS particle diameters can be greater than or equal to about 5 nm, greater than or equal to about 7 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.

[0226] Semiconductor nanoparticles may also include halogens (e.g., Cl) (e.g., chlorine). In semiconductor nanoparticles, the molar ratio of halogen (e.g., Cl) to zinc may be greater than or equal to about 0.005:1, greater than or equal to about 0.01:1, greater than or equal to about 0.02:1, greater than or equal to about 0.03:1, greater than or equal to about 0.04:1, greater than or equal to about 0.05:1, greater than or equal to about 0.08:1, greater than or equal to about 0.1:1, greater than or equal to about 0.15:1, or greater than or equal to about 0.2:1. In semiconductor nanoparticles, the molar ratio of halogen to zinc can be less than or equal to about 1:1, less than or equal to about 0.9:1, less than or equal to about 0.7:1, less than or equal to about 0.6:1, less than or equal to about 0.4:1, less than or equal to about 0.2:1, less than or equal to about 0.12:1, less than or equal to about 0.09:1, less than or equal to about 0.07:1, less than or equal to about 0.06:1, or less than or equal to about 0.05:1.

[0227] In semiconductor nanoparticles, the molar ratio of halogen (e.g., Cl) to selenium can be greater than or equal to about 0.005:1, greater than or equal to about 0.01:1, greater than or equal to about 0.02:1, greater than or equal to about 0.03:1, greater than or equal to about 0.04:1, greater than or equal to about 0.05:1, greater than or equal to about 0.08:1, greater than or equal to about 0.1:1, greater than or equal to about 0.15:1, or greater than or equal to about 0.2:1. In semiconductor nanoparticles, the molar ratio of halogen to selenium can be less than or equal to about 1:1, less than or equal to about 0.9:1, less than or equal to about 0.7:1, less than or equal to about 0.6:1, less than or equal to about 0.4:1, less than or equal to about 0.2:1, less than or equal to about 0.12:1, less than or equal to about 0.09:1, less than or equal to about 0.07:1, less than or equal to about 0.06:1, or less than or equal to about 0.05:1.

[0228] In semiconductor nanoparticles, the molar ratio of carbon to zinc can be greater than or equal to approximately 0.005:1, greater than or equal to approximately 0.01:1, greater than or equal to approximately 0.05:1, greater than or equal to approximately 0.1:1, greater than or equal to approximately 0.15:1, greater than or equal to approximately 0.2:1, greater than or equal to approximately 0.25:1, greater than or equal to approximately 0.3:1, greater than or equal to approximately 0.35:1, greater than or equal to approximately 0.4:1, or greater than or equal to approximately 0.45:1. In semiconductor nanoparticles, the molar ratio of carbon to zinc can be less than or equal to approximately 1:1, less than or equal to approximately 0.9:1, less than or equal to approximately 0.7:1, or less than or equal to approximately 0.5:1.

[0229] In semiconductor nanoparticles, the molar ratio of carbon to selenium can be greater than or equal to approximately 0.005:1, greater than or equal to approximately 0.01:1, greater than or equal to approximately 0.05:1, greater than or equal to approximately 0.1:1, greater than or equal to approximately 0.15:1, greater than or equal to approximately 0.2:1, greater than or equal to approximately 0.3:1, greater than or equal to approximately 0.4:1, greater than or equal to approximately 0.5:1, greater than or equal to approximately 0.7:1, greater than or equal to approximately 0.8:1, greater than or equal to approximately 0.9:1, or greater than or equal to approximately 0.95:1. In semiconductor nanoparticles, the molar ratio of carbon to selenium can be less than or equal to approximately 2:1, less than or equal to approximately 1.5:1, less than or equal to approximately 1:1, less than or equal to approximately 0.9:1, less than or equal to approximately 0.7:1, or less than or equal to approximately 0.5:1.

[0230] In semiconductor nanoparticles, the molar ratio of sulfur to selenium can be greater than or equal to about 0.4:1, greater than or equal to about 0.5:1, greater than or equal to about 0.6:1, greater than or equal to about 0.7:1, greater than or equal to about 0.8:1, or greater than or equal to about 0.9:1. In semiconductor nanoparticles, the molar ratio of sulfur to selenium can be less than or equal to about 1:1, less than or equal to about 0.95:1, less than or equal to about 0.85:1, less than or equal to about 0.75:1, less than or equal to about 0.65:1, less than or equal to about 0.55:1, or less than or equal to about 0.45:1.

[0231] In semiconductor nanoparticles, the amount or molar amount (e.g., atomic ratio) of fluorine (or fluoride) relative to zinc may be less than about 0.13:1, less than or equal to about 0.12:1, less than or equal to about 0.11:1, less than or equal to about 0.1:1, less than or equal to about 0.09:1, less than or equal to about 0.07:1, less than or equal to about 0.05:1, or less than or equal to about 0.04:1. In semiconductor nanoparticles, the amount of fluorine may be less than about 1.9 atomic% of the total elemental mass, or less than about 1 atom of the total elemental mass.

[0232] The molar amounts or molar ratios between elements described herein (e.g., those included in semiconductor nanoparticles or light-emitting layers) can be determined, for example, by using appropriate analytical tools (e.g., inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray photoelectron spectroscopy (XPS), ion chromatography, transmission electron microscopy energy-dispersive X-ray spectroscopy (TEM-EDX), scanning electron microscopy energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray fluorescence (XRF), or combinations thereof).

[0233] Semiconductor nanoparticles can be synthesized by the methods described herein. In embodiments, the method for preparing semiconductor nanoparticles includes contacting (e.g., reacting) a zinc precursor and a sulfur precursor in the presence of particles comprising a first semiconductor nanocrystal and an optional second semiconductor nanocrystal at a reaction temperature to form a third semiconductor nanocrystal comprising zinc and sulfur, and the method further includes adding an organic compound containing an NH bond (hereinafter referred to as an additive) to the reaction medium. The additive may include C3 to C30, C5 to C24, C6 to C22, C8 to C18, or C10 to C16 primary amine compounds, carbamic acids, or combinations thereof.

[0234] The inventors have surprisingly discovered that, when the method described herein is followed, a controllable amount of NH-containing ligands can be provided (e.g., directed or coordinated) to semiconductor nanoparticles (or their surface). Therefore, semiconductor nanoparticles comprising the organic ligands described herein can be advantageously used in subsequent solution processes while maintaining dispersion characteristics, and electroluminescent devices comprising semiconductor nanoparticles can exhibit improved lifetime characteristics.

[0235] In the methods of the embodiments, a nitrogen-containing organic ligand compound (e.g., an additive) may be added during the coating or formation of a semiconductor nanocrystal layer comprising zinc and sulfur (e.g., the outermost shell layer), or the nitrogen-containing organic ligand compound (e.g., an additive) may be added to the reaction system after the coating has begun but before the reaction has been completed. The semiconductor nanoparticles thus prepared may exhibit the surface properties described herein and, for example, may contribute to improved device lifetime when applied, for example, to the emitting layer of an electroluminescent device.

[0236] In embodiments, the method may include preparing semiconductor nanocrystals having a size of several nanometers using a wet chemical process. In the wet chemical process, crystal particles are grown by reacting a precursor material in an organic solvent, and the growth of the crystals can be controlled by coordinating the organic solvent or a ligand compound to the surface of the semiconductor nanocrystals. In embodiments, the method for preparing semiconductor nanoparticles includes preparing particles comprising a first semiconductor nanocrystal and a second semiconductor nanocrystal.

[0237] Details regarding the first and second semiconductor nanocrystals are as described herein. In the methods of the embodiments, when present, the second semiconductor nanocrystal may comprise zinc and selenium (e.g., ZnSe, ZnSeS, or combinations thereof). The second semiconductor nanocrystal may be disposed on the first semiconductor nanocrystal. The second semiconductor nanocrystal may be an intermediate shell layer of semiconductor nanoparticles.

[0238] In embodiments of the method, the preparation of particles including a first semiconductor nanocrystal and an optional second semiconductor nanocrystal is not particularly limited and can be appropriately selected.

[0239] In the embodiments, the first semiconductor nanocrystal or the core comprising it may be prepared by appropriate methods taking into account its composition and the desired properties of the final nanoparticles, or may be commercially available.

[0240] In an embodiment, the first semiconductor nanocrystal or core comprises a zinc chalcogenide containing zinc, selenium, and tellurium, and the first semiconductor nanocrystal or core can be obtained by: preparing a zinc precursor solution comprising a zinc precursor and an organic ligand; preparing a selenium precursor and a tellurium precursor; heating the zinc precursor solution to the nucleation reaction temperature; and adding the selenium precursor and the tellurium precursor (optionally, together with the organic ligand) to continue the nucleation reaction.

[0241] In the nucleation reaction, the ratio between precursors (e.g., the molar ratio of selenium precursor to tellurium precursor) or the reaction time can be appropriately selected taking into account the emission wavelength of the final semiconductor nanoparticles, the reactivity of the precursors, and the reaction temperature. The nucleation reaction temperature can be appropriately selected. It can be greater than or equal to about 240°C, greater than or equal to about 250°C, greater than or equal to about 260°C, greater than or equal to about 270°C, greater than or equal to about 280°C, or, for example, greater than or equal to about 290°C. The reaction temperature used for nucleation can be in the range of about 280°C to about 340°C (e.g., about 290°C to about 330°C or about 300°C to about 320°C). The reaction time used for nucleation can be adjusted taking into account the desired nucleus size and the reactivity of the precursors, and is not particularly limited. For example, the reaction time can 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 can be less than or equal to about 2 hours, but is not limited thereto. The formed nuclei may be separated from the reaction system (e.g., by non-solvent precipitation), or they may not need to be separated. The separated nuclei may be washed (if necessary) and added to subsequent reactions.

[0242] The semiconductor nanoparticles in the embodiments may also include a second semiconductor nanocrystal or an intermediate shell containing the second semiconductor nanocrystal, and the method of forming the second semiconductor nanocrystal or the intermediate shell containing the second semiconductor nanocrystal is not particularly limited and can be appropriately selected.

[0243] In embodiments of the method, forming a second semiconductor nanocrystal (or an intermediate shell containing the second semiconductor nanocrystal) on the first semiconductor nanocrystal may include: mixing a zinc precursor with a chalcogenide precursor (e.g., a selenium precursor and optionally a sulfur precursor) in the presence of an organic solvent and the first semiconductor nanocrystal at a reaction temperature (reaction).

[0244] There are no particular restrictions on organic ligands, organic solvents, and precursors, and they can be selected appropriately.

[0245] Organic solvents may include C6 to C22 primary amines (such as hexadecylamine), C6 to C22 secondary amines (such as dioctylamine), C6 to C40 tertiary amines (such as trioctylamine), nitrogen-containing heterocyclic compounds (such as pyridine), C6 to C40 olefins (such as octadecene), C6 to C40 aliphatic hydrocarbons (such as hexadecane, octadecane, or squalane), aromatic hydrocarbons substituted with C6 to C30 alkyl groups (such as phenyldodecane, phenyltetradecane, or phenylhexadecane), primary, secondary, or tertiary phosphines substituted with at least one (e.g., 1, 2, or 3) C6 to C22 alkyl groups (e.g., trioctylphosphine), phosphine oxides substituted with (e.g., 1, 2, or 3) C6 to C22 alkyl groups (e.g., trioctylphosphine oxide), C12 to C22 aromatic ethers (such as phenyl ethers or benzyl ethers), or combinations thereof.

[0246] Organic ligands can coordinate to the surface of the prepared semiconductor nanoparticles, allowing the semiconductor nanoparticles to be well dispersed in solution. Organic ligands may include RCOOH, RNH2, R2NH, R3N, RSH, RH2PO, R2HPO, R3PO, RH2P, R2HP, R3P, ROH, RCOOR', RPO(OH)2, R2POOH (wherein R and R' independently comprise substituted or unsubstituted aliphatic hydrocarbon groups of C1 or larger, C6 or larger, or C10 or larger and C40 or smaller, C35 or smaller, or C25 or smaller, or substituted or unsubstituted aromatic hydrocarbon groups of C6 to C40, or combinations thereof), or combinations thereof. Ligands may be used alone or as a combination of two or more compounds.

[0247] Examples of organic ligands may include: methanethiol, ethanethiol, propanethiol, butanethiol, pentathiol, hexanethiol, heptanethiol, octanethiol, nonanethiol, decanethiol, dodecanethiol, hexadecanethiol, octadecanethiol, benzylthiol; methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, octylamine, dodecylamine, hexadecylamine, 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; substituted or unsubstituted methylphosphine (e.g., trimethylphosphine, methyldiphenylphosphine, etc.), substituted or unsubstituted ethylphosphine (e.g., triethylphosphine, ethyldiphenylphosphine, etc.), substituted or unsubstituted propylphosphine, substituted or unsubstituted butylphosphine, substituted or Unsubstituted pentylphosphine, substituted or unsubstituted octylphosphine (e.g., trioctylphosphine (TOP) etc.); phosphine oxides, such as substituted or unsubstituted methylphosphine oxides (e.g., trimethylphosphine oxide, methyldiphenylphosphine oxide etc.), substituted or unsubstituted ethylphosphine oxides (e.g., triethylphosphine oxide, ethyldiphenylphosphine oxide etc.), substituted or unsubstituted propylphosphine oxides, substituted or unsubstituted butylphosphine oxides, substituted or unsubstituted octylphosphine oxides (e.g., trioctylphosphine oxide (TOPO) etc.); diphenylphosphine, triphenylphosphine, or oxides thereof; C5 to C20 alkylphosphino acids, such as hexylphosphino acid, octylphosphino acid, dodecylphosphino acid, tetradecylphosphino acid, hexadecylphosphino acid, or octadecylphosphino acid; C5 to C20 alkylphosphino acids; etc., but the examples are not limited thereto. Organic ligands may be used alone or in combination of two or more.

[0248] Zinc precursors can be Zn metal powder, ZnO, alkylated Zn compounds (e.g., C2 to C30 dialkyl zinc (such as diethylzinc)), alcohol Zn (e.g., zinc ethoxide), carboxylic acid Zn (e.g., zinc acetate), nitric acid Zn, perchloric acid Zn, sulfuric acid Zn, acetylacetone Zn, halogenated Zn (e.g., zinc chloride), cyanide Zn, hydroxide Zn, carbonate Zn, peroxide Zn, or combinations thereof. Examples of zinc precursors can be dimethyl zinc, diethylzinc, zinc acetate, zinc acetylacetone, zinc iodide, zinc bromide, zinc chloride, zinc fluoride, zinc carbonate, zinc cyanide, zinc nitrate, zinc oxide, zinc peroxide, zinc perchlorate, zinc sulfate, or combinations thereof.

[0249] Selenium precursors may include, but are not limited to, selenium-trioctylphosphine (“Se-TOP”), selenium-tributylphosphine (“Se-TBP”), selenium-triphenylphosphine (“Se-TPP”), selenium-diphenylphosphine (“Se-DPP”), or combinations thereof.

[0250] Tellurium precursors may include, but are not limited to, tellurium-tributylphosphine (“Te-TBP”), tellurium-triphenylphosphine (“Te-TPP”), tellurium-diphenylphosphine (“Te-DPP”), or combinations thereof.

[0251] The sulfur precursor may be hexamethylenetetramine, octanethiol, decanethiol, dodecanethiol, hexadecanethiol, mercaptopropylsilane, thio-trioctylphosphine (“S-TOP”), thio-tributylphosphine (“S-TBP”), thio-triphenylphosphine (“S-TPP”), thio-trioctylamine (“S-TOA”), bis(trialkylsilyl)sulfide, bis(trialkylsilylalkyl)sulfide (e.g., bis(trimethylsilylmethyl)sulfide), ammonium sulfide, sodium sulfide, or combinations thereof.

[0252] Prior to undergoing subsequent reactions (e.g., the formation of a semiconductor nanocrystal shell comprising zinc and sulfur), the particles comprising a first semiconductor nanocrystal and optionally a second semiconductor nanocrystal can be separated and washed in a manner described herein. The separated and washed particles can be dispersed in a suitable organic solvent (e.g., an aromatic solvent (such as toluene) or an aliphatic hydrocarbon solvent (such as octane)) and added to the subsequent reaction.

[0253] In the method of the embodiment, in a reaction medium comprising an organic solvent and optionally an organic ligand, a zinc precursor and a sulfur precursor may be contacted (e.g., reacted) at a reaction temperature in the presence of particles comprising a first semiconductor nanocrystal and optionally a second semiconductor nanocrystal, thereby forming a third semiconductor nanocrystal comprising zinc and sulfur. Through the reaction, a shell comprising zinc and sulfur (semiconductor nanocrystal shell) may be formed on the particles.

[0254] The method of the embodiments further includes adding a nitrogen-containing organic compound (e.g., an organic compound comprising NH bonds; hereinafter referred to as an additive) to the reaction medium. In the embodiments, the additive may be added to the reaction system before or during the formation of the third semiconductor nanocrystal, and the zinc precursor and sulfur precursor may be contacted (or reacted) in the presence of the additive. In the embodiments, the additive may even be added to the reaction medium after the formation of the third semiconductor nanocrystal is completed, while the temperature of the reaction solution is maintained at a predetermined temperature (e.g., a first temperature).

[0255] In the embodiments, the reaction temperature may be greater than or equal to about 220°C (e.g., greater than or equal to about 230°C) and less than or equal to about 380°C, and additives may be added at the first temperature.

[0256] The first temperature may be equal to or lower than the reaction temperature. The difference between the reaction temperature and the first temperature may be greater than or equal to about 50°C, greater than or equal to about 60°C, greater than or equal to about 70°C, greater than or equal to about 80°C, greater than or equal to about 90°C, greater than or equal to about 100°C, or greater than or equal to about 110°C. The difference between the reaction temperature and the first temperature may be less than or equal to about 200°C, less than or equal to about 190°C, less than or equal to about 180°C, less than or equal to about 170°C, less than or equal to about 160°C, less than or equal to about 150°C, less than or equal to about 140°C, less than or equal to about 130°C, less than or equal to about 120°C, less than or equal to about 100°C, or less than or equal to about 90°C.

[0257] The reaction temperature can be greater than or equal to about 245°C, greater than or equal to about 250°C, greater than or equal to about 260°C, greater than or equal to about 270°C, greater than or equal to about 280°C, greater than or equal to about 290°C, greater than or equal to about 300°C, greater than or equal to about 310°C, greater than or equal to about 320°C, or greater than or equal to about 330°C. The reaction temperature can vary with reaction time. For example, the reaction temperature can include a first reaction temperature and a second reaction temperature. The ranges of the first and second reaction temperatures are the same as the range of the reaction temperature. The first reaction temperature can be higher than the second reaction temperature. The first reaction temperature can be lower than the second reaction temperature.

[0258] In an embodiment, the first temperature may be within the following ranges: greater than or equal to about 150°C, greater than or equal to about 160°C, greater than or equal to about 170°C, greater than or equal to about 180°C, greater than or equal to about 190°C, greater than or equal to about 200°C, greater than or equal to about 210°C, or greater than or equal to about 220°C; less than or equal to about 300°C, less than or equal to about 280°C, less than or equal to about 270°C, less than or equal to about 260°C, less than or equal to about 250°C, less than or equal to about 240°C, less than or equal to about 230°C, less than or equal to about 220°C, less than or equal to about 200°C, less than or equal to about 190°C, or less than or equal to about 180°C; or combinations thereof.

[0259] By adding additives to the reaction medium, non-cadmium semiconductor nanoparticles exhibiting the ligand composition described herein can be obtained. Unlike semiconductor nanoparticles obtained by ligand exchange according to the prior art, the non-cadmium semiconductor nanoparticles having the ligand composition described herein according to the embodiments can help improve the lifetime of electroluminescent devices.

[0260] Additives may include amine compounds of C3 to C30, C5 to C28, C6 to C25, C7 to C24, C8 to C23, C9 to C24, C10 to C22, C11 to C21, C12 to C20, C13 to C19, C14 to C18, or C15 to C16 (e.g., primary amine compounds having an aliphatic hydrocarbon group (e.g., alkyl) with a defined number of carbon atoms), carbamic acid compounds, imidazole compounds, or combinations thereof. Additives may include amine compounds (such as pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, octadecylamine, oleylamine, or combinations thereof).

[0261] There are no particular restrictions on the methods of adding additives, and appropriate choices can be made.

[0262] Based on the total molar number of zinc precursors, the amount of additive injected can be greater than or equal to about 0.1 mol%, greater than or equal to about 0.5 mol%, greater than or equal to about 1 mol%, greater than or equal to about 2 mol%, greater than or equal to about 3 mol%, greater than or equal to about 4 mol%, greater than or equal to about 5 mol%, greater than or equal to about 6 mol%, greater than or equal to about 7 mol%, or greater than or equal to about 8 mol%. Based on the total molar number of zinc precursors, the amount of additive injected can be less than or equal to about 30 mol%, less than or equal to about 25 mol%, less than or equal to about 20 mol%, less than or equal to about 15 mol%, less than or equal to about 10 mol%, less than or equal to about 9 mol%, or less than or equal to about 8 mol%.

[0263] In the semiconductor nanoparticles of the embodiments, when present, additional ligands may be derived from zinc precursors. In the embodiments, the additional ligands include a first organic ligand and a second organic ligand, and the methods of the embodiments may involve, for example, the use of two types of zinc precursors. The zinc precursor (zinc carboxylate) includes a first zinc precursor comprising a first organic ligand and zinc ions (e.g., first zinc carboxylate) and a second zinc precursor comprising a second organic ligand and zinc ions (e.g., second zinc carboxylate). Details regarding the first organic ligand, the second organic ligand, the organic solvent, and the sulfur precursor are as described herein. The sulfur precursor used for the formation of the ZnS shell is as described herein. In the methods of the embodiments, the sulfur precursor may include a thiol compound (e.g., a monothiol compound having C1 to C30, C5 to C24, or C8 to C12 alkyl groups (such as dodecylthiol)).

[0264] In the method of the embodiment, the ligand composition can be further controlled by using a zinc precursor with a relatively long organic chain (the second zinc precursor) together with a zinc precursor with a shorter organic chain (the first zinc precursor), and the organic ligand composition thereby controlled can contribute to the improvement of electroluminescence properties.

[0265] In the embodiments, zinc precursors with long-chain carboxylate groups (e.g., second zinc precursors) can exhibit significant differences in pKa compared to the first zinc precursor, and the combination of these zinc precursors can contribute to the uniform growth of the zinc sulfide (ZnS) shell. Furthermore, this combination is believed to optimize the total organic content of the ligand system located in the outermost layer of the semiconductor nanoparticles, thereby enabling improved properties of the electroluminescent device during operation and effectively preventing device degradation for extended lifetime.

[0266] The first zinc precursor may comprise a first organic ligand and zinc ions, and the first zinc precursor may be obtained by reacting a carboxylic acid (hereinafter, the first carboxylic acid) corresponding to the first organic ligand with a suitable zinc compound (e.g., zinc acetate). The second zinc precursor may comprise a second organic ligand and zinc ions, and the second zinc precursor may be obtained by reacting a carboxylic acid (hereinafter, the second carboxylic acid) corresponding to the second organic ligand with a suitable zinc compound (e.g., zinc acetate). Suitable zinc compounds may include (e.g., those used for nucleus synthesis and ZnSe shell formation) the zinc precursors described herein. Details of the first and second organic ligands are as described herein.

[0267] The first carboxylic acid is a carboxylic acid containing a first organic ligand. In the examples, the first carboxylic acid may be represented by the following chemical formula 2:

[0268] Chemical formula 2

[0269]

[0270] The definitions of R and n are the same as those in chemical formula 1.

[0271] The first carboxylic acid may have a pKa greater than or equal to about 4.8, greater than or equal to about 4.9, greater than or equal to about 5.5, greater than or equal to about 5.8, greater than or equal to about 6.5, or greater than or equal to about 7. The first carboxylic acid may have a pKa lower than that of the second carboxylic acid. In embodiments, the first carboxylic acid may have a pKa less than or equal to about 9, less than or equal to about 8.8, less than or equal to about 8.3, less than or equal to about 7.5, less than or equal to about 6.7, less than or equal to about 5.8, or less than or equal to about 4.9.

[0272] The first carboxylic acid may include propionic acid, valeric acid, hexanoic acid, octanoic acid, ethylhexanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, myristic acid, palmitic acid, ethylbutyric acid, propylvaleric acid, methylbutyric acid, butyloctanoic acid, or combinations thereof.

[0273] The second carboxylic acid is a carboxylic acid containing a second organic ligand as described above. In embodiments, the second organic ligand may include linolenic acid, linoleic acid, oleic acid, transoleic acid, stearic acid, myristic acid, palmitic acid, or combinations thereof.

[0274] The second carboxylic acid may have a pKa greater than or equal to about 8.9, greater than or equal to about 9, greater than or equal to about 9.1, greater than or equal to about 9.8, greater than or equal to about 10, greater than or equal to about 10.1, or greater than or equal to about 10.14.

[0275] In the embodiments, the first zinc precursor may have the following structure, but is not limited thereto:

[0276]

[0277]

[0278] .

[0279] In the embodiments, the second zinc precursor may have the following structure, but is not limited thereto:

[0280] .

[0281] This method may include adding a metal halide (e.g., a metal chloride) to a reaction medium. The metal chloride may include zinc chloride. The zinc precursor and the sulfur precursor may be contacted (or reacted) in the presence of additives and the metal halide.

[0282] Metal halides may include zinc halides, aluminum halides, or combinations thereof. Zinc halides may include zinc chloride, zinc fluoride, zinc bromide, zinc iodide, or combinations thereof. Aluminum halides may include aluminum chloride, aluminum bromide, aluminum fluoride, aluminum iodide, or combinations thereof.

[0283] In embodiments, the reaction medium comprising an organic solvent and optionally an organic ligand, as described herein, may be subjected to vacuum treatment. Vacuum treatment may include heating (or vacuum-treating) the solvent and optionally the ligand compound under vacuum to a predetermined temperature (e.g., greater than or equal to about 100°C). The vacuum-treated reaction medium may be purged with an inert gas atmosphere and reheated to a predetermined temperature (e.g., greater than or equal to about 120°C, or the reaction temperature).

[0284] In this embodiment, nanoparticles and a sulfur precursor may be added to a reaction medium heated to a predetermined temperature. In this embodiment, a first zinc precursor may be added to the reaction medium (once, twice, or more than twice) and brought into contact with the sulfur precursor, then a second zinc precursor may be added to the reaction medium and brought into contact with the sulfur precursor. In this embodiment, a second zinc precursor may be added to the reaction medium (once, twice, or more than twice) and brought into contact with the sulfur precursor first, then a first zinc precursor may be added to the reaction medium and brought into contact with the sulfur precursor.

[0285] The first zinc precursor may be added to the reaction medium in predetermined amounts two or more times. The second zinc precursor may be added to the reaction medium in two or more separate portions. In embodiments, the reaction between the first zinc precursor and the sulfur precursor may be carried out in the presence of additives. In embodiments, the reaction between the second zinc precursor and the sulfur precursor may be carried out in the presence of additives.

[0286] In one embodiment, the metal halide may be added to the reaction medium after the first or second zinc precursor has contacted the sulfur precursor. In another embodiment, the additive may be added to the reaction medium together with the metal halide.

[0287] In the method of this embodiment, a first zinc precursor may first contact a sulfur precursor, and then a second zinc precursor may contact the sulfur precursor. The second zinc precursor may be added to and mixed into the reaction medium before, simultaneously with, or after the addition of the metal halide. In the method of this embodiment, the second zinc precursor may first contact a sulfur precursor, and then the first zinc precursor may contact the sulfur precursor. The first zinc precursor may be added to and mixed into the reaction medium before, simultaneously with, or after the addition of the metal halide.

[0288] In embodiments, relative to 1 mole of the first zinc precursor, the amount of the second zinc precursor may be greater than or equal to about 0.01 moles, greater than or equal to about 0.03 moles, greater than or equal to about 0.05 moles, greater than or equal to about 0.07 moles, greater than or equal to about 0.09 moles, greater than or equal to about 0.1 moles, greater than or equal to about 0.2 moles, greater than or equal to about 0.3 moles, greater than or equal to about 0.4 moles, greater than or equal to about 0.5 moles, greater than or equal to about 0.6 moles, greater than or equal to about 0.7 moles, greater than or equal to about 0.8 moles, greater than or equal to about 0.9 moles, greater than or equal to about 1 mole, greater than or equal to about 1.2 moles, greater than or equal to about 1.5 moles, greater than or equal to about 1.7 moles, greater than or equal to about 1.9 moles, etc. Greater than or equal to about 2 moles, greater than or equal to about 2.1 moles, greater than or equal to about 2.3 moles, greater than or equal to about 2.5 moles, greater than or equal to about 2.7 moles, greater than or equal to about 2.9 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, greater than or equal to about 9.5 moles, greater than or equal to about 10 moles, greater than or equal to about 50 moles, or greater than or equal to about 100 moles.

[0289] In an embodiment, relative to 1 mole of the first zinc precursor, the amount of the second zinc precursor may be less than or equal to about 100 moles, less than or equal to about 90 moles, less than or equal to about 80 moles, less than or equal to about 70 moles, less than or equal to about 60 moles, less than or equal to about 50 moles, less than or equal to about 40 moles, less than or equal to about 30 moles, less than or equal to about 20 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 0.8 moles, less than or equal to about 0.6 moles, less than or equal to about 0.4 moles, less than or equal to about 0.3 moles, less than or equal to about 0.2 moles, less than or equal to about 0.06 moles, or less than or equal to about 0.03 moles.

[0290] In embodiments, relative to 1 mole of total zinc precursor (i.e., the sum of the first and second zinc precursors), the amount of metal halide may be greater than or equal to about 0.01 moles, greater than or equal to about 0.03 moles, greater than or equal to about 0.04 moles, greater than or equal to about 0.05 moles, greater than or equal to about 0.07 moles, greater than or equal to about 0.09 moles, greater than or equal to about 0.1 moles, greater than or equal to about 0.12 moles, greater than or equal to about 0.14 moles, greater than or equal to about 0.16 moles, greater than or equal to about 0.18 moles, greater than or equal to about 0.2 moles, greater than or equal to about 0.21 moles, greater than or equal to about 0.23 moles, greater than or equal to about 0.25 moles, or greater than or equal to about 0.2 7 moles, greater than or equal to about 0.29 moles, greater than or equal to about 0.3 moles, greater than or equal to about 0.35 moles, greater than or equal to about 0.4 moles, greater than or equal to about 0.45 moles, greater than or equal to about 0.5 moles, greater than or equal to about 0.55 moles, greater than or equal to about 0.6 moles, greater than or equal to about 0.65 moles, greater than or equal to about 0.7 moles, greater than or equal to about 0.75 moles, greater than or equal to about 0.8 moles, greater than or equal to about 0.85 moles, greater than or equal to about 0.9 moles, greater than or equal to about 0.95 moles, greater than or equal to about 1 mole, greater than or equal to about 5 moles, greater than or equal to about 100 moles.

[0291] In the embodiments, relative to 1 mole of total zinc precursor, the amount of metal halide may be less than or equal to about 100 moles, less than or equal to about 90 moles, less than or equal to about 80 moles, less than or equal to about 70 moles, less than or equal to about 40 moles, less than or equal to about 10 moles, less than or equal to about 3 moles, less than or equal to about 1 mole, less than or equal to about 0.96 moles, less than or equal to about 0.84 moles, less than or equal to about 0.72 moles, less than or equal to about 0.63 moles, less than or equal to about 0.58 moles, less than or equal to about 0.52 moles, less than or equal to about 0.49 moles, less than or equal to about 0.43 moles, etc. The amounts are approximately 0.41 moles or less than or equal to approximately 0.4 moles, approximately 0.38 moles or less than or equal to approximately 0.34 moles, approximately 0.28 moles or less than or equal to approximately 0.26 moles, approximately 0.24 moles or less than or equal to approximately 0.22 moles, approximately 0.2 moles or less than or equal to approximately 0.2 moles, approximately 0.19 moles or less than or equal to approximately 0.17 moles, approximately 0.15 moles or less than or equal to approximately 0.13 moles, approximately 0.11 moles or less than or equal to approximately 0.08 moles, approximately 0.06 moles or less than or equal to approximately 0.03 moles.

[0292] The predetermined temperature or reaction temperature can be appropriately selected. In an embodiment, the vacuum-treated reaction medium can be heated to a first temperature, and then a first semiconductor nanocrystal, a first zinc precursor (or a second zinc precursor), a sulfur precursor, and optional additives can be added, after which the reaction medium can be heated to the reaction temperature. The first temperature and the reaction temperature can be as described herein.

[0293] The reaction time can be appropriately selected taking into account factors such as the type of precursor, reaction temperature, and the desired thickness of the ZnS shell in the final semiconductor nanoparticles. Reaction times can be greater than or equal to approximately 10 minutes, greater than or equal to approximately 15 minutes, greater than or equal to approximately 20 minutes, greater than or equal to approximately 25 minutes, greater than or equal to approximately 30 minutes, greater than or equal to approximately 35 minutes, or greater than or equal to approximately 40 minutes. Reaction times can be less than or equal to approximately 200 minutes, less than or equal to approximately 180 minutes, less than or equal to approximately 160 minutes, less than or equal to approximately 140 minutes, less than or equal to approximately 120 minutes, less than or equal to approximately 100 minutes, less than or equal to approximately 90 minutes, or less than or equal to approximately 80 minutes.

[0294] After the reaction is complete, excess organic material not coordinated to the surface can be removed by adding an excess of non-solvent, followed by centrifugation of the resulting mixture to recover particles including the first or second semiconductor nanocrystals, or the obtained semiconductor nanoparticles. For example, adding a non-solvent to the reaction product after the reaction is complete can separate semiconductor nanoparticles coordinated with ligand compounds. The non-solvent can be a polar solvent miscible with the solvent used in the core-forming reaction and / or shell-forming reaction but unable to disperse the manufactured nanocrystals. The non-solvent can be determined based on the solvent used in the reaction and can include, for example, acetone, ethanol, butanol, isopropanol, water, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), diethyl ether, formaldehyde, acetaldehyde, ethylene glycol, solvents with similar solubility parameters to the solvents listed above, or combinations thereof, but is not limited thereto. Separation can be performed by centrifugation, precipitation, chromatography, or distillation. If necessary, the separated nanocrystals can be washed by adding them to a washing solvent. There are no particular restrictions on the washing solvent, and it can be a solvent with a similar solubility parameter to the ligand. Examples of solvents may include hexane, heptane, octane, chloroform, toluene, benzene, etc.

[0295] The semiconductor nanoparticles of the embodiments may be non-dispersible in water, any of the non-solvents listed above, or mixtures thereof. The semiconductor nanoparticles of the embodiments may be insoluble in water. The semiconductor nanoparticles of the embodiments may be dispersed in the aforementioned organic solvents. In the embodiments, the semiconductor nanoparticles may be dispersed in C6 to C40 aliphatic hydrocarbons, C6 to C40 aromatic hydrocarbons, or mixtures thereof.

[0296] The obtained semiconductor nanoparticles can exhibit the properties described herein.

[0297] In this embodiment, semiconductor nanoparticles can form a composition (ink) for an inkjet printing process, and an emitter layer pattern can be provided by the inkjet printing process. The composition for the inkjet process may include the semiconductor nanoparticles of this embodiment and a liquid carrier. The semiconductor nanoparticles of this embodiment can form a colloidal dispersion in the liquid carrier. At least a portion of the liquid carrier can be removed from the emitter layer after the inkjet process.

[0298] The liquid carrier may include an organic solvent. The organic solvent may include the dispersing solvent described herein. The organic solvent may be an organic solvent having a relatively high boiling point at atmospheric or normal pressure. The boiling point of the organic solvent or liquid carrier may be greater than or equal to about 120°C, greater than or equal to about 130°C, greater than or equal to about 140°C, greater than or equal to about 150°C, greater than or equal to about 160°C, greater than or equal to about 170°C, or greater than or equal to about 180°C. The boiling point of the organic solvent may be less than or equal to about 300°C, less than or equal to about 280°C, less than or equal to about 270°C, less than or equal to about 250°C, or less than or equal to about 200°C. The organic solvent may include substituted or unsubstituted aromatic solvents (such as cyclohexylbenzene), substituted or unsubstituted C6 to C15 aliphatic hydrocarbon solvents (such as hexane, octane, decane), or combinations thereof. When using mixed solvents, the mixing ratio may be adjusted taking into account the conditions used in the inkjet process (e.g., boiling point, viscosity, etc.). For example, when using a mixture of aromatic and aliphatic solvents, the ratio can be adjusted to 1:0.1 to 1:10, 1:0.3 to 1:3, 1:0.5 to 1:2 (volume:volume), but is not limited thereto.

[0299] Semiconductor nanoparticles can be included in the ink composition by having the properties described herein, thereby contributing to the composition exhibiting a suitable viscosity. The viscosity can be in the range of about 0.5 centipoise (cP) to about 30 cP, about 1 cP to about 15 cP, about 1.5 cP to about 10 cP, about 2 cP to about 8 cP, about 2.5 cP to about 5 cP, about 2.8 cP to about 3.5 cP, or combinations thereof.

[0300] Compositions for inkjet printing may exhibit surface tension or wettability relative to a common layer (e.g., a hole-assisted layer or an electron-assisted layer). Surface tension may be in the range of about 10 millinewtons per meter (mN / m) to about 100 mN / m, about 15 mN / m to about 80 mN / m, about 20 mN / m to about 50 mN / m, about 25 mN / m to about 45 mN / m, about 30 mN / m to about 40 mN / m, about 33 mN / m to about 38 mN / m, or combinations thereof.

[0301] Forming a light-emitting layer by inkjet printing may include: placing or accommodating an ink composition comprising semiconductor nanoparticles in a device equipped with an inkjet printing nozzle; and ejecting / depositing droplets of the composition from the nozzle toward a desired location (e.g., the surface of a hole transport layer (“HTL”) or an electron transport layer defined by a partition wall or dam (such as a pixel-defined layer (PDL)). (See...) Figure 4 and Figure 5 )

[0302] In the electroluminescent device of the embodiments, the thickness of the emitting layer may be suitably selected. In the embodiments, the emitting layer 3 or 30 may comprise a monolayer of semiconductor nanoparticles. In the embodiments, the emitting layer 3 or 30 may comprise a monolayer of semiconductor nanoparticles (e.g., one or more, two or more, three or more, or four or more and 20 or fewer, 10 or fewer, 9 or fewer, 8 or fewer, 7 or fewer, or 6 or fewer). The emitting layer 3 or 30 may have a thickness greater than or equal to about 5 nm (e.g., 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 (e.g., less than or equal to about 150 nm, less than or equal to about 100 nm, less than or equal to about 90 nm, less than or equal to about 80 nm, less than or equal to about 70 nm, less than or equal to about 60 nm, or less than or equal to about 50 nm). The emitter layer 3 or 30 may have a thickness of, for example, about 10 nm to about 150 nm, about 20 nm to about 100 nm, about 30 nm to about 50 nm, or a combination thereof.

[0303] The emitting layer 3 or 30 can be formed by preparing a composition comprising a nanostructure (configured to emit the desired light) and applying or depositing the composition onto a substrate (e.g., including an electrode or charge-assisted layer) by means of a suitable method (e.g., spin coating, inkjet printing, etc.).

[0304] Forming the emitter layer may also include heat-treating the coated or deposited semiconductor nanoparticle layer. The heat treatment temperature (e.g., hot-state treatment or heating treatment) is not particularly limited and may be suitably selected taking into account the boiling point of the organic solvent. For example, the heat treatment temperature may be greater than or equal to about 60°C, or greater than or equal to about 70°C and less than or equal to about 250°C, or less than or equal to about 180°C. The type of organic solvent used for the coating solution is not particularly limited and may be suitably selected. In embodiments, the organic solvent may include substituted or unsubstituted aliphatic hydrocarbon organic solvents, substituted or unsubstituted aromatic hydrocarbon organic solvents, substituted or unsubstituted alicyclic hydrocarbon solvents, acetate solvents, or combinations thereof.

[0305] In embodiments, the emitting layer may be a single layer or a multilayer structure having at least two layers. In a multilayer structure, adjacent layers (e.g., a first emitting layer and a second emitting layer) may be configured to emit a first light (e.g., green, blue, or red light). In a multilayer structure, adjacent layers (e.g., a first emitting layer and a second emitting layer) may have the same or different compositions, ligands, or combinations thereof.

[0306] In embodiments, the (multilayer) emitter layer may have a halogen content that varies (increases or decreases) in the thickness direction. In embodiments, in the (multilayer) emitter layer, the amount of halogen may increase in the direction toward the electron-assisted layer. In the (multilayer) emitter layer, the amount or content of organic ligands may decrease in the direction toward the electron-assisted layer. In the (multilayer) emitter layer, the amount or content of organic ligands may increase in the direction toward the electron-assisted layer.

[0307] The electroluminescent device may further include a charge (hole or electron) auxiliary layer between the first electrode and the second electrode (e.g., anode and cathode). In embodiments, the electroluminescent device may include a hole auxiliary layer 20 or an electron auxiliary layer 40 between the anode 10 and the emitting layer 30, between the cathode 50 and the emitting layer 30, or combinations thereof. (See...) Figure 2 and 3 )

[0308] The electroluminescent device according to an embodiment may further include a hole auxiliary layer. The hole auxiliary layer 20 may be disposed between the first electrode 10 and the emitting layer 30. The hole auxiliary layer 20 may include a hole injection layer, a hole transport layer, an electron blocking layer, or a combination thereof. The hole auxiliary layer 20 may be a single-component layer or a multilayer structure wherein adjacent layers comprise different components.

[0309] To enhance the mobility of holes transferred from the hole assist layer 20 to the emitter layer 30, the hole assist layer 20 may have a HOMO energy level that matches the HOMO energy level of the emitter layer 30. In an embodiment, the hole assist layer 20 may include a hole injection layer near the first electrode 10 and a hole transport layer near the emitter layer 30.

[0310] The materials included in the hole assist 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, poly(N-vinylcarbazole), poly(3,4-ethylenedioxythiophene) (“PEDOT”), poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (“PEDOT:PSS”), polyaniline, polypyrrole, N,N,N',N'-tetra(4-methoxyphenyl)-benzidine (“T…”). PD”), 4,4'-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (“α-NPD”), 4,4',4"-tris[phenyl(m-tolyl)amino]triphenylamine (“m-MTDATA”), 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 (e.g., graphene oxide), or combinations thereof, but not limited thereto.

[0311] In one or more hole-assisted layers, the thickness of each layer may be appropriately selected. For example, the thickness of each layer may be greater than or equal to about 5 nm, greater than or equal to about 10 nm, greater than or equal to about 15 nm, 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, 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.

[0312] An electron auxiliary layer 40 may be disposed between the emitter 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 blocks hole movement, or a combination thereof.

[0313] In an embodiment, an electron injection layer may be disposed between the electron transport layer and the cathode. For example, a hole blocking layer may be disposed between the emitter layer and the electron transport (injection) layer, but is not limited thereto. The thickness of each layer may be appropriately selected. For example, the thickness of each layer may be greater than or equal to about 1 nm and less than or equal to about 500 nm, but is not limited thereto. The electron injection layer may be an organic layer formed by vapor deposition. The electron transport layer may include inorganic oxide nanoparticles, or may be an organic layer formed by vapor deposition.

[0314] Electron transport layer (“ETL”), electron injection layer, hole blocking layer, or combinations thereof may include, for example, 1,4,5,8-naphthalene-tetracarboxylic dianhydride (“NTCDA”), copper bath (“BCP”), tris[3-(3-pyridyl)-trimethylyl]borane (“3TPYMB”), LiF, tris(8-hydroxyquinoline)aluminum (“Alq3”), tris(8-hydroxyquinoline)gallium (“Gaq3”), tris(8-hydroxyquinoline)indium (“Inq3”), bis(8- Zinc(hydroxyquinoline) (“Znq2”), zinc(2(2-hydroxyphenyl)benzothiazole) (“Zn(BTZ)2”), beryllium(10-hydroxybenzo[h]quinoline) (“BeBq2”), 8-(4-(4,6-di(naphthyl-2-yl)-1,3,5-triazin-2-yl)phenyl)quinolone (“ET204”), lithium 8-hydroxyquinoline (“Liq”), n-type metal oxides (e.g., ZnO, HfO2, etc.) or combinations thereof, but not limited thereto.

[0315] The electron auxiliary layer 40 may include an electron transport layer. The electron transport layer may include multiple nanoparticles. The multiple nanoparticles may include a zinc-containing metal oxide.

[0316] Metal oxides may include zinc oxide, zinc magnesium oxide, or combinations thereof. Metal oxides 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 the embodiments, the formula Zn 1- x M x In O, M can be magnesium (Mg). In the examples, in the formula Zn 1-x M x In O, x can be greater than or equal to about 0.01 and less than or equal to about 0.3 (e.g., 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).

[0317] The absolute value of the LUMO of the aforementioned nanostructures included in the emitter 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 (e.g., 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.

[0318] In embodiments, the thickness of each electron-assisted layer 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... Approximately 17nm, greater than or equal to approximately 18nm, greater than or equal to approximately 19nm, or greater than or equal to approximately 20nm and less than or equal to approximately 120nm, less than or equal to approximately 110nm, less than or equal to approximately 100nm, less than or equal to approximately 90nm, less than or equal to approximately 80nm, less than or equal to approximately 70nm, less than or equal to approximately 60nm, less than or equal to approximately 50nm, less than or equal to approximately 40nm, less than or equal to approximately 30nm, or less than or equal to approximately 25nm, but not limited thereto.

[0319] The device according to the embodiments may have a general structure. In the embodiments, in the device, the anode 10 disposed on the transparent substrate 100 may include a transparent electrode based on a metal oxide (e.g., an ITO electrode), and the cathode 50 facing the anode 10 may include a conductive metal (e.g., a conductive metal with a relatively low work function (such as Mg, Al, etc.)). A hole auxiliary 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 or polyvinylcarbazole (“PVK”) or a combination thereof; or a combination thereof) may be disposed between the anode 10 and the emitter layer 30. The hole injection layer may be disposed near the transparent electrode, and the hole transport layer may be disposed near the emitter layer. An electron auxiliary layer 40 (e.g., an electron injection / transport layer) may be disposed between the emitter layer 30 and the second electrode 50. (See...) Figure 2 )

[0320] The device according to the embodiment may have an inverted structure. Here, the cathode 50 disposed on the transparent substrate 100 may include a transparent electrode based on a metal oxide (e.g., ITO), and the anode 10 facing the cathode may include a metal (e.g., a metal with a relatively high work function, Au, Ag, etc.). For example, an n-type metal oxide (optionally, a doped n-type metal oxide) (crystalline Zn metal oxide) or the like may be disposed as an electron auxiliary layer 40 (e.g., an electron transport layer) between the cathode 50 and the emitter layer 30, and a hole auxiliary layer 20 (e.g., a hole transport layer including TFB, PVK, or combinations thereof; a hole injection layer including MoO3 or other p-type metal oxides; or combinations thereof) may be disposed between the anode 10 and the emitter layer 30 (see [link to documentation]). Figure 3 ).

[0321] The aforementioned devices can be manufactured by suitable methods. For example, an electroluminescent device can be manufactured by forming a hole-assisted layer on a substrate on which electrodes are optionally disposed (e.g., via deposition or coating), forming an emission layer including nanostructures (e.g., a pattern of the aforementioned nanostructures), and forming electrodes (optionally, an electron-assisted layer and electrodes) on the light-emitting layer (e.g., via vapor deposition or coating). The methods for forming the electrodes / hole-assisted layer / electron-assisted layer can be suitably selected and are not particularly limited.

[0322] In embodiments, various methods (such as vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) process, inkjet printing, laser printing, and laser-induced thermal imaging (LITI)) can be used to form each layer included in the hole transport region, the light-emitting layer, and each layer included in the electron transport region in a predetermined area. For example, the emitting layer can be formed by inkjet printing. The inkjet process is as described herein.

[0323] When each layer comprising the hole transport region, the luminescent layer, and each layer comprising the electron transport region is formed by vacuum deposition, the deposition conditions can be appropriately selected. For example, the deposition temperature can be from about 100°C to about 500°C, and the vacuum level can be about 10. -8 torr to about 10 -3 The deposition rate can range from about 0.01 Å / sec to about 100 Å / sec. The deposition conditions can be selected taking into account the materials to be included in the layer to be formed and the structure of the layer to be formed.

[0324] Electroluminescent devices can be configured to emit blue light. The wavelength range of blue light is as described herein. Electroluminescent devices can be configured to emit green light. The wavelength range of green light is as described herein. Electroluminescent devices can be configured to emit red light. The wavelength range of red light is as described herein.

[0325] In the electroluminescent device of the embodiments, the maximum external quantum efficiency (“EQE”) may be 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%. In the electroluminescent device of the embodiments, the maximum external quantum efficiency (“EQE”) may be 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%.

[0326] Electroluminescent devices can have a density greater than or equal to approximately 40,000 nits (cd / m²). 2 Maximum brightness of approximately 50,000 nits, 60,000 nits, 70,000 nits, 80,000 nits, 90,000 nits, 95,000 nits, 100,000 nits, 105,000 nits, 110,000 nits, 115,000 nits, 120,000 nits, or 125,000 nits or more. Maximum brightness can range from approximately 3,000 nits to approximately 500,000 nits.

[0327] Electroluminescent devices can exhibit improved lifetime. In an embodiment, the lifetime of the electroluminescent device can be measured while it is driven at a predetermined initial brightness (e.g., 146 nits or 650 nits).

[0328] The lifetime 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 120 hours, greater than or equal to about 130 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, greater than or equal to about 500 hours, greater than or equal to about 600 hours, greater than or equal to about 700 hours, greater than or equal to about 800 hours, greater than or equal to about 900 hours, greater than or equal to about 1,000 hours, greater than or equal to about 1,500 hours, or greater.

[0329] The lifetime T90 of electroluminescent devices 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, and greater than or equal to about 20 hours. 0 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, greater than or equal to about 500 hours, greater than or equal to about 600 hours, greater than or equal to about 700 hours, greater than or equal to about 800 hours, greater than or equal to about 900 hours, greater than or equal to about 1,000 hours, greater than or equal to about 1,500 hours, or more.

[0330] In embodiments, T50 may be in the range of about 150 hours to about 5,000 hours, about 400 hours to about 4,000 hours, about 500 hours to about 3,500 hours, about 750 hours to about 2,000 hours, about 1,000 hours to about 1,500 hours, or a combination thereof.

[0331] In embodiments, T90 may be within the range of about 13 hours to about 5,000 hours, about 15 hours to about 2,800 hours, about 18 hours to about 1,200 hours, about 22 hours to about 1,000 hours, about 31 hours to about 800 hours, about 50 hours to about 700 hours, about 60 hours to about 500 hours, about 80 hours to about 400 hours, or combinations thereof.

[0332] In an embodiment, the display device includes the electroluminescent device described herein.

[0333] The display device may include a first pixel and a second pixel configured to emit light different from that of the first pixel.

[0334] A display device (e.g., a display panel) may include a first pixel and a second pixel configured to emit light of a different color than that of the first pixel. In one embodiment, the first light emitted from the emitting layer may be extracted via a second electrode (e.g., in the Z direction) (see...). Figure 4 or Figure 5 In one embodiment, the first light can be extracted via the (transparent) first electrode and optionally via the substrate 100 (see [link]). Figure 3 The emission layer may be disposed within pixels (or subpixels) in a display device (display panel) as described below (see...). Figure 4 or Figure 5 ).

[0335] Reference Figure 6 According to an embodiment, the display panel 1000 may include a display area 1000D for displaying images and a non-display area 1000P disposed around the display area 1000D, and the adhesive element may be located in the non-display area 1000P.

[0336] Display area 1000D may include a plurality of pixels PX arranged along rows (e.g., the x-direction) and / or columns (e.g., the y-direction), and each pixel PX may include a plurality of sub-pixels PX1, PX2, and PX3 displaying different colors. As an example, a construction is shown in which three sub-pixels PX1, PX2, and PX3 constitute a pixel PX, but the construction is not limited thereto. Additional sub-pixels (such as white sub-pixels) may be further included, and one or more sub-pixels displaying the same color may be included. The plurality of pixels PX may be arranged, for example, in a Bayer matrix, a PenTile matrix, and / or a diamond matrix, but are not limited thereto.

[0337] Each of the sub-pixels PX1, PX2, and PX3 can be configured to display a color of the three primary colors or a combination of the three primary colors (e.g., red, green, blue, or a combination thereof (e.g., white light)). For example, the first sub-pixel PX1 can be configured to display red, the second sub-pixel PX2 can be configured to display green, and the third sub-pixel PX3 can be configured to display blue.

[0338] In the figures, each of the sub-pixels is depicted as having the same size, but this disclosure is not limited thereto. For example, at least one of the sub-pixels may be larger or smaller than another sub-pixel, or have a shape different from that of another sub-pixel.

[0339] In one embodiment, the display panel may include a light-emitting panel, which may include a lower substrate 110, a buffer layer 111, a thin-film transistor (TFT), and light-emitting elements 180. The display panel may also include circuit elements for switching and / or driving each of the light-emitting elements.

[0340] Reference Figure 7 In the light-emitting panel of this embodiment, light-emitting elements 180 may be provided for each sub-pixel PX1, PX2, and PX3. The light-emitting elements 180 provided in each sub-pixel PX1, PX2, and PX3 may be driven independently. Sub-pixels may include blue sub-pixels, red sub-pixels, or green sub-pixels. At least one of the light-emitting elements 180 may be an electroluminescent element according to the embodiments described herein.

[0341] The details of the substrate are the same as described herein. Buffer layer 111 may comprise organic, inorganic, or organic-inorganic materials. Buffer layer 111 may comprise, for example, oxides, nitrides, or oxynitrides, and may comprise, for example, silicon oxide, silicon nitride, silicon oxynitride, or combinations thereof, but is not limited thereto. Buffer layer 111 may be a single layer, or two or more layers, and may cover a portion or the entire surface of the underlying substrate 110. Buffer layer 111 may be omitted.

[0342] The thin-film transistor (TFT) can be a three-terminal element used for switching and / or driving the light-emitting element 180, and may include one, two, or more TFTs for each sub-pixel. The TFT may include a gate electrode 124, a semiconductor layer 154 stacked with the gate electrode 124, a gate insulating layer 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. A coplanar top-gate structure is shown as an example, but the structure is not limited to this, and various structures are possible.

[0343] The gate electrode 124 is electrically connected to the gate line (not shown) and may include, for example, a low-resistance metal (such as aluminum (Al), molybdenum (Mo), copper (Cu), titanium (Ti), silver (Ag), gold (Au), alloys thereof, or combinations thereof), but is not limited thereto.

[0344] Semiconductor layer 154 may be an inorganic semiconductor (such as amorphous silicon, polycrystalline silicon, or oxide semiconductor); an organic semiconductor; an organic-inorganic semiconductor; or a combination thereof. For example, semiconductor layer 154 may include an oxide semiconductor comprising at least one of indium (In), zinc (Zn), tin (Sn), and gallium (Ga), and the oxide semiconductor may include, for example, indium-gallium-zinc oxide, zinc-tin oxide, or combinations thereof, but is not limited thereto. Semiconductor layer 154 may include a channel region and a doped region, the doped region being disposed on both sides of the channel region and electrically connected to the source electrode 173 and the drain electrode 175, respectively.

[0345] The gate insulating layer 140 may comprise organic, inorganic, or organic-inorganic materials, and may include, for example, oxides, nitrides, or oxynitrides, and may include, for example, silicon oxide, silicon nitride, silicon oxynitride, or combinations thereof, but is not limited thereto. The accompanying drawings show an example in which the gate insulating layer 140 is formed over the entire surface of the lower substrate 110, but this disclosure is not limited thereto, and the gate insulating layer 140 may be selectively formed between the gate electrode 124 and the semiconductor layer 154. The gate insulating layer 140 may be formed of one, two, or more layers.

[0346] The source electrode 173 and drain electrode 175 may comprise, for example, low-resistance metals (such as aluminum (Al), molybdenum (Mo), copper (Cu), titanium (Ti), silver (Ag), gold (Au), alloys thereof, or combinations thereof), but are not limited thereto. The source electrode 173 and drain electrode 175 may be electrically connected to doped regions of the semiconductor layer 154, respectively. The source electrode 173 may be electrically connected to a data line (not shown), and the drain electrode 175 may be electrically connected to the light-emitting element 180.

[0347] An interlayer insulating layer 145 may be additionally formed between the gate electrode 124 and the source / drain electrodes 173 and 175. The interlayer insulating layer 145 may include, but is not limited to, organic, inorganic, or organic-inorganic materials (e.g., oxides, nitrides, or oxynitrides; for example, silicon oxide, silicon nitride, silicon oxynitride, or combinations thereof). The interlayer insulating layer 145 may be formed of one, two, or more layers.

[0348] A protective layer 160 may be formed on a thin-film transistor (TFT). The protective layer 160 may be, for example, a passivation layer. The protective layer 160 may include, but is not limited to, organic, inorganic, or organic-inorganic materials (e.g., polyacrylic acid, polyimide, polyamide, poly(amide-imide), or combinations thereof). The protective layer 160 may be formed of one, two, three, or more layers.

[0349] In an embodiment, one of the first electrodes 1, 10 and the second electrodes 5, 50 may be a pixel electrode connected to the TFT, and the other of them may be a common electrode.

[0350] In embodiments, the electroluminescent device or the display device including the electroluminescent device may be used as a top-emitting type, a bottom-emitting type, a dual-emitting type, or a combination thereof.

[0351] In one embodiment, the first electrodes 1 and 10 can be light-transmitting electrodes, and the second electrodes 5 and 50 can be reflective electrodes. The display panel can be a bottom-emitting type display panel that emits light toward the first electrode 10 and (if present) the lower substrate 110. In another embodiment, the first electrodes 1 and 10 can be reflective electrodes, and the second electrodes 5 and 50 can be light-transmitting electrodes. The display panel can be a top-emitting type display panel that emits light toward the first electrode 10 and (if present) the opposite sides of the lower substrate 110. In yet another embodiment, both the first and second electrodes can be transparent electrodes, and the display panel 1000 can be a two-sided emitting type display panel that emits light on the substrate side and on the opposite sides of the substrate.

[0352] Display devices or electronic devices may include (or may be) devices or equipment such as: televisions, virtual reality / augmented reality (VR / AR), handheld terminals, monitors, laptop computers, electronic display panels, cameras, or components for autonomous (e.g., autonomous) vehicles.

[0353] Specific examples are described below. However, the examples described below are for illustrative or explanatory purposes only, and the scope of the disclosure is not limited thereto.

[0354] Example

[0355] 1. Photoluminescence (PL) analysis and TRPL analysis

[0356] The photoluminescence spectrum and absolute QY of nanoparticles were obtained at room temperature using a Hitachi F-7000 spectrophotometer or a Hamamatsu QY spectrophotometer (Quantaurus-QY absolute PL quantum yield spectrophotometer C11347-11) with an excitation wavelength of 372 nm.

[0357] 2. GC Analysis

[0358] Gas chromatography analysis was performed using an Agilent GC-MS 7890B / 5977A. No standards were used. After separating the crude product containing the manufactured semiconductor nanoparticles twice with ethanol (EtOH) and drying under vacuum, 0.1 mg of the manufactured semiconductor nanoparticles was mixed with 1 μL of TMAH (tetramethylammonium hydroxide) and incubated in the hood for 2 minutes prior to py-GC / MS measurements.

[0359] Pyrolysis temperature: 450℃

[0360] Column: 30m × 0.25mm × 0.25mm (UA5)

[0361] Mobile phase: He2 (1 mL / min)

[0362] Inlet temperature: 300℃

[0363] Furnace temperature: 50℃ (hold for 2 min), then increase to 320℃ at a rate of 20℃ / min (hold for 10 min).

[0364] Analyzer: Quadrupole type (range: 10 m / z to 550 m / z)

[0365] 3. TGA and IR spectra

[0366] (1) Thermogravimetric analysis was performed using a Trios V3.2 system (TA Instruments) under nitrogen atmosphere at a heating rate of 10 °C / min from 20 °C to 600 °C. The weight loss from 200 °C to 550 °C was measured as the organic matter content.

[0367] (2) Infrared spectral analysis was performed using an Agilent Cary Varian 670 FTIR spectrometer.

[0368] 4. Electroluminescence measurement and lifetime

[0369] The current was measured according to the applied voltage using a Keithley 2635B source meter, and the electroluminescence properties (e.g., luminance and EQE) of the light-emitting device were measured using a CS2000 spectrometer.

[0370] T90(h): The time (in hours) taken for the brightness to reach 90% of the initial brightness when driven at a predetermined brightness (e.g., 650 nit or 146 nit).

[0371] Unless otherwise stated, the following synthesis is carried out under an inert gas atmosphere (e.g., under nitrogen). Unless otherwise stated, precursor contents are provided in molar amounts.

[0372] Reference Example 1: Preparation of particles containing a first semiconductor nanocrystal and a second semiconductor nanocrystal

[0373] Selenium (Se), sulfur (S), and tellurium (Te) were dispersed in trioctylphosphine (TOP) to obtain a 2-volume molar (M) Se / TOP stock solution, a 1-M S / TOP stock solution, and a 0.1-M Te / TOP stock solution.

[0374] 4.5 mmol of zinc acetate and oleic acid were added to a 300 mL reaction flask containing trioctylamine (TOA) and heated to 120 °C under vacuum. After 1 hour, nitrogen was introduced into the reactor. After heating to 240-300 °C, the prepared Se / TOP stock solution and Te / TOP stock solution were rapidly injected at a Te:Se molar ratio of 1:15. The reaction was allowed to proceed for 40 minutes. After the reaction was complete, and while the reaction solution was at or near room temperature, ethanol was added to the reaction solution to promote the formation of precipitate nanoparticles. ZnTeSe semiconductor nanocrystals were obtained by centrifugation. The obtained precipitate was dispersed in hexane to obtain ZnSeTe nanocrystal cores. The average size of the nanocrystal cores was approximately 3 nm.

[0375] Zinc acetate and oleic acid were added to a 300 mL reaction flask containing TOA, and the mixture was vacuum-treated at 120 °C. Nitrogen (N2) was introduced into the flask, and the flask was heated to the reaction temperature (340 °C). The hexane dispersion of the ZnSeTe core was rapidly added to the reaction flask, followed by the addition of a Se / TOP stock solution, and the reaction continued. Regarding the formation of the ZnSe shell, the amount of selenium precursor was 0.67 mol relative to 1 mol of zinc precursor.

[0376] After the reaction was complete, the reactor was cooled to room temperature, and ethanol was added to the reaction solution to precipitate nanoparticles containing first semiconductor nanocrystals (ZnTeSe) and second semiconductor nanocrystals (ZnSe). The precipitate was recovered by centrifugation, and it was confirmed that the obtained nanoparticles could be dispersed in a hydrocarbon solvent (such as octane).

[0377] Reference Example 2: Synthesis of ZnMgO Nanoparticles

[0378] Zinc acetate dihydrate and magnesium acetate tetrahydrate were added to a reactor containing dimethyl sulfoxide and heated in air at 60°C. Subsequently, an ethanol solution of tetramethylammonium hydroxide pentahydrate was added to the reactor. After stirring the mixture for 1 hour, the resulting precipitate was separated from the reaction mixture using a centrifuge. The precipitate was dispersed in ethanol to obtain Zn. 1-x Mg x O nanoparticles (x=0.15). The obtained nanoparticles underwent transmission electron microscopy analysis. The particles have an average size of approximately 3 nm.

[0379] Preparation of semiconductor nanoparticles

[0380] Preparation Example 1:

[0381] Zinc acetate and ethylhexanoic acid (CAS No. 149-57-5, Sigma-Aldrich, molecular weight: 144.24 g / mol) were added separately to trioctylamine (at a molar ratio of zinc acetate to ethylhexanoic acid of 1:2), and the mixture was heated to 120 °C under vacuum for 1 hour to prepare the first zinc precursor.

[0382] .

[0383] In trioctylamine, zinc acetate and oleic acid are added separately (with a molar ratio of zinc acetate to oleic acid of 1:2), and the mixture is heated to 120°C under vacuum for 1 hour to prepare a second zinc precursor.

[0384] Prepare octylamine (manufacturer: Sigma Aldrich) as an additive.

[0385] Trioctylamine was placed in a 300 mL reaction flask and heated at 120 °C for 1 hour under vacuum, then the inside of the flask was purged with nitrogen (N2). While raising the temperature of the flask to 340 °C, an octane dispersion of particles prepared in Reference Example 1 was added, followed by the addition of additives, a first zinc precursor, and dodecyl mercaptan (a sulfur precursor). The additives were added at 220 °C.

[0386] The reaction was carried out at 340°C for 30 minutes, and then the flask temperature was lowered to 250°C. Zinc chloride and the second zinc precursor were then added, and the reaction was allowed to continue. The total reaction time was 70 minutes. The molar ratio of the first zinc precursor, the second zinc precursor, and the sulfur precursor (first zinc precursor: second zinc precursor: sulfur precursor) was 2.1:0.4:1.4.

[0387] The total amount of zinc precursor used was in a molar ratio of 2.5:0.4 to zinc chloride.

[0388] Based on the total amount of zinc precursor, the amount of amine used is 6 molar percentage.

[0389] After cooling the reactor to room temperature, ethanol was added to the reaction solution to promote the precipitation of semiconductor nanoparticles, and the nanoparticles were recovered by centrifugation. The obtained semiconductor nanoparticles were dispersed in octane. Photoluminescence spectroscopy analysis was performed on the obtained semiconductor nanoparticles, and the results are summarized in Table 1.

[0390] The obtained semiconductor nanoparticles were subjected to infrared spectroscopy analysis, and the results (with baseline correction applied) were summarized in... Figure 8 and Figure 9 From Figure 8 The results confirmed that the NH vibration peak appeared at approximately 3230 cm⁻¹. -1 At approximately 0.41 (minimum transmittance, first transmittance), the COO vibration peak appears at approximately 1550 cm⁻¹. -1 At approximately 0.1 (minimum transmittance, second transmittance), and the CH vibration peak appears at approximately 2927 cm⁻¹. -1 At (approximately 0.158 minimum transmittance, third transmittance).

[0391] Therefore, it is confirmed that the calculated first relative NH absorption rate is 4.1 and the calculated second relative NH absorption rate is 2.59.

[0392] from Figure 9 The results confirmed the existence of peaks attributable to the NH swing.

[0393] The obtained semiconductor nanoparticles were analyzed by gas chromatography (GC), and the results were summarized in Figure 10 According to Figure 10 The results confirmed the peaks attributable to the ethylhexanoate moiety (EHA) at a retention time of approximately 6.2 minutes, the peak attributable to the octylamine moiety (OcAm) at approximately 6.6 minutes, and a second peak at a retention time of approximately 13 minutes, which was attributed to the oleate moiety (OA). The area percentage of the ethylhexanoate peak relative to the area of ​​the second peak (100%) was 31.44%, and the area percentage of the octylamine peak was 11.85%.

[0394] Thermogravimetric analysis was performed on the obtained semiconductor nanoparticles. The results confirmed that the mass loss was 9.6 wt% in the temperature range of approximately 200 °C to approximately 550 °C.

[0395] Preparation Example 2:

[0396] Semiconductor nanoparticles were prepared in the same manner as in Preparation Example 1, except that oleylamine was used instead of octylamine as an additive. The obtained semiconductor nanoparticles were dispersed in octane. Photoluminescence spectroscopy analysis was performed on the obtained semiconductor nanoparticles, and the results are summarized in Table 1.

[0397] Preparation Example 3:

[0398] Semiconductor nanoparticles were prepared in the same manner as in Preparation Example 1, except that the timing of additive addition was adjusted as follows:

[0399] After the reaction was carried out at 340°C for 30 minutes, the flask temperature was lowered to 250°C, and the additive was added together with the second zinc precursor.

[0400] The obtained semiconductor nanoparticles were dispersed in octane. Photoluminescence spectroscopy analysis was performed on the obtained semiconductor nanoparticles, and the results are summarized in Table 1.

[0401] Preparation Example 4:

[0402] Semiconductor nanoparticles were prepared in the same manner as in Preparation Example 1, except that oleylamine was used instead of octylamine as an additive and the timing of the additive addition was adjusted as follows:

[0403] After the reaction was carried out at 340°C for 30 minutes, the flask temperature was lowered to 250°C, and the additive was added together with the second zinc precursor.

[0404] The obtained semiconductor nanoparticles were dispersed in octane. Photoluminescence spectroscopy analysis was performed on the obtained semiconductor nanoparticles, and the results are summarized in Table 1.

[0405] Preparation Example 5:

[0406] Semiconductor nanoparticles were prepared in the same manner as in Preparation Example 1, except that hexylamine was used instead of octylamine as an additive and the timing of the additive addition was adjusted as follows:

[0407] After the reaction was carried out at 340°C for 30 minutes, the flask temperature was lowered to 250°C, and the additive was added together with the second zinc precursor.

[0408] The obtained semiconductor nanoparticles were dispersed in octane. Photoluminescence spectroscopy analysis was performed on the obtained semiconductor nanoparticles, and the results are summarized in Table 1.

[0409] Preparation Example 6:

[0410] Semiconductor nanoparticles were prepared in the same manner as in Preparation Example 1, except that dodecylamine was used instead of octylamine as an additive and the timing of additive addition was adjusted as follows:

[0411] After the reaction was carried out at 340°C for 30 minutes, the flask temperature was lowered to 250°C, and the additive was added together with the second zinc precursor.

[0412] The obtained semiconductor nanoparticles were dispersed in octane. Photoluminescence spectroscopy analysis was performed on the obtained semiconductor nanoparticles, and the results are summarized in Table 1.

[0413] Comparative preparation example 1:

[0414] Semiconductor nanoparticles were prepared in the same manner as in Preparation Example 1, except that octylamine was not used. The prepared semiconductor nanoparticles were dispersed in octane.

[0415] The obtained semiconductor nanoparticles were subjected to infrared spectroscopy analysis, and the results were summarized in... Figure 8 and Figure 9 From Figure 8 The results confirmed that the NH vibration peak appeared at approximately 3230 cm⁻¹. -1 At approximately 0.55 (minimum transmittance, first transmittance), the COO vibration peak appears at approximately 1550 cm⁻¹. -1 At approximately 0.1 (minimum transmittance, second transmittance), and the CH vibration peak appears at approximately 2927 cm⁻¹. -1 At (approximately 0.158 minimum transmittance, third transmittance).

[0416] Therefore, it is confirmed that the first relative NH absorption rate is 5.5 and the second relative NH absorption rate is 3.48.

[0417] from Figure 9 The results confirm that there are no peaks attributable to the NH swing.

[0418] Comparative preparation example 2:

[0419] The semiconductor nanoparticles obtained in Comparative Preparation Example 1 were subjected to a surface ligand exchange reaction as follows to obtain ligand-exchanged semiconductor nanoparticles:

[0420] The prepared semiconductor nanoparticle dispersion in octane and octylamine were added to octadecene and stirred at 70 °C for 20 min. The reaction solution was cooled to room temperature, and ethanol was added to promote the precipitation of the semiconductor nanoparticles. The precipitated semiconductor nanoparticles were then recovered by centrifugation. The obtained semiconductor nanoparticles were dispersed in octane. Photoluminescence spectroscopy analysis of the obtained semiconductor nanoparticles was performed, and the results are summarized in Table 1.

[0421] Table 1

[0422] PWL: Peak Emission Wavelength

[0423] QY: Quantum Yield

[0424] Device Examples

[0425] Comparison Example 1

[0426] An electroluminescent device was fabricated using the semiconductor nanoparticles prepared in Comparative Preparation Example 1. This electroluminescent device has a structure of ITO / PEDOT:PSS (300 Å) / TFB (250 Å) / semiconductor nanoparticle emitting layer (360 Å) / ZnMgO (240 Å) / Al, and its lifetime was measured.

[0427] On a glass substrate with an ITO electrode (first electrode) deposited thereon, a PEDOT:PSS layer and a TFB layer are formed by spin-coating as a hole injection layer and a hole transport layer, respectively. A semiconductor nanoparticle solution prepared in Comparative Fabrication Example 1 is spin-coated onto the formed TFB layer (25 nm) to form an emission layer. A zinc oxide magnesium nanoparticle layer is formed on the emission layer as an electron-assisted layer, and then an Al electrode is deposited to fabricate an electroluminescent device.

[0428] The lifespan of the manufactured devices was measured. The results are summarized in Table 2.

[0429] Example 1

[0430] Electroluminescent devices were fabricated in the same manner as in Comparative Example 1, except that the semiconductor nanoparticles prepared in Preparation Example 1 (octylamine) were used instead of those prepared in Comparative Preparation Example 1. The lifetime of the fabricated devices was measured, and the results are summarized in Table 2.

[0431] Example 2

[0432] The electroluminescent device was fabricated in the same manner as in Comparative Example 1, except that the semiconductor nanoparticles prepared in Preparation Example 4 (oleylamine) were used instead of the semiconductor nanoparticles prepared in Comparative Preparation Example 1. The lifetime of the fabricated device was measured, and the results are summarized in Table 2.

[0433] Example 3

[0434] The electroluminescent device was fabricated in the same manner as in Comparative Example 1, except that the semiconductor nanoparticles prepared in Preparation Example 6 (dodecylamine) were used instead of the semiconductor nanoparticles prepared in Comparative Preparation Example 1. The lifetime of the fabricated device was measured, and the results are summarized in Table 2.

[0435] Table 2

[0436] Relative T90 (%): [T90 (hours) of the given device / T90 (hours) of Comparison Example 1] × 100

[0437] The results in Table 2 confirm that the example electroluminescent devices exhibit 2 to 3 times the improved lifetime characteristics compared to the comparative example electroluminescent devices.

[0438] In this embodiment, the semiconductor nanoparticles include:

[0439] A first semiconductor nanocrystal, comprising zinc, selenium, and optionally tellurium; and a semiconductor nanocrystal shell disposed on the first semiconductor nanocrystal and comprising zinc and sulfur.

[0440] Semiconductor nanoparticles do not include cadmium.

[0441] The semiconductor nanoparticles also include organic ligands containing NH bonds, and in Fourier transform infrared (FTIR) spectroscopy, the semiconductor nanoparticles exhibit a first relative NH absorbance value greater than or equal to about 0.85 and less than or equal to about 8 according to the following equation:

[0442] First relative NH absorption rate = First transmittance / Second transmittance

[0443] The first transmittance exists at approximately 3190 cm. -1 Approximately 3270cm -1 (For example, approximately 3230cm) -1 The minimum transmittance of the first peak within the range of ), and

[0444] The second transmittance exists at approximately 1520 cm. -1 Approximately 1575cm -1(For example, approximately 1550cm) -1 The minimum transmittance of the second peak within the range of ).

[0445] In the embodiments, in the FTIR spectrum, the semiconductor nanoparticles may exhibit a second relative NH absorbance value of less than or equal to about 5, less than or equal to about 4.5, or less than or equal to about 3.48 according to the following equation:

[0446] Second relative NH absorption rate = First transmittance / Third transmittance

[0447] The first transmittance exists at approximately 3190 cm. -1 Approximately 3270cm -1 (For example, approximately 3230cm) -1 The minimum transmittance of the first peak within the range of ), and

[0448] The third transmittance exists at approximately 2890 cm. -1 Approximately 2970cm -1 (For example, approximately 2927cm) -1 The minimum transmittance of the third peak within the range of ).

[0449] In an embodiment, the first peak may be an NH peak (e.g., an NH vibrational peak). Semiconductor nanoparticles may exhibit an NH peak (e.g., an NH vibrational peak) in the infrared spectrum.

[0450] In the embodiments, the second peak may be a carboxylate peak (e.g., a COO (vibrational) peak). Semiconductor nanoparticles may exhibit a carboxylate peak (e.g., a COO vibrational peak) in the infrared spectrum. The second peak may be a vibrational peak of the carbonyl moiety.

[0451] In this embodiment, the third peak may be a CH (vibrational) peak. Semiconductor nanoparticles may exhibit a CH peak in the infrared spectrum.

[0452] In an embodiment, the first peak or its minimum transmittance may be present at approximately 3190 cm⁻¹. -1 Approximately 3250cm -1 or approximately 3190cm -1 Approximately 3235cm -1 Within the range.

[0453] In the embodiment, the second peak or its minimum transmittance may exist at approximately 1530 cm⁻¹. -1 Approximately 1572cm -1 Within the range. The second peak or its minimum transmittance can exist at approximately 1540 cm⁻¹. -1 Approximately 1565cm -1 Within the range. The second peak or its minimum transmittance can exist at approximately 1545 cm⁻¹.-1 Approximately 1560cm -1 Within the range.

[0454] In the embodiment, the third peak or its minimum transmittance may be present at approximately 2920 cm⁻¹. -1 Approximately 2940cm -1 Approximately 2925cm -1 Approximately 2935cm -1 or approximately 2927cm -1 Approximately 2932cm -1 Within the range.

[0455] In an embodiment, the first relative NH absorption rate value may be greater than or equal to about 0.9, greater than or equal to about 1, or greater than or equal to about 1.2.

[0456] In an embodiment, the first relative NH absorption rate value may be less than or equal to about 5.5, less than or equal to about 5, or less than or equal to about 4.5.

[0457] In the embodiments, the second relative NH absorption rate value may be less than or equal to about 3, less than or equal to about 2.8, or less than or equal to about 2.6.

[0458] In the embodiments, the second relative NH absorption rate value may be greater than or equal to about 0.1, greater than or equal to about 0.5, or greater than or equal to about 1.

[0459] In the embodiments, semiconductor nanoparticles can be visualized at 800 cm⁻¹ in Fourier transform infrared spectroscopy. -1 Up to 900cm -1 The peaks within the range of NH groups are attributed to NH groups.

[0460] In embodiments, the semiconductor nanoparticles may further include a first organic ligand having a carboxylate moiety, a second organic ligand having a carboxylate moiety, or a combination thereof, wherein the first organic ligand may have a total number of carbon atoms greater than or equal to about 3 and less than or equal to about 15, and the second organic ligand may have a total number of carbon atoms greater than about 15.

[0461] In an embodiment, the second organic ligand may have a total number of carbon atoms less than or equal to about 25.

[0462] In embodiments, the semiconductor nanoparticles may further include halogens (or halides) (e.g., chlorine (or chlorides)). In the semiconductor nanoparticles, the molar ratio of chlorine to zinc may be greater than or equal to about 0.01:1, greater than or equal to about 0.05:1, greater than or equal to about 0.1:1, greater than or equal to about 0.15:1, or greater than or equal to about 0.2:1. In the semiconductor nanoparticles, the molar ratio of chlorine to zinc may be less than or equal to about 1:1, less than or equal to about 0.9:1, less than or equal to about 0.7:1, or less than or equal to about 0.5:1.

[0463] In the embodiments, the amount of fluorine relative to zinc (e.g., atomic ratio) in the semiconductor nanoparticles may be less than about 0.13:1, less than or equal to about 0.1:1, less than or equal to about 0.05:1, or less than or equal to about 0.04:1.

[0464] In the embodiments, the amount of fluorine in the semiconductor nanoparticles may be less than about 1.9 atomic percent of the total amount of the elements, or less than about 1 atom of the total amount of the elements.

[0465] In the embodiments, the semiconductor nanoparticles may not exhibit fluorine peaks in XPS analysis.

[0466] In an embodiment, the semiconductor nanocrystal shell may include a first shell layer and a second shell layer disposed on the first shell layer. The first shell layer may include zinc and selenium (second semiconductor nanocrystals). The first shell layer or the second semiconductor nanocrystal may include zinc selenide, zinc telluride selenide, zinc sulfide selenide, or combinations thereof. The second shell layer may include zinc and sulfur (third semiconductor nanocrystals). The second shell layer or the third semiconductor nanocrystal may include zinc sulfide selenide, zinc sulfide, or combinations thereof.

[0467] In an embodiment, the first light may exhibit a red light spectrum, a green light spectrum, or a blue light spectrum.

[0468] In an embodiment, the first light may be blue light. The peak emission wavelength of the first light or blue light may be greater than or equal to about 440 nm, or greater than or equal to about 460 nm and less than or equal to about 480 nm.

[0469] In an embodiment, the first light may be green light. The peak emission wavelength of the first light or green light may be greater than or equal to about 500 nm and less than or equal to about 580 nm.

[0470] In an embodiment, the first light may be red light. The peak emission wavelength of the first light or red light may be greater than or equal to about 600 nm and less than or equal to about 680 nm.

[0471] In an embodiment, the first light may have a peak emission full width at half maximum (FWHM) greater than or equal to about 1 nm, or greater than or equal to about 20 nm and less than or equal to about 50 nm, or less than or equal to about 45 nm.

[0472] In the embodiments, the semiconductor nanoparticles may have a quantum yield of more than or equal to about 80%, or more than or equal to about 89%.

[0473] In the embodiments, the method for preparing semiconductor nanoparticles includes:

[0474] A third semiconductor nanocrystal comprising zinc and sulfur is formed by contacting (e.g., reacting) a zinc precursor and a sulfur precursor in a reaction medium comprising an organic solvent and optional organic ligands, in the presence of particles comprising a first semiconductor nanocrystal and optional second semiconductor nanocrystals, at a reaction temperature.

[0475] The method of the embodiments further includes adding an organic compound comprising an NH bond (hereinafter referred to as an additive) to the reaction medium. The additive may include C3 to C30 primary amine compounds, carbamic acids, or combinations thereof.

[0476] In the embodiments, contact (or reaction) between the zinc precursor and the sulfur precursor can be carried out in the presence of additives.

[0477] In embodiments, the reaction temperature may be greater than or equal to about 220°C (e.g., greater than or equal to about 280°C) and less than or equal to about 350°C, and the additive may be added at a first temperature, wherein the first temperature may be lower than the reaction temperature. The first temperature may be within the range of greater than or equal to about 200°C and less than or equal to about 300°C, greater than or equal to about 210°C and less than or equal to about 260°C, greater than or equal to about 220°C and less than or equal to about 250°C, or a combination thereof.

[0478] In this embodiment, the additive may be present in the reaction system prior to the initiation of the formation of the third semiconductor nanocrystal. The additive may also be added to the reaction medium after the initiation of the formation of the third semiconductor nanocrystal.

[0479] In embodiments, the method may include adding a metal chloride to the reaction medium. The metal chloride may include zinc chloride. Contacting (or reacting) the zinc precursor and the sulfur precursor may be carried out in the presence of additives and the metal chloride.

[0480] In embodiments, the zinc precursor may include a first zinc precursor comprising a first organic ligand and zinc ions, and a second zinc precursor comprising a second organic ligand and zinc ions. The first organic ligand and the second organic ligand may have different numbers of carbon atoms. The second organic ligand may have a larger number of carbon atoms than the first organic ligand. The second organic ligand may have a larger molecular weight than the first organic ligand.

[0481] In the embodiments, the first organic ligand may include a hexanoate group, a methylbutyrate group, a butyloctanoate group, or a combination thereof. The first organic ligand may include a hexanoate moiety substituted with a C1 to C3 alkyl group, a butyrate moiety substituted with a C1 to C3 alkyl group, a valerate moiety substituted with a C1 to C3 alkyl group, an octanoate moiety substituted with a C1 to C4 alkyl group, or a combination thereof.

[0482] In embodiments, the second organic ligand may comprise a straight-chain or branched aliphatic hydrocarbon group (e.g., alkyl, alkenyl, or alkynyl) of C13 to C25, C14 to C23, C15 to C22, C16 to C21, C17 to C20, or C18 to C19. The second organic ligand may comprise an aliphatic hydrocarbon group of C17 or larger. In embodiments, the second organic ligand may comprise a carboxylate group having an aliphatic hydrocarbon group of C15 to C30.

[0483] In the embodiments, the second organic ligand may include (e.g., one or more, or two or more) carbon-carbon double bonds in the aliphatic hydrocarbon group chain.

[0484] In the embodiments, the first organic ligand may include a branched alkyl group, and the second organic ligand may include a straight-chain alkenyl group.

[0485] In one embodiment, the electroluminescent device includes a spaced-apart first electrode and a second electrode, and an emitting layer disposed between the first electrode and the second electrode, wherein the emitting layer includes the semiconductor nanoparticles described above. Details of the semiconductor nanoparticles are as described herein.

[0486] In one embodiment, the emitting layer may be configured to emit first light in response to the application of a voltage.

[0487] In an embodiment, the peak emission wavelength of the first light or semiconductor nanoparticle (electroluminescence or photoluminescence) may be greater than or equal to about 440 nm, or greater than or equal to about 460 nm and less than or equal to about 480 nm, or less than or equal to about 470 nm.

[0488] In one embodiment, the peak emission wavelength of the first optical or semiconductor nanoparticle may be greater than or equal to about 500 nm, or greater than or equal to about 510 nm and less than or equal to about 580 nm, or less than or equal to about 540 nm. In another embodiment, the peak emission wavelength of the first optical or semiconductor nanoparticle may be greater than or equal to about 600 nm, or greater than or equal to about 610 nm and less than or equal to about 680 nm, or less than or equal to about 635 nm.

[0489] In an embodiment, the first electrode may be an anode, and the second electrode may be a cathode.

[0490] In embodiments, the electroluminescent device may further include a charge-assisted layer between the emitting layer and the first electrode, between the emitting layer and the second electrode, or between the emitting layer and the first electrode and between the emitting layer and the second electrode.

[0491] In some embodiments, the electroluminescent device may further include a hole-assisted layer between the emitting layer and the first electrode. The electroluminescent device may also include an electron-assisted layer between the emitting layer and the second electrode.

[0492] In embodiments, the charge-assisted layer may include a hole-assisted layer comprising an organic compound, an electron-assisted layer comprising metal oxide nanoparticles, or a combination thereof.

[0493] In an embodiment, the electroluminescent device may have a density greater than or equal to about 10,000 cd / m². 2 Greater than or equal to approximately 30,000 cd / m³ 2 Or greater than or equal to approximately 50,000 cd / m³ 2 Maximum brightness.

[0494] In embodiments, the electroluminescent device may have a maximum external quantum efficiency of about 3%, about 5%, or about 7%. The electroluminescent device may have a T90 of about 30 hours (e.g., when measured at an initial brightness of about 146 nits (e.g., 650 nits or 1000 nits)).

[0495] The embodiments relate to electronic devices or display devices that include electroluminescent devices.

[0496] In embodiments, the display device or electronic device may include a virtual reality display device, an augmented reality display device, a portable terminal device, a monitor, a laptop computer, a television set, a bulletin board, a camera, or an automotive component.

[0497] While this disclosure has been described in conjunction with what are now considered to be practical exemplary embodiments, it will be understood that the invention is not limited to the disclosed embodiments, but rather is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A semiconductor nanoparticle, comprising: A first semiconductor nanocrystal comprising zinc, selenium and optionally tellurium; And A semiconductor nanocrystal shell disposed on the first semiconductor nanocrystal, the semiconductor nanocrystal shell comprising zinc and sulfur, and the semiconductor nanoparticle not comprising cadmium, Wherein the semiconductor nanoparticle further comprises an organic ligand comprising an N-H bond, and in Fourier transform infrared spectroscopy, the semiconductor nanoparticle exhibits a first relative N-H absorption rate value greater than or equal to 0.85 and less than or equal to 8 according to the following equation: First relative N-H absorption rate value = First transmittance / Second transmittance, The first transmittance is at 3190cm. -1 Up to 3270cm -1 The minimum transmittance of the first peak within the range, and The second transmittance is at 1520cm. -1 Up to 1575cm -1 The minimum transmittance of the second peak within the range.

2. The semiconductor nanoparticles according to claim 1, wherein, The first peak is an N-H peak, and the second peak is a COO peak.

3. The semiconductor nanoparticles according to claim 1, wherein, In Fourier transform infrared spectroscopy, the semiconductor nanoparticle exhibits a second relative N-H absorption rate value less than or equal to 5 according to the following equation: Second relative N-H absorption rate value = First transmittance / Third transmittance, The first transmittance is at 3190cm. -1 Up to 3270cm -1 The minimum transmittance of the first peak within the range, and the third transmittance is at 2890 cm⁻¹. -1 Up to 2970cm -1 The minimum transmittance of the third peak within the range.

4. The semiconductor nanoparticles according to claim 3, wherein, The first peak is an N-H peak, and the third peak is a C-H peak.

5. The semiconductor nanoparticles according to claim 3, wherein, The second relative N-H absorption rate value is less than or equal to 3.

4.

6. The semiconductor nanoparticle according to claim 1, in, The first peak is at 3190cm. -1 Up to 3235cm -1 It exhibits the lowest transmittance within the range, and The second peak is at 1545cm. -1 Up to 1560cm -1 It exhibits the lowest transmittance within the range.

7. The semiconductor nanoparticles according to claim 1, wherein, The first relative N-H absorption rate value is greater than or equal to 1.2 and less than 5.

5.

8. The semiconductor nanoparticle according to claim 1, in, The semiconductor nanoparticle further comprises a first organic ligand having a carboxylate moiety, a second organic ligand having a carboxylate moiety or a combination thereof, and The first organic ligand has a total carbon atom number greater than or equal to 3 and less than or equal to 15, and the second organic ligand has a total carbon atom number greater than 15.

9. The semiconductor nanoparticles according to claim 1, wherein, The semiconductor nanoparticle further comprises chlorine.

10. The semiconductor nanoparticles according to claim 1, wherein, In the semiconductor nanoparticle: The atomic ratio of fluorine to zinc is less than 0.05:1, or The amount of fluorine is less than 1.9 atomic percent of the total amount of elements of the semiconductor nanoparticle.

11. The semiconductor nanoparticles according to claim 1, wherein, The semiconductor nanocrystal shell comprises a first shell layer and a second shell layer disposed on the first shell layer, wherein the first shell layer comprises zinc and selenium, and the second shell layer comprises zinc and sulfur.

12. The semiconductor nanoparticle according to any one of claims 1 to 11, wherein The semiconductor nanoparticle is configured to emit blue light having a peak emission wavelength greater than or equal to 450 nm and less than or equal to 480 nm The semiconductor nanoparticle has a quantum yield greater than or equal to 89%, and The semiconductor nanoparticle is configured to exhibit a full width at half maximum greater than or equal to 20 nm and less than or equal to 50 nm.

13. A method for preparing a semiconductor nanoparticle, in, The semiconductor nanoparticle comprises a first semiconductor nanocrystal comprising zinc, selenium and optionally tellurium, and the semiconductor nanoparticle does not comprise cadmium, The semiconductor nanoparticle further comprises an organic ligand comprising an N-H bond, and in Fourier transform infrared spectroscopy, the semiconductor nanoparticle exhibits a first relative N-H absorption rate value greater than or equal to 0.85 and less than or equal to 8 according to the following equation: First relative N-H absorption rate value = First transmittance / Second transmittance, The first transmittance is at 3190cm. -1 Up to 3270cm -1 The minimum transmittance of the first peak within the range, and The second transmittance is at 1520cm. -1 Up to 1575cm -1 The minimum transmittance of the second peak within the range, and Wherein the method comprises: A third semiconductor nanocrystal comprising zinc and sulfur is formed by contacting a zinc precursor and a sulfur precursor at a reaction temperature in the presence of particles comprising a first semiconductor nanocrystal and an optional second semiconductor nanocrystal in a reaction medium comprising an organic solvent and optional organic ligands; and Additives, including organic compounds with NH bonds, are added to the reaction medium.

14. The method according to claim 13, in, The steps for forming the third semiconductor nanocrystals include contacting the zinc precursor and the sulfur precursor at a reaction temperature in the presence of additives.

15. The method according to claim 13, wherein, The reaction temperature is greater than or equal to 220°C and less than or equal to 350°C, and the additives are added at a temperature greater than or equal to 180°C and less than or equal to 280°C.

16. The method according to claim 13, further comprising: Metal halides are added to the reaction medium.

17. The method according to claim 13, wherein, Additives include C3 to C30 primary amine compounds, carbamic acids, or combinations thereof.

18. The method according to any one of claims 13 to 17, wherein, The zinc precursor includes a first zinc precursor comprising a first organic ligand and zinc ions, and a second zinc precursor comprising a second organic ligand and zinc ions. The first organic ligand includes a hexanoate moiety substituted with C1 to C3 alkyl, a butanoate moiety substituted with C1 to C3 alkyl, a valerate moiety substituted with C1 to C3 alkyl, an octanoate moiety substituted with C1 to C4 alkyl, or a combination thereof. The second organic ligand includes a carboxylate group having an aliphatic hydrocarbon group of C15 to C30.

19. An electroluminescent device, comprising: The first electrode and the second electrode are spaced apart. And an emission layer, disposed between the first electrode and the second electrode. The emitter layer includes semiconductor nanoparticles. The semiconductor nanoparticles include: a first semiconductor nanocrystal comprising zinc, selenium, and optionally tellurium; and a semiconductor nanocrystal shell disposed on the first semiconductor nanocrystal and comprising zinc and sulfur. Semiconductor nanoparticles do not include cadmium. The semiconductor nanoparticles also include organic ligands containing NH bonds, and in Fourier transform infrared spectroscopy, the semiconductor nanoparticles exhibit a first relative NH absorbance value greater than or equal to 0.85 and less than or equal to 8 according to the following equation: First relative NH absorption rate = First transmittance / Second transmittance The first transmittance is at 3190cm. -1 Up to 3270cm -1 The minimum transmittance of the first peak within the range, and The second transmittance is at 1520cm. -1 Up to 1575cm -1 The minimum transmittance of the second peak within the range.

20. A display device, comprising: The electroluminescent device according to claim 19.

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