Electroluminescent device, method of manufacturing the same, and display device including the same

Abstract

An electroluminescent device, a method of manufacturing the same, and a display device including the same. The electroluminescent device includes a first electrode, a second electrode, a light emitting layer disposed between the first electrode and the second electrode, an electron transport layer disposed between the light emitting layer and the second electrode, and an organic layer. The light emitting layer includes semiconductor nanoparticles, the electron transport layer includes metal oxide nanoparticles, and the metal oxide nanoparticles have a size of 1 nm or more and 50 nm or less. The organic layer includes a polymer, and the polymer includes a repeating unit having a hydroxyl group.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority of Korean Patent Application No. 10 - 2024 - 0002499, filed on January 5, 2024, with the Korean Intellectual Property Office, and all benefits arising therefrom, the entire content of which is incorporated herein by reference. Technical field

[0003] The present disclosure relates to light - emitting (e.g., electroluminescent) devices, methods for manufacturing the devices, and display devices including the light - emitting devices. Background art

[0004] Semiconductor nanoparticles having a nanoscale size (e.g., semiconductor nanocrystal particles) can exhibit light - emitting properties. For example, quantum dots including semiconductor nanocrystals can exhibit quantum confinement effects. When electrons in an excited state generated by light excitation or an applied voltage transition from the conduction band to the valence band, light emission from the semiconductor nanoparticles can occur. The semiconductor nanoparticles can be configured to emit light in a desired wavelength region by adjusting the size of the semiconductor nanoparticles, the composition of the semiconductor nanoparticles, or a combination thereof.

[0005] Semiconductor nanoparticles can be used, for example, in light - emitting devices (e.g., electroluminescent devices) or display devices including electroluminescent devices. Summary of the invention

[0006] Embodiments provide a light - emitting device that emits light, for example, by applying a voltage to a device including nanostructures (e.g., semiconductor nanoparticles such as quantum dots) in an emission layer, for example, with or without a separate irradiation light source.

[0007] Embodiments provide a display device (e.g., a quantum dot - light - emitting diode (QD - LED) display device) that includes a plurality of semiconductor nanoparticles such as quantum dots as components of a light - emitting layer in a pixel configuration (e.g., in a configuration of blue pixels, red pixels, green pixels, or a combination thereof).

[0008] In an embodiment, an electroluminescent device includes: a first electrode and a second electrode (thin - film conductor) (e.g., spaced apart, e.g., each electrode has a surface opposite to the other), a light - emitting layer disposed between the first electrode and the second electrode, an electron - transport layer disposed between the light - emitting layer and the second electrode, and an organic layer. The light - emitting layer includes semiconductor nanoparticles, and the electron - transport layer includes metal - oxide nanoparticles. The metal - oxide nanoparticles have a size greater than or equal to about 1 nm and less than or equal to about 50 nm. The organic layer includes a polymer, and the polymer includes repeating units having hydroxyl groups.

[0009] The organic layer may be disposed on or above the electron transport layer and, optionally, on or above the second electrode.

[0010] The electron transport layer may have a first surface facing the light-emitting layer and a second surface opposite the first surface, and the organic layer may be disposed on or above the second surface of the electron transport layer (e.g., directly on the second surface of the electron transport layer or spaced apart therefrom).

[0011] The organic layer may be disposed or arranged to be spaced apart from the electron transport layer and the second electrode. The organic layer may be disposed to face the electron transport layer and / or the second electrode. The second electrode may be disposed between the organic layer and the electron transport layer.

[0012] The second electrode may have a first surface facing the surface of the electron transport layer and a second surface opposite the first surface, and the organic layer may be spaced apart therefrom, and the organic layer may be disposed to face at least a part (or all) of the surface of the electron transport layer and / or at least a part (or all) of the second surface of the second electrode.

[0013] In an embodiment, the electroluminescent device may further include a container configured to accommodate at least the electron transport layer and the second electrode. The container may include a light-transmitting component (e.g., a light-transmitting material or a light-transmitting component). The container may further include additional components (e.g., bonded or linked to the light-transmitting component) such as a sealing material. The container may be an encapsulation element for the stacked structure. The container or the light-transmitting component may include an organic material such as a polymer, an inorganic material such as glass, an organic and inorganic hybrid material, or a combination thereof. The container may be an integrated element including a single component or material. The container may be an element including a plurality of components or materials joined to form the container.

[0014] The organic layer may be disposed on the surface of the container (or the light-transmitting component) (e.g., the surface facing the second electrode). The organic layer may be applied or coated on the surface of the container or the light-transmitting component.

[0015] The electroluminescent device may further include a hole assisting layer between the light-emitting layer and the first electrode. The hole assisting layer may include a hole transport layer (e.g., including an organic compound), a hole injection layer, or a combination thereof. The organic material of the hole injection layer or the hole transport layer may include an arylamine compound such as TPD, an imidazole compound such as TPBi, a carbazole biphenyl compound such as CBP, a carbazole phenylamine compound such as TCTA, a naphthyl biphenyl diamine compound such as NPB, a polymer such as PEDOT:PSS, PVK, or TFB, or a combination thereof, but is not limited thereto.

[0016] The semiconductor nanoparticles may include a first semiconductor nanocrystal and a second semiconductor nanocrystal. The first semiconductor nanocrystal includes zinc, selenium, and tellurium. The second semiconductor nanocrystal includes a zinc chalcogenide and is different from the first semiconductor nanocrystal. The semiconductor nanoparticles may include: a first semiconductor nanocrystal including a (III-V compound or an indium phosphide (InP) compound including) indium, phosphorus, and optionally zinc; and a second semiconductor nanocrystal including a zinc chalcogenide and different from the first semiconductor nanocrystal.

[0017] The size or average size (hereinafter referred to as "size") of the semiconductor nanoparticles may be greater than or equal to about 4 nanometers (nm), greater than or equal to about 5 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, or greater than or equal to about 10 nm. The size of the semiconductor nanoparticles may be less than or equal to about 30 nm, less than or equal to about 20 nm, less than or equal to about 15 nm, less than or equal to about 12 nm, or less than or equal to about 10 nm.

[0018] The semiconductor nanoparticles may have a core-shell structure including a core and a shell. The core includes the first semiconductor nanocrystal, and the shell is disposed on the core and includes the second semiconductor nanocrystal.

[0019] The electron transport layer may be adjacent to the light-emitting layer (or directly disposed on the light-emitting layer).

[0020] The size or average size (hereinafter referred to as "size") of the metal oxide nanoparticles may be greater than or equal to about 1 nm, or greater than or equal to about 3 nm. The size of the metal oxide nanoparticles may be less than or equal to about 50 nm, less than or equal to about 30 nm, less than or equal to about 20 nm, less than or equal to about 10 nm, or less than or equal to about 8 nm.

[0021] The metal oxide nanoparticles may include zinc oxide (nanoparticles). The metal oxide nanoparticles may include: zinc; and optionally an alkaline earth metal, Zr, W, Li, Ti, Y, Al, Ga, In, Sn, Co, V, or a combination thereof. The metal oxide nanoparticles may further include an alkali metal. The metal oxide nanoparticles may include zinc, an alkaline earth metal, and optionally an alkali metal.

[0022] The metal oxide nanoparticles may include Zn 1-x M xA compound represented by O, where M is Mg, Ga, Ca, Zr, Co, W, Li, Ti, Y, Al, or a combination thereof, and 0 ≤ x ≤ 0.5. x can be greater than or equal to about 0.01, greater than or equal to about 0.03, greater than or equal to about 0.05, greater than or equal to about 0.1, or greater than or equal to about 0.15. x can be less than or equal to about 0.45, or less than or equal to about 0.4.

[0023] The polymer may include repeating units represented by Chemical Formula 1:

[0024] Chemical Formula 1

[0025]

[0026] where A is a direct bond, -C(O)-, -O-, an ester linkage (-C(O)O- or -OC(O)-), -C(O)NH-, -NH-, -S-, -S(O)-, or a combination thereof,

[0027] L is a direct bond, a substituted or unsubstituted (e.g., divalent) C1-C30, C2-C15, C3-C20, C4-C8, C5-C6, C1-C10 aliphatic hydrocarbon group (e.g., alkylene or alkenylene), or a substituted or unsubstituted C6-C20 arylene (e.g., phenylene),

[0028] R are the same or different and are each independently hydrogen or a substituted or unsubstituted C1 to C30 (or C5 to C10) alkyl group, and

[0029] * is the moiety that binds to an adjacent atom (e.g., in the main chain).

[0030] The polymer may include polyvinyl alcohol, polyvinylphenol, poly(hydroxyalkyl) (meth)acrylate, poly(hydroxyalkyl) (meth)acrylamide, or a combination thereof. The polymer may include (or be) a copolymer or a homopolymer.

[0031] The polymer may have an average (number-average or weight-average) molecular weight as follows: greater than or equal to about 500 g / mol, greater than or equal to about 1000 g / mol, greater than or equal to about 5000 g / mol, or greater than or equal to about 10,000 g / mol. The polymer may have a number-average or weight-average molecular weight as follows: less than or equal to about 5,000,000 g / mol, less than or equal to about 3,000,000 g / mol, or less than or equal to about 1,000,000 g / mol.

[0032] The polymer can be a water-soluble polymer. The polymer can have the following solubility in water or alcohol: greater than or equal to about 1 gram per liter (g / L), greater than or equal to about 10 g / L, or greater than or equal to about 30 g / L. For example, at room temperature, for example, at a temperature of about 20°C to about 23°C. The solubility of the polymer in water or alcohol can be less than or equal to about 5000 g / L, less than or equal to about 4000 g / L, less than or equal to about 3000 g / L, less than or equal to about 1500 g / L, less than or equal to about 1000 g / L, less than or equal to about 500 g / L, or less than or equal to about 200 g / L. For example, at room temperature, for example, at a temperature of about 20°C to about 23°C.

[0033] The polymer can exhibit a pH, for example, greater than or equal to about 4.5 and less than or equal to about 8.5, or greater than or equal to about 5 and less than or equal to about 8.5, or less than or equal to about 7, or less than or equal to about 5.5, for example, when dissolved in water or a C1-C10 alcohol.

[0034] When analyzed by NMR, the polymer can exhibit a hydroxyl peak (for example, three peaks) between 4 - 5 ppm.

[0035] The organic layer can have the following thickness: greater than or equal to about 1 nm, greater than or equal to about 10 nm, greater than or equal to about 100 nm, greater than or equal to about 1 micrometer (μm), greater than or equal to about 2 μm, greater than or equal to about 3 μm, greater than or equal to about 4 μm, greater than or equal to about 5 μm, greater than or equal to about 10 μm, greater than or equal to about 100 μm, or greater than or equal to about 1000 μm. The thickness of the organic layer can be less than or equal to about 1 millimeter, less than or equal to about 900 μm, less than or equal to about 100 μm, less than or equal to about 50 μm, less than or equal to about 35 μm, less than or equal to about 10 μm, less than or equal to about 9 μm, or less than or equal to about 7 μm.

[0036] After immersion in a first solvent including water, a C1-C10 alcohol (such as ethanol), dimethyl sulfoxide, an ether solvent, a ketone solvent, an ester solvent, or a mixture thereof, the organic layer or the polymer can be at least partially or completely dissolved.

[0037] The organic layer or the polymer can include polyvinyl alcohol, polyvinylphenol, poly(hydroxyalkyl) (meth)acrylate, polyhydroxyalkyl (meth)acrylamide, or a combination thereof.

[0038] The temperature of the first solvent can be greater than or equal to about 25°C and less than or equal to about 100°C, 50°C or lower, or 30°C or lower. The first solvent can include: water; ethanol; a mixture of water and ethanol; a mixture of water and DMSO; or a mixture of ethanol and DMSO.

[0039] The organic layer or polymer material may further include or may not include additives. The additives may include: inorganic acids such as sulfuric acid, C2-50 carboxylic acid compounds (e.g., represented by R(COOH) n ), sulfinic acid compounds (e.g., represented by R(SO2H) n ), sulfonic acid compounds (e.g., represented by R(SO3H) n ), or combinations thereof. In the formula, R is a substituted or unsubstituted C1 (or C6) to C50 aliphatic or aromatic hydrocarbon group, and n is an integer from 1 to 10, 2 to 8, or 3 to 5. In an embodiment, the organic layer or polymer material may not include additives.

[0040] Based on the total weight of the organic layer, the amount of the crosslinked polymer in the organic layer or polymer may be less than about 1 weight percentage (wt%), or less than or equal to about 0.9 wt%.

[0041] The organic layer may include or may not include a crosslinked polymer.

[0042] The second electrode may have a thickness greater than about 10 nm, greater than or equal to 11 nm, or greater than or equal to about 15 nm. The second electrode may have a thickness less than or equal to about 80 nm, less than or equal to about 60 nm, less than or equal to about 50 nm, or less than or equal to about 40 nm. The thin film conductor may include silver, aluminum, magnesium, tungsten, nickel, cobalt, platinum, palladium, calcium, LiF, gold, copper, or combinations thereof (e.g., alloys). The second electrode or thin film conductor may include silver and magnesium.

[0043] The light-emitting layer may be configured to emit a first light.

[0044] The second electrode may be configured to exhibit a light transmittance of greater than or equal to about 25%, greater than or equal to about 35%, or greater than or equal to about 40% for the first light. The light transmittance may be less than or equal to about 90%, less than or equal to about 70%, or less than or equal to about 55%.

[0045] The first electrode may be configured to reflect at least a portion of the first light.

[0046] In an embodiment, a method of preparing or manufacturing an electroluminescent device includes:

[0047] Forming a light-emitting layer including semiconductor nanoparticles on a first electrode;

[0048] Forming an electron transport layer including metal oxide nanoparticles on the light-emitting layer;

[0049] Forming a thin film conductor (or second electrode) on the electron transport layer to obtain a stacked structure; and

[0050] Performing post-treatment of a stacked structure with a polymer comprising repeating units having hydroxyl groups (or an organic layer comprising the polymer).

[0051] Wherein the post-treatment comprises

[0052] Placing the stacked structure and the polymer in a first space; and maintaining the first space at a post-treatment temperature greater than or equal to about 40 °C. The post-treatment temperature can be less than or equal to about 200 °C, less than or equal to about 180 °C, or less than or equal to about 150 °C.

[0053] The polymer can be in the form of a composition for forming an organic layer.

[0054] Details regarding the polymer and the organic layer are as described herein.

[0055] The method can further include providing a container to the stacked structure, and the container can be configured to define at least a portion of the first space. Details regarding the container are the same as those described herein. In an embodiment, the container can be a furnace (oven) or a chamber. In an embodiment, the container can be an encapsulation glass. The container can be a furnace comprising a hollow chamber and an element configured to heat the chamber in a controlled manner.

[0056] The method can further include preparing a polymer composition (e.g., a composition for forming an organic layer) comprising the polymer and a liquid carrier (e.g., a solvent).

[0057] The method can include applying the polymer composition onto an electron transport layer (and optionally a second electrode).

[0058] The method can further include applying the composition onto the electron transport layer (and optionally the second electrode).

[0059] The method can include applying the composition onto the surface of the container in such a manner that the composition or the organic layer faces the electron transport layer and / or the second electrode.

[0060] The method can further include removing at least a portion of the liquid carrier from the applied organic layer-forming composition.

[0061] The liquid carrier can include water, C1-10 alcohols, sulfoxide solvents such as dimethyl sulfoxide, nitrile solvents, ester solvents, or a combination thereof. The liquid carrier can include water, ethanol, methanol, propanol, acetonitrile, ethyl acetate, dimethyl sulfoxide, or a combination thereof.

[0062] The first space may be an enclosed space, e.g., a sealed space or an airtight or gas-impermeable space. The temperature of the post-treatment may be greater than or equal to about 45 °C, greater than or equal to about 50 °C, greater than or equal to about 70 °C, or greater than or equal to about 90 °C and less than or equal to about 180 °C, less than or equal to about 150 °C, less than or equal to about 120 °C, or less than or equal to about 100 °C. The post-treatment may be carried out for a predetermined time. The predetermined time may be greater than or equal to about 10 minutes, greater than or equal to about 30 minutes, greater than or equal to about 1 hour, greater than or equal to about 2 hours, greater than or equal to about 5 hours and less than or equal to about 10 days, or less than or equal to about 10 hours, less than or equal to about 3 hours.

[0063] The method may further include removing the container after the post-treatment.

[0064] The method may further include providing a conductive layer on the thin film conductor after the post-treatment to form a conductor thin film (or a second electrode) having an increased thickness.

[0065] In an embodiment, the display device may include the light-emitting device (e.g., an electroluminescent device).

[0066] In an embodiment, the electronic device may include the light-emitting device.

[0067] The display device or the electronic device may include (or may be) an AR / VR device, a handheld terminal, a monitor, a laptop, a TV, an electronic display board, a camera, an electronic display assembly for an autonomous vehicle or an electric vehicle.

[0068] According to an embodiment, the light-emitting device may exhibit improved light-emitting properties and lifetime characteristics. The device of the embodiment may exhibit improved stability by maintaining the electroluminescent properties at a desired level even under high-temperature exposure or over an extended period or time in a storage environment. The method of the embodiment may more easily enable mass production of a front-emission type (front-facing emission type) light-emitting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The above and other advantages and features of the present disclosure will become more apparent by referring to the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings, wherein:

[0070] Figure 1A is a schematic cross-sectional view of an electroluminescent device according to an embodiment;

[0071] Figure 1B is a schematic cross-sectional view of an electroluminescent device according to an embodiment;

[0072] Figure 2A is a schematic cross-sectional view of an electroluminescent device according to an embodiment;

[0073] Figure 2B is a schematic cross-sectional view of an electroluminescent device according to an embodiment;

[0074] Figure 2C is a schematic cross-sectional view of an electroluminescent device according to an embodiment;

[0075] Figure 3A is a schematic cross-sectional view of an electroluminescent device according to an embodiment;

[0076] Figure 3B is a schematic cross-sectional view of an electroluminescent device according to an embodiment;

[0077] Figure 3C is a schematic cross-sectional view of an electroluminescent device according to an embodiment;

[0078] Figure 4 is a schematic cross-sectional view of an electroluminescent device according to an embodiment;

[0079] Figure 5A is a schematic cross-sectional view of a light-emitting device according to an embodiment;

[0080] Figure 5B is Figure 5A a plan view of the light-emitting device.

[0081] Figure 6A shows a schematic cross-sectional view of a stacked structure in a post-treatment during the manufacturing process of a light-emitting device according to an embodiment.

[0082] Figure 6B shows a schematic cross-sectional view of a stacked structure obtained by the following process: wherein the stacked structure is removed from the container after the post-treatment during the manufacturing process of a light-emitting device according to Figure 6A and then a second electrode is formed and a new container (without an organic layer) is provided.

[0083] Figure 7 is a diagram schematically showing an example of a post-treatment (using a furnace or a chamber as a container) during the manufacturing process of a light-emitting device according to an embodiment.

[0084] Figure 8 is a schematic cross-sectional view of a light-emitting device (RGB pixel) according to an embodiment.

[0085] Figure 9 is a schematic plan view of a display panel according to an embodiment.

[0086] Figure 10 shows a schematic cross-sectional view of the display panel taken along line IV-IV of Figure 9 the display panel. Detailed Embodiments

[0087] With reference to the following exemplary embodiments and the accompanying drawings, the advantages and features of the present disclosure, as well as the methods for achieving them, will become apparent. However, the embodiments should not be construed as being limited to the embodiments set forth herein. Instead, 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.

[0088] To clearly explain the present disclosure, parts not relevant to the description are omitted, and the same reference numerals are assigned to the same or similar elements throughout the specification. In the drawings, the thicknesses of layers, films, panels, regions, etc. are exaggerated for clarity. Also, in the drawings, the thicknesses of some layers and regions are exaggerated for ease of description. Therefore, the embodiments described herein should not be construed as being limited to the specific shapes of the regions shown herein, but include, for example, deviations in shape caused by manufacturing. For example, a region shown or described as flat may typically have rough and / or non-linear features. Additionally, sharp corners shown may be rounded. Thus, the regions shown in the figures are schematic in nature, and their shapes are not intended to illustrate the exact shape of the regions and are not intended to limit the scope of the claims.

[0089] 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, it can be directly on the other element, or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, no intervening elements are present. Additionally, being "on" a reference portion means being disposed above or below the reference portion, and does not necessarily mean "above".

[0090] It will be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, components (assemblies), regions, layers, and / or portions, these elements, components (assemblies), regions, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component (assembly), region, layer, or portion from another element, component (assembly), region, layer, or portion. Thus, without departing from the teachings herein, the "first element", "component (assembly)", "region", "layer", or "portion" discussed below may be referred to as a second element, component (assembly), region, layer, or portion.

[0091] The terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms, including "at least one", unless the context clearly indicates otherwise. "At least one" is not to be construed as limiting "one". "Or" means "and / or".

[0092] 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 "comprises" or "comprising", when used in this specification, specify the presence of the stated features, regions, wholes, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, regions, wholes, steps, operations, elements, components, and / or groups thereof.

[0093] As used herein, the term "cross-section" means the situation where the cross-section of a given object is cut (e.g., in a substantially vertical direction) and observed in the transverse direction.

[0094] Unless otherwise defined, all terms used herein (including technical and scientific terms) 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, should be interpreted as having a meaning consistent with their meaning in the context of this disclosure and the relevant art, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0095] Hereinafter, 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 energy level. Further, 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 based on the vacuum energy level of "0 electron volts (eV)", while when the work function or energy level is called "shallow", "low", or "small", the work function or energy level has a small absolute value based on the vacuum energy level of "0 eV".

[0096] As used herein, the average (value) can be the mean or the median. In an embodiment, the average (value) can be the mean average.

[0097] As used herein, the term "peak emission wavelength" is the wavelength at which the given emission spectrum of light reaches its maximum.

[0098] As used herein, the term "group" may refer to a group of the periodic table.

[0099] As used herein, "Group I" refers to Group IA and Group IB, and examples may include, but are not limited to, Li, Na, K, Rb, and Cs.

[0100] As used herein, "Group II" refers to Group IIA and Group IIB, and examples of Group II metals may be, but are not limited to, Cd, Zn, Hg, and Mg.

[0101] As used herein, "Group III" refers to Group IIIA and Group IIIB, and examples of Group IIIA metals may be, but are not limited to, Al, In, Ga, and Tl, and examples of Group IIIB may be, but are not limited to, scandium, yttrium, etc.

[0102] As used herein, "Group IV" refers to Group IVA and Group IVB, and examples of Group IVA metals may be, but are not limited to, Si, Ge, and Sn, and examples of Group IVB metals may be, but are not limited to, titanium, zirconium, hafnium, etc.

[0103] As used herein, "Group V" includes Group VA and includes, but is not limited to, nitrogen, phosphorus, arsenic, antimony, and bismuth.

[0104] As used herein, "Group VI" includes Group VIA and includes, but is not limited to, sulfur, selenium, and tellurium.

[0105] As used herein, "metal" includes metalloids such as Si.

[0106] As used herein, the number of carbon atoms in a group or molecule may be referred to as a subscript (e.g., C 6-50 ) or C6 to C50.

[0107] As used herein, unless otherwise defined, "substituted" means replacing at least one hydrogen of a compound or group with a corresponding group moiety including: C1-C30 alkyl, C2-C30 alkenyl, C2-C30 alkynyl, C6-C30 aryl, C7-C30 alkylaryl, C1-C30 alkoxy, C1-C30 heteroalkyl, C3-C30 heteroalkylaryl, C3-C30 cycloalkyl, C3-C15 cycloalkenyl, C6-C30 cycloalkynyl, C2-C30 heterocycloalkyl, halogen (-F, -Cl, -Br or -I), hydroxy (-OH), nitro (-NO2), cyano (-CN), amino (-NRR', where R and R' are each independently hydrogen or C1-C6 alkyl), azido (-N3), amidino (-C(=NH)NH2), hydrazino (-NHNH2), hydrazo (=N(NH2)), aldehyde (-C(=O)H), carbamoyl (-C(O)NH2), mercapto (-SH), ester (-C(=O)OR, where R is C1-C6 alkyl or C6-C12 aryl), carboxy (-COOH) or its salt (-C(=O)OM, where M is an organic or inorganic cation), sulfonic acid group (-SO3H) or its salt (-SO3M, where M is an organic or inorganic cation), phosphoric acid group (-PO3H2) or its salt (-PO3MH or -PO3M2, where M is an organic or inorganic cation), or a combination thereof.

[0108] As used herein, unless otherwise defined, "hydrocarbon" or "hydrocarbon group" means a compound or group containing carbon and hydrogen (e.g., alkyl, alkenyl, alkynyl or aryl). A hydrocarbon group can be a monovalent group or a group with a valence greater than 1, which is formed by removing hydrogen atoms, e.g., one or more hydrogen atoms, from an alkane, alkene, alkyne or arene. In a hydrocarbon or hydrocarbon group, a methylene group, e.g., at least one methylene group, can be replaced by an oxygen (oxide) moiety, a carbonyl moiety, an ester moiety, -NH-, or a combination thereof. Unless otherwise stated to the contrary, a hydrocarbon compound or hydrocarbon group (alkyl, alkenyl, alkynyl or aryl) can have 1 to 60, 2 to 32, 3 to 24, or 4 to 12 carbon atoms.

[0109] As used herein, unless otherwise defined, "alkyl" means a straight-chain or branched-chain saturated monovalent hydrocarbon group (such as methyl, ethyl, hexyl, etc.). In an embodiment, an alkyl can have 1 to 50 carbon atoms, or 1 to 18 carbon atoms, or 1 to 12 carbon atoms.

[0110] As used herein, unless otherwise defined, "alkenyl" means a straight-chain or branched-chain monovalent hydrocarbon group having a carbon-carbon double bond. In an embodiment, an alkenyl can have 2 to 50 carbon atoms, or 2 to 18 carbon atoms, or 2 to 12 carbon atoms.

[0111] As used herein, when no definition is provided otherwise, "alkynyl" refers to a straight-chain or branched-chain monovalent hydrocarbon group having a carbon-carbon triple bond. In embodiments, the alkynyl may have 2 to 50 carbon atoms, or 2 to 18 carbon atoms, or 2 to 12 carbon atoms.

[0112] As used herein, when no definition is provided otherwise, "aryl" refers to a group formed by removing hydrogen, such as at least one hydrogen, from an aromatic hydrocarbon (e.g., phenyl or naphthyl). In embodiments, the aryl may have 6 to 50 carbon atoms, or 6 to 18 carbon atoms, or 6 to 12 carbon atoms.

[0113] As used herein, when no definition is provided otherwise, "hetero" refers to containing 1 to 3 heteroatoms, such as N, O, S, Si, P, or a combination thereof.

[0114] As used herein, when no definition is provided otherwise, "alkoxy" refers to an alkyl group attached to oxygen (e.g., alkyl-O-), such as methoxy, ethoxy, or sec-butoxy.

[0115] As used herein, when no definition is provided otherwise, "amine" is a compound represented by NR3, where each R is independently hydrogen, a C1-C12 alkyl group, a C7-C20 alkylaryl group, a C7-C20 arylalkyl group, or a C6-C18 aryl group.

[0116] As used herein, "poly(meth)acrylate" refers to polyacrylate, polymethacrylate, or a combination thereof.

[0117] In embodiments, the "alkali metal salt" of a polymeric acid (e.g., polyacrylic acid or polystyrene sulfonic acid) compound may include a partial alkali metal salt of a given polymeric acid, a complete alkali metal salt of the polymeric acid, or a combination thereof.

[0118] As used herein, the expression "excluding cadmium (or other harmful heavy metals)" may refer to a situation where the concentration of cadmium (or another heavy metal considered harmful) may be less than or equal to about 100 parts per million by weight (ppmw), less than or equal to about 50 ppmw, less than or equal to about 10 ppmw, less than or equal to about 1 ppmw, less than or equal to about 0.1 ppmw, less than or equal to about 0.01 ppmw, or about zero. In embodiments, 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 of a given analytical tool (e.g., an inductively coupled plasma atomic emission spectrometry instrument) or its impurity level.

[0119] Unless otherwise noted, the numerical ranges recited herein are inclusive. Unless otherwise noted, the numerical ranges recited herein include any real number within the endpoints of the recited range and include the endpoints. As used herein, the upper and lower endpoints of each numerical range set forth may be independently combined to provide a range.

[0120] As used herein, "about" includes the recited value and means within an acceptable deviation range for the specific value as determined by one of ordinary skill in the art in view of the measurements discussed and the error associated with the measurement of the specific quantity (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations of the recited value, or within ±5%.

[0121] As used herein, a nanoparticle is a structure having a region or characteristic scale that has a nanoscale dimension (e.g., at least one region or characteristic scale having a nanoscale dimension). In embodiments, the scale (or average scale) of the nanostructure is less than or equal to about 500 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. In embodiments, the nanoparticle can have any suitable shape. The nanoparticle (e.g., a semiconductor nanoparticle or a metal oxide nanoparticle) can include nanowires, nanorods, nanotubes, branched nanostructures, nanorings, nanotripods, nanobipods, nanodots, multi-legged shapes such as at least two legs, and the like, and is not limited thereto. The nanoparticle can be, for example, substantially crystalline, substantially single crystal, polycrystalline, (e.g., at least partially) amorphous, or a combination thereof.

[0122] In embodiments, semiconductor nanoparticles such as quantum dots can exhibit quantum confinement or exciton confinement. As used herein, the term "quantum dot" or "semiconductor nanostructure" is not limited in terms of its shape unless otherwise defined. The semiconductor nanoparticle or quantum dot can have a size smaller than the Bohr excitation diameter of the bulk crystal material having the same composition and can exhibit a quantum confinement effect. By controlling the size of the nanocrystal that serves as the emission center, the semiconductor nanoparticle or quantum dot can emit light corresponding to its bandgap energy.

[0123] As used herein, the term "T50" is the time (hours, hr) when, for example, when a given device is driven (e.g., operated) starting with a predetermined initial luminance (e.g., 650 nits or 146 nits), the luminance (e.g., brightness) of the given device decreases to 50% of the initial luminance (100%).

[0124] As used herein, the term "T90" is the time (hr) at which the luminance (e.g., brightness) of a given device decreases to 90% of the initial luminance (100%) when the given device is started driving at a predetermined initial luminance (e.g., 650 nits or 146 nits).

[0125] 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 a measure of how effectively a given device converts electrons into photons and allows the photons to escape. The EQE can be determined by the following equation:

[0126] EQE = injection efficiency × (solid-state) quantum yield × extraction efficiency

[0127] Where the injection efficiency is the proportion of electrons passing through the device that are injected into the active region, the quantum yield is the proportion of all radiative electron-hole recombinations in the active region that produce photons, and the extraction efficiency is the proportion of photons generated in the active region that escape from the given device.

[0128] As used herein, the maximum EQE is the maximum value of the EQE.

[0129] As used herein, the maximum luminance is the highest value of the luminance for a given device.

[0130] As used herein, the phrase quantum efficiency can be used interchangeably with the phrase quantum yield. In embodiments, the quantum efficiency can be a relative quantum yield or an absolute quantum yield, e.g., it can be easily measured by any suitable (e.g., commercially available) device. The quantum efficiency (or quantum yield) can be measured in solution state or solid state (as a complex). In embodiments, the "quantum yield (or quantum efficiency)" can be the ratio of photons emitted (e.g., by a nanostructure or a group of nanostructures) to photons absorbed. In embodiments, the quantum efficiency can be determined by any suitable method. For example, there can be two methods for measuring fluorescence quantum yield or efficiency: an absolute method and a relative method.

[0131] The absolute method directly obtains the quantum yield by detecting all sample fluorescence using an integrating sphere. In the relative method, the fluorescence intensity of a standard sample (e.g., a standard dye) can be compared with the fluorescence intensity of an unknown sample to calculate the quantum yield of the unknown sample. Coumarin 153, Coumarin 545, Rhodamine 101 inner salt, Anthracene, and Rhodamine 6G can be used as standard dyes, depending on their photoluminescence (PL) wavelength, but are not limited thereto.

[0132] The bandgap energy of semiconductor nanoparticles can vary with the size and composition of the nanocrystals. For example, as the size of the semiconductor nanoparticles increases, the bandgap energy of the semiconductor nanoparticles can become smaller, e.g., narrower, and the semiconductor nanoparticles can emit light, e.g., with an increased emission wavelength. Semiconductor nanocrystals can be used as light-emitting materials in a variety of fields, e.g., in display devices, energy devices, or bioluminescent devices.

[0133] An electroluminescent device based on semiconductor nanoparticles (hereinafter, also referred to as QD-LED) can emit light by applying a voltage and includes semiconductor nanoparticles or quantum dots as a light-emitting material. A QD-LED using an emission principle different from that of an organic light-emitting diode (OLED) can exhibit light emission with more desirable optical properties, e.g., higher purity, colors (e.g., red, green, and blue), and improved color reproducibility, and thus can be the basis for next-generation display devices. A method of manufacturing a QD-LED can include a solution process, which can reduce (e.g., decrease) the manufacturing cost. In addition, the semiconductor nanoparticles in a QD-LED can be based on inorganic materials, contributing to achieving increased display (light emission) stability over time. It is desirable to develop technologies that can improve the physical properties and lifetime characteristics of the device.

[0134] In an embodiment of a QD-LED, holes and electrons provided from two electrodes (e.g., a cathode and an anode) and passing through several common layers can meet and combine in an emission layer (EML, emission layer, QD emission layer) to form excitons, resulting in light emission. In an embodiment of a QD-LED, common layers can be provided between the light-emitting layer and the electrodes, e.g., to facilitate the injection of holes and electrons when a voltage is applied, and thus the design of these common layers can have an impact on the properties of the device (e.g., optical or stability properties).

[0135] For example, it can be required that the electron transport layer have an electron mobility sufficient to balance holes - electrons in the light-emitting layer, and in this case, electrons can be effectively transferred from the electrode to the quantum dot light-emitting layer. Additionally, it can be required that the electron transport layer have an appropriate deep HOMO energy level to sufficiently block holes from the quantum dot light-emitting layer.

[0136] Furthermore, quantum dots or semiconductor nanoparticles that exhibit desirable electroluminescent properties can contain harmful heavy metals, such as cadmium (Cd), lead, mercury, or combinations thereof. Therefore, it can be desirable to provide an electroluminescent device or a display device having a light-emitting layer substantially free of such heavy metals.

[0137] In an embodiment, an electroluminescent device can be a device configured to emit desired light by applying a voltage, e.g., with or without a separate light source.

[0138] In an embodiment, a light-emitting device (or a stacked structure) includes: a first electrode (e.g., a hole injection conductor) 1 and a thin film conductor (e.g., an electron injection conductor or a second electrode) 5 that are spaced apart (e.g., facing each other); an emission layer 3 disposed between the first electrode and the thin film conductor and including semiconductor nanoparticles; and an electron transport layer or an electron assisting layer 4 including an electron transport layer between the emission layer 3 and the thin film conductor 5. The electron transport layer may include metal oxide nanoparticles. The above emission layer may be configured to emit a first light by applying a voltage (e.g., between the above first electrode and the above conductor thin film).

[0139] In an embodiment, the electroluminescent device may further include organic layers 6, 60. The organic layers may include polymers. The polymers include repeating units having hydroxyl groups. The polymers may be copolymers including repeating units having hydroxyl groups.

[0140] The electroluminescent device may further include hole assisting layers 2, 20. The hole assisting layers may include a hole transport layer (HTL, e.g., including an organic compound), a hole injection layer (HIL), or a combination thereof. (See: Figure 1A and 1B 、 Figure 2A 、 2B and 2C)

[0141] In the electroluminescent device of the embodiment, the organic layer 6 may be disposed on the electron transport layer 4 and / or optionally on the second electrode 5. The organic layer 6 may be disposed adjacent to the electron transport layer and the second electrode 5 (see Figure 1A 、 1B 、and Figure 3A 、 3B and Figure 3C ). The organic layer 6 may be included (disposed) (see Figure 2A 、 2B and Figure 8 ) to be spaced apart from the electron transport layer 4 and the second electrode 5, for example, in a non-contact manner or a remote manner (see Figure 2A 、 Figure 2C 、 Figure 4 、 Figure 5A and Figure 8 ).

[0142] The electroluminescent device of the embodiment may further include a container (e.g., a light-transmitting member) configured to accommodate the electron transport layer and the conductor thin film or the second electrode; or further include at least a part of the stacked structure of the first electrode and the emission layer in addition to the electron transport layer and the conductor thin film. See, for example, Figure 2B 、 2C。The container may include a light-transmissive component, and may further include additional components, seals, etc. The container may include a transparent component, an opaque component (e.g., an additional component such as a sealing component), or a combination thereof. A first surface of the container may face the second electrode, and an organic layer may be disposed on the first surface of the container adjacent to or in contact with the container or the light-transmissive component. A first surface of the organic layer may be adjacent to the container, and a second surface opposite the first surface may face the second electrode and / or the electron transport layer. (See Figure 2A , Figure 2B and Figure 2C , Figure 4 , Figure 5A , Figure 8 ).

[0143] In an embodiment, an electroluminescent device capable of exhibiting improved lifetime and improved electroluminescent characteristics (e.g., device efficiency and brightness) is described herein. In the electroluminescent device of the embodiment, hole leakage through an electron assisting layer (e.g., an electron transport layer) can be substantially (substantially) blocked, and thus, the electroluminescent device of the embodiment can exhibit an increase in electron transport characteristics, thereby achieving an improved electron-hole balance, and can suppress or prevent deterioration of the device due to charging.

[0144] In the electroluminescent device of the embodiment, the organic layer or polymer may be formed from a composition having a relatively low viscosity and may not exhibit light absorption characteristics within a predetermined wavelength range (e.g., 320 nm to 440 nm), so it can be used, for example, with substantially no limitation on the light-emitting mode for a display device (e.g., can be used for both bottom-emission type devices and top-emission type devices). In the light-emitting device of the embodiment, the electron transport layer (ETL) may exhibit improved electron mobility, which can contribute to an improved hole-electron balance in the light-emitting layer and can effectively transfer electrons from the electrode to the light-emitting layer.

[0145] In the electroluminescent device of the embodiment, the electron assisting layer (e.g., the electron transport layer) may have a HOMO energy level with a desired depth and can suppress the emergence of trapping (trap) energy levels, for example, effectively blocking unwanted hole movement from the light-emitting layer including semiconductor nanoparticles (e.g., quantum dots) to the second electrode.

[0146] In the electroluminescent device of the embodiment, the thin film conductor can also be used as the second electrode. The second electrode may include a thin film conductor. The first electrode or the second electrode may include (or may be) an anode or a cathode. In an embodiment, the first electrode may include a cathode (or an anode), and the second electrode may include an anode (or a cathode). In an embodiment, the second electrode includes an electron injection conductor, e.g., a cathode, and the first electrode includes a hole injection conductor, e.g., an anode.

[0147] In a display device including a light-emitting device of an embodiment, a first electrode may be disposed on a (transparent) substrate 100, see, for example Figure 3A , or on the substrate and a driving circuit Figure 2C . In an embodiment, first light emitted from the light-emitting layer may pass through the second electrode and a first surface of the container and be extracted from the device (e.g., in the Z direction). In an embodiment, first light may be extracted through the (transparent) first electrode and optionally the substrate 100. The light-emitting layer may be disposed in a pixel (or sub-pixel) of a display device (display panel) to be described later.

[0148] In an electroluminescent device of an embodiment, the light-emitting layers 3, 30 may be disposed between a first electrode (e.g., an anode) 1, 10 and a second electrode (e.g., a cathode) 5, 50. The conductor thin film may be the second electrode, or the second electrode may include the conductor thin film. The second electrode or cathode 5, 50 may include an electron injection conductor. The anode 1, 10 may include a hole injection conductor. The work functions of the electron / hole injection conductors included in the cathode and the anode may be appropriately adjusted and are 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.

[0149] The electron / hole injection conductor may include a metal-based material (e.g., a metal, a metal compound, an alloy, or a combination thereof), such as aluminum, magnesium, tungsten, nickel, cobalt, platinum, palladium, calcium, LiF, etc.; a metal oxide, such as indium gallium oxide or indium tin oxide (ITO); or a conductive polymer (e.g., having a relatively high work function), such as polyethylenedioxythiophene, but is not limited thereto.

[0150] The first electrode, the second electrode, or a combination thereof may be a light-transmissive electrode or a transparent electrode. In an embodiment, both the first electrode and the second electrode may be light-transmissive electrodes. The first electrode, the second electrode, or a combination thereof may be a patterned electrode.

[0151] The first electrode, the second electrode, or a combination thereof may be disposed on a (e.g., insulating) substrate 100 and optionally a driving circuit such as a TFT. The substrate 100 may be a substrate including an insulating material. The substrate may include glass; polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), etc., polycarbonate, and polyacrylate; polysiloxane (e.g., polydimethylsiloxane (PDMS)); inorganic materials such as Al2O3 or ZnO; or a combination thereof, but is not limited thereto. The thickness of the substrate may be appropriately selected considering the substrate material, but there is no particular limitation. The substrate may be a flexible substrate. The substrate may further include a region for blue pixels, a region for red pixels, a region for green pixels, or a combination thereof.

[0152] The substrate 100 or the container (or the light-transmitting component included in the container) may be optically transparent. The substrate 100 or the container (or the light-transmitting component) may have a light transmittance as follows: greater than or equal to about 50%, greater than or equal to about 60%, greater than or equal to about 70%, greater than or equal to about 80%, greater than or equal to about 85%, or greater than or equal to about 90% and less than or equal to about 100%, for example, less than or equal to about 99%, or less than or equal to about 95%. For light emitted from, for example, semiconductor nanoparticles included in the light-emitting layer, the substrate or the container (or the light-transmitting component included in the container) may have a light transmittance as follows: greater than or equal to about 50%, greater than or equal to about 60%, greater than or equal to about 70%, greater than or equal to about 80%, greater than or equal to about 85%, greater than or equal to about 90%, greater than or equal to about 95%, or greater than or equal to about 99% and less than or equal to about 100%, for example, less than or equal to about 99%, or less than or equal to about 95%. In an embodiment, the substrate or the container (or the light-transmitting component) may be opaque or reflective.

[0153] In an embodiment, thin-film transistors may be provided in each region of the substrate, but are not limited thereto. In an embodiment, the source electrode or the drain electrode of the thin-film transistor may be electrically connected to the first electrode or the second electrode. In an embodiment, a light-transmitting electrode may be provided on a (for example, insulating) transparent substrate. The substrate 100 may be a rigid or flexible substrate.

[0154] The electrode may include or be made of the following: for example, metal oxides such as indium tin oxide (ITO) or indium zinc oxide (IZO), indium gallium tin oxide, indium zinc tin oxide; metal nitrides such as titanium nitride; conductive polymers such as polyaniline; LiF / Mg:Ag; single-layer or multi-layer metal thin films; or a combination thereof. In an embodiment, the electrode (for example, the first electrode and / or the second electrode) may include aluminum (Al), lithium-aluminum (Li:Al) alloy, magnesium-silver (Mg:Ag) alloy, lithium fluoride-aluminum (LiF:Al), gold, silver, or a combination thereof. The ratio of the alloy may be appropriately selected and is not particularly limited. The electrode may be formed by vacuum deposition, thermal deposition, sputtering deposition, etc.

[0155] The thickness of each of the electrodes (the first electrode, the second electrode, or a combination thereof) or the thickness of the thin film conductor is not particularly limited and can be appropriately selected in consideration of device efficiency and the emission type of the device (e.g., top emission or bottom emission). For example, the thickness of the electrode (or thin film conductor) 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 (or thin film conductor) 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, less than or equal to about 60 nm, less than or equal to about 50 nm, less than or equal to about 40 nm, less than or equal to about 30 nm, or less than or equal to about 25 nm.

[0156] A light-transmissive electrode or a non-light-transmissive or non-transmissive electrode (e.g., a reflective electrode) can be formed by adjusting the composition and / or thickness of the electrode. In an embodiment, the non-transmissive electrode can include a metal layer (e.g., aluminum, silver, etc.) disposed between layers of a metal oxide (e.g., a light-transmissive metal oxide), such as indium tin oxide. In an embodiment, the light-transmissive electrode can include a light-transmissive metal oxide, a thin metal or alloy film, or a combination thereof. The light-transmissive electrode can include a transparent electrode and a semi-transparent electrode.

[0157] In the electroluminescent device of the embodiment, the second electrode or the thin film conductor can have a thickness as follows: greater than or equal to about 1 nm, such as greater than or equal to about 5 nm, or greater than or equal to about 9 nm and less than 100 nm, less than or equal to about 99 nm, or less than or equal to about 95 nm. The thickness of the second electrode or the thin film conductor can be greater than about 10 nm, greater than or equal to about 11 nm, greater than or equal to about 12 nm, greater than or equal to about 13 nm, greater than or equal to about 14 nm, greater than or equal to about 15 nm, greater than or equal to about 16 nm, greater than or equal to about 17 nm, greater than or equal to about 18 nm, greater than or equal to about 19 nm, or greater than or equal to about 20 nm. The thin film conductor can have a thickness less than or equal to about 80 nm, less than or equal to about 60 nm, less than or equal to about 50 nm, or less than or equal to about 40 nm.

[0158] In the electroluminescent device of the embodiment, the second electrode or the thin film conductor may have the following light transmittance for the first light: greater than or equal to about 20%, greater than or equal to about 25%, greater than or equal to about 30%, greater than or equal to about 35%, greater than or equal to about 40%, greater than or equal to about 45%, greater than or equal to about 50%, greater than or equal to about 55%, 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 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 75%, greater than or equal to about 78%, greater than or equal to about 80%, greater than or equal to about 82%, greater than or equal to about 85%, or greater than or equal to about 89%. The light transmittance for the first light may be less than or equal to about 100%, less than or equal to about 99%, less than or equal to about 98%, less than or equal to about 97%, less than or equal to about 96%, less than or equal to about 95%, less than or equal to about 94%, less than or equal to about 93%, less than or equal to about 92%, less than or equal to about 91%, less than or equal to about 90%, less than or equal to about 89%, less than or equal to about 88%, less than or equal to about 87%, less than or equal to about 86%, less than or equal to about 85%, less than or equal to about 84%, less than or equal to about 83%, less than or equal to about 82%, less than or equal to about 80%, less than or equal to about 79%, less than or equal to about 76%, less than or equal to about 73%, less than or equal to about 68%, less than or equal to about 66%, less than or equal to about 64%, less than or equal to about 61%, less than or equal to about 60%, less than or equal to about 55%, less than or equal to about 50%, less than or equal to about 49%, less than or equal to about 48%, or less than or equal to about 47%.

[0159] In an embodiment of the light-emitting device, the second electrode or the first electrode may be configured to reflect at least a portion (e.g., 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%, greater than or equal to about 95%, or greater than or equal to about 99%) of the first light. In an embodiment of the light-emitting device, the second electrode or the first electrode may include a multilayer structure, e.g., having a structure of ITO / aluminum / ITO, ITO / Ag / ITO, Ag / ITO; a conductive metal electrode such as Ag, Al, Cu, Au, tungsten, nickel, cobalt, platinum; or a combination thereof.

[0160] The first electrode, the second electrode, or the conductive thin film (hereinafter, may be simply referred to as "electrode") may include silver, aluminum, magnesium, tungsten, nickel, cobalt, platinum, palladium, calcium, LiF, gold, copper, or a combination thereof (e.g., an alloy thereof). The electrode may include silver and magnesium, an alloy thereof, aluminum and magnesium, or an alloy thereof, or a combination thereof. The electrode may be an electrode that can be formed by thermal deposition. In an embodiment, the electrode may exhibit metal pores and / or grain boundaries in its cross-sectional view obtained by using a microscope or an electron microscope. In an embodiment, the electrode may not exhibit metal pores and / or grain boundaries in its cross-sectional view obtained by using a microscope or an electron microscope.

[0161] In the electroluminescent device and the method of manufacturing the same according to the embodiment, the thin film conductor may exhibit conductivity sufficient to be used as an electrode, and at the same time, under the post-treatment conditions described herein, moisture and optionally acid supplied from the organic layer or the polymer may pass through the thin film conductor and reach the electron transport layer including metal oxide nanoparticles. Without wishing to be bound by theory, it is believed that the moisture and optionally acid reaching the electron transport layer may modify the surface of the metal oxide nanoparticles, whereby hydroxide ions (OH - ) and hydrogen ions (H + ) can be supplied to the metal oxide nanoparticles in the electron transport layer to passivate surface defects through chemical reactions. Including the post-treated electron transport layer in the electroluminescent device according to the embodiment may reduce the hole leakage current, which can be confirmed by the lower driving voltage and higher efficiency of the device compared to the device before the post-treatment. Including the post-treated electron transport layer in the electroluminescent device according to the embodiment may increase the hole blocking performance and electron mobility of the electron transport layer, and this may contribute to the improvement of the brightness of the device. Including the post-treated electron transport layer in the electroluminescent device according to the embodiment may alleviate the charging phenomenon at the interface between the light emitting layer and the electron transport layer, and the device according to the embodiment may exhibit reduced interface degradation and increased lifetime.

[0162] The light emitting layer 3, 30 may be disposed between the first electrode 1, 10 and the second electrode 5, 50 (e.g., the anode 10 and the cathode 50). The light emitting layer may include semiconductor nanoparticles (e.g., blue light emitting nanoparticles, red light emitting nanoparticles, or green light emitting nanoparticles). The light emitting layer may include a single layer of one or more (e.g., 2 or more or 3 or more and 10 or less) semiconductor nanoparticles.

[0163] The light-emitting layer can be patterned. In an embodiment, the patterned light-emitting layer can include a blue light-emitting layer 30B disposed in a blue pixel, a red light-emitting layer 30R disposed in a red pixel, a green light-emitting layer 30G disposed in a green pixel, or a combination thereof. In an embodiment, the light-emitting layer can include a red light-emitting layer disposed in a red pixel and a green light-emitting layer disposed in a green pixel. Each (e.g., red, green, or blue) light-emitting layer can be (e.g., optically) separated from an adjacent light-emitting layer by a partition wall. In an embodiment, a partition wall or a dam (e.g., a black matrix or a pixel definition layer, PDL) can be disposed between the red light-emitting layer, the green light-emitting layer, and the blue light-emitting layer (see Figures 4 to 8 , Figure 10 ). In an embodiment, the red light-emitting layer 30R, the green light-emitting layer 30G, and the blue light-emitting layer 30B can be optically isolated from each other.

[0164] In an embodiment, the light-emitting layer 3, 30, or the semiconductor nanoparticles can not include cadmium. In an embodiment, the light-emitting layer 3, 30, or the semiconductor nanoparticles can not include mercury, lead, or a combination thereof.

[0165] In an embodiment, the semiconductor nanoparticles can have a core-shell structure. In an embodiment, the semiconductor nanoparticles or the core-shell structure can include: a core including a first semiconductor nanocrystal and a shell disposed on the core and including a second semiconductor nanocrystal having a composition different from that of the first semiconductor nanocrystal.

[0166] The semiconductor nanoparticles (or the first semiconductor nanocrystal, the second semiconductor nanocrystal, or a combination thereof) can include a II-VI group compound, a III-V group compound, a IV-VI group compound, a group IV element or compound, a I-III-VI group compound, a II-III-VI group compound, a I-II-IV-VI group compound, or a combination thereof. In an embodiment, the light-emitting layer or the semiconductor nanoparticles (e.g., the first semiconductor nanocrystal or the second semiconductor nanocrystal) can not include cadmium. In an embodiment, the light-emitting layer or the semiconductor nanoparticles (e.g., the first semiconductor nanocrystal or the second semiconductor nanocrystal) can not include lead. In an embodiment, the light-emitting layer or the semiconductor nanoparticles (e.g., the first semiconductor nanocrystal or the second semiconductor nanocrystal) can not include a combination of lead and cadmium.

[0167] The II-VI compounds may be: binary compounds such as ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, or combinations thereof; ternary compounds such as ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, or combinations thereof; quaternary compounds such as HgZnTeS, HgZnSeS, HgZnSeTe, HgZnSTe, or combinations thereof; or combinations thereof. The II-VI compounds may further include group III metals.

[0168] The III-V compounds may be: binary compounds such as GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, or combinations thereof; ternary compounds such as GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, or combinations thereof; quaternary compounds such as GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, or combinations thereof; or combinations thereof. The III-V compounds may further include group II metals (such as InZnP).

[0169] The IV-VI compounds may be: binary compounds such as SnS, SnSe, SnTe, PbS, PbSe, PbTe, or combinations thereof; ternary compounds such as SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, or combinations thereof; quaternary compounds such as SnPbSSe, SnPbSeTe, SnPbSTe, or combinations thereof; or combinations thereof.

[0170] Examples of the I-III-VI compounds may be CuInSe2, CuInS2, CuInGaSe, and CuInGaS, but are not limited thereto.

[0171] Examples of I-II-IV-VI group compounds may be CuZnSnSe and CuZnSnS, but are not limited thereto. Examples of I-III-VI semiconductor compounds may include: ternary compounds such as AgInS, AgInS2, AgInSe2, AgGaS, AgGaS2, AgGaSe2, CuInS, CuInS2, CuInSe2, CuGaS2, CuGaSe2, CuGaO2, AgGaO2 or AgAlO2; quaternary compounds such as AgInGaS2, AgInGaSe2; or combinations thereof.

[0172] Examples of I-II-IV-VI group compounds include, but are not limited to, CuZnSnSe and CuZnSnS.

[0173] Group IV elements or compounds may include: elemental substances (single elements) such as Si, Ge or combinations thereof; binary compounds such as SiC, SiGe or combinations thereof; or combinations thereof.

[0174] Each element included in a multi-component compound such as a binary compound, a ternary compound or a quaternary compound may be present in the particles at a uniform concentration or at a non-uniform concentration. For example, the above chemical formulas indicate the types of elements included in the compounds, and the stoichiometry between the elements in the compounds may be different from the listed chemical formulas. For example, the chemical formula "AgInGaS2" may include AgIn x Ga 1-x S2 (where x is a real number greater than 0 and less than or equal to 1), but is not limited thereto.

[0175] In an embodiment, the semiconductor nanoparticles or the first semiconductor nanocrystals may include a metal and a non-metal, the metal including indium, zinc or combinations thereof, and the non-metal including phosphorus, selenium, tellurium, sulfur or combinations thereof. In an embodiment, the second semiconductor nanocrystals may include a metal and a non-metal, the metal including indium, zinc or combinations thereof, and the non-metal including phosphorus, selenium, tellurium, sulfur or combinations thereof.

[0176] In an embodiment, the first semiconductor nanocrystals may include InP, InZnP, ZnSe, ZnSeS, ZnSeTe or combinations thereof; the second semiconductor nanocrystals may include ZnSe, ZnSeS, ZnS, ZnTeSe or combinations thereof. In an embodiment, the shell may include zinc, sulfur and optionally selenium in the outermost layer.

[0177] In an embodiment, the semiconductor nanoparticles can emit blue light or green light and can include a core and a shell, the core including ZnSeTe, ZnSe, or a combination thereof, and the shell including a zinc chalcogenide (e.g., ZnS, ZnSe, ZnSeS, or a combination thereof). The amount of sulfur in the shell can increase or decrease in the radial direction (from the core towards the surface), e.g., the amount of sulfur can have a concentration gradient where the sulfur concentration varies radially (e.g., decreases or increases in the direction towards the core).

[0178] In an embodiment, the semiconductor nanoparticles can emit red light or green light, the core can include InP, InZnP, or a combination thereof, and the shell can include a Group II metal and a non-metal, the Group II metal including zinc and the non-metal including sulfur, selenium, or a combination thereof.

[0179] In an embodiment, due to the core-shell structure of the semiconductor nanoparticles, an alloyed intermediate layer may or may not be present at the interface between the core and the shell. The alloyed intermediate layer can include a homogeneous alloy or can have a concentration gradient. The gradient alloy can have a concentration gradient where the concentration of the elements of the shell varies radially (e.g., decreases or increases in the direction towards the core).

[0180] In an embodiment, the shell can have a composition that varies in the radial direction. In an embodiment, the shell can be a multi-layer shell including two or more layers. In the multi-layer shell, two adjacent layers can have different compositions from each other. In the multi-layer shell, a layer, e.g., at least one layer, can independently include semiconductor nanocrystals having a single composition. In the multi-layer shell, a layer, e.g., at least one layer, can independently have alloyed semiconductor nanocrystals. In the multi-layer shell, a layer, e.g., at least one layer, can have a concentration gradient that varies radially in terms of the composition of the semiconductor nanocrystals.

[0181] In an embodiment, in the semiconductor nanoparticles having a core-shell structure, the shell material can have a larger (e.g., higher) bandgap energy than the bandgap energy of the core. The material of the shell can have a smaller (e.g., lower) bandgap energy than the bandgap energy of the core. In the case of a multi-layer shell, the bandgap energy of the outermost layer material of the shell can be greater than the bandgap energy of the core and the inner layer material (the layer closer to the core) of the shell. In the case of a multi-layer shell, the semiconductor nanocrystals of each layer are selected to have an appropriate bandgap so as to effectively exhibit, e.g., demonstrate, the quantum confinement effect.

[0182] The semiconductor nanoparticles according to an embodiment can include, for example, organic ligands bound or coordinated to their surface.

[0183] The absorption / emission wavelength of the semiconductor nanoparticles can be controlled by adjusting the composition, size, or a combination thereof of the semiconductor nanoparticles. The semiconductor nanoparticles included in the light-emitting layers 3, 30 can be configured to emit light of a desired color. The semiconductor nanoparticles can include blue light-emitting semiconductor nanoparticles, green light-emitting semiconductor nanoparticles, or red light-emitting semiconductor nanoparticles.

[0184] In an embodiment, the maximum emission peak wavelength of the semiconductor nanoparticles or the light-emitting layer (or the light emitted from the electroluminescent device) can be in the ultraviolet to infrared or longer wavelength range, or in the visible light range such as the green light range, the red light range, or the blue light range.

[0185] In an embodiment, the emission peak wavelength of the semiconductor nanoparticles or the light-emitting layer (or the light emitted from the electroluminescent device) can 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 emission peak wavelength of the semiconductor nanoparticles or the light-emitting layer (or the light emitted from the electroluminescent device) can be less than or equal to about 1000 nm, less than or equal to about 900 nm, 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 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 emission peak wavelength of the semiconductor nanoparticles or the light-emitting layer (or the light emitted from the electroluminescent device) can be from about 500 nm to about 650 nm.

[0186] The semiconductor nanoparticles (or the light emitted from the electroluminescent device) can emit green light (e.g., when a voltage is applied or when irradiated with light), and its maximum emission peak wavelength can 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, such as less than or equal to about 540 nm, or less than or equal to about 530 nm.

[0187] Semiconductor nanoparticles (or the light emitted from an electroluminescent device) can emit red light (e.g., when a voltage is applied or irradiated with light), and the wavelength of its maximum emission peak can be in the range of greater than or equal to about 600 nm, such as 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.

[0188] Semiconductor nanoparticles (or the light emitted from an electroluminescent device) can emit blue light (e.g., when a voltage is applied or irradiated with light), and the wavelength of its maximum emission peak can be greater than or equal to about 430 nm (e.g., greater than or equal to about 450 nm, greater than or equal to about 455 nm, greater than or equal to about 460 nm, greater than or equal to about 465 nm) 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, or less than or equal to about 465 nm).

[0189] In an embodiment, the semiconductor nanoparticles can exhibit an emission spectrum (e.g., a photoluminescence or electroluminescence spectrum) with a relatively narrow full width at half maximum. In an embodiment, in the photoluminescence or electroluminescence spectrum, the semiconductor nanoparticles can exhibit a full width at half maximum of 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. The full width at half maximum can 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.

[0190] The semiconductor nanoparticles can exhibit (or can be configured to exhibit) a quantum efficiency (or quantum yield) of greater than or equal to about 10%, such as greater than or equal to about 30%, 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 about 100%.

[0191] Semiconductor nanoparticles may have a size (or average size, which may be simply referred to as "size" hereinafter) greater than or equal to about 1 nm and less than or equal to about 100 nm, greater than or equal to about 2 nm and less than or equal to about 50 nm, or greater than or equal to about 3 nm and less than or equal to about 15 nm. The size may be a diameter or an equivalent diameter converted by assuming a sphere from an electron microscope image when it is not spherical. The size may be calculated from the results of inductively coupled plasma atomic emission spectrometry (ICP-AES) analysis. In an embodiment, the semiconductor nanoparticles may have a size of about 1 nm to about 50 nm, such as about 2 nm (or about 3 nm) to about 35 nm. In an embodiment, the size (or average size) of the semiconductor nanoparticles may be 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, or greater than or equal to about 12 nm. In an embodiment, the size (or average 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.

[0192] The shape of the semiconductor nanoparticles or semiconductor nanostructures is not particularly limited. For example, the shape of the semiconductor nanoparticles may include, but is not limited to, spheres, polyhedra, pyramids, multi-legged shapes, hexahedra, cubes, cuboids, nanotubes, nanorods, nanowires, nanosheets, or combinations thereof.

[0193] The semiconductor nanoparticles can be prepared by an appropriate method. The semiconductor nanoparticles can be prepared, for example, by chemical wet methods, in which nanocrystal particles can grow through reactions between precursors in a reaction system including an organic solvent and an organic ligand. The organic ligand or organic solvent can coordinate to the surface of the semiconductor nanocrystal (coordinate with the surface of the semiconductor nanocrystal or coordinate to the surface of the semiconductor nanocrystal) to control its growth.

[0194] In an embodiment, for example, a method of preparing semiconductor nanoparticles having a core / shell structure may include: obtaining a core; reacting a first shell precursor containing a metal (such as zinc) and a second shell precursor containing a non-metal element (such as selenium, sulfur, or a combination thereof) in the presence of the core in a reaction medium including an organic ligand and an organic solvent at a reaction temperature (such as greater than or equal to about 180 °C, greater than or equal to about 200 °C, greater than or equal to about 240 °C, or greater than or equal to about 280 °C and less than or equal to about 360 °C, less than or equal to about 340 °C, or less than or equal to about 320 °C) to form a shell including a second semiconductor nanocrystal on the core including a first semiconductor nanocrystal. The method may further include separating the core from the reaction system that produced it and dispersing the core in an organic solvent to obtain a core solution.

[0195] In an embodiment, to form the shell, the solvent and optionally the first shell precursor and the ligand compound may be heated under vacuum at a predetermined temperature (such as greater than or equal to about 100 °C) (also referred to herein as vacuum treatment), and then after introducing an inert gas into the reaction vessel, the mixture may be heat-treated again at a predetermined temperature (such as greater than or equal to 100 °C). Then, the core and the second shell precursor may be added to the mixture and heated at the reaction temperature. The shell precursors may be added simultaneously or sequentially in different proportions during the reaction time.

[0196] In the semiconductor nanoparticles of an embodiment, the core may be prepared in a suitable manner. In an embodiment, the organic solvent may include C6-C22 primary amines such as hexadecylamine, C6-C22 secondary amines such as dioctylamine, C6-C40 tertiary amines such as trioctylamine, nitrogen-containing heterocyclic compounds such as pyridine, C6-C40 olefins such as octadecene, C6-C40 aliphatic hydrocarbons such as hexadecane, octadecane, or squalane, aromatic hydrocarbons substituted with C6-C30 alkyl groups such as phenyldodecane, phenyltetradecane, or phenylhexadecane, primary, secondary, or tertiary phosphines (such as trioctylphosphine) substituted with C6 to C22 alkyl groups, for example at least one (such as 1, 2, or 3) C6 to C22 alkyl groups, phosphine oxides (such as trioctylphosphine oxide) substituted with C6 to C22 alkyl groups (such as 1, 2, or 3 C6 to C22 alkyl groups), C12-C22 aromatic ethers such as phenyl ether or benzyl ether, or a combination thereof. Combinations including more than one type of organic solvent may be used.

[0197] The organic ligand may include RCOOH, RNH2, R2NH, R3N, RSH, RH2PO, R2HPO, R3PO, RH2P, R2HP, R3P, ROH, RCOOR', RPO(OH)2, R2POOH, or a combination thereof. Here, R and R' are each independently a substituted or unsubstituted aliphatic hydrocarbon group having 3 or more, 6 or more, or 10 or more carbon atoms and about 40 or fewer, 35 or fewer, or 25 or fewer carbon atoms (e.g., alkyl, alkenyl, alkynyl, etc.), a substituted or unsubstituted aromatic hydrocarbon group having 6 to 40 carbon atoms (e.g., aryl), or a combination thereof. In an embodiment, at least two different organic ligands may be used.

[0198] In an embodiment, after completion of the reaction (for forming the core or for forming the shell), a non-solvent is added to the reaction product, and the nanoparticles coordinated with the ligand compound can be separated. The non-solvent may be a polar solvent that is miscible with the solvent used in the core formation reaction, shell formation reaction, or a combination thereof and cannot disperse the prepared nanocrystals. The non-solvent can be selected depending on the solvent used in the reaction and may include, for example, acetone, ethanol, butanol, isopropanol, ethylene glycol, water, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), diethyl ether, formaldehyde, acetaldehyde, solvents having solubility parameters similar to the foregoing non-solvents, or a combination thereof. The semiconductor nanocrystal particles can be separated by centrifugation, sedimentation, or chromatography. If desired, the separated nanocrystals can be washed with a washing solvent. The washing solvent is not particularly limited and may have a solubility parameter similar to that of the ligand and may include, for example, hexane, heptane, octane, chloroform, toluene, benzene, etc.

[0199] The semiconductor nanoparticles of the embodiment may be non-dispersible or insoluble in water, the foregoing non-solvent, or a combination thereof. The semiconductor nanoparticles of the embodiment may be dispersed in the foregoing organic solvents. In an embodiment, the foregoing semiconductor nanoparticles may be dispersed in a substituted or unsubstituted aliphatic hydrocarbon having 6 to 40 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon having 6 to 40 carbon atoms, or a combination thereof.

[0200] The prepared semiconductor nanoparticles can be treated with a halogen compound. By treating with a halogen compound, at least a part of the organic ligand can be replaced by a halogen. The halogen-treated semiconductor nanoparticles may include a reduced amount of the organic ligand. The halogen treatment can be carried out as follows: The semiconductor nanoparticles are contacted with a halogen compound (e.g., a metal halide, such as zinc chloride) in an organic solvent at a predetermined temperature of about 30°C to about 100°C or about 50°C to about 150°C. The halogen-treated semiconductor nanoparticles can be separated using the foregoing non-solvent.

[0201] In the electroluminescent device or display device of the embodiment, the thickness of the light-emitting layer can be appropriately selected. The light-emitting layer can have a thickness greater than or equal to about 5 nm, such as greater than or equal to about 10 nm, greater than or equal to about 20 nm, or greater than or equal to about 30 nm and less than or equal to about 200 nm, 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 light-emitting layer can have a thickness of, for example, about 10 nm to about 150 nm, about 20 nm to about 100 nm, or about 30 nm to about 50 nm.

[0202] In an embodiment, the formation of the light-emitting layer including semiconductor nanoparticles can be carried out as follows: obtaining a coating solution including semiconductor nanoparticles and an organic solvent (for example, an alkane solvent such as octane, heptane, etc., an aromatic solvent such as toluene, or a combination thereof), and applying or depositing the coating solution on a substrate or a charge assisting layer (for example, a hole assisting layer) in an appropriate manner (for example, by spin coating, inkjet printing, etc.). The type of the organic solvent for the coating solution is not particularly limited and can be appropriately selected. In an embodiment, the organic solvent can include a substituted or unsubstituted aliphatic hydrocarbon, a substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted alicyclic hydrocarbon, an acetate solvent, or a combination thereof.

[0203] In an embodiment, the formation of the light-emitting layer can further include contacting a film of semiconductor nanoparticles with an organic solution containing a metal halide (for example, zinc chloride). In an embodiment, the light-emitting layer can include: a first light-emitting layer including first semiconductor nanoparticles and a second light-emitting layer including second semiconductor nanoparticles, wherein the first semiconductor nanoparticles have a surface with halogen (for example, chlorine) exchange, and the second light-emitting layer has an increased amount of organic ligands. The amount of halogen (for example, chlorine) and the amount of organic ligands in the light-emitting layer can be controlled in an appropriate manner (for example, post-treatment of the formed layer). In an embodiment, a thin film of semiconductor nanoparticles having an organic ligand (for example, having a carboxylic acid group) is formed, which is then treated with a solution containing a metal halide (for example, zinc chloride in an alcohol solvent) to control the amount of the organic ligand of the semiconductor nanoparticles in the thin film. The treated thin film can have an increased amount of halogen, show (for example, exhibit) changed properties (for example, solubility) with respect to, for example, the organic solvent, and subsequently, it may be possible to form a layer of semiconductor nanoparticles having different amounts of organic ligands (for example, halogen-treated semiconductor nanoparticles or semiconductor nanoparticles having a ligand with a carboxylic acid group) on the treated thin film.

[0204] In an embodiment, the light-emitting layer may be a single layer or a multilayer structure having at least two layers. In the multilayer structure, adjacent layers (e.g., a first light-emitting layer and a second light-emitting layer) may be configured to emit a first light (e.g., green light, blue light, or red light). In the multilayer structure, adjacent layers (e.g., a first light-emitting layer and a second light-emitting layer) may have the same or different compositions, ligands, or combinations thereof. In an embodiment, the (multilayer) light-emitting layer may exhibit a varying (increasing or decreasing) halogen content in the thickness direction. In an embodiment, in the (multilayer) light-emitting layer, the amount of halogen may increase in the direction toward the electron-assisted layer. In the (multilayer) light-emitting layer, the amount of the organic ligand may decrease in the direction toward the electron-assisted layer. In the (multilayer) light-emitting layer, the content of the organic ligand may increase in the direction toward the electron-assisted layer.

[0205] In an embodiment, the light-emitting layer thus formed (or treated with a halogen solution) may be washed with an organic washing solvent (water or a water-miscible organic solvent). The manner of washing is not particularly limited and may be performed by spin drying, dipping, or a combination thereof.

[0206] The light-emitting layer may be heat-treated. The heat treatment may be performed in air or in an inert gas atmosphere. The temperature of the heat treatment may be greater than or equal to about 50 °C, greater than or equal to about 70 °C, greater than or equal to about 90 °C, greater than or equal to about 100 °C, greater than or equal to about 120 °C, greater than or equal to about 150 °C, greater than or equal to about 170 °C, or greater than or equal to about 200 °C. The temperature of the heat treatment may be less than or equal to about 250 °C, less than or equal to about 230 °C, less than or equal to about 200 °C, less than or equal to about 180 °C, less than or equal to about 160 °C, less than or equal to about 140 °C, or less than or equal to about 130 °C.

[0207] The light-emitting device of the embodiment includes an electron-assisted layer 4, 40 disposed on the light-emitting layer 3, 30, e.g., between the light-emitting layer and a second electrode or a thin film conductor (hereinafter, “second electrode”) 5, 50. In the electron-assisted layer 4, 40, electron transport, injection, or both transport and injection may occur. The electron-assisted layer 4, 40 includes an electron transport layer (ETL). The electron transport layer includes (a plurality of) metal oxide nanoparticles. The electron-assisted layer 4, 40 may further include an electron injection layer, a hole blocking layer, or a combination thereof. The electron injection layer, the hole blocking layer, or a combination thereof may be disposed between the electron transport layer and the second electrode, but is not limited thereto. In an embodiment, the hole blocking layer may be disposed between the electron injection layer and the electron transport layer. In an embodiment, the electron transport layer may be disposed between the electron injection layer and the hole blocking layer. The electron transport layer may be adjacent to the light-emitting layer (e.g., directly adjacent to the light-emitting layer or directly disposed on the light-emitting layer). In an embodiment, the light-emitting layer 3, 30 may be in contact with the electron transport layer (directly disposed on the electron transport layer).

[0208] The metal oxide (nanoparticle) may include zinc oxide. The metal oxide (nanoparticle) or zinc oxide may include: zinc; and optionally a Group IIA metal, Zr, W, Li, Ti, Y, Al, gallium, indium, tin (Sn), cobalt (Co), vanadium (V), or a combination thereof. The metal oxide (nanoparticle) or zinc oxide may include zinc, a Group IIA metal, and optionally an alkali metal.

[0209] The metal oxide (nanoparticle) or zinc oxide may include a compound represented by Zn 1-x M x O, where M is Mg, Ga, Ca, Zr, Co, W, Li, Ti, Y, Al, or a combination thereof, and 0 ≤ x ≤ 0.5. x may be greater than or equal to about 0.01, greater than or equal to about 0.03, greater than or equal to about 0.05, greater than or equal to about 0.07, greater than or equal to about 0.1, greater than or equal to about 0.13, greater than or equal to about 0.15, greater than or equal to about 0.17, greater than or equal to about 0.2, greater than or equal to about 0.23, or greater than or equal to about 0.25. x may be less than or equal to about 0.47, less than or equal to about 0.45, less than or equal to about 0.43, less than or equal to about 0.4, less than or equal to about 0.37, less than or equal to about 0.35, or less than or equal to about 0.3. The metal oxide or zinc oxide may further include magnesium. The electron transport layer or zinc oxide may include Zn 1-x Mg x O (x is greater than or equal to 0, or greater than 0 and less than or equal to about 0.5, x being the same as defined herein), ZnO, or a combination thereof. The zinc oxide may further include magnesium.

[0210] The size or average size (hereinafter referred to as "size") of the metal oxide 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 2.5 nm, greater than or equal to about 3 nm, or greater than or equal to about 3.5 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, less than or equal to about 5 nm, or less than or equal to about 4.5 nm. The size of the metal oxide nanoparticles may be the diameter or the equivalent diameter. The equivalent diameter is a value obtained by converting the size of a non-spherical particle into the diameter of a spherical particle. The size of the nanoparticles may be analyzed by appropriate means such as electron microscopy methods like TEM or XRD measurement. In this specification, the size may refer to the size of a single particle or the average size of a group of particles.

[0211] In an embodiment, metal oxide nanoparticles (e.g., zinc oxide nanoparticles) can be prepared by any suitable method, which is not particularly limited. The preparation of the metal oxide nanoparticles can include a sol-gel reaction. In an embodiment, zinc oxide (e.g., zinc magnesium oxide) nanoparticles can be prepared by: placing a zinc compound (e.g., an organozinc compound, such as zinc acetate dihydrate) and optionally an additional metal compound (e.g., an additional organometallic compound, such as magnesium acetate tetrahydrate) in an organic solvent (e.g., dimethyl sulfoxide) in a flask in a desired molar ratio, and heating it at a predetermined temperature (e.g., about 40 °C to about 120 °C, or about 60 °C to about 100 °C) (e.g., in air), and adding a precipitation promoter solution (e.g., a solution of tetramethylammonium hydroxide pentahydrate and ethanol) at a predetermined rate while stirring (e.g., while stirring). The prepared zinc oxide nanoparticles (e.g., Zn x Mg 1-x O nanoparticles) can be recovered from the reaction solution, e.g., by centrifugation.

[0212] In an embodiment, the electron assisting layer or the electron transporting layer can be prepared by a solution process. In an embodiment, the electron assisting layer or the electron transporting layer can be prepared by: dispersing a plurality of metal oxide nanoparticles in an organic solvent (e.g., a polar solvent, a non-polar solvent, or a combination thereof) to obtain a precursor dispersion of the electron transporting layer, and then applying it to a surface to form a film. The precursor dispersion of the electron transporting layer can be applied to the light emitting layer. The solution process can further include removing the organic solvent from the formed film, e.g., by evaporation. The organic solvent can include a C1 to C10 alcohol solvent or a combination thereof.

[0213] In an embodiment, the thickness of the electron transport layer (ETL) can be greater than or equal to about 3 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, greater than or equal to about 14 nm, greater than or equal to about 15 nm, greater than or equal to about 16 nm, greater than or equal to about 17 nm, greater than or equal to about 18 nm, greater than or equal to about 19 nm, greater than or equal to about 20 nm, greater than or equal to about 21 nm, greater than or equal to about 22 nm, greater than or equal to about 23 nm, greater than or equal to about 24 nm, greater than or equal to about 25 nm, greater than or equal to about 26 nm, greater than or equal to about 27 nm, greater than or equal to about 28 nm, greater than or equal to about 29 nm, greater than or equal to about 30 nm, greater than or equal to about 31 nm, greater than or equal to about 32 nm, greater than or equal to about 33 nm, greater than or equal to about 34 nm, or greater than or equal to about 35 nm. The thickness of the electron transport layer can be 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 45 nm, less than or equal to about 40 nm, or less than or equal to about 35 nm.

[0214] The thickness of the electron injection layer, hole blocking layer, or a combination thereof is not particularly limited and can be appropriately selected. The thickness of the electron injection layer, hole blocking layer, or a combination thereof can be greater than or equal to about 5 nm, greater than or equal to about 6 nm, greater than or equal to about 7 nm, greater than or equal to about 8 nm, greater than or equal to about 9 nm, greater than or equal to about 10 nm, greater than or equal to about 11 nm, greater than or equal to about 12 nm, greater than or equal to about 13 nm, greater than or equal to about 14 nm, greater than or equal to about 15 nm, greater than or equal to about 16 nm, greater than or equal to about 17 nm, greater than or equal to about 18 nm, greater than or equal to about 19 nm, or greater than or equal to about 20 nm and less than or equal to about 500 nm, less than or equal to about 120 nm, less than or equal to about 110 nm, less than or equal to about 100 nm, less than or equal to about 90 nm, less than or equal to about 80 nm, less than or equal to about 70 nm, less than or equal to about 60 nm, less than or equal to about 50 nm, less than or equal to about 40 nm, less than or equal to about 30 nm, or less than or equal to about 25 nm, but is not limited thereto.

[0215] In an embodiment, materials for an electron injection layer, a hole blocking layer, or a combination thereof may include 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA), bathocuproine (BCP), tris[3-(3-pyridyl)-mesityl]borane (3TPYMB), LiF, tris(8-hydroxyquinoline)aluminum (Alq3), tris(8-hydroxyquinoline)gallium (Gaq3), tris(8-hydroxyquinoline)indium (Inq3), bis-(8-hydroxyquinoline)zinc (Znq2), bis[2-(2-hydroxyphenyl)benzothiazole]zinc (Zn(BTZ)2), bis(10-hydroxybenzo[h]quinolinato)beryllium (BeBq2), 8-(4-(4,6-bis(naphthalen-2-yl)-1,3,5-triazin-2-yl)phenyl)quinolone (ET204), lithium 8-hydroxyquinolate (Liq), 2,2',2''-(1,3,5-benzenetriyl)-tris(1-phenyl-1H-benzoimidazole) (TPBi), n-type metal oxides (e.g., ZnO, HfO2, etc.), 8-(4-(4,6-bis(naphthalen-2-yl)-1,3,5-triazin-2-yl)phenyl)quinolone:lithium 8-hydroxyquinolate (ET204:Liq), or a combination thereof, but not limited thereto.

[0216] In the electron transport layer, metal oxide nanoparticles may provide higher electron mobility than organic semiconductor materials, and a light-emitting layer (e.g., in combination with an electron transport layer including metal oxide nanoparticles) may exhibit desired levels of electroluminescent properties. In addition, an emissive layer based on semiconductor nanoparticles may be formed by a solution process, and an electron transport layer based on metal oxide nanoparticles may be formed by a solution process on the emissive layer, thereby providing a relatively efficient (highly efficient) and advantageous process for manufacturing the device.

[0217] The inventors have found in their studies that a combination of an electron assisting layer including metal oxide nanoparticles and a light-emitting layer including semiconductor nanoparticles may not provide desired levels of improvement in both electroluminescent properties and lifetime characteristics. For example, metal oxide nanoparticles (e.g., zinc magnesium oxide nanoparticles) may grow by a sol-gel reaction involving precursors (e.g., Zn(CH3COO)2, Mg(CH3COO)2) in the presence of a base. Without wishing to be bound by any theory, it is believed that, as a result of the synthesis, various surface chemical species such as metal ions, e.g., (Zn 2+ , Mg 2+ ), O 2- , OH - , CH3COO -They may exist on the surface of metal oxide nanoparticles, and these surface chemical species can be the source of surface defects of the nanoparticles and act as defect energy levels in the ETL. Without wishing to be bound by any theory, it is believed that the surface defects present on metal oxide (e.g., ZnMgO) particles can have energy levels close to the HOMO energy level of quantum dots or semiconductor nanoparticles, and thus can be used as trapping (trap) sites for holes and can lead to an increase in leakage current.

[0218] Metal oxide nanoparticles in the electron assisting layer or electron transport layer can include various defects generated during their manufacturing process and film formation process, and these defects can provide various energy levels within the nanoparticles to be used as channels for hole movement. Thus, the electron transport layer based on metal oxide nanoparticles can exhibit reduced hole blocking performance or relatively high hole leakage current, which can adversely affect the electroluminescent properties (e.g., luminous efficiency) of the device.

[0219] In addition, without wishing to be bound by any theory, surface defects that may exist on or in metal oxide nanoparticles can cause unwanted charge accumulation at the interface between the electron transport layer and the light emitting layer or in the electron transport layer. The accumulation of this charge can lead to unwanted charging (e.g., within the electron transport layer or at the interface between the light emitting layer and the electron transport layer), and can result in a reduction in the brightness or lifetime of the QD-LED device.

[0220] The electroluminescent device or method of manufacturing the same according to an embodiment includes using an organic layer or polymer material as described herein, or using an organic layer forming composition, and the electron transport layer containing metal oxide nanoparticles can be post-treated as described herein. The electroluminescent device according to an embodiment including the post-treated electron transport layer can exhibit improved electroluminescent properties and lifetime characteristics. In the post-treatment of the method according to an embodiment, moisture and / or acid components can easily diffuse into the electron transport layer (in a contacting manner or in a remote manner), and the electron transport layer can be easily used for both bottom-emission type and front-emission type devices.

[0221] Not wishing to be bound by any theory, it is believed that in the post-treatment of embodiments employing the existing organic layer (or polymer material) and conductor thin film (or second electrode), (diffused) moisture (and optionally acid) can induce modification (e.g., surface modification or surface chemical reaction) of metal oxide nanoparticles contained on or in the electron transport layer. This surface modification can passivate defects on the nanoparticle surface, and by improving the electrical properties of the metal oxide, the modified metal oxide nanoparticles can exhibit increased conductivity to a desired degree, and when applied to the electron transport layer, it can exhibit effectively reduced hole leakage current and effectively reduced charge accumulation, and thereby can suppress or mitigate charging problems or difficulties. Therefore, the electroluminescent device of the embodiment can exhibit an extended lifespan and improved efficiency.

[0222] The inventors have also found that after heat treatment at an elevated temperature for a predetermined time, e.g., during the manufacturing step, the electroluminescent device can exhibit a (significant or substantial) change (e.g., reduction) in electroluminescent performance and / or the driving voltage of the device for a predetermined brightness can increase significantly. However, the electroluminescent device according to the embodiment is less sensitive to higher temperatures and, in fact, quite surprisingly exhibits improved electroluminescent properties after heat treatment at an elevated temperature for a predetermined time, i.e., a very opposite effect to what a person of ordinary skill in the art would expect. In other words, the electroluminescent device according to the embodiment exhibits a relatively small increase (if any) in the driving voltage after exposure to high temperature at a predetermined brightness.

[0223] In the electroluminescent device of the embodiment, an organic layer or polymer can be provided on or above the electron transport layer (and optionally the second electrode). The organic layer can include a polymer, and the polymer can include repeating units having hydroxyl groups. In the embodiment, the introduction of the organic layer or polymer as described herein can prevent or inhibit the electroluminescent device from exhibiting a substantial or significant reduction in electroluminescent properties and / or a sharp increase in the driving voltage of the device, even after the device is stored at an elevated temperature for an extended period.

[0224] In the embodiment, the electron transport layer or electron assisting layer can include a first surface facing the light emitting layer and an opposite second surface, and the organic layer or polymer can be disposed on at least a part or all of the second surface of the electron transport layer or electron assisting layer. In the embodiment, the second electrode includes a first surface facing the electron transport layer and an opposite second surface, and the organic layer or polymer can be disposed on at least a part or all of the second surface of the second electrode.

[0225] In the embodiment, the organic layer or polymer can be in direct contact with the second surface of the electron transport layer and the second surface of the second electrode. (See Figure 1A , Figure 1B ,Figure 3A , Figure 3B , Figure 3C and Figure 6B ). In an embodiment, the organic layer or polymer may be spaced apart from the electron transport layer or the second electrode and may be disposed to face the electron transport layer or the second electrode. The electroluminescent device of the embodiment may further include a container configured to receive at least a part or all of a stacked structure including a first electrode, an emission layer, an electron transport layer, and a second electrode (or a conductor thin film), and the organic layer or polymer may be disposed on the surface of the container (see Figure 2A , Figure 2B , Figure 2C , Figure 4 , Figure 5A and Figure 8 ).

[0226] The organic layer or polymer material may be disposed to face the (surface of the) thin film conductor. The organic layer or polymer material may be disposed to face the electron transport layer. The second electrode or the thin film conductor may be disposed between the organic layer (or polymer) and the electron transport layer.

[0227] Without wishing to be bound by any theory, the hydrogen ions and / or moisture provided by the organic layer or polymer material may passivate the defects on the surface of the metal oxide nanoparticles (e.g., by a chemical reaction) to remove the trapping (trap) sites, suppress the leakage leakage current of holes generated through the trapping sites of the metal oxide (e.g., ZnMgO) nanoparticles, and / or enhance the hole blocking ability of the metal oxide-based electron transport layer. Without wishing to be bound by any particular theory, it is believed that the electroluminescent device of the embodiment may exhibit an increased external quantum efficiency (EQE) because the post-treatment may result in a more efficient hole-electron combination than the currently known techniques using known manufacturing methods (e.g., steps that may include heat treatment at an elevated temperature for an extended period of time).

[0228] In addition, the post-treatment may provide surface modification of the metal oxide nanoparticles, thereby reducing the trapping sites and the charge accumulation at the trapping sites, and thus may prevent or suppress unwanted charging in the device. Additionally, when driven at a desired voltage for a long time, the device of the embodiment may exhibit reduced / suppressed deterioration of the semiconductor nanoparticles or ETL material (e.g., metal oxide nanoparticles), and thus may exhibit improved (e.g., extended) device lifetime.

[0229] The polymer may include a repeating unit represented by Chemical Formula 1:

[0230] Chemical Formula 1

[0231]

[0232] Wherein A is a direct bond, -C(O)-, -O-, an ester linkage (such as -C(O)O- or -OC(O)-), -C(O)NH-, -NH-, -S-, -S(O)-, or a combination thereof, and L is a direct bond, a substituted or unsubstituted divalent C1 to C30, C2-C15, C3-C10 aliphatic hydrocarbon group (e.g., alkylene, alkenylene), a substituted or unsubstituted C6-C20 or C8-C15 arylene group (e.g., phenylene), and R are the same or different and each independently is hydrogen, or a substituted or unsubstituted C1 to C30 (or C5 to C10) alkyl group, and * is a moiety that is linked to an adjacent atom (or adjacent repeating unit) (e.g., in the main chain).

[0233] In the polymers of an embodiment, both A and L in Formula 1 can be direct bonds.

[0234] In the polymers of an embodiment, A in Formula 1 can be an ester linkage (such as -C(O)O- or -OC(O)-), -C(O)-, or C(O)NH, and L in Formula 1 can be a substituted or unsubstituted divalent C1 to C30, C2-C15, or C3-C10 aliphatic hydrocarbon group (e.g., alkylene such as propylene, ethylene, methylene, butylene, pentylene, etc.; alkenylene).

[0235] In the polymers of an embodiment, A in Formula 1 can be a direct bond, and L in Formula 1 can be a substituted or unsubstituted C6-C20 arylene group (e.g., phenylene).

[0236] The polymer can be a copolymer having different repeating units. In addition to the repeating unit represented by Formula 1, the copolymer can further include additional repeating units, for example, (meth)acrylate repeating units, (meth)acrylic acid repeating units, or a combination thereof.

[0237] The polymer can include: polyvinyl alcohol or its copolymer; polyvinyl phenol or its copolymer; polyvinyl phenol-(co)(meth)acrylate; poly(hydroxyalkyl)(meth)acrylate or its copolymer; polyhydroxyalkyl(meth)acrylamide or its copolymer; or a combination thereof.

[0238] The polymer can be a hydrophilic polymer. The polymer can be soluble in water or in a water-miscible organic solvent (e.g., C1-C10 or C2-C5 alcohol, DMSO). The polymer can be a water-soluble polymer

[0239] The polymer may include polyvinyl alcohol. The polymer may be a non-gelled polymer. The polymer may be a linear polymer. The polymer may be a copolymer. The polymer may be a homopolymer. The polymer may include a first repeating unit (a unit derived from vinyl alcohol) represented by Chemical Formula 2 or Chemical Formula 2-1 and optionally a second repeating unit (a unit derived from vinyl acetate) represented by Chemical Formula 3 or Chemical Formula 3-1:

[0240] Chemical Formula 2

[0241]

[0242] Chemical Formula 2-1

[0243]

[0244] Chemical Formula 3

[0245]

[0246] Chemical Formula 3-1

[0247]

[0248] In the above formulas, * is a moiety connected to an adjacent repeating unit, R is the same or different and each independently is hydrogen or a substituted or unsubstituted C1 to C30 (or C5 to C10) alkyl group, and R' is a substituted or unsubstituted C1-C10 (C2-C5) alkyl group.

[0249] In the polymer (e.g., polyvinyl alcohol), the molar percentage of the first repeating unit relative to the total content (moles) of the first and second repeating units (e.g., the degree of hydrolysis of the polymer) may be greater than or equal to about 50%, greater than or equal to about 55%, greater than or equal to about 60%, greater than or equal to about 65%, greater than or equal to about 70%, greater than or equal to about 75%, greater than or equal to about 80%, greater than or equal to about 85%, greater than or equal to about 90%, greater than or equal to about 95%, or greater than or equal to about 99%. The degree of hydrolysis of the polymer may be in the range of about 78% to 100%, 80% to 99%, 82% to 98%, 85% to 95%, or a combination thereof.

[0250] The polymer (e.g., polyvinyl alcohol) or its copolymer may be synthesized by various synthetic methods or may be commercially available.

[0251] The polymer may include a repeating unit represented by Chemical Formula 4 or Chemical Formula 4-1, or polyvinylphenol or its copolymer including a repeating unit represented by Chemical Formula 4 or Chemical Formula 4-1:

[0252] Chemical Formula 4

[0253]

[0254] Chemical formula 4-1

[0255]

[0256] In the above formula, R is the same or different and each independently is hydrogen or a substituted or unsubstituted C1 to C30 (or C5 to C10) alkyl group, and * is the part connected to the adjacent repeating unit. Except for the hydroxyl group, the phenyl group of Chemical formula 4 or Chemical formula 4-1 may have additional substituents, and the types of the additional substituents can refer to the definitions of the substituents described herein.

[0257] Polyvinylphenol or its copolymer can be synthesized by various synthetic methods or can be commercially obtained.

[0258] The polymer may include repeating units represented by Chemical formula 5 or Chemical formula 5-1; or a poly(hydroxyalkyl) acrylate or its copolymer including repeating units represented by Chemical formula 5 or Chemical formula 5-1:

[0259] Chemical formula 5

[0260]

[0261] Chemical formula 5-1

[0262]

[0263] Wherein R is the same or different and each independently is hydrogen or a substituted or unsubstituted C1 to C30 (or C5 to C10) alkyl group, and L is a substituted or unsubstituted C1 to 10 alkylene group (for example, methylene, ethylene, propylene, butylene, pentylene, etc.), and * is the part connected to the adjacent repeating unit.

[0264] The poly(hydroxyalkyl) acrylate or its copolymer can be synthesized by various synthetic methods or commercially obtained.

[0265] The polymer has a solubility in water or alcohol as follows: greater than or equal to about 1 g / L, greater than or equal to about 5 g / L, greater than or equal to about 10 g / L, greater than or equal to about 15 g / L, greater than or equal to about 20 g / L, greater than or equal to about 33 g / L, greater than or equal to about 50 g / L, greater than or equal to about 55 g / L, greater than or equal to about 65 g / L, greater than or equal to about 70 g / L, greater than or equal to about 85 g / L, greater than or equal to about 100 g / L, greater than or equal to about 150 g / L, greater than or equal to about 200 g / L, greater than or equal to about 250 g / L, or greater than or equal to about 300 g / L. The polymer has a solubility in water or alcohol as follows: less than or equal to about 5000 g / L, less than or equal to about 4000 g / L, less than or equal to about 3000 g / L, less than or equal to about 1000 g / L, less than or equal to about 800 g / L, less than or equal to about 600 g / L, less than or equal to about 500 g / L, less than or equal to about 400 g / L, less than or equal to about 350 g / L, less than or equal to about 200 g / L, less than or equal to about 130 g / L, less than or equal to about 90 g / L, or less than or equal to about 80 g / L. The polymer can be a water-soluble polymer.

[0266] The polymer can be water-soluble. In an embodiment, the water-soluble polymer can form a solution (e.g., an aqueous solution or an alcohol solution) having a polymer concentration of greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, based on the total weight of the solution (e.g., at 25 °C or at a temperature below 80 °C).

[0267] The polymer contains hydroxyl groups within its repeating units, which can be confirmed by appropriate analysis. In an embodiment, the polymer can exhibit a hydroxyl peak between about 4 ppm and about 5 ppm (e.g., three peaks), as confirmed by NMR analysis.

[0268] When dissolved in water or an alcohol, the polymer may exhibit a pH greater than or equal to about 4.5, greater than or equal to about 5, greater than or equal to about 5.5, greater than or equal to about 6, greater than or equal to about 6.5, greater than or equal to about 7, greater than or equal to about 7.5, or greater than or equal to about 7.8, greater than or equal to about 8, greater than or equal to about 8.2 and less than or equal to about 9, less than or equal to about 8.7, less than or equal to about 8.5, less than or equal to about 8.3, less than or equal to about 8, less than or equal to about 7.6, less than or equal to about 7.2, or less than or equal to about 6.8. In a solution (e.g., an aqueous solution or an alcohol solution), the concentration of the polymer may be from about 5 wt% to about 80 wt%, from about 10 wt% to about 75 wt%, from about 15 wt% to about 70 wt%, from about 18 wt% to about 65 wt%, from about 20 wt% to about 60 wt%, from about 25 wt% to about 55 wt%, from about 30 wt% to about 50 wt%, or a combination thereof.

[0269] The polymer may be soluble or insoluble in a C1 to C5 alcohol (e.g., ethanol). In an embodiment, the polymer may be soluble in a C1 to C5 alcohol (e.g., ethanol), DMSO, water, or a combination thereof.

[0270] In an embodiment, the polymer (or copolymer) may have an average (e.g., weight-average or number-average) molecular weight (unit: g / mol) that is greater than or equal to about 50, greater than or equal to about 80, greater than or equal to about 100, greater than or equal to about 150, greater than or equal to about 200, greater than or equal to about 250, greater than or equal to about 300, greater than or equal to about 350, greater than or equal to about 400, greater than or equal to about 450, greater than or equal to about 500, greater than or equal to about 550, greater than or equal to about 600, greater than or equal to about 650, greater than or equal to about 700, greater than or equal to about 750, greater than or equal to about 800, greater than or equal to about 900, greater than or equal to about 1000, greater than or equal to about 1100, greater than or equal to about 1200, greater than or equal to about 1300, greater than or equal to about 1400, greater than or equal to about 1500, greater than or equal to about 1600, greater than or equal to about 1700, greater than or equal to about 1800, greater than or equal to about 1900, greater than or equal to about 2000, greater than or equal to about 2100, greater than or equal to about 2200, greater than or equal to about 2300, greater than or equal to about 2400, greater than or equal to about 2500, greater than or equal to about 3000, greater than or equal to about 3500, greater than or equal to about 4000, greater than or equal to about 4500, greater than or equal to about 5000, greater than or equal to about 5500, greater than or equal to about 6000, greater than or equal to about 7000, greater than or equal to about 8000, greater than or equal to about 9000, greater than or equal to about 10,000, greater than or equal to about 15000, greater than or equal to about 20,000, greater than or equal to about 25000, greater than or equal to about 30,000, greater than or equal to about 35,000, greater than or equal to about 40,000, greater than or equal to about 45,000, greater than or equal to about 50,000, greater than or equal to about 55,000, greater than or equal to about 60,000, greater than or equal to about 65,000, greater than or equal to about 70,000, greater than or equal to about 75,000, greater than or equal to about 80,000, greater than or equal to about 85,000, greater than or equal to about 90,000, greater than or equal to about 95,000, greater than or equal to about 100,000, greater than or equal to about 120,000, greater than or equal to about 140,000, greater than or equal to about 160,000, greater than or equal to about 180,000, greater than or equal to about 200,000, greater than or equal to about 220,000, greater than or equal to about 240,000, greater than or equal to about 260,000, greater than or equal to about 280,000, greater than or equal to about 300,000, greater than or equal to about 350,000, greater than or equal to about 400,000, greater than or equal to about 450,000, greater than or equal to about 500,000, or greater than or equal to about 550,000.The average (e.g., weight-average or number-average) molecular weight of the polymer may be less than or equal to about 8,000,000, less than or equal to about 7,000,000, less than or equal to about 6,000,000, less than or equal to about 5,000,000, less than or equal to about 4,000,000, less than or equal to about 3,000,000, less than or equal to about 2,000,000, less than or equal to about 1,500,000, less than or equal to about 1,200,000, less than or equal to about 1,000,000, less than or equal to about 900,000, less than or equal to about 800,000, less than or equal to about 700,000, less than or equal to about 600,000, less than or equal to about 500,000, less than or equal to about 450,000, less than or equal to about 200,000, less than or equal to about 150,000, less than or equal to about 100,000, less than or equal to about 90,000, less than or equal to about 80,000, less than or equal to about 70,000, less than or equal to about 50,000, less than or equal to about 30,000, less than or equal to about 23,000, or less than or equal to about 20,000.

[0271] The molecular weight of the polymer can be obtained considering the degree of polymerization and molecular weight (e.g., g / mol) of the monomers or repeating units derived therefrom, and can exhibit a molecular weight distribution. The average molecular weight of the polymer can be a number-average molecular weight, a weight-average molecular weight, or a viscosity-average molecular weight.

[0272] In an embodiment, the average molecular weight of the polymer can be measured by using a solution of the polymer. To reduce the interaction between the molecules of the polymer, the molecular weight can be measured by a dilute solution. The concentration of the polymer solution can be appropriately selected, and a solution in which 1 gram or less of the polymer is dissolved per 100 mL, for example, can be used for measurement. The average molecular weight of the polymer can be measured by an appropriate method, such as gel permeation chromatography, end-group analysis, osmotic pressure method, capillary viscometry, etc.

[0273] In gel permeation chromatography, the polymer dissolved in a solvent can be separated according to its size, and the results obtained can be calibrated using a standard material with a determined molecular weight. In the end-group analysis method, the molecular weight can be measured as follows: by dissolving the polymer in a solvent to quantify a functional group (e.g., carboxyl group). According to established standards, using commercially available devices, each measurement method can easily and reproducibly provide substantially the same information about the molecular weight. The number-average molecular weight, weight-average molecular weight, and viscosity-average molecular weight of the polymer can be related to each other.

[0274] The polymer may be commercially available from various manufacturers. The manufacturers provide information about the polymer (e.g., number average molecular weight, weight average molecular weight, etc.), and thus polymers with desired levels and types of molecular weight values may be commercially available.

[0275] In an embodiment, the polymer or the organic layer may have a relatively high level of solubility in water or a water-miscible organic solvent (e.g., alcohol, DMSO, etc.), and when manufacturing the organic layer, the viscosity of the solution for coating can be adjusted relatively freely. Therefore, compared with an adhesive composition having a high viscosity (e.g., a composition based on a curable resin), a high degree of freedom can be provided when forming a film.

[0276] The organic layer or the polymer may further include or may not include additives. The additives may include: inorganic acids such as hydrochloric acid, phosphoric acid, carbonic acid, or sulfuric acid; C2-50 carboxylic acid compounds (e.g., represented by R(COOH) n ), sulfinic acid compounds (e.g., represented by R(SO2H) n ), sulfonic acid compounds (e.g., represented by R(SO3H) n ), or combinations thereof. In the above formula, R may be a substituted or unsubstituted C1 to C50 aliphatic or aromatic hydrocarbon group, such as a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group, and n is an integer from 1 to 10, 2 to 8, or 3 to 6. The carboxylic acid compound, sulfinic acid compound, sulfonic acid compound, or combinations thereof may further include a hydroxyl group.

[0277] The additives may include polycarboxylic acid compounds having two or more carboxylic acid groups. The polycarboxylic acid compound may be a non-polymeric compound. The polycarboxylic acid compound may be a compound having 2 to 10 carboxylic acid groups. The polycarboxylic acid compound may have 1 to 10, 2 to 5, or 3 to 4 C1-C100, C2-C60, or C6-C15 aliphatic hydrocarbon groups, 1 to 10, 2 to 5, or 3 to 4 C6-C50 or C6-C15 aromatic hydrocarbon groups, or combinations thereof. The polycarboxylic acid compound may further include a hydroxyl group.

[0278] The polycarboxylic acid compound may include HOOC-A-(COOH) mA compound represented, wherein A is a single bond, a carbon atom, a substituted or unsubstituted C1 to C100 (C1-C50, C5-C15, C6-C12) aliphatic hydrocarbon group such as an alkylene group, an alkenylene group, or an alkynylene group, a substituted or unsubstituted C6 to C40 aromatic hydrocarbon group, or a combination thereof, m is greater than or equal to about 1, greater than or equal to about 2, greater than or equal to about 3, or greater than or equal to about 4 and less than or equal to about 10, less than or equal to about 8, less than or equal to about 6, less than or equal to about 3. In the group A, at least one methylene group can be replaced by C(O), NH, O, C(O)O, C(O)NH, or a combination thereof. The polycarboxylic acid compound can have the following number of carbon atoms: greater than or equal to about 2, greater than or equal to about 3, 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, or greater than or equal to about 8. The polycarboxylic acid compound can have the following number of carbon atoms: less than or equal to about 100, less than or equal to about 60, less than or equal to about 15, less than or equal to about 14, less than or equal to about 13, less than or equal to about 12, less than or equal to about 11, less than or equal to about 10, less than or equal to about 9, less than or equal to about 8, less than or equal to about 7, less than or equal to about 6, or less than or equal to about 5.

[0279] The additive can include benzoic acid, succinic acid, maleic acid, fumaric acid, malic acid, glutaric acid, adipic acid, pimelic acid, citric acid, oxalic acid, malonic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, trimesic acid, azelaic acid, suberic acid, tartaric acid, itaconic acid, dodecanedioic acid, sulfuric acid, acetic acid, (meth)acrylic acid, or a combination thereof.

[0280] In the organic layer or polymer material, based on the total weight of the organic layer, the amount of the crosslinked polymer (e.g., crosslinked poly(meth)acrylate, crosslinked epoxy resin, crosslinked polysiloxane, crosslinked polyurethane polymer, crosslinked thiol-ene polymer, etc.) can be less than or equal to about 5 wt%, less than or equal to about 3 wt%, less than or equal to about 1 wt%, less than or equal to about 0.9 wt%, less than or equal to about 0.8 wt%, less than or equal to about 0.7 wt%, less than or equal to about 0.6 wt%, less than or equal to about 0.5 wt%, less than or equal to about 0.4 wt%, less than or equal to about 0.3 wt%, less than or equal to about 0.2 wt%, or less than or equal to about 0.1 wt%. The organic layer can be substantially free of the crosslinked polymer.

[0281] The organic layer or polymer can be configured to dissolve at least a part of it if immersed in water (or a C1 to C5 alcohol). The temperature of the water (or the temperature of the C1 to C5 alcohol) can be greater than or equal to about 20 °C, greater than or equal to about 25 °C, or greater than or equal to about 30 °C. The temperature of the water (or the temperature of the C1 to C5 alcohol) can be less than or equal to its boiling point (e.g., about 50 °C or lower, or about 30 °C or lower).

[0282] In an embodiment, the thickness of the organic layer or polymer may be greater than or equal to about 10 nm, greater than or equal to about 30 nm, greater than or equal to about 50 nm, greater than or equal to about 70 nm, greater than or equal to about 90 nm, greater than or equal to about 100 nm, greater than or equal to about 120 nm, greater than or equal to about 140 nm, greater than or equal to about 160 nm, greater than or equal to about 180 nm, greater than or equal to about 200 nm, greater than or equal to about 250 nm, greater than or equal to about 300 nm, greater than or equal to about 350 nm, greater than or equal to about 400 nm, greater than or equal to about 450 nm, greater than or equal to about 500 nm, greater than or equal to about 550 nm, greater than or equal to about 600 nm, greater than or equal to about 650 nm, greater than or equal to about 700 nm, greater than or equal to about 750 nm, greater than or equal to about 800 nm, greater than or equal to about 850 nm, greater than or equal to about 900 nm, greater than or equal to about 950 nm, greater than or equal to about 1 micrometer (μm), or greater than or equal to about 1.5 μm.

[0283] The thickness of the organic layer may be less than or equal to about 1 centimeter, such as less than or equal to about 50 millimeters (mm), less than or equal to about 10 mm, less than or equal to about 1 mm, less than or equal to about 0.5 mm, less than or equal to about 0.15 mm, less than or equal to about 100 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 9 μm, less than or equal to about 8 μm, less than or equal to about 7 μm, less than or equal to about 6 μm, less than or equal to about 5 μm, less than or equal to about 4 μm, less than or equal to about 3 μm, less than or equal to about 2 μm, or less than or equal to about 1 μm. The thickness of the organic layer may be greater than or equal to about 10 nm, greater than or equal to about 100 nm, greater than or equal to about 500 nm, greater than or equal to about 1 μm, or greater than or equal to about 1.5 μm.

[0284] The electroluminescent device of the embodiment may further include a container configured to accommodate at least a portion of a stacked structure including a first electrode, a light-emitting layer, an electron transport layer, and a conductor thin film (or a second electrode). The container may include a light-transmissive member. Additional members (e.g., light-transmissive or light-impermeable materials, sealing materials) connected to the light-transmissive member may be further included. In an embodiment, the container may be an integrated (one-piece) material or structure. In an embodiment, the container may be formed by combining multiple components. In an embodiment, the container may be an integrated light-transmissive member (e.g., an element or material, see Figure 2Band Figure 8 a packaging glass). In an embodiment, the container may include a light-transmissive component and a sealant. The container may be a packaging element for a stacked structure.

[0285] The container or the light-transmissive component may include an organic material such as a polymer, an inorganic material such as glass, an organic / inorganic hybrid material, or a combination thereof. The container may be a furnace or a chamber. Details of the container (e.g., material, transmittance, etc.) may refer to the details of the substrate described herein. In an embodiment, the furnace may be a device or apparatus configured to expose a given material to a high-temperature environment (e.g., the post-treatment temperature described herein, such as a temperature of 50 °C or higher, 70 °C or higher, 90 °C or higher), and the heating method is not particularly limited. The furnace includes a hollow chamber and includes a heating element configured to heat the chamber in a controlled manner. The hollow chamber may provide the defined space.

[0286] In an electroluminescent device of an embodiment, the organic layer may be disposed adjacent to or in contact with the container or the light-transmissive component. The organic layer may be applied or coated on the surface of the container or the light-transmissive component. In an electroluminescent device of an embodiment, the container including the organic layer may be replaced with a new container after post-treatment, and thus, the electroluminescent device of the embodiment may not include the organic layer.

[0287] In an embodiment, the electroluminescent device may further include a hole auxiliary layer 2, 20 between the first electrode 1, 10 and the light-emitting layer 3, 30. The hole auxiliary layer 2, 20 may include a hole injection layer, a hole transport layer, an electron blocking layer, or a combination thereof. The hole auxiliary layer 2, 20 may be a single layer or a multi-layer structure in which adjacent layers include different components. (Refer to Figure 1A 、 1B 、2A and 2B)

[0288] The hole auxiliary layer 2, 20 may have the following HOMO energy level: it may match the HOMO energy level of the light-emitting layer 3, 30 to enhance the mobility of holes transferred from the hole auxiliary layer 2, 20 to the light-emitting layer 3, 30. In an embodiment, the hole auxiliary layer 2, 20 may include a hole injection layer adjacent to the first electrode 1, 10 (e.g., adjacent thereto) and a hole transport layer adjacent to the light-emitting layer 3, 30 (e.g., adjacent thereto).

[0289] In an embodiment, the materials included in the hole auxiliary layers 2 and 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-dioctyl-fluorene-co-N-(4-butylphenyl)-diphenylamine) (TFB), polyarylamine (polyarylamine), poly(N-vinylcarbazole), poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), polyaniline, polypyrrole, N,N,N',N'-tetrakis(4-methoxyphenyl)-benzidine (TPD), 4,4'-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), m-MTDATA (4,4',4”-tris[phenyl(m-tolyl)amino]triphenylamine), 4,4',4”-tris(N-carbazolyl)-triphenylamine (TCTA), 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), p-type metal oxides (e.g., NiO, WO3, MoO3, etc.), carbon-based materials such as graphene oxide, or combinations thereof, but not limited thereto.

[0290] In the hole auxiliary layer, the thickness of each layer can be appropriately selected. For example, the thickness of each layer can be greater than or equal to about 5 nm, greater than or equal to about 10 nm, greater than or equal to about 15 nm, or greater than or equal to about 20 nm and less than or equal to about 100 nm, less than or equal to about 90 nm, less than or equal to about 80 nm, less than or equal to about 70 nm, less than or equal to about 60 nm, less than or equal to about 50 nm, 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 not limited thereto.

[0291] According to the Figure 3A device of the embodiment shown, it can have a normal structure. In the device of the embodiment, the anode 10 disposed on the transparent substrate 100 may include a metal oxide-based transparent electrode (e.g., ITO electrode), and the cathode 50 facing the anode 10 may include a conductive metal (e.g., having 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, polyvinylcarbazole (PVK), or a combination thereof; or a combination thereof) may be disposed between the transparent electrode 10 and the light-emitting layer 30. The hole injection layer can be disposed adjacent to the transparent electrode (e.g., adjacent thereto), and the hole transport layer can be disposed adjacent to the light-emitting layer (e.g., adjacent thereto). An electron transport layer or an electron auxiliary layer including it (e.g., an electron injection / transport layer) 40 may be disposed between the light-emitting layer 30 and the cathode 50. (See: Figure 3A , Figure 3B , Figure 3C , Figure 5A , Figure 8)

[0292] In an embodiment, an electroluminescent device of the embodiment can be manufactured by a method including the following:

[0293] Form a light-emitting (e.g., patterned) layer including semiconductor nanoparticles on or above a first electrode, form an electron transport layer on the light-emitting layer, and form a second electrode or a thin film conductor on or above the electron transport layer to obtain a stacked structure. The method further includes forming an organic layer on or above the electron transport layer and performing post-treatment on the stacked structure.

[0294] In an embodiment, the method may further include forming a hole assisting layer on the first electrode (e.g., disposed on a substrate), for example, via physical deposition (e.g., vapor deposition) or a coating process. The method may further include forming an electron injection layer and / or a hole blocking layer on or above the electron transport layer. The formation of the light-emitting layer (or patterned layer) of semiconductor nanoparticles is the same as described herein.

[0295] The post-treatment can be performed using the organic layer or polymer described herein and optionally a container. In an embodiment, the post-treatment may include:

[0296] Placing at least a part of the stacked structure (e.g., the electron transport layer and the thin film conductor) and the organic layer or polymer in a first space; and

[0297] Maintaining (or heating) the first space at a post-treatment temperature greater than or equal to about 40 °C.

[0298] The post-treatment temperature can be less than or equal to about 200 °C, less than or equal to about 180 °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, or less than or equal to about 120 °C.

[0299] The method may further include providing a container to the stacked structure. The container can be configured to define at least a part of the first space. Details regarding the container are the same as described herein. The space can be an enclosed space, for example, a sealed space or an airtight or gas-impermeable space. The method may include removing the container or separating the stacked structure from the container after the post-treatment. The post-treatment can be performed for a predetermined time.

[0300] The container may include a light-transmissive component (e.g., a light-transmissive material or component). The container can be or include a packaging glass configured to accommodate at least a part (or all) of the stacked structure. The container can be a separate device or a separate apparatus that can control temperature, such as a furnace or a chamber, and provide a space (e.g., an enclosed space).

[0301] Details of the container and the post-treatment are the same as those described herein.

[0302] In the method of the embodiment, a stacked structure can be obtained by forming a light-emitting layer and an electron transport layer on a first electrode and, for example, between a pixel defining layer PDL, and then forming a thin film conductor on the electron transport layer (see Figure 5A and 5B ). The method may further include, for example, forming a hole assisting layer on the first electrode before forming the light-emitting layer. The organic layer (or polymer material) and the container are provided to the stacked structure thus obtained such that at least a part of the organic layer (or polymer material) and the stacked structure (e.g., the electron transport layer and the thin film conductor) can be disposed in the space defined by the container. (See Figure 5A 、 Figure 6A and Figure 8 ). In an embodiment, the container may be a furnace or a chamber (see Figure 7 ).

[0303] Surprisingly, the inventors have found that by maintaining the organic layer (or polymer material) and the stacked structure in a first space at a predetermined post-treatment temperature, for example, for a predetermined time, the properties of the light-emitting device can be significantly improved. Without wishing to be bound by any theory, it is believed that the organic layer or polymer material can provide moisture and optionally an acid such as H + . The released moisture and optionally the released acid can diffuse through the thin film conductor to modify the surface of the metal oxide particles in the electron transport layer, thereby improving the properties of the light-emitting device.

[0304] In an embodiment, the thin film conductor or the second electrode may have a prescribed thickness and have conductivity capable of serving as an electron injection conductor, and may allow the moisture and optionally the acid released from the organic layer or polymer material to diffuse or spread (e.g., downward) and transfer to the electron transport layer provided under the thin film conductor. By providing a moisture vapor (and optionally an acid) environment and providing a relatively high temperature environment, the surface modification reaction can be promoted.

[0305] The method may further include preparing an organic layer forming composition including the polymer and a liquid carrier. The organic layer forming composition may further or may not further include additives. Details of the polymer and the additives are the same as those described herein. The concentrations of the polymer and the additives can be appropriately selected in consideration of the type of the compound and the thickness of the organic layer to be formed.

[0306] The method may include applying the organic layer-forming composition on the electron transport layer (and optionally the second electrode). The method may include applying the organic layer-forming composition on the surface of a container (e.g., applying to the surface of the container) such that the container faces the electron transport layer or the second electrode. In the method of an embodiment, the organic layer-forming composition may be applied to the electron transport layer (and the second electrode) or the surface of the container to form an organic layer. The method may include removing (e.g., evaporating) at least a portion of the liquid carrier from the applied composition to form an organic layer.

[0307] The liquid carrier may include: water; C1-10 alcohols such as ethanol, methanol, propanol, isopropanol, (iso)propanol, (iso)butanol, (iso)pentanol, hexanol, heptanol, octanol, nonanol, etc.; nitrile solvents such as acetonitrile, etc.; sulfoxide solvents such as dimethyl sulfoxide, diethyl sulfoxide, ethyl methyl sulfoxide; ester solvents such as ethyl acetate, or a combination thereof. The liquid carrier may include a mixture of water and C1-10 alcohols. The liquid carrier may include or be water.

[0308] The polymer may be well-dissolved in water or an organic solvent (e.g., an alcohol), for example, having a desired level of solubility in water or an organic solvent to relatively easily form a (transparent) organic layer-forming composition having an appropriate viscosity. The viscosity of the organic layer-forming composition at room temperature (e.g., about 20-30 °C or about 25 °C) may be in the range of about 2 centipoises (cPs) to about 2000 cPs, about 3 cPs to about 1500 cPs, about 7 cPs to about 1200 cPs, about 10 cPs to about 1000 cPs, about 15 cPs to about 800 cPs, about 20 cPs to about 700 cPs, about 30 cPs to about 500 cPs, about 40 cPs to about 150 cPs, about 50 cPs to about 100 cPs, or a combination thereof, but is not limited thereto.

[0309] In the organic layer-forming composition, the concentration of the polymer can be appropriately selected in consideration of the type of the polymer, the desired thickness of the organic layer, etc. In an embodiment, the concentration of the polymer in the organic layer-forming composition can be respectively greater than or equal to about 0.01 wt%, greater than or equal to about 0.05 wt%, greater than or equal to about 0.1 wt%, greater than or equal to about 0.5 wt%, greater than or equal to about 1 wt%, greater than or equal to about 2 wt%, greater than or equal to about 3 wt%, greater than or equal to about 3.3 wt%, greater than or equal to about 4 wt%, greater than or equal to about 5 wt%, greater than or equal to about 6 wt%, greater than or equal to about 7 wt%, greater than or equal to about 8 wt%, greater than or equal to about 9 wt%, greater than or equal to about 10 wt%, greater than or equal to about 11 wt%, greater than or equal to about 12 wt%, greater than or equal to about 13 wt%, greater than or equal to about 14 wt%, greater than or equal to about 15 wt%, greater than or equal to about 16 wt%, greater than or equal to about 17 wt%, greater than or equal to about 18 wt%, greater than or equal to about 19 wt%, greater than or equal to about 20 wt%, greater than or equal to about 21 wt%, greater than or equal to about 22 wt%, greater than or equal to about 23 wt%, greater than or equal to about 24 wt%, greater than or equal to about 25 wt%, greater than or equal to about 26 wt%, greater than or equal to about 27 wt%, greater than or equal to about 28 wt%, greater than or equal to about 29 wt%, greater than or equal to about 30 wt%, greater than or equal to about 31 wt%, greater than or equal to about 32 wt%, greater than or equal to about 33 wt%, greater than or equal to about 34 wt%, greater than or equal to about 35 wt%, greater than or equal to about 36 wt%, greater than or equal to about 37 wt%, greater than or equal to about 38 wt%, greater than or equal to about 39 wt%, or greater than or equal to about 40 wt%, based on the total weight of the composition. The concentration of the polymer in the organic layer-forming composition can be respectively less than or equal to about 99 wt%, less than or equal to about 90 wt%, less than or equal to about 85 wt%, less than or equal to about 80 wt%, less than or equal to about 75 wt%, less than or equal to about 70 wt%, less than or equal to about 65 wt%, less than or equal to about 60 wt%, less than or equal to about 55 wt%, less than or equal to about 50 wt%, less than or equal to about 45 wt%, less than or equal to about 40 wt%, less than or equal to about 35 wt%, less than or equal to about 30 wt%, less than or equal to about 25 wt%, less than or equal to about 20 wt%, less than or equal to about 15 wt%, less than or equal to about 10 wt%, or less than or equal to about 5 wt%, based on the total weight of the composition.

[0310] In an embodiment, the organic layer-forming composition may further include an additive, and the concentration of the additive in the organic layer-forming composition may be in the range of from about 0.0001 mole / L (M) to about 10 M, from about 0.0005 M to about 5 M, from about 0.001 M to about 4 M, from about 0.005 M to about 3 M, from about 0.01 M to about 2 M, from about 0.05 M to about 1.5 M, from about 0.1 M to about 1.3 M, from about 0.1 M to about 1.2 M, from about 0.15 M to about 1 M, from about 0.15 M to about 0.9 M, from about 0.2 M to about 0.8 M, from about 0.3 M to about 0.7 M, from about 0.4 M to about 0.6 M, from about 0.45 M to about 0.55 M, or a combination thereof.

[0311] The organic layer-forming composition may exhibit a pH greater than or equal to about 1, greater than or equal to about 1.5, greater than or equal to about 2, greater than or equal to about 3, greater than or equal to about 3.5, greater than or equal to about 4, greater than or equal to about 4.5, greater than or equal to about 5, or greater than or equal to about 5.5 and less than or equal to about 8, less than or equal to about 7.5, less than or equal to about 7, less than or equal to about 6.5, less than or equal to about 6, less than or equal to about 5.5, less than or equal to about 5.2, less than or equal to about 5, or less than or equal to about 4.8, or less than or equal to about 4. The concentration of the organic layer-forming composition at these pH levels may be the same as those described herein.

[0312] The method of applying the organic layer-forming composition is not particularly limited and may be appropriately selected. The application may involve spin coating, drop coating, or a combination thereof. After applying the organic layer-forming composition, the excess composition may be removed by rotation or the like.

[0313] The formation of the organic layer may not involve polymerization and / or crosslinking reactions. Thus, based on the total weight of the organic layer or the polymer, the amount of the crosslinked polymer in the organic layer may be less than 1 wt%. Without wishing to be bound by a particular theory, it is believed that providing a layer containing a crosslinked polymer (e.g., as a main component) on or above the electron transport layer may result in undesirable and significant light absorption in the wavelength range of interest. In other words, the crosslinked polymer makes it difficult or at least less effective to extract light from the device, e.g., for a front-emitting type display panel having a second electrode as a transparent electrode.

[0314] In addition, the present inventors have found that an organic layer-forming composition including a crosslinked resin may cause a significant increase in viscosity, and thus it may become more difficult to form an organic layer having a desired or controlled thickness. The present inventors have found that an organic layer including a crosslinked resin as a main component does not sufficiently provide moisture and optionally an acid component to achieve the purpose of the methods described herein.

[0315] In an embodiment, the post-treatment can be carried out in a suitable atmosphere (e.g., in an inert gas atmosphere, in an oxygen-free atmosphere, or in air).

[0316] In the organic layer of the embodiment, the polymer material (e.g., having the molecular weight described herein) can exhibit hydrophilicity, and thus, a limited amount of moisture can optionally be present in the organic layer or the polymer material together with relatively unstable acid moieties (e.g., COOH groups). In an embodiment, the organic layer or the polymer material can readily and gradually release moisture and optionally acid components over time under a predetermined atmosphere (e.g., an inert gas atmosphere or ambient atmosphere) and at the post-treatment temperature described herein. The released moisture and optionally the released acid components can diffuse (e.g., through a thin film conductor of a predetermined thickness) to reach the metal oxide nanoparticles present in the electron assisting layer, promoting surface modification of the nanoparticles. For example, the moisture and optionally the acid components can gradually move to the electron assisting layer and can interact or react (e.g., participate in a dehydration condensation reaction) with the metal oxide nanoparticles (e.g., with the hydroxyl groups or defect sites that may be present on the surface of the metal oxide nanoparticles). It is believed that the interaction and reaction can modify the surface of the metal oxide nanoparticles, possibly eliminating defects and / or causing growth of the metal oxide nanoparticles.

[0317] The post-treatment temperature can be greater than or equal to about 40 °C, greater than or equal to about 45 °C, greater than or equal to about 50 °C, greater than or equal to about 55 °C, greater than or equal to about 60 °C, greater than or equal to about 65 °C, greater than or equal to about 70 °C, or greater than or equal to about 75 °C. The post-treatment temperature can 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 160 °C, less than or equal to about 150 °C, less than or equal to about 140 °C, less than or equal to about 120 °C, less than or equal to about 100 °C, less than or equal to about 90 °C, less than or equal to about 80 °C, or less than or equal to about 70 °C.

[0318] The post-treatment time can be greater than or equal to about 30 minutes, greater than or equal to about 1 hour, greater than or equal to about 2 hours, greater than or equal to about 3 hours, greater than or equal to about 5 hours, greater than or equal to about 7 hours, greater than or equal to about 12 hours, greater than or equal to about 20 hours, greater than or equal to about 24 hours, greater than or equal to about 36 hours, greater than or equal to about 48 hours, or greater than or equal to about 50 hours. The post-treatment time can be less than or equal to about 30 days, less than or equal to about 20 days, less than or equal to about 10 days, less than or equal to about 5 days, less than or equal to about 3 days, less than or equal to about 70 hours, less than or equal to about 50 hours, less than or equal to about 2 days, less than or equal to about 30 hours, less than or equal to about 1 day, less than or equal to about 18 hours, less than or equal to about 14 hours, less than or equal to about 8 hours, less than or equal to about 6 hours, less than or equal to about 5 hours, less than or equal to about 4 hours, less than or equal to about 3 hours, less than or equal to about 2 hours, or less than or equal to about 1 hour.

[0319] The method of the embodiment can further include removing the container after post-treatment and providing a conductive layer on the thin film conductor to increase the thickness of the thin film conductor or the second electrode. After the thin film conductor or the second electrode obtains the increased thickness as needed, a new container can be used (e.g., placed). (See Figure 6A and Figure 6B ).

[0320] In an embodiment, a light-emitting device or an electroluminescent device (hereinafter referred to as "light-emitting device") includes a first electrode (e.g., a hole injection conductor or an anode) and a second electrode, a light-emitting layer disposed between the first electrode and the second electrode; and an electron transport layer between the light-emitting layer and the second electrode, and

[0321] the light-emitting layer includes semiconductor nanoparticles, and the light-emitting layer is configured to emit a first light.

[0322] The electron transport layer includes metal oxide nanoparticles, and the metal oxide nanoparticles have a size greater than or equal to about 1 nm and less than or equal to about 30 nm. The metal oxide nanoparticles include zinc and optionally a Group IIA metal, Zr, W, Li, Ti, Y, Al, gallium, indium, tin (Sn), cobalt (Co), vanadium (V), or a combination thereof

[0323] The second electrode has a thickness greater than or equal to about 1 nm (or greater than or equal to about 11 nm) and less than or equal to about 50 nm, and the second electrode has a light transmittance for the first light greater than or equal to about 50% and less than or equal to about 100%, and the first electrode is configured to reflect at least a part of the first light.

[0324] The first electrode may include a hole injection conductor, and the second electrode may include an electron injection conductor.

[0325] The semiconductor nanoparticles or the light emitting layer may not contain cadmium, lead, mercury, or a combination thereof.

[0326] The second electrode may have a thickness greater than or equal to about 15 nm and less than or equal to about 40 nm.

[0327] The first electrode may be configured to reflect at least a portion of the first light.

[0328] The light emitting device may be configured to emit green light when a voltage is applied. The light emitting device may be configured to emit blue light when a voltage is applied. The light emitting device may be configured to emit red light when a voltage is applied.

[0329] The light emitting device may further include an organic layer or a polymer, for example, disposed on the electron transport layer. The organic layer and the polymer are the same as those described herein.

[0330] The organic layer or the polymer material may be disposed spaced apart from the electron transport layer and the second electrode. The organic layer may be disposed facing the electron transport layer and the second electrode or the conductor thin film.

[0331] The electron transport layer may have a first surface facing the emission layer and a second surface opposite to the first surface, and the organic layer or the polymer material may be disposed on the second surface. The organic layer or the polymer material may be disposed spaced apart from the electron transport layer (e.g., separated from the electron transport layer).

[0332] The organic layer or the polymer material may have a thickness greater than or equal to about 10 nm, or greater than or equal to about 100 nm. The thickness of the organic layer or the polymer material may be less than or equal to about 100 micrometers (μm), or less than or equal to about 10 μm.

[0333] The thin film conductor or the second electrode may have a first surface facing the surface of the electron assisting layer and a second surface opposite to the first surface, and the organic layer or the polymer material may be disposed spaced apart from the electron transport layer and / or the second electrode and may be disposed facing at least a portion (e.g., all) of the surface of the electron transport layer and / or at least a portion (e.g., all) of the second surface of the second electrode.

[0334] Details of the light emitting device (e.g., its elements such as semiconductor nanoparticles, metal oxide nanoparticles, first / second electrodes, thin film conductors, organic layers or polymers) are the same as those described herein. For details of the second electrode, reference may also be made to the description of the conductor thin film.

[0335] The light-emitting device of the embodiment can be configured to emit red light, green light, or blue light. The details of the red light, green light, or blue light (e.g., wavelength) are the same as those described herein.

[0336] In an embodiment, the light-emitting (or electroluminescent) device can have a maximum external quantum efficiency (EQE) as follows: greater than or equal to about 1%, greater than or equal to about 2%, greater than or equal to about 3%, greater than or equal to about 4%, greater than or equal to about 5%, greater than or equal to about 5.5%, greater than or equal to about 6%, greater than or equal to about 6.5%, greater than or equal to about 7%, greater than or equal to about 7.5%, greater than or equal to about 7.7%, greater than or equal to about 8%, greater than or equal to about 8.5%, greater than or equal to about 9%, greater than or equal to about 9.5%, greater than or equal to about 10%, greater than or equal to about 10.5%, greater than or equal to about 11%, greater than or equal to about 11.5%, greater than or equal to about 12%, greater than or equal to about 12.5%, greater than or equal to about 13%, greater than or equal to about 13.5%, or greater than or equal to about 14%. The maximum external quantum efficiency (EQE) can be less than or equal to about 60%, 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%.

[0337] The light-emitting (or electroluminescent) device of the embodiment can exhibit a maximum luminance greater than or equal to about 10,000 candela per square meter (cd / m 2 )、greater than or equal to about 30,000 cd / m 2 、greater than or equal to about 40,000 cd / m 2 、greater than or equal to about 60,000 cd / m 2 、greater than or equal to about 65,000 cd / m 2 、greater than or equal to about 70,000 cd / m 2 、greater than or equal to about 80,000 cd / m 2 、greater than or equal to about 90,000 cd / m 2 、greater than or equal to about 100,000 cd / m 2 、greater than or equal to about 110,000 cd / m 2 、or greater than or equal to about 120,000 cd / m 2 .

[0338] The light-emitting (or electroluminescent) device of the embodiment may exhibit a maximum luminous efficiency greater than or equal to about 5 candela per ampere (cd / A), greater than or equal to about 5.5 cd / A, greater than or equal to about 6 cd / A, greater than or equal to about 7 cd / A, greater than or equal to about 8 cd / A, greater than or equal to about 9 cd / A, greater than or equal to about 10 cd / A, greater than or equal to about 15 cd / A, greater than or equal to about 20 cd / A, or greater than or equal to about 30 cd / A.

[0339] In an embodiment, when measured by driving the device at a predetermined initial luminance (e.g., about 650 nits or about 146 nits), the light-emitting (or electroluminescent) device may exhibit a T50 greater than or equal to about 10 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 40 hours, greater than or equal to about 50 hours, greater than or equal to about 60 hours, greater than or equal to about 65 hours, greater than or equal to about 70 hours, greater than or equal to about 80 hours, greater than or equal to about 90 hours, greater than or equal to about 100 hours, greater than or equal to about 120 hours, greater than or equal to about 150 hours, greater than or equal to about 180 hours, greater than or equal to about 200 hours, or greater than or equal to about 250 hours.

[0340] In an embodiment, when measured by driving the device at a predetermined initial luminance (e.g., about 650 nits or about 146 nits), the light-emitting device may have a T90 greater than or equal to about 5 hours, such as greater than or equal to about 6 hours, greater than or equal to about 7 hours, greater than or equal to about 7.5 hours, greater than or equal to about 8 hours, greater than or equal to about 9 hours, greater than or equal to about 10 hours, greater than or equal to about 20 hours, greater than or equal to about 30 hours, greater than or equal to about 40 hours, greater than or equal to about 50 hours, greater than or equal to about 60 hours, greater than or equal to about 70 hours, greater than or equal to about 80 hours, greater than or equal to about 90 hours, greater than or equal to about 100 hours, greater than or equal to about 110 hours, greater than or equal to about 120 hours, or greater than or equal to about 130 hours. The T90 may be from about 35 hours to about 1500 hours, from about 55 hours to about 1200 hours, from about 85 hours to about 1000 hours, from about 105 hours to about 900 hours, from about 115 hours to about 800 hours, from about 145 hours to about 500 hours, or a combination thereof.

[0341] The light-emitting (or electroluminescent) device may exhibit increased stability. After heat treatment at about 70 °C for about 2 days in air or an inert atmosphere and driving at about 146 nits, the light-emitting (or electroluminescent) device of the embodiment may exhibit a voltage increase less than or equal to about 30% or less than or equal to about 25% of the initial voltage without heat treatment.

[0342] In an embodiment, the display device includes a light-emitting (e.g., electroluminescent) device as described herein.

[0343] The display device (e.g., a display panel) may include a first pixel and a second pixel configured to emit light different from that of the first pixel.

[0344] Referring Figure 9 , the display panel 1000 according to an embodiment includes a display area 1000D for displaying an image and a non-display area 1000P provided around the display area 1000D, and bonding elements may be located in the non-display area 1000P.

[0345] The 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 that display different colors. As an example, a configuration is shown in which three sub-pixels PX1, PX2, and PX3 constitute one pixel PX, but the configuration is not limited thereto. Additional sub-pixels such as white sub-pixels may be further included, and one or more sub-pixels that display 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.

[0346] Each of the sub-pixels PX1, PX2, and PX3 may be configured to display a color as follows: primary colors or a combination of primary colors, e.g., red, green, blue, or a combination thereof (e.g., white light). For example, the first sub-pixel PX1 may be configured to display red, the second sub-pixel PX2 may be configured to display green, and the third sub-pixel PX3 may be configured to display blue.

[0347] In the figure, each sub-pixel is depicted as having the same size, but the present disclosure is not limited thereto. For example, at least one of the sub-pixels may be larger or smaller than the other sub-pixels, or may have a different shape from the other sub-pixels.

[0348] In an embodiment, the display panel of the embodiment may include a light-emitting panel 100, and the light-emitting panel 100 may include a lower substrate 110, a buffer layer 111, thin-film transistors TFTs, and light-emitting elements 180. The display panel may further include circuit elements for switching (changing) and / or driving the light-emitting elements respectively.

[0349] Referring Figure 10, in the light-emitting panel of the embodiment, light-emitting elements 180 may be provided for each of the sub-pixels PX1, PX2, and PX3. The light-emitting elements 180 provided in each of the sub-pixels PX1, PX2, and PX3 may be independently driven. The sub-pixels may include blue sub-pixels, red sub-pixels, or green sub-pixels. At least one of the light-emitting elements 180 may be an electroluminescent element according to the embodiment described herein.

[0350] Details of the substrate are the same as those described herein. The buffer layer 111 may include an organic material, an inorganic material, or an organic-inorganic material. The buffer layer 111 may include, for example, an oxide, a nitride, or a oxynitride, and may include, for example, silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof, but is not limited thereto. The buffer layer 111 may be one layer, two layers, or more layers, and may cover a part or the entire surface of the lower substrate 110. The buffer layer 111 may be omitted.

[0351] The thin-film transistor TFT may be a three-terminal element for switching and / or driving the light-emitting element 180, and one, two, or more may be included for each sub-pixel. The thin-film transistor TFT may include a gate electrode 124, a semiconductor layer 154 overlapping 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 thereto, and various structures may be provided.

[0352] The gate electrode 124 is electrically connected to a 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), an alloy thereof, or a combination thereof, but is not limited thereto.

[0353] The semiconductor layer 154 may be an inorganic semiconductor such as amorphous silicon, polycrystalline silicon, or an oxide semiconductor; an organic semiconductor; an organic-inorganic semiconductor; or a combination thereof. For example, the semiconductor layer 154 may include an oxide semiconductor including 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 a combination thereof, but they are not limited thereto. The semiconductor layer 154 may include a channel region and doping regions provided on both sides of the channel region and electrically connected to the source electrode 173 and the drain electrode 175, respectively.

[0354] The gate insulating layer 140 may include an organic material, an inorganic material, or an organic-inorganic material, and may include, for example, an oxide, a nitride, or a oxynitride, and may include, for example, silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof, but is not limited thereto. In the drawings, an example is shown in which the gate insulating layer 140 is formed on the entire surface of the lower substrate 110, but the present disclosure is not limited thereto, and may be selectively formed between the gate electrode 124 and the semiconductor 154. The gate insulating layer 140 may be formed of one layer or two or more layers.

[0355] The source electrode 173 and the drain electrode 175 may include, for example, a low-resistance metal such as aluminum (Al), molybdenum (Mo), copper (Cu), titanium (Ti), silver (Ag), gold (Au), an alloy thereof, or a combination thereof, but is not limited thereto. The source electrode 173 and the drain electrode 175 may be electrically connected to the doped regions of the semiconductor layer 154, respectively. The source electrode 173 is electrically connected to a data line (not shown), and the drain electrode 175 is electrically connected to the light-emitting element 180.

[0356] An interlayer insulating layer 145 is further formed between the gate electrode 124 and the source / drain electrodes 173 and 175. The interlayer insulating layer 145 may include an organic material, an inorganic material, or an organic-inorganic material, such as an oxide, a nitride, or a oxynitride, such as silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof, but is not limited thereto. The interlayer insulating layer 145 may be formed of one layer or two or more layers.

[0357] A protective layer 160 is formed on the thin film transistor TFT. The protective layer 160 may be, for example, a passivation layer. The protective layer 160 may include an organic material, an inorganic material, or an organic-inorganic material, such as polyacrylic acid, polyimide, polyamide, poly(amide-imide), or a combination thereof, but is not limited thereto. The protective layer 160 may be formed of one layer or two or three or more layers.

[0358] 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.

[0359] In an embodiment, the light-emitting device or the display device including the same may be used in a top-emission type, a bottom-emission type, a double-emission type, or a combination thereof.

[0360] In an embodiment, the first electrodes 1 and 10 may be light-transmissive electrodes and the second electrodes 5 and 50 may be reflective electrodes, and the display panel may be a bottom-emission type display panel that emits light toward the first electrode 10 and the substrate 100 (if any). In an embodiment, the first electrodes 1 and 10 may be reflective electrodes and the second electrodes 5 and 50 may be light-transmissive electrodes, and the display panel may be a top-emission type display panel that emits light toward the opposite side of the first electrode 10 and the substrate 100 (if any). In an embodiment, both the first electrode and the second electrode may be semi-transparent electrodes, and the display panel 1000 may be a dual-side emission type display panel that emits light on the substrate side and on the opposite side of the substrate.

[0361] The display device or the electronic device may include (or may be) a television, a virtual reality / augmented reality (VR / AR) device, a handheld terminal, a monitor, a laptop computer, an electronic display board, a camera, or a component for an autonomous (e.g., self-driving) vehicle.

[0362] Specific embodiments are described below. However, the embodiments described below are only for specific illustration or explanation of the present disclosure, and the scope of the present disclosure is not limited thereto.

[0363] Embodiment

[0364] 1. Electroluminescence measurement

[0365] The current according to the applied voltage is measured using a Keithley 2635B source meter, and the electroluminescence properties (e.g., luminance) of the light-emitting device are measured using a CS2000 spectrometer.

[0366] 2. Lifetime characteristics

[0367] T90 and T50 are measured at an initial luminance of about 146 nits.

[0368] 3. Electron microscope analysis

[0369] Transmission electron microscopy analysis is performed using a UTF30 Tecnai electron microscope.

[0370] Unless otherwise specified, the following preparations are carried out in an inert gas atmosphere (e.g., under nitrogen). Unless otherwise specified, the precursor contents are provided as molar contents.

[0371] Synthesis Example 1:

[0372] 2 M (moles per liter) stock solutions of Se / trioctylphosphine (TOP), 1 M of S / TOP, and 0.1 M of Te / TOP were prepared by dispersing selenium (Se), sulfur (S), and tellurium (Te) in TOP, respectively. In a reactor containing trioctylamine, 0.125 millimoles (mmol) of zinc acetate and oleic acid were added to the reactor and heated at 120 °C under vacuum. After 1 hour, nitrogen was introduced into the reactor.

[0373] The reactor was heated to 300 °C, and the Se / TOP and Te / TOP stock solutions with a Te:Se molar ratio of 1:15 were rapidly added to the reactor (e.g., injected into the reactor). After 40 minutes, the reaction was completed, and the reaction solution was rapidly cooled to room temperature, and acetone was added to the reactor. The resulting product mixture was centrifuged, and the precipitate was separated and dispersed in toluene to prepare a ZnSeTe core particle dispersion.

[0374] 1.8 mmol of zinc acetate and oleic acid were added to a flask containing trioctylamine, and the prepared mixture was heated at 120 °C under vacuum for 10 minutes. Then nitrogen (N2) was introduced into the reactor, the reactor was heated to 180 °C, and the prepared ZnTeSe core particle dispersion was rapidly added to the reactor. The Se / TOP and S / TOP stock solutions were also added to the reactor, and the reactor temperature was raised to about 280 °C. After 2 hours, the reaction was completed, the reactor was cooled to room temperature, and ethanol was added to promote the precipitation of the semiconductor nanoparticles, which were separated by centrifugation. The prepared semiconductor nanoparticles emitted blue light, and photoluminescence spectroscopy analysis using a Hitachi F-7000 spectrophotometer confirmed that the blue light had a maximum emission peak wavelength of about 455 nanometers (nm).

[0375] The synthesized semiconductor nanoparticles were precipitated with ethanol (optical density of 0.25 at 420 nm, 6 milliliters (mL)) and centrifuged, and the separated nanoparticles were dispersed in octane or cyclohexylbenzene to prepare a dispersion.

[0376] Synthesis Example 2: Synthesis of ZnMgO Nanoparticles

[0377] Zinc acetate dihydrate and magnesium acetate tetrahydrate were added to a reactor including dimethyl sulfoxide in a molar ratio according to the formula of interest and heated at 60 °C in an air atmosphere. Subsequently, a solution of tetramethylammonium hydroxide pentahydrate and ethanol was added dropwise to the reactor at a rate of 3 milliliters per minute (mL / min). After stirring the mixture, the prepared Zn 1-x Mg x O nanoparticles were centrifuged, separated, and dispersed in ethanol to provide Zn 1-x Mg xAn ethanol dispersion of O(x = 0.15) nanoparticles.

[0378] The prepared nanoparticles were analyzed by transmission electron microscopy analysis, and the results showed that the particles had an average particle size of about 3 nm.

[0379] Example 1:

[0380] A dispersion of zinc magnesium oxide nanoparticles prepared in Synthesis Example 2 was used as an electron transport layer dispersion (hereinafter, ETL dispersion).

[0381] Polyvinyl alcohol (average molecular weight: 22,000, manufacturer: Daejung Chemicals, degree of hydrolysis: 86 - 88%, product name: polyvinyl alcohol 500) was dissolved in water to prepare an organic layer-forming composition (PVA concentration: 3.3 wt%).

[0382] A glass substrate deposited with indium tin oxide (ITO) was surface-treated with ultraviolet (UV)-ozone for 15 minutes, then spin-coated with a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) solution (H.C. Starks), and heated at 230 °C for 30 minutes in an air atmosphere to provide a hole injection layer (HIL) with a thickness of 120 nm.

[0383] Subsequently, a solution of poly[(9,9-dioctylfluorene-2,7-diyl-co-(4,4'-(N-4-butylphenyl)diphenylamine)] (TFB) (Sumitomo) was spin-coated on the hole injection layer and heated at 230 °C for 30 minutes to provide a hole transport layer (HTL) with a thickness of 35 nm.

[0384] A cyclohexylbenzene dispersion of semiconductor nanoparticles prepared in Synthesis Example 1 was spin-coated on the prepared hole transport layer to prepare a light-emitting layer with a thickness of 30 nm, and then it was heat-treated at a temperature of about 140 °C for 30 minutes in an air atmosphere.

[0385] The ETL dispersion was spin-coated on the heat-treated light-emitting layer and heat-treated at 140 °C to form an electron transport layer with a thickness of about 50 nm.

[0386] Magnesium and silver (molar ratio = 10:1) were thermally evaporated on the obtained electron transport layer to form a second electrode with a thickness of 20 nm, thereby obtaining a stacked structure (hereinafter, may be referred to as a QD stack).

[0387] As Figure 5AAs shown, the prepared organic layer-forming composition is placed in the form of drops and then spin-coated onto the surface of an open box-shaped container (e.g., encapsulation glass), and then the solvent is removed to form an organic layer 60 with a thickness of about 3 μm.

[0388] In a sealed space defined by the container (i.e., encapsulation glass), a stacked structure is placed such that the organic layer is spaced apart from and faces the thin-film conductor, as Figure 5A shown. The included stacked structure is heated on a hot plate at 100 °C and held for 3 hours to obtain a light-emitting device.

[0389] The electroluminescence properties of the prepared light-emitting device are measured, and the results are shown in Table 1.

[0390] Comparative Example 1

[0391] A light-emitting device is prepared in the same manner as in Example 1, except that the organic layer is not formed.

[0392] The electroluminescence properties of the prepared light-emitting device are measured, and the results are shown in Table 1.

[0393] Example 2

[0394] A light-emitting device is prepared in the same manner as in Example 1, except that: an organic layer-forming composition (PVA concentration: 3.3 wt%) prepared by dissolving polyvinyl alcohol (average molecular weight: 66,000, manufacturer: Daejung Chemicals, degree of hydrolysis: 88 - 89%, product name: polyvinyl alcohol 1500) in water is used.

[0395] The electroluminescence properties of the prepared light-emitting device are measured, and the results are shown in Table 1.

[0396] Example 3

[0397] A light-emitting device is prepared in the same manner as in Example 1, except that: an organic layer-forming composition (PVP concentration: 3.3 wt%) prepared by dissolving poly(4-vinylphenol) (PVP, average molecular weight: Mw 25,000, manufacturer: Sigma-Aldrich) in water is used to form the organic layer, instead of the PVA composition.

[0398] The electroluminescence properties of the prepared light-emitting device are measured, and the results are shown in Table 1.

[0399] Example 4

[0400] A light-emitting device was prepared in the same manner as in Example 1, except that: an organic layer-forming composition containing pHEMA (pHEMA concentration: 3.3 wt%) prepared by dissolving poly(2-hydroxyethyl methacrylate) (pHEMA, average molecular weight: Mw 20,000, manufacturer: Sigma-Aldrich) in ethanol was used to form the organic layer, instead of the PVA composition.

[0401] The electroluminescence properties of the prepared light-emitting device were measured, and the results are shown in Table 1.

[0402] Example 5

[0403] A light-emitting device was prepared in the same manner as in Example 1, except that: malic acid was added to a polyvinyl alcohol solution prepared by dissolving PVA (average molecular weight: 22,000, manufacturer: Daejung Chemicals, product name: polyvinyl alcohol 500) in water at a concentration of 0.1 M.

[0404] The electroluminescence properties of the prepared light-emitting device were measured, and the results are shown in Table 1.

[0405] Table 1

[0406]

[0407] MA: Malic acid

[0408] PVA: Polyvinyl alcohol

[0409] PVP: Poly(4-vinylphenol)

[0410] pHEMA: Poly(2-hydroxyethyl methacrylate)

[0411] Relative maximum EQE (%): Maximum external quantum efficiency of a given device / Maximum external quantum efficiency of Comparative Example 1 × 100.

[0412] Relative luminance (%): Luminance of a given device / Luminance of Comparative Example 1 × 100

[0413] Relative T50 (%): T50 (hours) of a given device / T50 (hours) of Comparative Example 1 × 100

[0414] It was confirmed from the results in Table 1 that the light-emitting devices of the examples exhibited similar or significantly higher luminance and extended lifetimes compared to the light-emitting device of Comparative Example 1.

[0415] Experimental Example 1

[0416] The light-emitting device fabricated in Example 1 was heat-treated on a hot plate at 120 °C for 3 hours. The electroluminescence properties of the device after the heat treatment were measured, and the results are summarized in Table 2.

[0417] The light-emitting device fabricated in Comparative Example 1 was heat-treated on a hot plate at 120 °C for 3 hours. The electroluminescence properties of the device after the heat treatment were measured, and the results are summarized in Table 2.

[0418] Table 2

[0419] Number of hours of heat treatment Relative brightness at 5 V Voltage at 5 mA Comparative Example 1 0 hour 100％ 4.8 V Comparative Example 1 3 hours 4％ 7.5 V Example 1 0 hour 100％ 4 V Example 1 3 hours 129％ 4.2 V

[0420] According to the results in Table 2, after heat treatment at 120 °C for 3 hours, the electroluminescent device of Example 1 showed a smaller increase in voltage (i.e., resistance) at a given current and an increase in brightness. In contrast, after heat treatment at 120 °C for 3 hours, the electroluminescent device of Comparative Example 1 showed a substantial (significant) increase in voltage (i.e., resistance) at a given current and a significant decrease in brightness.

[0421] Although the present disclosure has been described in connection with what is presently considered to be practical embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. An electroluminescent device, comprising a first electrode; a second electrode; a light-emitting layer disposed between the first electrode and the second electrode, wherein the light-emitting layer comprises semiconductor nanoparticles; an electron transport layer disposed between the light-emitting layer and the second electrode; and an organic layer comprising a polymer, the polymer comprising repeating units having hydroxyl groups, wherein the electron transport layer comprises metal oxide nanoparticles, and the metal oxide nanoparticles have a size greater than or equal to 1 nm and less than or equal to 50 nm.

2. The electroluminescent device according to claim 1, wherein the organic layer is disposed on the electron transport layer and the second electrode.

3. The electroluminescent device according to claim 1, wherein the polymer comprises repeating units represented by Chemical Formula 1: Chemical Formula 1 wherein A is a direct bond, -C(O)-, -O-, -C(O)O-, -OC(O)-, -C(O)NH-, -NH-, -S-, -S(O)-, or a combination thereof, L is a direct bond, a substituted or unsubstituted C1-C30 aliphatic hydrocarbon group, or a substituted or unsubstituted C6-C20 arylene group, R are the same or different and are each independently hydrogen or a substituted or unsubstituted C1 to C30 alkyl group, and * is a moiety that binds to an adjacent repeating unit.

4. The electroluminescent device according to claim 1, wherein the polymer comprises a first repeating unit represented by Chemical Formula 2 and optionally a second repeating unit represented by Chemical Formula 3: Chemical Formula 2 Chemical Formula 3 wherein, * is a moiety that connects to an adjacent repeating unit, R are the same or different and are each independently hydrogen or a substituted or unsubstituted C1 to C30 alkyl group, and R' is a substituted or unsubstituted C1-C10 alkyl group.

5. The electroluminescent device according to claim 4, wherein the polymer has a solubility in water greater than or equal to 1 g / L and less than or equal to 1000 g / L.

6. The electroluminescent device according to claim 1, wherein the polymer comprises repeating units represented by Chemical Formula 4, repeating units represented by Chemical Formula 5, or a combination thereof: Chemical Formula 4 wherein * is a moiety that connects to an adjacent repeating unit, R are the same or different and are each independently hydrogen or a substituted or unsubstituted C1 to C30 alkyl group, and optionally, the benzene ring is unsubstituted or further substituted; Chemical Formula 5 wherein R are the same or different and are each independently hydrogen or a substituted or unsubstituted C1 to C30 alkyl group, L is a substituted or unsubstituted C1 to C10 alkylene group, and * is a moiety that connects to an adjacent repeating unit.

7. The electroluminescent device according to claim 6, wherein the polymer has a solubility in C1 to C5 alcohols greater than or equal to 3 g / L and less than or equal to 1000 g / L.

8. The electroluminescent device according to claim 1, wherein the polymer has a weight average molecular weight greater than or equal to 500 g / mol and less than or equal to 500,000 g / mol.

9. The electroluminescent device according to claim 1, wherein the polymer has a weight average molecular weight of greater than or equal to 1000 g / mol and less than or equal to 100,000 g / mol, and wherein the polymer has a solubility in water or alcohol of greater than or equal to 10 g / L and less than or equal to 500 g / L, or the polymer has a pH of greater than or equal to 5 and less than or equal to 8.

5.

10. The electroluminescent device according to claim 1, wherein the thickness of the organic layer is greater than or equal to 10 nm and less than or equal to 100 microns.

11. The electroluminescent device according to claim 1, wherein the organic layer is spaced apart from the electron transport layer and the second electrode, and is disposed to face the electron transport layer or the second electrode.

12. The electroluminescent device according to claim 1, wherein the light emitting layer is configured to emit a first light, and wherein the second electrode has a thickness of greater than or equal to 11 nm and less than or equal to 50 nm, and is configured to exhibit a light transmittance of 20% or more for the first light, and the first electrode is configured to reflect at least a portion of the first light.

13. The electroluminescent device according to claim 1, wherein the metal oxide nanoparticles comprise zinc; and an alkali metal, alkaline earth metal, Zr, W, Li, Ti, Y, Al, Ga, In, Sn, Co, V, or a combination thereof.

14. The electroluminescent device according to claim 1, wherein the polymer comprises polyvinyl alcohol, polyvinylphenol, poly(hydroxyalkyl) (meth)acrylate, polyhydroxyalkyl (meth)acrylamide, or a combination thereof.

15. A display device, comprising the electroluminescent device according to any one of claims 1-14.

16. A method of manufacturing the electroluminescent device according to any one of claims 1-14, the method comprising: forming a light emitting layer comprising semiconductor nanoparticles on a first electrode; forming an electron transport layer comprising metal oxide nanoparticles on the light emitting layer; forming a thin film conductor on the electron transport layer to obtain a stacked structure; and performing post-treatment of the stacked structure, wherein the post-treatment comprises: placing at least a portion of the stacked structure and the polymer in a first space; maintaining the first space at a post-treatment temperature of greater than or equal to 40 °C and less than or equal to 200 °C; and wherein the at least a portion of the stacked structure comprises the electron transport layer and the thin film conductor.

17. The method according to claim 16, further comprising applying an organic layer forming composition comprising the polymer and a liquid carrier to the electron transport layer or the second electrode; and optionally, wherein the liquid carrier comprises water, C1-10 alcohol, sulfoxide solvent, nitrile solvent, ester solvent, or a combination thereof.

18. The method according to claim 16, wherein the first space is a container, and an organic layer-forming composition comprising the polymer and a liquid carrier is applied to a first surface of the container, wherein the first surface faces the electron transport layer or the second electrode; and optionally, wherein the liquid carrier comprises water, a C1-10 alcohol, a sulfoxide solvent, a nitrile solvent, an ester solvent, or a combination thereof.

19. The method according to claim 16, wherein the polymer comprises polyvinyl alcohol, polyvinylphenol, poly(hydroxyalkyl) (meth)acrylate, polyhydroxyalkyl (meth)acrylamide, or a combination thereof.

20. The method according to claim 16, wherein the polymer has a weight average molecular weight greater than or equal to 500 g / mol and less than or equal to 500,000 g / mol; wherein the polymer has a solubility greater than or equal to 1 g / L and less than or equal to 1000 g / L; or wherein the polymer is configured to exhibit a pH greater than or equal to 4.5 and less than or equal to 8.

5.

21. The method according to claim 16, wherein the post-treatment temperature is greater than or equal to 50 °C and less than or equal to 120 °C, and the time of the post-treatment is greater than or equal to 10 minutes and less than or equal to 10 days.

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