Method of manufacturing light emitting device, light emitting device, and electronic apparatus including same

Abstract

The invention relates to a method of manufacturing a light emitting device, a light emitting device, and an electronic apparatus including the same. The method of manufacturing the light emitting device includes: forming a light emitting layer including semiconductor nanoparticles on a first electrode; forming an electron transport layer including metal oxide nanoparticles on the light emitting layer; forming a thin film conductor on the electron transport layer; placing the electron transport layer, the thin film conductor, and an acid material together in a space defined by a container; and maintaining the defined space at a post-treatment temperature of greater than or equal to about 40 DEG C and less than or equal to about 200 DEG C. The light emitting layer is configured to emit first light when a voltage is applied, the thin film conductor has a thickness greater than or equal to about 1 nm and less than 100 nm, and the acid material includes a polymeric acid, a non-polymeric carboxylic acid compound, or a combination thereof.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority and all benefits arising therefrom to Korean Patent Application No. 10 - 2023 - 0188857, filed on December 21, 2023, the entire contents of which are incorporated herein by reference. Technical field

[0003] The present disclosure relates to a light - emitting (e.g., electroluminescent) device and a display device including the electroluminescent device. 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 a quantum confinement effect. When electrons in an excited state generated by light excitation or voltage application 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 a light - emitting device (e.g., an electroluminescent device) or a display device including an electroluminescent device. Summary of the invention

[0006] Embodiments provide a method of manufacturing a light - emitting device that emits light, for example, by applying a voltage (e.g., with or without a separate irradiation light source) to a nanostructure (e.g., semiconductor nanoparticles such as quantum dots).

[0007] Embodiments provide the light - emitting device.

[0008] Embodiments provide a display device (e.g., a quantum dot - light - emitting diode (QD - LED) display device) including a plurality of semiconductor nanoparticles such as quantum dots as components of a light - emitting layer in a pixel configuration (e.g., a configuration of blue pixels, red pixels, green pixels, or a combination thereof).

[0009] In an embodiment, a method of manufacturing a light-emitting device includes: forming a light-emitting layer including semiconductor nanoparticles on a first electrode; forming an electron transport layer including metal oxide nanoparticles on the light-emitting layer; forming a thin film conductor (or a second electrode) on the electron transport layer to obtain a stacked structure; and performing a post-treatment of the stacked structure with an acid material and a container, wherein the light-emitting layer is configured to emit a first light when a voltage is applied, and the thickness of the thin film conductor is greater than or equal to about 1 nanometer (nm) and less than 100 nm. The post-treatment includes placing at least a part of the stacked structure (e.g., the electron transport layer and the thin film conductor) and the acid material together in a space defined by the container; and maintaining the defined space at a post-treatment temperature greater than or equal to about 40 degrees Celsius (°C) and less than or equal to about 200 °C. The acid material includes a polymeric acid compound, a non-polymeric carboxylic acid compound, or a combination thereof.

[0010] In the stacked structure, the first electrode, the light-emitting layer, the electron transport layer, and the thin film conductor may be sequentially stacked.

[0011] The space may be a closed space.

[0012] The light-emitting 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.

[0013] The semiconductor nanoparticles may include a first semiconductor nanocrystal including zinc, selenium, and tellurium, and a second semiconductor nanocrystal including a zinc chalcogenide, the second semiconductor nanocrystal being different from the first semiconductor nanocrystal. The semiconductor nanoparticles may include: a first semiconductor nanocrystal including indium, phosphorus, and optionally zinc (a group III-V compound including indium, phosphorus, and optionally zinc or an indium phosphide compound); and a second semiconductor nanocrystal including a zinc chalcogenide and being different from the first semiconductor nanocrystal.

[0014] The size or average size (hereinafter, "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.

[0015] The semiconductor nanoparticles may have a core-shell structure, the core-shell structure including a core containing the first semiconductor nanocrystal and a shell disposed on the core and containing the second semiconductor nanocrystal.

[0016] The electron transport layer may be adjacent to the light-emitting layer (or directly disposed on the light-emitting layer).

[0017] 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 10 nm, or less than or equal to about 8 nm.

[0018] The metal oxide nanoparticles may include zinc oxide. 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. In an embodiment, the metal oxide may include zinc, an alkaline earth metal, and optionally an alkali metal.

[0019] The metal oxide nanoparticles 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 0.1, or greater than or equal to about 0.15. x may be less than or equal to about 0.45, or less than or equal to about 0.4.

[0020] The thin film conductor may have a thickness greater than about 10 nm, or greater than or equal to 11 nm. The thin film conductor 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.

[0021] The thin film conductor 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%.

[0022] The first electrode may be configured to reflect at least a portion of the first light.

[0023] The thin film conductor may include silver, aluminum, magnesium, tungsten, nickel, cobalt, platinum, palladium, calcium, LiF, gold, copper, or a combination thereof (e.g., an alloy). The thin film conductor may include silver and magnesium.

[0024] For water or alcohol, the acid material may have a solubility of greater than or equal to about 1 gram per liter (g / L), e.g., at a temperature of about 20 °C. The solubility of the acid material may 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, or less than or equal to about 1000 g / L.

[0025] The acid material (e.g., a polymeric acid compound) may include carboxylic acid groups (e.g., COOH), phosphonic acid groups (PO(OH)2), sulfonic acid groups (SO3H), or combinations thereof, e.g., in the repeating unit.

[0026] The acid material (e.g., a non-polymeric carboxylic acid compound or a polymeric acid compound) may have a molecular weight or average molecular weight (hereinafter referred to as "molecular weight") of greater than or equal to about 50 grams per mole (g / mol), greater than or equal to about 100 g / mol, greater than or equal to about 200 g / mol, greater than or equal to about 800 g / mol, or greater than or equal to about 20,000 g / mol and less than or equal to about 8,000,000 g / mol, less than or equal to about 1,000,000 g / mol, less than or equal to about 550,000 g / mol, or less than or equal to about 400 g / mol. The molecular weight of the acid material (e.g., a non-polymeric carboxylic acid compound or a polymeric acid compound) may be greater than or equal to about 1200 g / mol, e.g., greater than or equal to about 1700 g / mol. The molecular weight of the acid material may be less than or equal to about 1,200,000 g / mol, e.g., less than or equal to about 500,000 g / mol.

[0027] In an embodiment, the non-polymeric carboxylic acid compound may have a molecular weight within the above range or within the ranges described herein, e.g., greater than or equal to about 100 grams per mole (g / mol) and less than or equal to about 500 g / mol.

[0028] In an embodiment, the polymeric acid compound may have a molecular weight (e.g., average molecular weight) within the above range or within the ranges described herein, e.g., greater than or equal to about 20,000 g / mol and less than or equal to about 550,000 g / mol.

[0029] The acidic material may be provided in the form of a film or layer (i.e., may be a film or layer of the acid material) or in the form of a solution (e.g., prepared by dissolving the acid material in a solvent such as water or an organic solvent). In an embodiment, the acid material may be a film or layer of a polymeric acid compound (hereinafter, may be referred to as a "film"). The acid material may be spaced apart from the electron transport layer and the thin film conductor. The acid material (or film) may be disposed facing the thin film conductor (e.g., the main surface of the thin film). The acid material (film) may be disposed facing the electron transport layer.

[0030] The acid material film may have a 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 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 acid material film may have a thickness less than or equal to about 1 centimeter, less than or equal to about 50 millimeters, less than or equal to about 1.5 millimeters, less than or equal to about 900 μm, less than or equal to about 100 μm, less than or equal to about 50 μm, or less than or equal to about 10 μm.

[0031] For water, the acid material (or its film) or the polymeric acid compound may exhibit a solubility greater than or equal to about 1 gram per liter (g / L), or greater 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. At room temperature, for example at a temperature of about 20°C to about 23°C, for C1 to C5 alcohols, the acid material (or its film) or the polymeric acid compound may exhibit a solubility greater than or equal to about 1 g / L, or greater than or equal to about 200 g / L.

[0032] For water or for C1 to C5 alcohols, the acid material (or its film) or the polymeric acid compound may exhibit a solubility 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, or less than or equal to about 600 g / L.

[0033] The acid material (or its film) or the polymeric acid compound may exhibit a pH greater than or equal to about 0.5, or greater than or equal to about 1 and less than or equal to about 5, or less than or equal to about 4.5 in a solution state (for example, in an aqueous solution).

[0034] The acid material or the polymeric acid compound may include polyacrylic acid compounds, polymethacrylic acid, polyacrylic acid-methacrylic acid, alkali metal salts of poly(meth)acrylic acid (for example, sodium salts), copolymers including (meth)acrylic acid repeating units, polyvinylphosphonic acid, poly(aromatic sulfonic acids) such as poly(4-styrenesulfonic acid), poly(4-styrenesulfonic acid-co-maleic acid), alkali metal salts of poly(aromatic sulfonic acids) (for example, partial salts), poly(vinylsulfonic acid), alkali metal salts of poly(vinylsulfonic acid) (for example, partial salts), polymaleic acid, or combinations thereof (for example, copolymers of at least two of the foregoing polymers or mixtures of at least two of the foregoing polymers). The alkali metal salt may be a partial alkali metal salt.

[0035] The acid material (or its film) may further include or may not include additives (e.g., inorganic acids such as sulfuric acid, 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-C50, C3-C25, or C5-C8 aliphatic or aromatic hydrocarbon group, and n is 1 to 10, 2 to 8, 3 to 6, or 4 to 5.

[0036] The acid material or non-polymeric carboxylic acid compound may include (or may be) a C2-50 carboxylic acid compound represented by R(COOH)n, where R is a substituted or unsubstituted C1-C50, C3-C25, or C5-C8 aliphatic or aromatic hydrocarbon group, and n is 1 to 10, 2 to 8, 3 to 6, or 4 to 5.

[0037] The acid material or non-polymeric carboxylic acid compound may include (or may be) a compound having 2 to 10 carboxylic acid groups (e.g., a polycarboxylic acid compound).

[0038] The non-polymeric (poly)carboxylic acid compound may have 1 to 10, 2 to 5, 3 to 4 substituted or unsubstituted C 1-50 's, C 2-50 's, C 6-15 's, or C 8-10 aliphatic hydrocarbon groups, 1 to 10, 2 to 5, 3 to 4 substituted or unsubstituted C 6-15 aromatic hydrocarbon groups, or combinations thereof.

[0039] The non-polymeric (poly)carboxylic acid compound may further include a hydroxyl group.

[0040] The acid material or non-polymeric carboxylic acid compound may 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 combinations thereof.

[0041] The acid material may include a polymeric acid compound and a non-polymeric carboxylic acid compound.

[0042] Based on the total weight of the acid material, the amount of the crosslinked polymer in the acid material may be less than about 1 weight percent (wt%), or less than or equal to about 0.9 wt%.

[0043] The acid material may not include a crosslinked (e.g., crosslinked) polymer.

[0044] At least a portion of the acid material may be configured to dissolve when immersed in water or a C1 to C5 alcohol. The acid material may be configured to at least partially dissolve when immersed in water or a C1-C5 alcohol. The temperature of the water or the C1 to C5 alcohol may be greater than or equal to about 20 °C or greater than or equal to about 25 °C. The temperature of the water or the C1 to C5 alcohol may be less than or equal to its boiling point (e.g., less than or equal to about 50 °C, or less than or equal to about 30 °C).

[0045] The container may include a light-transmitting component (e.g., a light-transmitting material or a light-transmitting composition). The container may include additional components (e.g., a sealing component). The container may be an encapsulation element (e.g., encapsulation glass) 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-inorganic hybrid material, or a combination thereof. The container may be a furnace (oven) or a chamber.

[0046] The container may be a furnace including a hollow chamber and an element configured to heat the chamber in a controlled manner, and the acid material may be provided in solution form.

[0047] The acid material (e.g., a polymeric acid compound) may be disposed adjacent to or in contact with the surface of the container or the light-transmitting component. The acid material may be applied or coated on the surface of the container or the light-transmitting component.

[0048] The method may further include preparing a composition including a liquid carrier (e.g., a solvent) and the acid material. The composition may further include the additive.

[0049] The method may further include applying the composition to the surface of the container to form a film of the acid material. The method may further include placing the composition in a separate container and setting the separate container in a space (e.g., a furnace or a chamber).

[0050] The composition may be obtained by dissolving the acid material and optionally the additive in the liquid carrier.

[0051] The liquid carrier or solvent may include water, a C1-10 alcohol, a nitrile solvent, an ester solvent, or a combination thereof.

[0052] The liquid carrier or solvent may contain water, ethanol, methanol, propanol, acetonitrile, ethyl acetate, or a combination thereof.

[0053] The defined space may be a closed space, e.g., a sealed space or an airtight or gas-tight 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, or less than or equal to about 120 °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 5 hours and less than or equal to about 10 days, or less than or equal to about 10 hours.

[0054] The method may further include separating the stacked structure from the container (e.g., removing the stacked structure from the defined space) after the post-treatment.

[0055] The method may further include providing a conductive layer on the thin film conductor after the post-treatment to form a thin film conductor (or a second electrode) with an increased thickness.

[0056] In an embodiment, the light-emitting device includes:

[0057] 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 disposed between the light-emitting layer and the second electrode;

[0058] wherein the light-emitting layer includes semiconductor nanoparticles, and the light-emitting layer is configured to emit a first light,

[0059] wherein 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, and 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,

[0060] the second electrode has a thickness greater than or equal to about 11 nm and less than or equal to about 50 nm, and

[0061] the second electrode exhibits a light transmittance greater than or equal to about 50% and less than or equal to about 100% for the first light, and

[0062] the first electrode is configured to reflect at least a portion of the first light.

[0063] The first electrode may include a hole injection conductor.

[0064] The second electrode may include an electron injection conductor.

[0065] The semiconductor nanoparticles or the light-emitting layer may not contain cadmium, lead, mercury, or a combination thereof.

[0066] The second electrode may have a thickness greater than or equal to about 12 nm.

[0067] The second electrode may have a thickness less than or equal to about 40 nm.

[0068] The light-emitting device may be configured to emit green light when a voltage is applied. The electroluminescent device may be configured to emit blue light when a voltage is applied. The electroluminescent device may be configured to emit red light when a voltage is applied.

[0069] The light-emitting device may further include a layer of an acid material (or an acid material film, hereinafter, "acid material film") disposed on the electron transport layer. Details of the acid material are the same as those described herein. The acid material may include a polymeric acid compound.

[0070] The acid material film may be disposed to be spaced apart from the electron transport layer and the second electrode. The acid material film may be disposed to face the electron transport layer and the second electrode or the thin film conductor.

[0071] The acid material film may be disposed to be spaced apart from the electron transport layer and the second electrode. The acid material film may be disposed to face the electron transport layer and the second electrode or the thin film conductor.

[0072] The electron transport layer may have a first surface facing the light-emitting layer and a second surface opposite to the first surface, and the acid material film may be disposed on or above the second surface.

[0073] The acid material film may be spaced apart from the electron transport layer (e.g., away from the electron transport layer).

[0074] The thickness of the acid material film may be greater than or equal to about 10 nm, or greater than or equal to about 100 nm. The thickness of the acid material layer may be less than or equal to about 100 micrometers (μm), or less than or equal to about 10 μm.

[0075] The thin film conductor or the second electrode may have a first surface facing the surface of the electron transport layer and a second surface opposite to the first surface. The acid material film may be disposed to be spaced apart from the electron transport layer and the second electrode and face at least a part (e.g., all) of the surface of the electron transport layer and / or at least a part (e.g., all) of the second surface of the second electrode.

[0076] Details of the semiconductor nanoparticles, metal oxide nanoparticles, the first electrode, and the acid material and its film are the same as those described herein. Details of the second electrode are the same as those described for the thin film conductor.

[0077] The light-emitting device (e.g., emitting blue light) may have 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, 6 cd / A, greater than or equal to about 6.5 cd / A, or greater than or equal to about 12 cd / A.

[0078] The light-emitting device may be configured to emit blue light and may have a T90 greater than or equal to about 20 hours, e.g., when operating at an initial brightness of about 650 nits.

[0079] The light-emitting device may exhibit a maximum brightness greater than or equal to about 60,000 nits (candela per square meter, cd / m 2 2), greater than or equal to about 70,000 nits, or greater than or equal to about 80,000 nits.

[0080] The light-emitting device may exhibit a maximum external quantum efficiency greater than or equal to about 6%, greater than or equal to about 8%, or greater than or equal to about 10%.

[0081] In an embodiment, a display device may include the light-emitting device (e.g., an electroluminescent device).

[0082] In an embodiment, an electronic device may include the light-emitting device.

[0083] The display device or the electronic device may include (or may be) an AR / VR device, a handheld terminal, a monitor, a laptop, a television, an electronic display board, a camera, an electronic display component for an autonomous vehicle or an electric vehicle.

[0084] According to an embodiment, there is provided a light-emitting device exhibiting improved luminous properties and lifetime characteristics. The method of the embodiment may facilitate, e.g., a large-scale manufacturing process of a front-emitting type light-emitting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] 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:

[0086] Figure 1A is a schematic cross-sectional view of a light-emitting device according to an embodiment;

[0087] Figure 1B is a schematic cross-sectional view of a light-emitting device according to an embodiment;

[0088] Figure 1C is a schematic cross-sectional view of a light-emitting device according to an embodiment;

[0089] Figure 2is a schematic cross-sectional view of a light-emitting device according to an embodiment;

[0090] Figure 3 is a schematic cross-sectional view of a light-emitting device according to an embodiment;

[0091] Figure 4 is a schematic cross-sectional view of a light-emitting device according to an embodiment;

[0092] Figure 5 is Figure 4 a plan view of the light-emitting device.

[0093] Figure 6 is a schematic cross-sectional view of a light-emitting device according to an embodiment.

[0094] Figure 7 shows a schematic cross-sectional view of a stacked structure for post-treatment in a process according to an embodiment.

[0095] Figure 8 shows a schematic cross-sectional view of the stacked structure obtained by the process, where the stacked structure is removed from the container after post-treatment in the process of manufacturing a light-emitting device according to Figure 7 and then a second electrode is formed and a new container (without a layer of acid material) is provided.

[0096] Figure 9 is a diagram schematically showing an example of post-treatment (using a furnace or a chamber as a container) during the manufacturing process of a light-emitting device according to an embodiment.

[0097] Figure 10 is a schematic cross-sectional view of a light-emitting device (RGB pixel) according to an embodiment.

[0098] Figure 11 is a schematic plan view of a display panel according to an embodiment.

[0099] Figure 12 is a schematic cross-sectional view of the display panel showing the Figure 11 display panel taken along line IV-IV.

[0100] Figure 13 is a flowchart of a method for manufacturing a light-emitting device according to an embodiment. Detailed Embodiments

[0101] With reference to the following example embodiments and the accompanying drawings, the advantages and features of the present disclosure and the methods for achieving them will become clear. However, the embodiments should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0102] To clearly explain the present disclosure, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar elements throughout the specification. In the drawings, for clarity, the thicknesses of layers, films, panels, regions, etc. are exaggerated. Also in the drawings, for ease of description, the thicknesses of some layers and regions are exaggerated. Accordingly, the embodiments described herein should not be construed as 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.

[0103] 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 part means being disposed above or below the reference part and does not necessarily mean “above.”

[0104] It will be understood that although the terms “first,” “second,” “third,” etc. may be used herein to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Thus, without departing from the teachings herein, the “first element,” “component,” “region,” “layer,” or “part” discussed below could be termed a second element, component, region, layer, or part.

[0105] 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” will not be construed as limiting “one.” “Or” means “and / or.”

[0106] 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.

[0107] As used herein, the term "cross-sectional view" is a view obtained by cutting a given three-dimensional object (e.g., in a substantially vertical direction) and looking at the cut surface horizontally. As used herein, the term "plan view" is an orthographic projection of a given three-dimensional object from a position in a horizontal plane passing through the object.

[0108] 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 belongs. 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.

[0109] 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)", and when the work function or energy level is referred to as "shallow", "low", or "small", the work function or energy level has a small absolute value based on the vacuum energy level of "0 eV".

[0110] As used herein, the average (value) may be a mean or a median. In an embodiment, the average (value) may be a mean average.

[0111] As used herein, the term "peak emission wavelength" is the wavelength at which a given emission spectrum of light reaches its maximum value.

[0112] As used herein, the term "group" may refer to a group of the periodic table.

[0113] 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.

[0114] 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.

[0115] 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 metals may be scandium, yttrium, etc., but are not limited to these.

[0116] As used herein, "Group IV" refers to Group IVA and Group IVB, and examples of Group IVA metals can be Si, Ge, and Sn, and examples of Group IVB metals can be titanium, zirconium, hafnium, etc., but are not limited thereto.

[0117] As used herein, "Group V" includes Group VA and includes nitrogen, phosphorus, arsenic, antimony, and bismuth, but is not limited thereto.

[0118] As used herein, "Group VI" includes Group VIA and includes sulfur, selenium, and tellurium, but is not limited thereto.

[0119] As used herein, "metal" includes metalloids such as Si.

[0120] 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.

[0121] As used herein, when no other definition is provided, "substituted (with)" means replacing at least one hydrogen of a compound or group with a corresponding group moiety including: C1 to C30 alkyl, C2 to C30 alkenyl, C2 to C30 alkynyl, C6 to C30 aryl, C7 to C30 alkylaryl, C1 to C30 alkoxy, C1 to C30 heteroalkyl, C3 to C30 heteroalkylaryl, C3 to C30 cycloalkyl, C3 to C15 cycloalkenyl, C6 to C30 cycloalkynyl, C2 to 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 to 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 to C6 alkyl or C6 to 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.

[0122] As used herein, when no other definition is provided, "hydrocarbon" or "hydrocarbon group" refers to a compound or group that includes 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 a hydrogen atom, e.g., one or more hydrogen atoms, from an alkane, alkene, alkyne, or aromatic hydrocarbon. 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.

[0123] As used herein, when no other definition is provided, "alkyl" refers to a straight-chain or branched-chain saturated monovalent hydrocarbon group (methyl, ethyl, hexyl, etc.). In embodiments, an alkyl can have 1 to 50 carbon atoms, or 1 to 18 carbon atoms, or 1 to 12 carbon atoms.

[0124] As used herein, when no other definition is provided, "alkenyl" refers to a straight-chain or branched-chain monovalent hydrocarbon group having a carbon-carbon double bond. In embodiments, an alkenyl can have 2 to 50 carbon atoms, or 2 to 18 carbon atoms, or 2 to 12 carbon atoms.

[0125] As used herein, when no other definition is provided, "alkynyl" refers to a straight-chain or branched-chain monovalent hydrocarbon group having a carbon-carbon triple bond. In embodiments, an alkynyl can have 2 to 50 carbon atoms, or 2 to 18 carbon atoms, or 2 to 12 carbon atoms.

[0126] As used herein, when no other definition is provided, "aryl" refers to a group formed by removing a hydrogen, e.g., at least one hydrogen, from an aromatic hydrocarbon (e.g., phenyl or naphthyl). In embodiments, an aryl can have 6 to 50 carbon atoms, or 6 to 18 carbon atoms, or 6 to 12 carbon atoms.

[0127] As used herein, when no other definition is provided, "hetero" refers to containing 1 to 3 heteroatoms, such as N, O, S, Si, P, or a combination thereof.

[0128] As used herein, when no other definition is provided, "alkoxy" refers to an alkyl group attached to oxygen (e.g., alkyl-O-), such as methoxy, ethoxy, or sec-butoxy.

[0129] As used herein, when no other definition is provided, "amine" refers to a compound represented by NR3, where each R is independently hydrogen, a C1-C12 alkyl, a C7-C20 alkylaryl, a C7-C20 arylalkyl, or a C6-C18 aryl.

[0130] As used herein, "poly(meth)acrylate" refers to polyacrylate, polymethacrylate, or a combination thereof.

[0131] In embodiments, "alkali metal salts" (e.g., alkali metal salts of polymeric acids such as poly(meth)acrylic acid or polystyrene sulfonic acid) can include partial alkali metal salts, complete alkali metal salts, or combinations thereof.

[0132] As used herein, the phrase "does not include cadmium (or other harmful heavy metals)" can mean that the concentration of cadmium (or additional heavy metals considered harmful) can 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) can be substantially absent, or if present, the amount of cadmium (or other heavy metals) can 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 as its impurity level.

[0133] Unless stated to the contrary, the numerical ranges recited herein are inclusive. Unless stated to the contrary, 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 recited for each numerical value can be combined independently to provide a range.

[0134] As used herein, "about" includes the recited value and means within an acceptable deviation for the particular value as determined by one of ordinary skill in the art in view of the measurements discussed and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations of the recited value, or within ±10%, 5%, 3%, or 1%.

[0135] As used herein, a nanoparticle is a structure having a region or characteristic scale with a nanoscale dimension (e.g., at least one region or characteristic scale with a nanoscale dimension). In embodiments, the scale (or average scale, average size, or average length) 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, nanotetrapods, 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.

[0136] 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 serving as the emission center, the semiconductor nanoparticle or quantum dot can emit light corresponding to its bandgap energy.

[0137] As used herein, the term "T50" is the time (hours, hr) when, for example, when a given device starts driving (e.g., operating) at a predetermined initial luminance (e.g., 650 nits), the luminance (e.g., brightness) of the given device decreases to 50% of the initial luminance (100%).

[0138] As used herein, the term "T90" is the time (hr) when, when a given device starts driving at a predetermined initial luminance (e.g., 650 nits), the luminance (e.g., brightness) of the given device decreases to 90% of the initial luminance (100%).

[0139] 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. EQE can be determined by the following equation:

[0140] EQE = injection efficiency × (solid-state) quantum yield × extraction efficiency

[0141] The injection efficiency is the proportion of electrons passing through the device in the injected active region, the quantum yield is the proportion of all radiative electron-hole recombinations in the active region that generate photons, and the extraction efficiency is the proportion of photons generated in the active region that escape from a given device.

[0142] As used herein, the maximum EQE is the maximum value of the EQE.

[0143] As used herein, the maximum brightness is the highest value of the brightness for a given device.

[0144] 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. For example, 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 the fluorescence quantum yield or efficiency: the absolute method and the relative method.

[0145] 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.

[0146] The bandgap energy of semiconductor nanoparticles can change 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 luminescent materials in various fields such as display devices, energy devices, or bioluminescent devices.

[0147] A light-emitting 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. The QD-LED, which uses an emission principle different from that of an organic light-emitting diode (OLED), can exhibit light emission with more desirable optical properties, such as 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 the QD-LED can be based on inorganic materials, contributing to achieving increased display (light emission) stability over time.

[0148] In an embodiment of the 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 the QD-LED, common layers can be provided between the light-emitting layer and the electrodes, for example, 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). For example, the electron transport layer can be required to have an electron mobility sufficient to balance the holes and electrons in the light-emitting layer, whereby electrons can be effectively transferred from the electrode to the quantum dot light-emitting layer. Additionally, the electron transport layer can be required to have an appropriate deep HOMO energy level and sufficiently block holes from the quantum dot light-emitting layer.

[0149] 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 a light-emitting device or a display device having a light-emitting layer substantially free of such heavy metals.

[0150] In an embodiment, the light-emitting device can be a device configured to emit desired light by applying a voltage, for example, with or without a separate light source.

[0151] In an embodiment, a light-emitting device includes: a first electrode (or hole injection conductor) 1 and a thin film conductor (e.g., an electron injection conductor or a second electrode, hereinafter referred to as “second electrode”) 5 spaced apart from each other (e.g., the first electrode 1 and the thin film conductor 5 each have a surface opposite to the other, i.e., each have surfaces facing each other); a light-emitting layer 3 disposed between the first electrode 1 and the thin film conductor 5, and an electron transport layer 4 (or an electron assisting layer including the same) disposed between the light-emitting layer 3 and the thin film conductor 5. The electron transport layer 4 includes metal oxide nanoparticles. The light-emitting layer 3 may be configured to emit a first light when a voltage is applied (e.g., between the first electrode and the second electrode). The thin film conductor 5 may have a thickness greater than or equal to about 1 nm or greater than or equal to about 11 nm and less than about 100 nm. In an embodiment, the light-emitting device may further include a hole assisting layer 2 between the light-emitting layer 3 and the first electrode 1. The hole assisting layer 2 may include a hole transport layer, a hole injection layer, or a combination thereof. The hole assisting layer may include an organic compound. See Figure 1A and Figure 1B 。

[0152] The light-emitting device according to an embodiment may include metal oxide nanoparticles (e.g., including zinc oxide such as ZnMgO, etc.) in the electron transport layer 4. Compared with an organic semiconductor material, the metal oxide nanoparticles may provide increased electron mobility. However, the present inventors have found that, in the case of a light-emitting device including the electron transport layer 4 containing metal oxide nanoparticles, holes may easily move through defects in the metal oxide nanoparticles, resulting in a relatively high level of hole leakage current, and from the perspective of the light-emitting device as a whole, this may lead to a reduction in efficiency. In addition, surface defects of the metal oxide nanoparticles may cause charging due to the accumulation of charges at the interface between the light-emitting layer / electron transport layer and inside the electron transport layer 4, which results in a reduction in the brightness and lifetime of the light-emitting device. In summary, the electron transport layer based on metal oxide nanoparticles has technical defects such as high leakage current due to defects in the metal oxide nanoparticles, resulting in a reduction in device efficiency (low hole blocking characteristics), material degradation or lifetime reduction caused by a large amount of charging at the QD / electron transport layer interface and internal trapping (traps) in the electron transport layer 4.

[0153] The present inventors have found that the light-emitting device according to an embodiment or a method of manufacturing the same may solve these technical defects regarding the electron transport layer 4 by using an acid material (or a layer thereof) in the manner described herein. In the light-emitting device according to an embodiment or a method of manufacturing the same, acid and moisture from the acid material may diffuse through the thin film conductor, whereby they may be utilized in manufacturing a display panel having a front common electrode covering the electron transport layer such that the electron transport layer is not exposed.

[0154] In the light-emitting device of the embodiment, an acid material (e.g., a polymeric acid compound, a non-polymeric acid compound such as an inorganic acid, a non-polymeric carboxylic acid compound, a non-polymeric sulfinic acid compound, or a non-polymeric sulfonic acid compound, or a combination thereof) or a film or layer of the acid material (hereinafter, may be referred to as "acid material") may be provided on or above the electron transport layer 4 or the thin-film conductor 5 (or the second electrode). (See Figure 1A , Figure 1B and Figure 1C ). In the light-emitting device of the embodiment, the acid material may be included to be spaced apart (in a non-contact or remote manner) from the electron transport layer 4 and the thin-film conductor 5. The light-emitting device of the embodiment may further include a container. The container may include a light-transmissive member, additional members such as a sealing material, or a combination thereof. The first surface of the container may face the thin-film conductor 5 (e.g., the second electrode), and the acid material may be provided on the first surface of the container to be adjacent to or in contact with the container. The acid material may be in the form of a film, and the acid material may be provided on the first surface of the container such that the first surface of the film is adjacent to the container, and the second surface of the acid material opposite to the first surface faces the thin-film conductor 5 and / or the electron transport layer 4. (See Figure 1A , Figure 1B and Figure 1C )

[0155] In an embodiment, a light-emitting device capable of exhibiting improved lifetime and electroluminescence characteristics (e.g., device efficiency and brightness) may be provided. The light-emitting device of the embodiment may substantially (substantially) block hole leakage through the electron assisting layer (e.g., the electron transport layer 4), exhibit increased electron transport properties, achieve improved electron-hole balance, and effectively suppress or prevent material degradation due to charging.

[0156] In the light-emitting device of the embodiment, the acid material may be formed of 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), and thus it may be used regardless of the light-emitting mode of the display device (e.g., may 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 may contribute to improved hole-electron balance in the light-emitting layer and may effectively transfer electrons from the electrode to the light-emitting layer.

[0157] In an embodiment of the light-emitting device, the electron assisting layer (e.g., the electron transport layer) may have a HOMO energy level with a desired depth and may suppress the appearance of trapping energy levels, e.g., effectively block unwanted hole movement from the light-emitting layer including semiconductor nanoparticles to the second electrode.

[0158] In the light-emitting device of the embodiment, the thin-film conductor can also be used as the second electrode. The second electrode can include the thin-film conductor. The first electrode or the second electrode can include (or can be) an anode or a cathode. In an embodiment, the first electrode can include a cathode (or an anode), and the second electrode can include an anode (or a cathode). In an embodiment, the second electrode includes an electron injection conductor, such as a cathode, and the first electrode includes a hole injection conductor, such as an anode.

[0159] In a light-emitting display device including the light-emitting device of the embodiment, the first electrode can be disposed on the (transparent) substrate 100 or on the substrate and the driving circuit. (See Figures 2 to 6 ). In an embodiment, the first light emitted from the light-emitting layer can pass through the second electrode and the first surface of the container and be extracted (e.g., in the Z direction). In an embodiment, the first light can be extracted through the (transparent) first electrode and optionally the substrate 100 (see Figure 7 and Figure 8 ). The light-emitting layer can be disposed in a pixel (or a sub-pixel) of a display device (display panel) to be described later.

[0160] In the light-emitting device of the embodiment, the light-emitting layers 3, 30 can be disposed between the first electrode (e.g., an anode) 1, 10 and the second electrode (e.g., a cathode) 5, 50. The cathodes 5, 50 can include electron injection conductors. The anodes 1, 10 can include hole injection conductors. The work functions of the electron / hole injection conductors included in the cathode and the anode can be appropriately adjusted and are not particularly limited. For example, the cathode can have a small work function, and the anode can have a relatively large work function, or vice versa.

[0161] The electron / hole injection conductor can 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.

[0162] The first electrode, the second electrode, or a combination thereof can be a light-transmissive electrode or a transparent electrode. In an embodiment, both the first electrode and the second electrode can be light-transmissive electrodes. The first electrode, the second electrode, or a combination thereof can be a patterned electrode.

[0163] The first electrode, the second electrode, or a combination thereof may be disposed on (e.g., an insulating) substrate 100. Substrate 100 may be a substrate including an insulating material. The substrate may include glass; various polymers such as polyesters, polycarbonates, and polyacrylates such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), etc.; polysiloxanes (e.g., polydimethylsiloxane (PDMS)); inorganic materials such as Al2O3 or ZnO; or a combination thereof, but 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.

[0164] Substrate 100 or the container (or the light-transmissive component included in the container) may be optically transparent. Substrate 100 or the container (or the light-transmissive component) may have a light transmittance of greater than or equal to about 50%, greater than or equal to about 60%, greater than or equal to about 70%, greater than or equal to about 80%, greater than or equal to about 85%, or greater than or equal to about 90% and less than or equal to about 100%, e.g., less than or equal to about 99%, or less than or equal to about 95%. For light emitted from semiconductor nanoparticles (e.g., included in the light-emitting layer), substrate or container (or the light-transmissive component included in the container) may have a transmittance of greater than or equal to about 50%, greater than or equal to about 60%, greater than or equal to about 70%, greater than or equal to about 80%, 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%, e.g., less than or equal to about 99%, or less than or equal to about 95%. In an embodiment, substrate or container (or the light-transmissive component) may be opaque or reflective.

[0165] In an embodiment, thin-film transistors may be disposed in each region of the substrate, but 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-transmissive electrode may be disposed on (e.g., an insulating) transparent substrate. Substrate 100 may be a rigid or flexible substrate.

[0166] The electrode may comprise 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 tin zinc oxide; metal nitrides such as titanium nitride; conductive polymers such as polyaniline; LiF / Mg:Ag; single or multi-layer metal thin films; or combinations thereof. In an embodiment, the electrode (e.g., the first electrode and / or the second electrode) may comprise aluminum (Al), lithium-aluminum (Li:Al) alloy, magnesium-silver (Mg:Ag) alloy, lithium fluoride-aluminum (LiF:Al), gold, silver, or combinations thereof. The ratio of the alloy can be appropriately selected and is not particularly limited. The electrode can be formed by vacuum deposition, thermal deposition, sputtering deposition, etc.

[0167] There is no particular limitation on the thickness of each of the electrodes (the first electrode, the second electrode, or a combination thereof), and it can be appropriately selected considering the device efficiency. 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, or less than or equal to about 100 nm.

[0168] A light-transmitting electrode or a non-light-transmitting 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 may include a metal layer (e.g., aluminum, silver, etc.) disposed between layers of a metal oxide (e.g., a light-transmitting metal oxide) such as indium tin oxide. In an embodiment, the light-transmitting electrode may include a light-transmitting metal oxide, a thin metal or alloy thin film, or a combination thereof. The light-transmitting electrode can include a transparent electrode and a semi-transparent electrode.

[0169] In the light-emitting device of the embodiment, the second electrode or the thin-film conductor may have a thickness greater than or equal to about 1 nm, such as greater than or equal to about 5 nm, 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 second electrode or the thin-film conductor may have a thickness 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 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.

[0170] In the light-emitting device of the embodiment, the first electrode, 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%.

[0171] In an embodiment of a light-emitting device, the second electrode or the first electrode may be configured to reflect at least a portion of the first light (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%). In an embodiment of a 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.

[0172] The thin-film conductor may include silver, aluminum, magnesium, tungsten, nickel, cobalt, platinum, palladium, calcium, LiF, gold, copper, or a combination thereof (e.g., an alloy thereof). The thin-film conductor may include silver and magnesium, an alloy thereof, aluminum and magnesium, or an alloy thereof, or a combination thereof. The thin-film conductor or the second electrode may be an electrode that can be formed by thermal deposition. In an embodiment, the thin-film conductor may exhibit metal pores and / or grain boundaries in a cross-sectional view thereof obtained by using a microscope or an electron microscope. In an embodiment, the thin-film conductor may not exhibit metal pores and / or grain boundaries in a cross-sectional view thereof obtained by using a microscope or an electron microscope.

[0173] In an embodiment of a light-emitting device and a method of manufacturing the same, 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, the acid and moisture supplied from the acid material (or a film thereof) may pass through the thin-film conductor and reach the electron transport layer including metal oxide nanoparticles. The acid and moisture reaching the electron transport layer may modify the surface of the metal oxide nanoparticles, whereby hydrogen ions (H + ) and hydroxide ions (OH - ) may be supplied to the metal oxide nanoparticles in the electron transport layer to passivate surface defects through a chemical reaction. Including a post-treated electron transport layer in an embodiment of a light-emitting device may reduce the hole leakage current, which may be confirmed by a lower driving voltage and a higher device efficiency than those of the device before the post-treatment. Including a post-treated electron transport layer in an embodiment of a light-emitting device may increase the hole blocking performance and electron mobility of the electron transport layer, and this may contribute to an improvement in the luminance of the device. Including a post-treated electron transport layer in an embodiment of a light-emitting device may alleviate the charging phenomenon at the interface between the light-emitting layer and the electron transport layer, and the device of the embodiment may exhibit reduced interface deterioration and increased lifetime.

[0174] The light-emitting layers 3, 30 may be disposed between the first electrodes 1, 10 and the second electrodes 5, 50 (e.g., anodes 1, 10 and cathodes 5, 50), and may include semiconductor nanoparticles (e.g., blue light-emitting nanoparticles, red light-emitting nanoparticles, green light-emitting nanoparticles, or a combination thereof). 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.

[0175] The light-emitting layer may be patterned. In an embodiment, the patterned light-emitting layer may include a blue light-emitting layer disposed in a blue pixel, a red light-emitting layer disposed in a red pixel, a green light-emitting layer disposed in a green pixel, or a combination thereof. In an embodiment, the light-emitting layer may include a red light-emitting layer disposed in a red pixel and a green light-emitting layer disposed in a green pixel. (e.g., red, green, or blue) light-emitting layers may each be (optically) separated from an adjacent light-emitting layer by a partition wall. In an embodiment, a partition wall or dam (e.g., a black matrix or a pixel defining layer) may 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, the green light-emitting layer, and the blue light-emitting layer may be optically isolated from each other.

[0176] In an embodiment, the light-emitting layers 3, 30 or the semiconductor nanoparticles may not include cadmium. In an embodiment, the light-emitting layers 3, 30 or the semiconductor nanoparticles may not include mercury, lead, or a combination thereof.

[0177] In an embodiment, the semiconductor nanoparticles may have a core-shell structure. In an embodiment, the semiconductor nanoparticles or the core-shell structure may 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.

[0178] The semiconductor nanoparticles (or the first semiconductor nanocrystal, the second semiconductor nanocrystal, or a combination thereof) may include II-VI group compounds, III-V group compounds, IV-VI group compounds, group IV elements or compounds, I-III-VI group compounds, II-III-VI group compounds, I-II-IV-VI group compounds, 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) may 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) may 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) may not include a combination of lead and cadmium.

[0179] The II-VI compounds can 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.

[0180] The III-V compounds can 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 (e.g., InZnP).

[0181] The IV-VI compounds can 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.

[0182] Examples of I-III-VI compounds can be CuInSe2, CuInS2, CuInGaSe, and CuInGaS, but are not limited thereto.

[0183] 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.

[0184] Examples of I-II-IV-VI group compounds include, but are not limited to, CuZnSnSe and CuZnSnS.

[0185] 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.

[0186] 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 mean 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.

[0187] 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.

[0188] 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.

[0189] In an embodiment, the semiconductor nanoparticles can emit blue light or green light and can include a core and a shell, where the core includes ZnSeTe, ZnSe, or a combination thereof, and the shell includes 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). For example, 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).

[0190] 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, where the Group II metal includes zinc and the non-metal includes sulfur, selenium, or a combination thereof.

[0191] 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).

[0192] 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.

[0193] 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., the quantum confinement effect.

[0194] The semiconductor nanoparticles according to an embodiment can include, for example, organic ligands bound or coordinated to their surface.

[0195] 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.

[0196] 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 wavelength range from ultraviolet to infrared. 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 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 maximum 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 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 600 nm, less than or equal to about 590 nm, less than or equal to about 580 nm, less than or equal to about 570 nm, less than or equal to about 560 nm, less than or equal to about 550 nm, or less than or equal to about 540 nm. The 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 range of the green light or red light wavelength, for example, in the range from greater than or equal to about 490 nm or greater than or equal to about 500 nm to less than or equal to about 660 nm or less than or equal to about 650 nm.

[0197] The semiconductor nanoparticles (or the light emitted from the electroluminescent device) can emit green light (for example, when a voltage is applied or when irradiated with light), and its maximum emission peak wavelength can be in the range from greater than or equal to about 500 nm (for example, 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 (for example, less than or equal to about 540 nm). The semiconductor nanoparticles (or the light emitted from the electroluminescent device) can emit red light (for example, when a voltage is applied or when irradiated with light), and its maximum emission peak wavelength can be in the range from greater than or equal to about 600 nm, for example 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.

[0198] 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, greater than or equal to about 440 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).

[0199] In an embodiment, the semiconductor nanoparticles can exhibit a luminescence spectrum (e.g., a photoluminescence or electroluminescence spectrum) having 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 that is 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.

[0200] The semiconductor nanoparticles can exhibit (or can be configured to exhibit) a quantum efficiency (or quantum yield) that is greater than or equal to about 10%, e.g., 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%.

[0201] The 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. The size may be a diameter or an equivalent diameter converted by assuming a spherical shape 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.

[0202] 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, polyhedrons, pyramids, multi-legged shapes, hexahedrons, cubes, cuboids, nanotubes, nanorods, nanowires, nanosheets, or combinations thereof.

[0203] The semiconductor nanoparticles can be prepared by appropriate methods. 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 nanocrystals (coordinate with the surface of the semiconductor nanocrystals or coordinate to the surface of the semiconductor nanocrystals) to control their growth.

[0204] 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-metallic 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. In the semiconductor nanoparticles of the embodiment, the core may be prepared in a suitable manner. The method may further include separating the core from the reaction system in which it is produced and dispersing the core in an organic solvent to obtain a core solution.

[0205] In an embodiment, to form the shell, the solvent and optionally 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 shell precursors 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.

[0206] 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-C22 alkyl groups, such as at least one (such as 1, 2, or 3) C6-C22 alkyl groups, phosphine oxides (such as trioctylphosphine oxide) substituted with C6-C22 alkyl groups, such as at least one (such as 1, 2, or 3) C6-C22 alkyl groups, C12-C22 aromatic ethers such as phenyl ether or benzyl ether, or a combination thereof.

[0207] 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 and about 40 or less, 35 or less, or 25 or less 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.

[0208] 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 that 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 those of 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.

[0209] 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 can be dispersed in the foregoing organic solvents. In an embodiment, the foregoing semiconductor nanoparticles can 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.

[0210] 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.

[0211] In the light-emitting device or display device of the embodiment, the thickness of the light-emitting layer can be appropriately selected. In the embodiment, the light-emitting layer can include a single layer of nanoparticles. In the embodiment, the light-emitting layer can include one or more, for example, two or more, three or more, or four or more and 20 or less, 10 or less, 9 or less, 8 or less, 7 or less, or 6 or less single layers of nanoparticles. The light-emitting layer can have a thickness greater than or equal to about 5 nm, for example, 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.

[0212] In the 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 the 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.

[0213] In an embodiment, the formation of the light-emitting layer may further include bringing a film of semiconductor nanoparticles into contact with an organic solution containing a metal halide (e.g., zinc chloride) (e.g., including an alcohol solvent). In an embodiment, the light-emitting layer may 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 (e.g., chlorine) exchange, and the second light-emitting layer has an increased amount of organic ligands. The amount of halogen (e.g., chlorine) and the amount of organic ligands in the light-emitting layer can be controlled in a suitable manner (e.g., post-treatment of the formed layer). In an embodiment, a thin film of semiconductor nanoparticles having organic ligands (e.g., having a carboxylic acid group) is formed, which is then treated with a solution containing a metal halide (e.g., zinc halide such as zinc chloride in an alcohol solvent) to control the amount of organic ligands of the semiconductor nanoparticles in the thin film. The treated thin film may have an increased amount of halogen and may exhibit (e.g., show) changed properties (e.g., solubility) with respect to, for example, an organic solvent, and then a layer of semiconductor nanoparticles having different amounts of organic ligands (e.g., halogen-treated semiconductor nanoparticles or semiconductor nanoparticles having ligands with a carboxylic acid group) may be formed on the treated thin film.

[0214] 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., the first light-emitting layer and the second light-emitting layer) may be configured to emit first light (e.g., green light, blue light, or red light). In the multilayer structure, adjacent layers (e.g., the first light-emitting layer and the second light-emitting layer) may have the same or different compositions, ligands, or combinations thereof. In an embodiment, the (multilayer) light-emitting layer may exhibit a halogen content that varies (increases or decreases) 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 assisting layer. In the (multilayer) light-emitting layer, the amount of organic ligands may decrease in the direction toward the electron assisting layer. In the (multilayer) light-emitting layer, the content of organic ligands may increase in the direction toward the electron assisting layer.

[0215] 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.

[0216] The light-emitting layer can be heat-treated. The heat treatment can be carried out in air or in an inert gas atmosphere. The temperature of the heat treatment can 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 can 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.

[0217] The light-emitting devices of the embodiments include electron assisting layers 4, 40 disposed on the light-emitting layers 3, 30, for example, between the light-emitting layer and a thin film conductor or a second electrode 5, 50. In the electron assisting layers 4, 40, the transport, injection, or transport and injection of electrons can occur. The electron assisting layers 4, 40 include an electron transport layer (ETL). The electron transport layer includes metal oxide nanoparticles. The electron assisting layers 4, 40 can 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 can be disposed between the electron transport layer and the second electrode, but is not limited thereto. In an embodiment, the hole blocking layer can be disposed between the electron injection layer and the electron transport layer. In an embodiment, the electron injection layer can be disposed between the hole blocking layer and the electron transport layer. The electron transport layer can 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 layers 3, 30 can contact the electron transport layer.

[0218] The second electrodes 5, 50 can have a first surface facing the surface of the electron transport layer (or the electron assisting layer) and a second surface opposite to the first surface. The metal oxide (nanoparticles) can include zinc oxide. The metal oxide (nanoparticles) or zinc oxide can 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. In an embodiment, the metal oxide (nanoparticles) or zinc oxide can include zinc, a Group IIA metal, and optionally an alkali metal.

[0219] The metal oxide (nanoparticles) or zinc oxide can include Zn 1-x M xA compound represented by O, wherein M is Mg, 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 0.07, 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 can 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 can further include magnesium. The electron transport layer or zinc oxide can 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, where x is as defined herein), ZnO, or a combination thereof. The zinc oxide can further include magnesium.

[0220] The size or average size (hereinafter referred to as "size") of the metal oxide nanoparticles can 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 can be the diameter or the equivalent diameter. The equivalent diameter is the value obtained by converting the size of a non-spherical particle into the diameter of a spherical particle. The size of the nanoparticles can be measured by appropriate means such as electron microscopy methods like TEM or XRD. In this specification, the size can refer to the size of a single particle or the average size of a group of particles.

[0221] 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 may 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.

[0222] 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 may further include removing the organic solvent from the formed film, e.g., by evaporation. The organic solvent may include a C1 to C10 alcohol solvent or a combination thereof.

[0223] 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.

[0224] 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, greater than or equal to about 20 nm, or greater than or equal to about 21 nm and less than or equal to about 120 nm, less than or equal to about 110 nm, less than or equal to about 100 nm, less than or equal to about 90 nm, less than or equal to about 80 nm, less than or equal to about 70 nm, less than or equal to about 60 nm, less than or equal to about 50 nm, less than or equal to about 40 nm, less than or equal to about 30 nm, or less than or equal to about 25 nm, but is not limited thereto.

[0225] 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-benzimidazole) (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..

[0226] In a light-emitting device of an embodiment, metal oxide nanoparticles included in an electron transport layer may provide an electron mobility higher than that of an organic semiconductor material, and a light-emitting layer (e.g., in combination with the electron transport layer including metal oxide nanoparticles) may exhibit desired levels of electroluminescent properties. In addition, an emission 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 on the emission layer by a solution process, which is advantageous in the process.

[0227] However, the present inventors have found that a combination of an electron assisting layer including metal oxide nanoparticles and a light-emitting layer including semiconductor nanoparticles may not provide desired improvements 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. As a result of the synthesis, various surface chemical species, such as metal ions, such as (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 for the nanoparticles and act as defect energy levels in the ETL. Surface defects existing 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.

[0228] It is believed that metal oxide nanoparticles in the electron assisting layer or electron transport layer may 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, and 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.

[0229] In addition, surface defects that may exist in metal oxide nanoparticles can cause a large amount of charge accumulation at the interface between the electron transport layer and the light emitting layer or in the electron transport layer, resulting in a decrease in the brightness or a shortened lifetime of the light emitting device including semiconductor nanoparticles.

[0230] In the light emitting device or method of manufacturing the same according to an embodiment, the electron transport layer including metal oxide nanoparticles can be post-processed by using an acid material (in the form of a film or a solution) and a thin film conductor in the manner described herein. The light emitting device according to an embodiment including the post-processed electron transport layer can exhibit improved electroluminescent properties and enhanced lifetime characteristics. In the post-processing using the acid material (film) and the thin film conductor, moisture and acid components can easily diffuse into the electron transport layer in a remote manner, and thus, it can be easily used in bottom emission type and front emission type devices.

[0231] In the post-processing according to an embodiment using an acid material and a thin film conductor, the acid and moisture can diffuse remotely and induce modification (e.g., surface modification) of the metal oxide nanoparticles contained in the electron transport layer, and thereby effectively reduce the hole leakage current and solve the charge accumulation and charging problems.

[0232] The acid components and moisture that diffuse remotely during the post-processing can induce surface chemical reactions of the metal oxide nanoparticles in the electron transport layer, provide passivation of the defects on the surface of the metal oxide nanoparticles, and increase the conductivity of the metal oxide nanoparticles. Therefore, the light emitting device according to an embodiment can exhibit an extended lifetime as well as improved efficiency.

[0233] In an embodiment, the acid material may be disposed near or on a stacked structure including a first electrode, a light-emitting layer, an electron transport layer, and a thin-film conductor. For example, it may be spaced apart from or remotely disposed (set remotely) from the thin-film conductor and the electron transport layer to release acid and moisture under the post-treatment conditions described herein. The released acid and the released moisture may (e.g., uniformly) diffuse through the thin-film conductor having a predetermined thickness to reach metal oxide (e.g., ZnMgO) nanoparticles in the electron transport layer. In the method of the embodiment, the acid material may be provided in the form of a solution. In the method of the embodiment or the device of the embodiment, the acid material may be provided in the form of a layer (e.g., a film). The light-emitting device of the embodiment may further include a container or a light-transmissive component configured to receive or accommodate at least a portion of the stacked structure, and the acid material may be disposed on the surface of the container (refer to Figure 1A , 1B and 1C). The surface of the acid material (film) may be disposed to face the thin-film conductor (e.g., face the main surface of the thin-film conductor). The acid material (film) may be disposed to face the electron transport layer (e.g., face the main surface of the electron transport layer).

[0234] The hydrogen ions and moisture supplied from the acid material in the embodiment may passivate the defects on the surface of the metal oxide nanoparticles, e.g., via a chemical reaction therebetween, to remove the trapping sites, thereby suppressing the leakage current of holes generated by the trapping sites in the metal oxide (e.g., ZnMgO) nanoparticles and enhancing the hole blocking ability of the metal oxide-based electron transport layer. The light-emitting device of the embodiment may exhibit an increased external quantum efficiency (EQE) because the post-treatment may result in more efficient hole-electron recombination than conventional techniques.

[0235] In addition, the post-treatment may provide surface modification of the metal oxide nanoparticles, thereby reducing the trapping sites, and may prevent or suppress charge accumulation at the trapping sites or unwanted charging in the device. Additionally, when driven at the required voltage for a long time, the device of the embodiment may exhibit reduced / suppressed degradation of the semiconductor nanoparticles or the ETL material (e.g., metal oxide nanoparticles), and thus may exhibit improved (e.g., extended) device lifetime.

[0236] In an embodiment, the acid material may include a polymeric acid compound, and the polymeric acid compound may (e.g., in its repeating unit) include a carboxyl group (COOH), a phosphonic acid group (PO(OH)2), a sulfonic acid group (SO3H), or a combination thereof. In an embodiment, the acid material may be a non-polymeric acid compound, including inorganic acids such as sulfuric acid, hydrochloric acid, etc.; C2-50 carboxylic acid compounds (e.g., represented by R(COOH) n ), sulfinic acid compounds (e.g., represented by R(SO2H) nrepresented); a sulfonic acid compound (e.g., represented by R(SO3H) n represented), or a combination thereof. In an embodiment, the acid material may include, for example, a non-polymeric carboxylic acid compound represented by R(COOH) n represented. In the above formula, R is a C1 to C50 or C3-C25 or C5-C8 substituted or unsubstituted aliphatic or aromatic hydrocarbon group, and n is 1 to 10 or 2 to 8 or 3 to 6, 4 to 5. The acid material may include a polymeric acid compound and a non-polymeric acid compound (e.g., a non-polymeric carboxylic acid compound).

[0237] In an embodiment, the acid material (e.g., a polymeric acid compound or a non-polymeric carboxylic acid compound) may have a molecular weight or an average molecular weight (hereinafter referred to as "molecular weight") that is greater than or equal to about 50 g / mol, greater than or equal to about 80 g / mol, greater than or equal to about 100 g / mol, greater than or equal to about 150 g / mol, greater than or equal to about 200 g / mol, greater than or equal to about 250 g / mol, greater than or equal to about 300 g / mol, greater than or equal to about 350 g / mol, greater than or equal to about 400 g / mol, greater than or equal to about 450 g / mol, greater than or equal to about 500 g / mol, greater than or equal to about 550 g / mol, greater than or equal to about 600 g / mol, greater than or equal to about 650 g / mol, greater than or equal to about 700 g / mol, greater than or equal to about 750 g / mol, greater than or equal to about 800 g / mol, greater than or equal to about 900 g / mol, greater than or equal to about 1000 g / mol, greater than or equal to about 1100 g / mol, greater than or equal to about 1200 g / mol, greater than or equal to about 1300 g / mol, greater than or equal to about 1400 g / mol, greater than or equal to about 1500 g / mol, greater than or equal to about 1600 g / mol, greater than or equal to about 1700 g / mol, greater than or equal to about 1800 g / mol, greater than or equal to about 1900 g / mol, greater than or equal to about 2000 g / mol, greater than or equal to about 2100 g / mol,Greater than or equal to about 2200 g / mol, greater than or equal to about 2300 g / mol, greater than or equal to about 2400 g / mol, greater than or equal to about 2500 g / mol, greater than or equal to about 3000 g / mol, greater than or equal to about 3500 g / mol, greater than or equal to about 4000 g / mol, greater than or equal to about 4500 g / mol, greater than or equal to about 5000 g / mol, greater than or equal to about 5500 g / mol, greater than or equal to about 6000 g / mol, greater than or equal to about 7000 g / mol, greater than or equal to about 8000 g / mol, greater than or equal to about 9000 g / mol, greater than or equal to about 10000 g / mol, greater than or equal to about 15000 g / mol, greater than or equal to about 20000 g / mol, greater than or equal to about 25000 g / mol, greater than or equal to about 30000 g / mol, greater than or equal to about 35000 g / mol, greater than or equal to about 40000 g / mol, greater than or equal to about 45000 g / mol, greater than or equal to about 50000 g / mol, greater than or equal to about 55000 g / mol, greater than or equal to about 60000 g / mol, greater than or equal to about 65000 g / mol, greater than or equal to about 70000 g / mol, greater than or equal to about 75000 g / mol, greater than or equal to about 80000 g / mol, greater than or equal to about 85000 g / mol, greater than or equal to about 90000 g / mol, greater than or equal to about 95000 g / mol, greater than or equal to about 100000 g / mol, greater than or equal to about 120000 g / mol, greater than or equal to about 140000 g / mol, greater than or equal to about 160000 g / mol, greater than or equal to about 180000 g / mol, greater than or equal to about 200000 g / mol, greater than or equal to about 220000 g / mol, greater than or equal to about 240000 g / mol, greater than or equal to about 260000 g / mol, greater than or equal to about 280000 g / mol, greater than or equal to about 300000 g / mol, greater than or equal to about 350000 g / mol, greater than or equal to about 400000 g / mol, greater than or equal to about 450000 g / mol, greater than or equal to about 500000 g / mol, greater than or equal to about 550000 g / mol, or a combination thereof.,

[0238] The molecular weight of the acid material can be less than or equal to about 8,000,000 g / mol, less than or equal to about 7,000,000 g / mol, less than or equal to about 6,000,000 g / mol, less than or equal to about 5,000,000 g / mol, less than or equal to about 4,000,000 g / mol, less than or equal to about 3,000,000 g / mol, less than or equal to about 2,000,000 g / mol, less than or equal to about 1,500,000 g / mol, less than or equal to about 1,200,000 g / mol, less than or equal to about 1,000,000 g / mol, less than or equal to about 900,000 g / mol, less than or equal to about 800,000 g / mol, less than or equal to about 700,000 g / mol, less than or equal to about 600,000 g / mol, less than or equal to about 500,000 g / mol, less than or equal to about 450,000 g / mol, less than or equal to about 200,000 g / mol, less than or equal to about 150,000 g / mol, less than or equal to about 100,000 g / mol, less than or equal to about 90,000 g / mol, less than or equal to about 80,000 g / mol, less than or equal to about 70,000 g / mol, less than or equal to about 50,000 g / mol, less than or equal to about 20,000 g / mol, less than or equal to about 10,000 g / mol, less than or equal to about 5,000 g / mol, less than or equal to about 3,000 g / mol, less than or equal to about 2,000 g / mol, less than or equal to about 1,000 g / mol, less than or equal to about 800 g / mol, less than or equal to about 500 g / mol, less than or equal to about 450 g / mol, less than or equal to about 400 g / mol, less than or equal to about 350 g / mol, less than or equal to about 300 g / mol, less than or equal to about 250 g / mol, less than or equal to about 200 g / mol, or a combination thereof.

[0239] In the case where the acid material is a polymeric acid compound, the molecular weight (i.e., the average molecular weight) of the polymeric acid compound can be obtained by considering the molecular weight of the monomer (e.g., g / mol) and the degree of polymerization of the repeating unit, and can exhibit a molecular weight distribution. The average molecular weight of the polymeric acid compound can be the average molecular weight of the polymer and can be the number average molecular weight, the weight average molecular weight, or the viscosity average molecular weight.

[0240] In an embodiment, the average molecular weight of the polymeric acid compound can be measured by using a solution of the polymeric acid compound. 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 g or less of the polymer is dissolved per 100 milliliters (mL), for example, can be used for the 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. In gel permeation chromatography, the polymer dissolved in a solvent can be separated according to its size (dimension), and the results obtained can be calibrated using a standard material having a determined molecular weight. In the end group analysis method, the molecular weight can be measured by quantifying the carboxyl groups by dissolving the polymer in a solvent. According to the established standards, using commercially available devices, each measurement method can easily and reproducibly provide substantially the same information regarding 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.

[0241] The acid material (e.g., polymeric acid compound, non-polymeric carboxylic acid compound, or a combination thereof) can be commercially available from various manufacturers. The manufacturers provide information on the acid material (e.g., in the case of a polymeric acid compound, number average molecular weight, weight average molecular weight, etc.), and thus polymeric acid compounds having desired levels and types of molecular weight values can be obtained commercially.

[0242] The acid material (e.g., a polymeric acid compound, a non-polymeric carboxylic acid compound, or a combination thereof) can be water-soluble and / or alcohol-soluble. In an embodiment, the acid material (e.g., a polymeric acid compound, a non-polymeric carboxylic acid compound, or a combination thereof) can have the following solubility in water or a C1 to C10 alcohol (e.g., ethanol) (e.g., at room temperature or at a temperature of 20 °C or at 25 °C): greater than or equal to about 1 g / L, greater than or equal to about 10 g / L, greater than or equal to about 20 g / L, greater than or equal to about 30 g / L, greater than or equal to about 40 g / L, greater than or equal to about 50 g / L, greater than or equal to about 60 g / L, greater than or equal to about 70 g / L, greater than or equal to about 80 g / L, greater than or equal to about 90 g / L, greater than or equal to about 100 g / L, greater than or equal to about 110 g / L, greater than or equal to about 120 g / L, greater than or equal to about 130 g / L, greater than or equal to about 140 g / L, greater than or equal to about 150 g / L, greater than or equal to about 160 g / L, greater than or equal to about 170 g / L, greater than or equal to about 180 g / L, greater than or equal to about 190 g / L, greater than or equal to about 200 g / L, greater than or equal to about 210 g / L, greater than or equal to about 220 g / L, greater than or equal to about 230 g / L, greater than or equal to about 240 g / L, greater than or equal to about 250 g / L, greater than or equal to about 260 g / L, greater than or equal to about 270 g / L, greater than or equal to about 280 g / L, greater than or equal to about 290 g / L, greater than or equal to about 300 g / L, or a combination thereof, but not limited thereto. In an embodiment, the solubility of the acid material in water or a C1 to C10 alcohol (e.g., ethanol) (e.g., at room temperature or at a temperature of 20 °C or at 25 °C) 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 1000 g / L, less than or equal to about 900 g / L, less than or equal to about 800 g / L, less than or equal to about 700 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 300 g / L, less than or equal to about 200 g / L, or a combination thereof, but not limited thereto.

[0243] In an embodiment, the acid material can have a relatively high level of solubility in water or a water-miscible organic solvent such as an alcohol solvent, and the viscosity of the composition or coating solution used to form the organic layer can be relatively easily controlled to form a layer or film. Thus, a higher degree of flexibility for forming a film or layer can be achieved compared to an adhesive composition having a relatively high viscosity (e.g., a composition based on a curable resin).

[0244] In an embodiment, the acid material may be configured to exhibit a pH in an aqueous solution state or an alcohol solution state as follows: less than or equal to about 5, less than or equal to about 4.9, less than or equal to about 4.7, less than or equal to about 4.4, less than or equal to about 4.2, less than or equal to about 4, less than or equal to about 3.8, less than or equal to about 3.6, less than or equal to about 3.4, less than or equal to about 3.2, less than or equal to about 3, less than or equal to about 2.8, less than or equal to about 2.6, less than or equal to about 2.4, less than or equal to about 2, less than or equal to about 1.8, less than or equal to about 1.7, less than or equal to about 1.6, less than or equal to about 1.55, less than or equal to about 1.5, or less than or equal to about 1. In an embodiment, the acid material may be configured to exhibit a pH in an aqueous solution state or an alcohol solution state as follows: greater than or equal to about 0.5, greater than or equal to about 1, greater than or equal to about 1.5, greater than or equal to about 1.8, greater than or equal to about 2, greater than or equal to about 2.5, 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, or greater than or equal to about 4.8. In an aqueous solution or an alcohol solution of the acid material, the concentration of the polymeric acid compound 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.

[0245] In an embodiment, the acid material may include a polymeric acid compound. The polymeric acid compound may include polyacrylic acid, polymethacrylic acid, polyacrylic acid-methacrylic acid, a (partial) alkali metal salt of polyacrylic acid, a copolymer including (meth)acrylic acid repeating units, a polyvinylphosphonic acid compound, a poly(aromatic sulfonic acid), a poly(vinylsulfonic acid) compound, polymaleic acid, or a combination thereof (e.g., a copolymer or a mixture thereof). The polymeric acid compound may further include an ester of the corresponding acid group (i.e., -COOR, where R is an alkyl or aryl group). The poly(aromatic sulfonic acid) may include polystyrene sulfonic acid, polystyrene sulfonic acid-co-maleic acid, an alkali metal salt thereof, or a combination thereof.

[0246] In an embodiment, the acid material may include a non-polymeric carboxylic acid compound. The non-polymeric carboxylic acid compound may include a compound represented by R(COOH) n wherein R is a substituted or unsubstituted C1 to C50 (C2-C10, C3-C6, C4-C5) aliphatic or aromatic hydrocarbon group, e.g., a substituted or unsubstituted alkyl or alkylene group, a substituted or unsubstituted alkenyl or alkenylene group, a substituted or unsubstituted alkynyl or alkynylene group, or a substituted or unsubstituted aryl or arylene group, and n is an integer from 1 to 10, 2 to 8, or 3 to 6.

[0247] Non-polymeric carboxylic acid compounds may include polycarboxylic acid compounds having two or more carboxylic acid groups. The polycarboxylic acid compounds may be compounds having 2 to 10, 3 to 7, 4 to 6, or 5 to 8 carboxylic acid groups. The polycarboxylic acid compounds may have 1 to 10, 2 to 5, 3 to 4 substituted or unsubstituted C 1-100 , C 2-50 , C 6-15 , C 3-5 aliphatic hydrocarbon groups, 1 to 10, 2 to 5, 3 to 4 substituted or unsubstituted C 6-15 aromatic hydrocarbon groups, or combinations thereof. The polycarboxylic acid compounds may further include hydroxyl groups.

[0248] Non-polymeric carboxylic acid compounds (e.g., polycarboxylic acid compounds) may include compounds represented by HOOC-A-(COOH) m , where A is a single bond, a carbon atom, a substituted or unsubstituted C1 to C100 (C1-C50, C2-C45, C3-C40, C4-C20, 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 may be replaced by CO, NH, O, COO, CONH or a combination thereof. The group A may further have a hydroxyl group. The non-polymeric carboxylic acid compound or the polycarboxylic acid compound may have a carbon number 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 non-polymeric carboxylic acid compound or the polycarboxylic acid compound may have a carbon number 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. The non-polymeric carboxylic acid compound or the polycarboxylic acid compound may 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, acetic acid, (meth)acrylic acid or combinations thereof.

[0249] The acid materials may include polymeric acid compounds and non-polymeric carboxylic acid compounds.

[0250] The acid material 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; 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 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, from 2 to 8, or from 3 to 6. The sulfinic acid compound, the sulfonic acid compound or a combination thereof may further include a hydroxyl group.

[0251] In the acid material (film), 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 urethane polymer, crosslinked thiol-ene polymer, etc.) may 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 acid material (film) may substantially not include a crosslinked polymer.

[0252] The acid material (film) may be configured to dissolve at least a part of it when immersed in water (or a C1 to C5 alcohol). The temperature of the water (or the temperature of the C1 to C5 alcohol) may be greater than or equal to about 25 °C. The temperature of the water (or the temperature of the C1 to C5 alcohol) may be less than or equal to its boiling point (e.g., less than or equal to about 50 °C, or less than or equal to about 30 °C).

[0253] In an embodiment, the acid material may be in the form of a thin film, and the acid material (or its film) may have an organic layer thickness 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.

[0254] The thickness of the acid material may be 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 acid material 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.

[0255] In an embodiment, the light-emitting device 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 thin film conductor (or a second electrode). The container may include a light-transmissive member (e.g., a light-transmissive material or a light-transmissive component). The container may further include additional components coupled or connected to the light-transmissive member, and the additional components may include a light-transmissive or non-light-transmissive material (a sealing material). In an embodiment, the container may be a single-piece material. In an embodiment, the container may be formed by combining a plurality of components. In an embodiment, the container may be a one-piece light-transmissive component or member (e.g., a packaging glass) (see: Figure 1B and Figure 7Encapsulating glass). In an embodiment, the container may include a light-transmissive component (e.g., a light-transmissive assembly) and a seal. The container may be an encapsulation element for a stacked structure. 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 description provided herein for the substrate. 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 a defined space.

[0256] In the light-emitting device of an embodiment, an acid material (film) may be provided adjacent to or in contact with the container or the light-transmissive component (or assembly). The acid material (film) may be applied or coated on the surface of the container or the light-transmissive component. The light-emitting device of an embodiment may not include an acid material (film).

[0257] In an embodiment, the light-emitting 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 multilayer structure in which adjacent layers include different components. (Refer to Figure 1A , 1B , and 2)

[0258] 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 close to the first electrode 1, 10 (e.g., adjacent thereto) and a hole transport layer close to the light-emitting layer 3, 30 (e.g., adjacent thereto).

[0259] In an embodiment, the material included in the hole auxiliary layer 2, 20 (e.g., hole transport layer, hole injection layer, or electron blocking layer) is not particularly limited and may include, for example, poly(9,9-dioctylfluorene-co-N-(4)-butylphenyl)-diphenylamine) (TFB), polyarylamine (polyarylamine), poly(N-vinylcarbazole), poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS), polyaniline, polypyrrole, N,N,N',N'-tetrakis(4-methoxyphenyl)-benzidine (TPD), 4,4'-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), m-MTDATA (4,4',4"-tris[phenyl(m-tolyl)amino]triphenylamine), 4,4',4"-tris(N-carbazolyl)-triphenylamine (TCTA), 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), p-type metal oxides (e.g., NiO, WO3, MoO3, etc.), carbon-based materials such as graphene oxide, or a combination thereof, but not limited thereto.

[0260] 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.

[0261] In the device of the embodiment, the anode 1, 10 disposed on the transparent substrate 100 may include a metal oxide-based transparent electrode (e.g., ITO electrode), and the cathode 5, 50 facing the anode 1, 10 may include a conductive metal (e.g., having a relatively low work function, such as Mg, Al, etc.). The hole auxiliary layer 2, 20 (e.g., hole injection layer such as PEDOT:PSS, p-type metal oxide, or a combination thereof; 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). The electron transport layer or the electron auxiliary layer including it (e.g., electron injection / transport layer) 40 may be disposed between the light-emitting layer 30 and the cathode 50.

[0262] In an embodiment, the light-emitting device may include anodes 1, 10 disposed on a substrate 100 and a driving circuit (e.g., a TFT, not shown); hole auxiliary layers 2, 20 disposed on the above anodes; light-emitting layers 3, 30 disposed on the hole auxiliary layers; electron auxiliary layers (or electron transport layers) 4, 40 disposed on the light-emitting layers; and cathodes or thin-film conductors 5, 50 disposed on the electron auxiliary layers. In an embodiment, the anode may be a reflective electrode, the cathode may be a transparent or semi-transparent electrode, and the light-emitting device may be a top-emission type light-emitting device. (See Figure 4 ). In an embodiment, the anode may be a transparent electrode, the second electrode may be a reflective electrode, and the light-emitting device may be a bottom-emission type. (See Figure 8 )

[0263] In an embodiment, the light-emitting device of the embodiment may be manufactured by a method including the following:

[0264] Forming a light-emitting (e.g., patterned) layer including semiconductor nanoparticles on or above a first electrode, forming an electron transport layer on the light-emitting layer, and forming a second electrode on or above the electron transport layer to form a stacked structure, and performing post-treatment on the stacked structure using an acid material and a container.

[0265] In an embodiment, the method may further include forming a hole auxiliary 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 that described herein.

[0266] In an embodiment, the post-treatment includes placing at least a part of the stacked structure (e.g., the electron transport layer and the second electrode) together with an acid material in a space (e.g., a closed space) defined by a container; and

[0267] Maintaining the stacked structure in the defined space at a post-treatment temperature greater than or equal to about 40 °C and less than or equal to about 200 °C; and wherein the acid material includes a polymeric acid, a non-polymeric acid compound (e.g., a non-polymeric carboxylic acid compound), or a combination thereof.

[0268] In an embodiment, the non-polymeric acid compound may include inorganic acids such as sulfuric acid, hydrochloric acid, etc.; 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) nrepresentation), or a combination thereof. In an embodiment, the acid material may include, for example, a non-polymeric C2-C51 carboxylic acid compound, such as R(COOH) n as represented. In the above formula, R is a C1 to C50 or C3-C25 or C5-C8 substituted or unsubstituted aliphatic or aromatic hydrocarbon group, and n is 1 to 10 or 2 to 8 or 3 to 6, 4 to 5. The acid material may include both polymeric acid compounds and non-polymeric acid compounds (e.g., non-polymeric carboxylic acid compounds). Further details of the acid material, polymeric acid compounds, and non-polymeric acid compounds are the same as those described herein.

[0269] The space may be an enclosed space, e.g., a sealed space or an airtight or gas-tight space. The method may further include removing the container or separating the stacked structure from the container after the post-treatment. The post-treatment may be performed for a predetermined time.

[0270] The container may include a light-transmissive component (e.g., a light-transmissive material or assembly). The container may be or include encapsulating glass configured to accommodate at least a part (or all) of the stacked structure. The container may be a separate device or apparatus that can control temperature and provide a space (e.g., an enclosed space), such as a furnace or a chamber.

[0271] Details of the container and the post-treatment are the same as those described herein.

[0272] In the method of an embodiment, a stacked structure may be obtained by forming a light-emitting layer and an electron transport layer on a first electrode and, for example, between pixel defining layers (PDLs), and then forming a thin film conductor on the electron transport layer (see Figure 4 and 5 ). The method may further include forming a hole assisting layer on the first electrode, e.g., before forming the light-emitting layer. An acid material and a container may be provided to the thus obtained stacked structure such that the acid material and at least a part of the stacked structure (e.g., the electron transport layer and the thin film conductor) can be placed in the space defined by the container. (See Figure 6 , Figure 7 and Figure 9 )

[0273] Surprisingly, the present inventors have found that by performing the post-treatment described herein, the properties of the light-emitting device can be significantly improved. The acid material can release acid and moisture under the post-treatment conditions described herein, and the released acid and the released moisture 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.

[0274] The thin film conductor may have a specified thickness such that it may have electrical conductivity capable of serving as an electron injection conductor and may allow the diffusion or propagation (e.g., downward) of acid / moisture released from the acid material and transfer to an electron transport layer provided under the thin film conductor. Providing an acid / moisture vapor environment and generating an environment of relatively high temperature may promote the surface modification reaction.

[0275] The method may further include preparing a composition containing an acid material including a liquid carrier (e.g., a solvent) and the acid material. Details of the acid material are the same as those described herein. The method may include providing the composition containing the acid material to a container or a space defined by the container. It may also include applying the composition containing the acid material to the surface of the container to form a film of the acid material. The composition containing the acid material may be obtained by dissolving the acid material and optionally an additive in the liquid carrier. Details of the additive are the same as those described above. The concentration of the additive may be appropriately selected in consideration of the type of the additive, the type of the acid material, and the thickness of the acid material film to be formed.

[0276] The liquid carrier may include an alcohol solvent such as ethanol, methanol, propanol, isopropanol, (iso)butanol, (iso)pentanol, hexanol, heptanol, octanol, nonanol, etc.; a nitrile solvent such as acetonitrile; an ester solvent such as ethyl acetate; or a combination thereof.

[0277] The acid material has a relatively high level of solubility in water or an organic solvent, and it can easily provide a composition containing the acid material having an appropriate viscosity. The viscosity of the composition containing the acid material may be 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 at room temperature (e.g., a temperature of about 20 °C to about 30 °C, or at 25 °C), but is not limited thereto.

[0278] The acid material concentration, the type of the acid material, the type of the additive, and the desired thickness of the organic layer may be appropriately selected in the composition containing the acid material.

[0279] In an embodiment, based on the total weight of the composition, the concentration of the acid material (e.g., a polymeric acid compound) in the composition containing the acid material can be 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 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%. In an embodiment, based on the total weight of the composition, the concentration of the acid material in the composition containing the acid material can be 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%.

[0280] If present, the concentration of the acid material (e.g., non-polymeric acid compound) or additive in the composition containing the acid material can be from about 0.0001 moles per liter (M) to about 10 M, 0.0005 M to about 5 M, 0.001 M to about 4 M, 0.005 M to about 3 M, 0.01 M to about 2 M, 0.05 M to about 1.5 M, 0.1 M to about 1.3 M, 0.1 M to about 1.2 M, 0.15 M to about 1 M, 0.15 M to about 0.9 M, 0.2 M to about 0.8 M, 0.3 M to about 0.7 M, 0.4 M to about 0.6 M, 0.45 M to about 0.55 M, or a combination thereof.

[0281] The manner of applying the composition containing the acid material is not particularly limited and can be appropriately selected. The application methods can include spin coating, blade coating, drop casting, or a combination. After applying the composition containing the acid material, the excess composition can be removed by rotation or the like.

[0282] The formation of the acid material (film) may not involve a polymerization reaction and / or a crosslinking reaction. Thus, the content of the crosslinked polymer in the acid material (film) can be less than 1 wt%. When a layer containing a crosslinked polymer (e.g., as a main component) is provided in the light extraction path, significant light absorption can occur in a predetermined wavelength range, and such a light-emitting device including the crosslinked polymer cannot be used for, for example, a top-emission type display panel where the second electrode serves as a transparent or light-extracting electrode. In addition, the acid material (film) containing a crosslinked resin can have a relatively high viscosity, which can make it difficult to form the acid material (film) to have a desired thickness. Furthermore, the present inventors have found that the acid material containing a crosslinked resin as a main component does not provide sufficient acid and moisture in the method of the embodiment.

[0283] In an embodiment, the post-treatment can be carried out in a suitable atmosphere (e.g., in an inert gas atmosphere or in an oxygen-free atmosphere or in air).

[0284] Since the acid material (e.g., having the molecular weight described herein) is a hydrophilic polymer or hydrophilic compound, a relatively increased amount of moisture and relatively labile acid moieties (e.g., COOH groups) may be present in the acid material (film). The acid material (film) of the embodiment can relatively easily and gradually release moisture and acid under a predetermined atmosphere (e.g., an inert gas atmosphere or an atmospheric atmosphere) and at a predetermined temperature. The released moisture and the released acid can diffuse through a thin film conductor having a specified thickness to reach the metal oxide nanoparticles present in the electron assisting layer, and surface modification thereof can be achieved. In the embodiment, the moisture and acid components that have relatively easily and gradually moved to the electron assisting layer can participate in interactions or reactions (e.g., dehydration condensation reactions, etc.) with the metal oxide nanoparticles (e.g., various defect sites or hydroxyl groups that may be present on the surface of the metal oxide nanoparticles). It is believed that these interactions and reactions can modify the surface of the metal oxide nanoparticles to eliminate defects and / or can lead to the growth of the nanoparticles.

[0285] 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 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.

[0286] The post-treatment time (i.e., the predetermined time of the post-treatment) can be greater than or equal to about 1 hour, 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 and 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 2 days, 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 7 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.

[0287] The method of the embodiment can further include forming a thin film conductor (or a second electrode) having an increased thickness by further providing a conductive layer on the thin film conductor after the post-treatment. (See Figure 8 ).

[0288] In an embodiment, the 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,

[0289] wherein the light-emitting layer includes semiconductor nanoparticles, and the light-emitting layer is configured to emit a first light,

[0290] 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 or less, and 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,

[0291] wherein the second electrode has a thickness greater than or equal to about 1 nm (or greater than 10 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%,

[0292] wherein the first electrode is configured to reflect at least a portion of the first light.

[0293] The first electrode may include a hole injection conductor, and the second electrode may include an electron injection conductor.

[0294] The semiconductor nanoparticles or the light-emitting layer may not contain cadmium, lead, mercury, or a combination thereof.

[0295] The second electrode may have a thickness greater than or equal to about 11 nm and less than or equal to about 40 nm.

[0296] The first electrode may be configured to reflect at least a portion of the first light.

[0297] 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.

[0298] The light-emitting device may further include a layer of an acid material disposed on the electron transport layer, and the acid material may include a polymeric acid compound, a non-polymeric carboxylic acid compound, or a combination thereof.

[0299] The layer (or film) of the acid material may be disposed spaced apart from the electron transport layer and the second electrode. The layer of the acid material may be disposed facing the electron transport layer and / or the second electrode or a thin film conductor.

[0300] The electron transport layer may have a first surface facing the light-emitting layer and a second surface opposite the first surface, and a layer of an acid material may be disposed on the second surface. The layer of the acid material may be spaced apart from (e.g., separated from) the electron transport layer.

[0301] The layer (or film) of the acid 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 acid material layer (or film) may be less than or equal to about 100 micrometers (μm), or less than or equal to about 10 μm.

[0302] 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 the first surface, and the acid material film may be disposed to be spaced apart from the electron transport layer and / or the second electrode, and may be disposed to face at least a part (e.g., all) of the surface of the electron transport layer and / or at least a part (e.g., all) of the second surface of the second electrode.

[0303] The light-emitting device (e.g., the details of its elements such as semiconductor nanoparticles, metal oxide nanoparticles, the first / second electrodes, the thin film conductor, the acid material, and the acid material layer or film are the same as those described herein. For the details of the second electrode, reference may also be made to the description of the thin film conductor.

[0304] The light-emitting device of the embodiment may be configured to emit red light, green light, or blue light. The details (e.g., wavelength) of the red light, green light, or blue light are the same as those described herein.

[0305] In an embodiment, the light-emitting device may have a maximum external quantum efficiency (EQE) as follows: 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) may 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%.

[0306] The light-emitting device of the embodiment may exhibit a maximum brightness as follows: 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 / m2 , 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 .

[0307] The light-emitting devices of the embodiments can exhibit the following maximum luminous efficiencies: 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. The light-emitting devices of the embodiments can exhibit a maximum luminous efficiency that is less than or equal to about 1000 cd / A, less than or equal to about 500 cd / A, or less than or equal to about 100 cd / A.

[0308] In an embodiment, as measured by driving the device at a predetermined initial brightness (e.g., about 650 nits), the light-emitting device can exhibit the following T50: 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.

[0309] In an embodiment, as measured by driving the device at a predetermined initial luminance (e.g., about 650 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.

[0310] In an embodiment, the display device includes the light-emitting device described herein.

[0311] The display device may include a first pixel and a second pixel, and the second pixel is configured to emit light different from that of the first pixel.

[0312] Referring Figure 11 , 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, in which the bonding elements may be located.

[0313] 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.

[0314] Each of the sub-pixels PX1, PX2, and PX3 may be configured to display a color of a primary color or a combination of primary colors, for example, 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.

[0315] InFigure 11 In this case, 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.

[0316] In an embodiment, the display panel of the embodiment may include a light-emitting panel, which 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 (turning on and off) and / or driving each of the light-emitting elements.

[0317] Referring to Figure 12 , 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 embodiments described herein.

[0318] 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 or two or more layers, and may cover a part or the entire surface of the lower substrate 110. The buffer layer 111 may be omitted.

[0319] The thin-film transistors TFTs may be three-terminal elements for switching and / or driving the light-emitting elements 180, and one or two or more may be included for each sub-pixel. The thin-film transistors TFTs may include gate electrodes 124, semiconductor layers 154 overlapping the gate electrodes 124, gate insulating layers 140 between the gate electrodes 124 and the semiconductor layers 154, and source electrodes 173 and drain electrodes 175 electrically connected to the semiconductor layers 154. A coplanar top-gate structure is shown as an example, but the structure is not limited thereto and may have various structures.

[0320] The gate electrodes 124 are electrically connected to gate lines (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.

[0321] 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 is not limited thereto. The semiconductor layer 154 may include a channel region and doping regions disposed on both sides of the channel region and electrically connected to the source electrode 173 and the drain electrode 175, respectively.

[0322] 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 figure, 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 layer 154. The gate insulating layer 140 may be formed of one layer or two or more layers.

[0323] 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 doping 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.

[0324] An interlayer insulating layer 145 is additionally 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.

[0325] The 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.

[0326] 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.

[0327] In an embodiment, the light-emitting device or the display device including the same may be a top-emission type, a bottom-emission type, a dual-emission type, or a combination thereof.

[0328] 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 lower substrate 110 (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 lower substrate 110 (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-emission type display panel that emits light on both the substrate side and the opposite side of the substrate.

[0329] The display device or the electronic device may include (or may be) a television, virtual reality / augmented reality (VR / AR), 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.

[0330] 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.

[0331] Examples

[0332] 1. Electroluminescence measurement

[0333] The current according to the applied voltage was measured using a Keithley 2635B source meter, and the electroluminescent properties (e.g., luminance) of the light-emitting device were measured using a CS2000 spectrometer.

[0334] 2. Lifetime characteristics

[0335] T90 and T50 were measured at an initial luminance of 650 nits.

[0336] 3. Electron microscope analysis

[0337] Transmission electron microscopy analysis was performed using a UTF30 Tecnai electron microscope.

[0338] Unless otherwise specified, the following syntheses are carried out under an inert gas atmosphere (e.g., under nitrogen). Unless otherwise specified, the precursor contents are provided as molar contents.

[0339] Synthesis Example 1:

[0340] 2 molar / liter (M) stock solutions of Se / trioctylphosphine (TOP), 1 M stock solution of S / TOP, and 0.1 M stock solution 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.

[0341] The reactor was heated to 300 °C, and the stock solutions of Se / TOP and Te / TOP with a Te:Se molar ratio of 1:20 were rapidly added (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.

[0342] 1.8 mmol amounts 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 stock solutions of Se / TOP and S / TOP were also added to the reactor, and the reactor temperature was raised to about 280 °C. After 2 hours, the reaction was completed, and 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).

[0343] The synthesized semiconductor nanoparticles were precipitated with ethanol (optical density at 420 nm of 0.25, 6 milliliters (mL)) and centrifuged, and the separated nanoparticles were dispersed in cyclohexylbenzene to prepare a QD dispersion.

[0344] Synthesis Example 2: Synthesis of ZnMgO Nanoparticles

[0345] Zinc acetate dihydrate and magnesium acetate tetrahydrate were added to a reactor including dimethyl sulfoxide in a predetermined molar ratio according to the following chemical formula 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.

[0346] 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.

[0347] Example 1:

[0348] A dispersion of zinc magnesium oxide nanoparticles prepared in Synthesis Example 2 was used as an electron transport layer dispersion (hereinafter, ETL dispersion). Polyacrylic acid (weight average molecular weight: 450,000, product name: poly(acrylic acid), PAA, Sigma - Aldrich (181285)) was dissolved in ethanol, and citric acid (HOC(COOH)(CH2COOH)2, CAS No. 77 - 92 - 9) was added at a concentration of 0.1 M to prepare a composition of an acid - containing material (concentration of the polymeric acid compound: 5 wt%).

[0349] The 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), heated at 150 °C for 10 minutes in an air atmosphere, and then heated again at 150 °C for 20 to 30 minutes in an N2 atmosphere to provide a hole - injection layer (HIL) with a thickness of 120 nm.

[0350] 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 150 °C for 30 minutes to provide a hole - transport layer (HTL) with a thickness of 40 nm.

[0351] A light - emitting layer with a thickness of 25 nm was prepared on the prepared hole - transport layer using the QD dispersion prepared in Synthesis Example 1, and then it was heat - treated in an argon atmosphere at a temperature of about 140 °C for 30 minutes. After the heat - treatment, an electron transport layer was formed on the light - emitting layer using the ETL dispersion and heat - treated at 140 °C to form an electron transport layer (thickness: 40 nm).

[0352] Magnesium and silver were thermally deposited on the prepared electron transport layer to prepare a second electrode or thin - film conductor with a thickness of about 20 nm, providing a stacked structure (hereinafter, referred to as "QD stack").

[0353] The fabricated stacked structure was subjected to the following post - treatment to obtain a light - emitting element:

[0354] As Figure 6 Or Figure 7As shown in [reference], the composition of the acid-containing material thus prepared is placed in the form of drops, and then spin-coated on the surface of an open box-shaped container (e.g., encapsulating glass), and then the solvent is removed therefrom to form an acid material film having a thickness of about 3 μm.

[0355] In the sealed space defined by the container (i.e., encapsulating glass), a stacked structure is placed such that the acid material film is spaced apart from and faces the thin film conductor, as Figure 6 or Figure 7 shown in [reference], and then kept in a constant temperature furnace at 70 °C for 5 days to obtain a light-emitting device.

[0356] The electroluminescence properties of the prepared light-emitting device were measured and the results are shown in Table 1.

[0357] Example 2

[0358] A light-emitting device was prepared in the same manner as in Example 1, except that malic acid (Cas.No. 6915-15-7, from Sigma Aldrich) was used instead of citric acid.

[0359] The electroluminescence properties of the prepared light-emitting device were measured and the results are shown in Table 1. The luminous efficiency of the prepared light-emitting device was about 13 cd / A.

[0360] Comparative Example 1

[0361] A light-emitting device was prepared in the same manner as in Example 1, except that the composition of the acid-containing material included an acrylate resin (LOCTITE AA366, from Henkel Co., Ltd.) and acrylic acid (from Sigma Aldrich), instead of PAA and citric acid.

[0362] The electroluminescence properties of the prepared light-emitting device were measured and the results are shown in Table 1. The luminous efficiency of the prepared light-emitting device was about 8 cd / A.

[0363] Table 1

[0364] acid material Max.EQE Max.Lum Relative T90 Relative T50 Example 1 PAA + CtA 9.6％ 43120 nits 8.8 2.6 Example 2 PAA + MA 11.1％ 97713 nits 19.7 6.1 Comparative Example 1 resin + AA 7.6％ 40007 nits 1 1

[0365] Max.EQE: Maximum external quantum efficiency

[0366] Max.Lum: Maximum luminance

[0367] Nit: cd / m 2

[0368] PAA: Polyacrylic acid

[0369] CtA: Citric acid

[0370] MA: Malic acid

[0371] Resin: Acrylate resin

[0372] Relative T50: T50 (hours) of the device / T50 (hours) of Comparative Example 1

[0373] Relative T90: T90 (hours) of the device / T90 (hours) of Comparative Example 1

[0374] It can be confirmed from the results in Table 1 that the electroluminescent device of the embodiment exhibits improved electroluminescent properties and an extended lifespan compared to the device of the comparative example.

[0375] Reference Example 1:

[0376] The electroluminescent properties of the stacked structure that has not undergone the post-treatment process were measured. The maximum EQE of the fabricated light-emitting device was 6.2%, and the maximum luminance was 30518 nits. The relative T90 and relative T50 of the stacked structure were 0.27 and 0.19, respectively.

[0377] Example 3

[0378] A light-emitting device was obtained in the same manner as in Example 1, except for the post-treatment as follows.

[0379] Polyacrylic acid (weight average molecular weight: 450,000, product name: poly(acrylic acid), PAA, manufacturer and product number: Sigma-Aldrich (181285)) was dissolved in ethanol (solid concentration: 5 wt%), and citric acid powder (HOC(COOH)(CH2COOH)2, Cas No. 77-92-9) was added thereto and dissolved (at a concentration of 0.1 M citric acid) to prepare a composition containing an acid material. The composition containing the acid material (PAA 5 wt% + CtA 0.1 M) was placed in a heat-resistant glass container, and as Figure 9 shown, the composition containing the acid material and the fabricated stacked structure were placed in a high-temperature sealing furnace (manufactured by LK lab Korea, model name: LO-VP232N), and then the temperature of the sealing furnace was maintained at 90 °C for 2 hours.

[0380] The electroluminescent properties of the fabricated light-emitting device were measured and the results are summarized in Table 2.

[0381] Example 4

[0382] Citric acid (HOC(COOH)(CH2COOH)2, Cas No. 77-92-9) was dissolved in water to prepare an aqueous citric acid solution with a concentration of 0.1 M. A light-emitting element was prepared according to the same method as in Example 3, except that only 10 ml of the prepared aqueous citric acid solution without PAA was placed in a heat-resistant glass beaker as the composition of the acid-containing material.

[0383] The fabricated light-emitting device was measured for electroluminescence properties and the results were summarized in Table 2.

[0384] Example 5

[0385] Citric acid (HOC(COOH)(CH2COOH)2 and Cas No. 77-92-9) was dissolved in water to prepare an aqueous citric acid solution with a concentration of 1 M. A light-emitting element was prepared according to the same method as in Example 3, except that only 10 ml of the prepared aqueous citric acid solution without PAA was placed in a heat-resistant glass beaker as the composition of the acid-containing material.

[0386] The fabricated light-emitting device was measured for electroluminescence properties and the results were summarized in Table 2.

[0387] Reference Example 2

[0388] In the absence of the composition of the acid-containing material, the stacked structure was placed in a high-temperature sealing furnace as shown in Figure 9 and then the temperature of the sealing furnace was maintained at 90 degrees for 2 hours.

[0389] The fabricated light-emitting device was measured for electroluminescence properties and the results were summarized in Table 2.

[0390] Table 2

[0391] acid material Max.EQE Max.Lum Relative T90 Example 3 PAA 5 wt% + CtA 0.1M about 6% 45591 nits 13.4 Example 4 <![CDATA[CtA 0.1 M (in H2O)]]> 9.2％ 44400 nits 19 Example 5 <![CDATA[CTA1M (in H2O)]]> 8.9％ 46149 nits 13.5 Reference Example 2 none 0.78％ 2551 nits 0.17

[0392] Max.EQE: Maximum external quantum efficiency

[0393] Max.Lum: Maximum luminance

[0394] Nit: cd / m 2

[0395] PAA: Polyacrylic acid

[0396] CtA: Citric acid

[0397] From the results in Table 2, it can be confirmed that compared with the reference example, the light-emitting device of the example can exhibit improved electroluminescence properties and lifetime characteristics.

[0398] Although the present disclosure has been described in connection with what are presently considered to be practical embodiments, it will 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. A method for manufacturing a light emitting device, comprising: forming a light emitting layer including semiconductor nanoparticles on the first electrode; forming an electron transport layer including metal oxide nanoparticles on the light emitting layer; forming a thin film conductor on the electron transport layer to obtain a stacked structure; and Post-processing the stacked structure with an acid material and a container, wherein the light emitting layer is configured to emit a first light when a voltage is applied, The thickness of the thin film conductor is greater than or equal to 1 nanometer (nm) and less than 100 nm. The post-processing includes placing at least a portion of the stacked structure together with the acid material in a space defined by the container; and maintaining the defined space at a post-processing temperature greater than or equal to 40 degrees Celsius (° C.) and less than or equal to 200° C.; wherein said at least a portion of said stacked structure comprises said electron transport layer and said thin film conductor; and The acid material includes a polymeric acid compound, a non-polymeric carboxylic acid compound, or a combination thereof.

2. The method of claim 1, wherein the acid material exhibits a solubility in water greater than or equal to 1 gram / liter.

3. The method of claim 1, wherein the metal oxide nanoparticles have a size greater than or equal to 1 nm and less than or equal to 30 nm, and the metal oxide nanoparticles comprise zinc; and optionally a Group IIA metal, Zr, W, Li, Ti, Y, gallium, indium, tin (Sn), cobalt (Co), vanadium (V), or a combination thereof.

4. The method according to claim 1, wherein the thin film conductor has a thickness greater than 10 nm and less than or equal to 50 nm, Alternatively, the thin film conductor comprises silver, aluminum, magnesium, tungsten, nickel, cobalt, platinum, palladium, calcium, LiF, copper, gold or a combination thereof.

5. The method according to claim 1, wherein the thin film conductor is configured to have a light transmittance greater than or equal to 25% and less than or equal to 100% with respect to the first light, and The first electrode is configured to reflect at least a portion of the first light.

6. The method of claim 1, wherein the acid material is spaced apart from the electron transport layer and the thin film conductor, and The acid material is placed facing the thin film conductor.

7. The method of claim 1, wherein the polymeric acid compound comprises a carboxyl (COOH) group, a phosphonic acid (PO(OH)2) group, a sulfonic acid (SO3H) group or a combination thereof in a repeating unit, and The non-polymeric carboxylic acid compound comprises R(COOH) n A carboxylic acid compound represented by wherein R is a C1 to C50 substituted or unsubstituted aliphatic or aromatic hydrocarbon group, and n is an integer of 2 to 10.

8. The method of claim 1, wherein the non-polymeric carboxylic acid compound has a molecular weight greater than or equal to 100 grams per mole (g / mol) and less than or equal to 500 g / mol, or The polymeric acid compound comprises an average molecular weight greater than or equal to 20,000 g / mol and less than or equal to 550,000 g / mol.

9. The method of claim 1, wherein the container is a furnace comprising a hollow chamber and elements configured to heat the chamber in a controlled manner, and the acid material is provided in the form of a solution.

10. The method of claim 1, wherein the polymeric acid compound comprises poly(meth)acrylic acid, a copolymer thereof, or a combination thereof.

11. The method of claim 1, wherein the non-polymeric carboxylic acid compound comprises 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, trimellitic acid, azelaic acid, suberic acid, tartaric acid, itaconic acid, dodecanedioic acid, acetic acid, or a combination thereof.

12. A light emitting device comprising: a first electrode and a second electrode, a light emitting layer disposed between the first electrode and the second electrode, and An electron transport layer disposed between the light-emitting layer and the second electrode; wherein the light emitting layer comprises semiconductor nanoparticles, and the light emitting layer is configured to emit a first light, wherein the electron transport layer comprises metal oxide nanoparticles having a size greater than or equal to 1 nm and less than or equal to 30 nm, and The metal oxide nanoparticles include zinc; and optionally a Group IIA metal, zirconium, tungsten, lithium, titanium, yttrium, aluminum, gallium, indium, tin, cobalt, vanadium, or a combination thereof, wherein the second electrode has a thickness greater than or equal to 11 nm and less than or equal to 50 nm, and the second electrode exhibits a light transmittance greater than or equal to 50% for the first light, and The first electrode is configured to reflect at least a portion of the first light. 13 . The light emitting device according to claim 12 , wherein the second electrode has a thickness greater than or equal to 12 nm and less than or equal to 40 nm. 14 . The light emitting device according to claim 12 , wherein the light emitting device further comprises a film of an acid material, and wherein the film of the acid material is spaced apart from the electron transport layer and the second electrode and disposed to face the electron transport layer and the second electrode.

15. A light-emitting device according to claim 14, wherein the film of the acid material comprises a polymeric acid compound containing a carboxyl group (COOH), a phosphonic acid (PO(OH)2) group, a sulfonic acid (SO3H) group or a combination thereof in a repeating unit; a non-polymeric carboxylic acid compound; or a combination thereof.

16. The light emitting device according to claim 15, wherein the polymeric acid compound comprises poly(meth)acrylic acid, a copolymer thereof, or a combination thereof, and The non-polymeric carboxylic acid compound comprises R(COOH) n A carboxylic acid compound represented by wherein R is a C1 to C50 substituted or unsubstituted aliphatic or aromatic hydrocarbon group, and n is an integer of 2 to 10.

17. The light emitting device according to claim 12, wherein: The light emitting layer is configured to emit blue light, and wherein the light emitting device exhibits a maximum quantum efficiency greater than or equal to 4%; greater than or equal to 4 candela / square meter (cd / m 2 )'s maximum brightness; a luminous efficiency greater than or equal to 12 candelas per ampere (cd / A); or a combination thereof.

18. An electronic device comprising the light emitting device according to any one of claims 12 to 17.

19. The electronic device of claim 18, wherein the electronic device comprises an augmented reality device, a virtual reality device, a handheld terminal, a monitor, a notebook computer, a television, an electronic display board, a camera, or an electronic component for an autonomous vehicle.

Images