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

Abstract

An electroluminescent device, a method of manufacturing the same, and a display device including the same. The electroluminescent device includes a first electrode and a second electrode spaced apart from each other, a light emitting layer disposed between the first electrode and the second electrode, an electron transport layer disposed between the light emitting layer and the second electrode, and an organic layer. The light emitting layer includes semiconductor nanoparticles, and the electron transport layer includes metal oxide nanoparticles. The organic layer includes a polymeric material and in the organic layer there is a first repeating unit having an acid functional group and a second repeating unit having a hydroxyl group, and the acid functional group includes a carboxylic acid group (COOH), a phosphonic acid (PO (OH) 2) group, a sulfonic acid (SO3H) group, or a combination thereof.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority of Korean Patent Application No. 10 - 2024 - 0002498, filed on January 5, 2024, with the Korean Intellectual Property Office, and all rights arising therefrom, 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, a method of manufacturing the light - emitting device, and a display device including the light - emitting device. Background art

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

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

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

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

[0008] In an embodiment, the electroluminescent device includes:

[0009] a first electrode and a second electrode (thin - film conductor) (e.g., spaced apart, e.g., each electrode having a surface opposite to the other),

[0010] a light - emitting layer disposed between the first electrode and the second electrode, an electron - transport layer disposed between the light - emitting layer and the second electrode, and

[0011] an organic layer including a polymer material.

[0012] The light-emitting layer includes semiconductor nanoparticles, and the electron transport layer includes metal oxide nanoparticles. The metal oxide nanoparticles have a size greater than or equal to about 1 nanometer (nm) and less than or equal to about 50 nm. The organic layer includes a polymer material, and in the organic layer or the polymer material, there are (or include) repeating units having an acid functional group (e.g., a first repeating unit) and repeating units having a hydroxyl group (e.g., a second repeating unit). The acid group may include a carboxylic acid group (e.g., -COOH), a phosphonic acid group (-PO(OH)2), a sulfonic acid group (-SO3H), or a combination thereof.

[0013] The polymer material (hereinafter, may also be simply referred to as "polymer") may include a first polymer and a second polymer. The polymer may be (or include) a mixture of the first polymer or the second polymer. The first polymer may include repeating units having an acid functional group (e.g., a first repeating unit). The second polymer may include repeating units having a hydroxyl group (e.g., a second repeating unit). In an embodiment, the polymer may include a copolymer that includes a first repeating unit having an acid functional group and a second repeating unit having a hydroxyl group.

[0014] The organic layer may be disposed on and / or optionally above the electron transport layer and / or the second electrode.

[0015] 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 organic layer may be disposed on or above the second surface of the electron transport layer (e.g., directly on the second surface of the electron transport layer or spaced apart therefrom).

[0016] The organic layer may be disposed to be spaced apart from the electron transport layer and the second electrode. The organic layer may be disposed to face the electron transport layer and the second electrode. The second electrode may be disposed between the organic layer and the electron transport layer.

[0017] 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 organic layer may be disposed on at least a part (or all) of the surface of the electron transport layer and / or at least a part (or all) of the second surface of the second electrode.

[0018] In an embodiment, the electroluminescent device may further include a container configured to accommodate at least an electron transport layer and a second electrode. The container may include a light-transmissive component (e.g., a light-transmissive material or a light-transmissive constituent (component)). The container may further include additional components (e.g., bonded or attached to the light-transmissive component), such as a sealing material. The container may be an encapsulation element for the 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 an integrated element including a single component or material. The container may be an element including a plurality of components or materials to be combined.

[0019] An organic layer may be disposed on a surface of the container (or the light-transmissive component) (e.g., a surface facing the second electrode). The organic layer may be applied or coated on the surface of the container or the light-transmissive component.

[0020] The electroluminescent device may further include a hole assisting layer between the light-emitting layer and the first electrode. The hole assisting layer may include a hole transport layer (e.g., including an organic compound), a hole injection layer, or a combination thereof. The organic material of the hole injection layer or the hole transport layer may include an arylamine compound such as TPD, an imidazole compound such as TPBi, a carbazole biphenyl compound such as CBP, a carbazole phenylamine compound such as TCTA, a naphthyl biphenyl diamine compound such as NPB, a polymer such as PEDOT:PSS, PVK, or TFB, or a combination thereof, but is not limited thereto.

[0021] The semiconductor nanoparticles may include a first semiconductor nanocrystal and a second semiconductor nanocrystal, the first semiconductor nanocrystal including zinc, selenium, and tellurium, the 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 (a III-V compound or an indium phosphide compound including) indium, phosphorus, and optionally zinc; and a second semiconductor nanocrystal including a zinc chalcogenide and being different from the first semiconductor nanocrystal.

[0022] The size or average size (hereinafter referred to as "size") of the semiconductor nanoparticles may be greater than or equal to about 4 nanometers (nm), greater than or equal to about 5 nm, greater than or equal to about 7 nm, greater than or equal to about 8 nm, greater than or equal to about 9 nm, or greater than or equal to about 10 nm. The size of the semiconductor nanoparticles may be less than or equal to about 30 nm, less than or equal to about 20 nm, less than or equal to about 15 nm, less than or equal to about 12 nm, or less than or equal to about 10 nm.

[0023] The semiconductor nanoparticles may have a core-shell structure, which includes a core and a shell, the core includes a first semiconductor nanocrystal, and the shell is disposed on the core and includes a second semiconductor nanocrystal.

[0024] The electron transport layer may be adjacent to the light-emitting layer (or directly disposed on the light-emitting layer).

[0025] 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.

[0026] The metal oxide nanoparticles may include zinc oxide nanoparticles. The metal oxide nanoparticles may include: zinc; and optionally a Group IIA metal, Zr, W, Li, Ti, Y, Al, Ga, In, Sn, Co, V, or a combination thereof. The metal oxide nanoparticles may further include an alkali metal. The metal oxide nanoparticles may include zinc, a Group IIA metal, and optionally an alkali metal.

[0027] 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.

[0028] The polymer or the first polymer may have a number average or weight average molecular weight as follows: greater than or equal to about 800 g / mol, greater than or equal to about 1200 g / mol, greater than or equal to about 2500 g / mol, greater than or equal to about 10,000 g / mol, greater than or equal to about 50,000 g / mol, greater than or equal to about 100,000 g / mol. The polymer or the first polymer may have a number average or weight average molecular weight as follows: less than or equal to about 5,000,000 g / mol, less than or equal to about 3,000,000 g / mol, less than or equal to about 1,500,000 g / mol, less than or equal to about 1,000,000 g / mol, less than or equal to about 800,000 g / mol, or less than or equal to about 500,000 g / mol.

[0029] The polymer or the first polymer may have a solubility in water of greater than or equal to about 1 gram per liter (g / L), greater than or equal to about 15 g / L, greater than or equal to about 40 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. The solubility of the polymer or the first polymer in water 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, less than or equal to about 1000 g / L, or less than or equal to about 500 g / L, for example, at room temperature, for example, at a temperature of about 20 °C to about 23 °C. The polymer or the first polymer may have a solubility in C1 to C5 alcohols of greater than or equal to about 1 gram per liter (g / L), greater than or equal to about 15 g / L, greater than or equal to about 40 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. The solubility of the polymer or the first polymer in C1 to C5 alcohols 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, less than or equal to about 1000 g / L, or less than or equal to about 500 g / L, for example, at room temperature, for example, at a temperature of about 20 °C to about 23 °C.

[0030] The polymer or the first polymer in a solution state (e.g., in an aqueous solution) may exhibit a pH greater than or equal to about 0.5, greater than or equal to 0.7, or greater than or equal to about 1 and less than or equal to about 7, less than or equal to about 6.5, less than or equal to about 5, less than or equal to about 4.5, less than or equal to about 3, less than or equal to about 2, less than or equal to about 2.5, or less than or equal to about 2.

[0031] The polymer or the first polymer may include a polyacrylic acid compound, polymethacrylic acid, polyacrylic acid-methacrylic acid, an alkali metal salt of poly(meth)acrylic acid (e.g., sodium salt) (or a partial alkali metal salt of poly(meth)acrylic acid), a copolymer including (meth)acrylic acid repeating units, polyvinylphosphonic acid, poly(aromatic sulfonic acid) such as poly(styrenesulfonic acid) or poly(styrenesulfonic acid-co-maleic acid), an alkali metal salt of poly(aromatic sulfonic acid) (e.g., partial salt), poly(vinylsulfonic acid), an alkali metal salt of poly(vinylsulfonic acid) (e.g., partial salt), polymaleic acid, alginic acid, or a combination thereof (e.g., a copolymer of at least two of the foregoing polymers or a mixture of at least two of the foregoing polymers).

[0032] The polymer or the second polymer may include repeating units represented by Chemical Formula 1:

[0033] Chemical Formula 1

[0034]

[0035] wherein A is a direct bond, -CO-, -O-, an ester linkage (-COO- or -OCO-), -CONH-, -NH-, -S-, -SO-, or a combination thereof,

[0036] L is a direct bond, a substituted or unsubstituted (e.g., divalent) C1-30, C2-15, C3-20, C4-8, C5-6 aliphatic hydrocarbon group (e.g., an alkylene or alkenylene group), or a substituted or unsubstituted C6-C20 arylene group (e.g., a phenylene group),

[0037] R are the same or different and each independently is hydrogen or a substituted or unsubstituted C1 to C30 (or C1 to C5) alkyl group, and

[0038] * is the moiety that binds to an adjacent atom (e.g., in the main chain).

[0039] The polymer or the second polymer may include polyvinyl alcohol.

[0040] The polymer or the second polymer may have a number-average or weight-average molecular weight of: greater than or equal to about 500 g / mol, greater than or equal to about 1000 g / mol, greater than or equal to about 5000 g / mol, or greater than or equal to about 10,000 g / mol. The polymer or the second polymer may have a number-average or weight-average molecular weight of: less than or equal to about 5,000,000 g / mol, less than or equal to about 3,000,000 g / mol, or less than or equal to about 1,000,000 g / mol.

[0041] The polymer or the second polymer may have a solubility in water or alcohol of greater than or equal to about 1 g / L, greater than or equal to about 10 g / L, greater than or equal to about 30 g / L, greater than or equal to about 33 g / L, greater than or equal to about 50 g / L, greater than or equal to about 150 g / L, or greater than or equal to about 200 g / L, e.g., at room temperature, e.g., at a temperature of about 20 °C to about 23 °C. The solubility of the polymer or the second polymer in water or alcohol 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, less than or equal to about 1500 g / L, less than or equal to about 1000 g / L, less than or equal to about 500 g / L, or less than or equal to about 200 g / L, e.g., at room temperature, e.g., at a temperature of about 20 °C to about 23 °C.

[0042] The polymer or the second polymer may exhibit a pH of, for example, greater than or equal to about 4.5 and less than or equal to about 8.5, or greater than or equal to about 5 and less than or equal to about 8, or less than or equal to about 7, or less than or equal to about 5.5 when dissolved in water.

[0043] The molar ratio between the first repeating unit (or acid functional group) (e.g., of the first polymer) and the second repeating unit (or hydroxyl group) (e.g., of the second polymer) in the organic layer (or the polymer) may be in the range of 1:0.01 to 1:100, 1:0.05 to 1:20, 1:0.075 to 1:15, 1:0.1 to 1:10, 1:0.3 to 1:3, 1:0.4 to 1:2.5, 1:0.45 to 1:2.3, 1:0.5 to 1:2, 1:0.6 to 1:1.7, 1:0.7 to 1:1.4, 1:0.8 to 1:1.25, 1:0.9 to 1:1.1, or 1:1 to 1:1.05, or a combination thereof.

[0044] The organic layer may have a thickness of: greater than or equal to about 1 nm, greater than or equal to about 10 nm, greater than or equal to about 100 nm, greater than or equal to about 1 micrometer (μm), greater than or equal to about 2 μm, greater than or equal to about 3 μm, greater than or equal to about 4 μm, greater than or equal to about 5 μm, greater than or equal to about 10 μm, greater than or equal to about 100 μm, or greater than or equal to about 1000 μm. The thickness of the organic layer may be 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, less than or equal to about 10 μm, less than or equal to about 9 μm, or less than or equal to about 7 μm.

[0045] The organic layer or the polymer material may include a copolymer that includes the first repeating unit and the second repeating unit. The copolymer may be an alternating copolymer, a block copolymer, a random copolymer, or a combination thereof. The organic layer or the polymer material may include a mixture of the first polymer and the second polymer.

[0046] The organic layer or the polymer material may be configured to dissolve at least partially or completely when immersed in a (mixed) solvent of water and C1 to C10 alcohols. The temperature of the mixed solvent may be greater than or equal to about 25°C and less than or equal to about 100°C, 80°C or lower, 50°C or lower, or 30°C or lower.

[0047] When dissolved in a mixed solvent, the organic layer or polymer material may exhibit a pH of, for example, greater than or equal to about 2.5, greater than or equal to about 3.5, greater than or equal to about 4, greater than or equal to about 4.5, greater than or equal to about 5.5 and less than or equal to about 7.5, less than or equal to about 7, less than or equal to about 6, or less than or equal to about 5.

[0048] The organic layer or polymer material may further include or may not include additives. The additives may include inorganic acids such as sulfuric acid, C2-50 carboxylic acid compounds (e.g., represented by R(COOH) n ), sulfinic acid compounds (e.g., represented by R(SO2H) n ), sulfonic acid compounds (e.g., represented by R(SO3H) n ), or combinations thereof. In the formula, R is a substituted or unsubstituted C1 (or C6) to C50 aliphatic or aromatic hydrocarbon group, and n is an integer from 1 to 10, 2 to 8, or 3 to 5. In an embodiment, the organic layer or polymer material may not include additives.

[0049] Based on the total weight of the organic layer, the amount of the crosslinked polymer in the organic layer or polymer material may be less than about 1 weight percent (wt%), or less than or equal to about 0.9 wt%.

[0050] The organic layer may not include a crosslinked polymer.

[0051] The second electrode may have a thickness greater than about 10 nm, greater than or equal to 11 nm, or greater than or equal to about 15 nm. The second electrode may have a thickness less than or equal to about 80 nm, less than or equal to about 60 nm, less than or equal to about 50 nm, or less than or equal to about 40 nm. The thin film conductor may include silver, aluminum, magnesium, tungsten, nickel, cobalt, platinum, palladium, calcium, LiF, gold, copper, or combinations thereof (e.g., alloys). The second electrode may include silver and magnesium.

[0052] The light-emitting layer may be configured to emit a first light.

[0053] The second electrode may be configured to exhibit a light transmittance of greater than or equal to about 25%, greater than or equal to about 35%, 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%.

[0054] The first electrode may be configured to reflect at least a portion of the first light.

[0055] In an embodiment, a method of manufacturing an electroluminescent device includes:

[0056] Forming a light-emitting layer including semiconductor nanoparticles on a first electrode;

[0057] Form an electron transport layer comprising metal oxide nanoparticles on the light-emitting layer;

[0058] Form a thin film conductor (or second electrode) on the electron transport layer to obtain a stacked structure; and

[0059] Perform post-treatment of the stacked structure using a polymer material comprising a repeating unit having an acid functional group (e.g., a first repeating unit) and a repeating unit having a hydroxyl group (e.g., a second repeating unit),

[0060] wherein the post-treatment comprises

[0061] Dispose the stacked structure and the polymer material together in a first space; and maintain the first space at a post-treatment temperature of greater than or equal to about 40 °C. The post-treatment temperature may be less than or equal to about 200 °C, less than or equal to about 180 °C, or less than or equal to about 150 °C.

[0062] The polymer material may be an organic layer or a composition for forming an organic layer.

[0063] The polymer material may comprise a mixture of a first polymer and a second polymer, the first polymer comprising the first repeating unit and the second polymer comprising the second repeating unit.

[0064] The polymer material may comprise a copolymer comprising the first repeating unit and the second repeating unit.

[0065] The method may further comprise providing a container to the stacked structure, and the container may be configured to define at least a portion of the first space. Details of the container are the same as those described herein. In an embodiment, the container may be an oven or a chamber. In an embodiment, the container may be encapsulation glass. The container may be an oven comprising a hollow chamber and an element configured to heat the chamber in a controlled manner.

[0066] The method may further comprise preparing a composition (e.g., a composition for forming an organic layer) comprising the polymer material (or polymer) and a liquid carrier (e.g., a solvent).

[0067] The method may comprise applying the composition to the electron transport layer (and optionally the second electrode).

[0068] The polymer material or polymer may comprise: a copolymer comprising both the first repeating unit and the second repeating unit; a mixture of a first polymer comprising the first repeating unit and a second polymer comprising the second repeating unit; or a combination thereof.

[0069] The method may further include applying the composition on the electron transport layer (and optionally the second electrode).

[0070] The method may include applying the composition to the surface of a container in a manner such that the organic layer faces the electron transport layer or the second electrode.

[0071] The method may further include removing at least a portion of the liquid carrier from the applied organic layer to form the composition.

[0072] The liquid carrier may include water, C1-10 alcohols, sulfoxide solvents such as dimethyl sulfoxide, nitrile solvents, ester solvents, or combinations thereof. The liquid carrier may include water, ethanol, methanol, propanol, acetonitrile, ethyl acetate, dimethyl sulfoxide, or combinations thereof.

[0073] The liquid carrier may include a mixture of water and C1-10 alcohols.

[0074] In an embodiment, the liquid carrier includes a mixed solvent of water and C1-10 alcohols, and the composition has a pH greater than or equal to about 2 and less than or equal to about 7.

[0075] The method may include preparing a first solution by dissolving the first polymer in a C1-10 alcohol, preparing a second solution by dissolving the second polymer in water, and mixing the first solution and the second solution to provide the composition.

[0076] The composition or the polymeric material may exhibit a pH greater than or equal to about 2, greater than or equal to about 3.5, greater than or equal to about 4, greater than or equal to about 4.5 and less than or equal to about 7.5, less than or equal to about 7, less than or equal to about 6, or less than or equal to about 5.5, less than or equal to about 5, for example, in a solution state.

[0077] The first space may be a closed space, for example, 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, less than or equal to about 150°C, or less than or equal to about 100°C. The post-treatment may be carried out for a predetermined time. The predetermined time may be greater than or equal to about 10 minutes, greater than or equal to about 30 minutes, greater than or equal to about 1 hour, greater than or equal to about 2 hours, greater than or equal to about 5 hours and less than or equal to about 10 days, less than or equal to about 10 hours, less than or equal to about 3 hours.

[0078] The method may further include removing the container after the post-treatment. The method may further include providing a new container with or without an organic layer to the stacked structure after removing the container.

[0079] The method may further include disposing a conductive layer on the thin film conductor after the post-treatment to form a conductor thin film (or a second electrode) having an increased thickness.

[0080] In an embodiment, the display device may include the light-emitting device (e.g., an electroluminescent device).

[0081] In an embodiment, the electronic device may include the light-emitting device.

[0082] The display device or the electronic device may include (or may be) an AR / VR device, a handheld terminal, a monitor, a laptop computer, a television, an electronic display board, a camera, an electronic display component for an autonomous vehicle or an electric vehicle.

[0083] According to an embodiment, there is provided a light-emitting device exhibiting improved light-emitting properties and lifetime characteristics. The device of the embodiment may exhibit improved stability by maintaining the electroluminescent properties at a desired level even under high-temperature exposure or over a long period in a storage environment. The method of the embodiment may enable mass production of a front-emission type (front-facing emission type) light-emitting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] The above and other advantages and features of the present disclosure will become more apparent by referring to the following detailed description of the exemplary embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0085] Figure 1A is a schematic cross-sectional view of an electroluminescent device according to an embodiment;

[0086] Figure 1B is a schematic cross-sectional view of an electroluminescent device according to an embodiment;

[0087] Figure 2A is a schematic cross-sectional view of an electroluminescent device according to an embodiment;

[0088] Figure 2B is a schematic cross-sectional view of an electroluminescent device according to an embodiment;

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

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

[0091] Figure 3B is a schematic cross-sectional view of an electroluminescent device according to an embodiment;

[0092] Figure 3C is a schematic cross-sectional view of an electroluminescent device according to an embodiment;

[0093] Figure 4 is a schematic cross-sectional view of an electroluminescent device according to an embodiment;

[0094] Figure 5A is a schematic cross-sectional view of a light-emitting device according to an embodiment;

[0095] Figure 5B is Figure 5A a plan view of the light-emitting device of

[0096] Figure 6A shows a schematic cross-sectional view of a stacked structure for post-treatment in the process of manufacturing a light-emitting device according to an embodiment.

[0097] Figure 6B shows a schematic cross-sectional view of a stacked structure obtained by the following process: wherein the stacked structure is removed from the container after post-treatment in the process of manufacturing a light-emitting device according to Figure 6A and then a second electrode is formed and a new container (without a polymer layer) is provided.

[0098] Figure 7 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.

[0099] Figure 8 is a schematic cross-sectional view of a light-emitting device (RGB pixel) according to an embodiment.

[0100] Figure 9 is a schematic plan view of a display panel according to an embodiment.

[0101] Figure 10 is a view showing a schematic cross-section of the Figure 9 display panel taken along line IV-IV. DETAILED DESCRIPTION

[0102] 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 apparent. 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.

[0103] 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.

[0104] Further, 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. Further, being "on" a reference part means being disposed above or below the reference part and does not necessarily mean "above".

[0105] It will be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, components (assemblies), regions, layers, and / or portions, these elements, components (assemblies), regions, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component (assembly), region, layer, or portion from another element, component (assembly), region, layer, or portion. Thus, without departing from the teachings herein, the "first element", "component (assembly)", "region", "layer", or "portion" discussed below may be referred to as a second element, component (assembly), region, layer, or portion.

[0106] 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 dictates otherwise. "At least one" will not be construed as limiting "one". "Or" means "and / or".

[0107] 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.

[0108] As used herein, the term "cross-section" means the situation where the cross-section of a given object is cut (e.g., in a substantially vertical direction) and observed in the transverse direction.

[0109] Unless otherwise defined, all terms (including technical and scientific terms) used herein 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.

[0110] 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. In addition, when the work function or energy level is referred to as "deep," "high," or "large," the work function or energy level has a large absolute value based on the vacuum energy level of "0 electron volts (eV)", while when the work function or energy level is 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".

[0111] As used herein, the average (value) can be the mean or the median. In an embodiment, the average (value) can be the mean average.

[0112] As used herein, the term "peak emission wavelength" is the wavelength at the maximum of a given emission spectrum of light.

[0113] As used herein, the term "group" can refer to a group of the periodic table.

[0114] As used herein, "Group I" refers to Group IA and Group IB, and examples can include, but are not limited to, Li, Na, K, Rb, and Cs.

[0115] As used herein, "Group II" refers to Group IIA and Group IIB, and examples of Group II metals can be, but are not limited to, Cd, Zn, Hg, and Mg.

[0116] As used herein, "Group III" refers to Group IIIA and Group IIIB, and examples of Group IIIA metals may be Al, In, Ga, and Tl, and examples of Group IIIB may be scandium, yttrium, etc., but are not limited thereto.

[0117] As used herein, "Group IV" refers to Group IVA and Group IVB, and examples of Group IVA metals may be Si, Ge, and Sn, and examples of Group IVB metals may be titanium, zirconium, hafnium, etc., but are not limited thereto.

[0118] As used herein, "Group V" includes Group VA and includes nitrogen, phosphorus, arsenic, antimony, and bismuth, but is not limited thereto.

[0119] As used herein, "Group VI" includes Group VIA and includes sulfur, selenium, and tellurium, but is not limited thereto.

[0120] As used herein, "metal" includes metalloids such as Si.

[0121] 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.

[0122] 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), azide (-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.

[0123] 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.

[0124] 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 from 1 to 50 carbon atoms, or from 1 to 18 carbon atoms, or from 1 to 12 carbon atoms.

[0125] 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 from 2 to 50 carbon atoms, or from 2 to 18 carbon atoms, or from 2 to 12 carbon atoms.

[0126] 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 from 2 to 50 carbon atoms, or from 2 to 18 carbon atoms, or from 2 to 12 carbon atoms.

[0127] 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 from 6 to 50 carbon atoms, or from 6 to 18 carbon atoms, or from 6 to 12 carbon atoms.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] As used herein, "poly(meth)acrylate" refers to polyacrylate, polymethacrylate, or a combination thereof.

[0132] In embodiments, the "alkali metal salt" of a polymeric acid (e.g., polyacrylic acid or polystyrene sulfonic acid) compound can include a partial alkali metal salt of a given polymeric acid, a complete alkali metal salt of the polymeric acid, or a combination thereof.

[0133] As used herein, the phrase "does not include cadmium (or other harmful heavy metals)" can refer to a situation where the concentration of cadmium (or additional heavy metals that are 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 its impurity level.

[0134] Unless stated to the contrary, the numerical ranges described herein are inclusive. Unless stated to the contrary, the numerical ranges described herein include any real number within the endpoints of the stated range and include the endpoints. As used herein, the upper and lower endpoints recited for each numerical value can be independently combined to provide a range.

[0135] As used herein, "about" includes the recited value and means within an acceptable deviation range for the specific value as determined by one of ordinary skill in the art in view of the measurements discussed and the errors associated with the measurement of a 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 ±5%.

[0136] As used herein, a nanoparticle is a structure having a region or characteristic scale that has a nanoscale dimension (e.g., at least one region or characteristic scale having a nanoscale dimension). In embodiments, the scale (or average scale) of the nanostructure is less than or equal to about 500 nm, less than or equal to about 300 nm, less than or equal to about 250 nm, less than or equal to about 150 nm, less than or equal to about 100 nm, less than or equal to about 50 nm, or less than or equal to about 30 nm. In embodiments, the nanoparticle can have any suitable shape.

[0137] The nanoparticle (e.g., semiconductor nanoparticle or metal oxide nanoparticle) may include nanowires, nanorods, nanotubes, branched nanostructures, nanoterapods, nanotripods, nanobipods, nanodots, multi-legged shapes such as at least two legs, etc., and is not limited thereto. The nanoparticle may be, for example, substantially crystalline, substantially single-crystalline, polycrystalline, (e.g., at least partially) amorphous, or a combination thereof.

[0138] In an embodiment, a semiconductor nanoparticle such as a quantum dot may 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 may have a size smaller than the Bohr excitation diameter of the bulk crystal material having the same composition, and may exhibit a quantum confinement effect. By controlling the size of the nanocrystal serving as the emission center, the semiconductor nanoparticle or quantum dot may emit light corresponding to its bandgap energy.

[0139] 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 or 146 nits), the luminance (e.g., brightness) of the given device decreases to 50% of the initial luminance (100%).

[0140] 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 or 146 nits), the luminance (e.g., brightness) of the given device decreases to 90% of the initial luminance (100%).

[0141] 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 may be a measure of how effectively a given device converts electrons into photons and allows the photons to escape. The EQE may be determined by the following equation:

[0142] EQE = injection efficiency × (solid-state) quantum yield × extraction efficiency

[0143] Where the injection efficiency is the proportion of electrons passing through the device that are injected into the active region, the quantum yield is the proportion of all electron-hole recombinations in the active region that are radiative and produce photons, and the extraction efficiency is the proportion of photons generated in the active region that escape from the given device.

[0144] As used herein, the maximum EQE is the maximum value of the EQE.

[0145] As used herein, the maximum brightness is the highest value of the brightness for a given device.

[0146] As used herein, the phrase "quantum efficiency" may be used interchangeably with the phrase "quantum yield". In an embodiment, the quantum efficiency may be a relative quantum yield or an absolute quantum yield, for example, which may be easily measured by any suitable (e.g., commercially available) device. The quantum efficiency (or quantum yield) may be measured in solution state or solid state (as a complex). In an embodiment, the "quantum yield (or quantum efficiency)" may be the ratio of the photons emitted (e.g., by a nanostructure or a group of nanostructures) to the photons absorbed. In an embodiment, the quantum efficiency may be determined by any suitable method. For example, there may be two methods for measuring the fluorescence quantum yield or efficiency: an absolute method and a relative method.

[0147] 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) may 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 may be used as standard dyes, depending on their photoluminescence (PL) wavelength, but are not limited thereto.

[0148] The bandgap energy of semiconductor nanoparticles may 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 may become smaller, e.g., narrower, and the semiconductor nanoparticles may emit light, e.g., with an increased emission wavelength. Semiconductor nanocrystals may be used as luminescent materials in various fields, such as in display devices, energy devices, or bioluminescent devices.

[0149] An electroluminescent device based on semiconductor nanoparticles (hereinafter, also referred to as QD-LED) may emit light by applying a voltage and includes semiconductor nanoparticles or quantum dots as a luminescent material. The QD-LED, using an emission principle different from that of an organic light-emitting diode (OLED), may 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 may be the basis for next-generation display devices. The method of manufacturing a QD-LED may include a solution process, which may reduce (e.g., decrease) the manufacturing cost. In addition, the semiconductor nanoparticles in the QD-LED may be based on inorganic materials, contributing to achieving increased display (light emission) stability over time. Technologies capable of improving the physical properties and lifetime characteristics of the device are desired.

[0150] In the QD-LED of the embodiment, 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 the emission layer (EML, emission layer, QD emission layer), 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).

[0151] For example, the electron transport layer may be required to have an electron mobility sufficient to balance holes - electrons in the light-emitting layer, and in this case, electrons can be effectively transferred from the electrode to the quantum dot light-emitting layer. Additionally, the electron transport layer may be required to have an appropriate deep HOMO level to sufficiently block holes from the quantum dot light-emitting layer.

[0152] Furthermore, quantum dots or semiconductor nanoparticles exhibiting desired electroluminescent properties may contain harmful heavy metals such as cadmium (Cd), lead, mercury, or combinations thereof. Thus, it may be desirable to provide an electroluminescent device or display device having a light-emitting layer substantially free of such heavy metals.

[0153] In an embodiment, the electroluminescent device may be a device configured to emit desired light by applying a voltage, for example, with or without a separate light source.

[0154] In an embodiment, the light-emitting device (or stacked structure) includes: a first electrode (e.g., a hole injection conductor) 1 and a thin film conductor (e.g., an electron injection conductor or a second electrode) 5 spaced apart (e.g., facing each other); an emission layer 3 disposed between the first electrode and the thin film conductor and including semiconductor nanoparticles; and an electron transport layer or an electron auxiliary layer 4 including an electron transport layer between the emission layer 3 and the thin film conductor 5. The electron transport layer may include metal oxide nanoparticles. The emission layer may be configured to emit a first light by applying a voltage (e.g., between the above-mentioned first electrode and the above-mentioned conductor thin film).

[0155] In an embodiment, the electroluminescent device may further include organic layers 6, 60. The organic layers 6, 60 include a polymeric material, and the organic layer or the polymeric material includes a repeating unit having an acid functional group (first repeating unit) and a repeating unit having a hydroxyl group (second repeating unit). The polymeric material in the organic layer may include a mixture of two or more polymers (a first polymer including the first repeating unit and a second polymer including the second repeating unit), a copolymer (including the first and second repeating units), or a combination thereof. In an embodiment, the organic layer or the polymeric material may include a first polymer and a second polymer (e.g., a mixture of the first polymer and the second polymer). The first polymer may include an acid functional group (or a repeating unit having an acid functional group). The acid functional group may include a carboxyl group (COOH), a phosphonic acid (PO(OH)2) group, a sulfonic acid (SO3H) group, or a combination thereof. The second polymer includes a hydroxyl group (a second repeating unit having a hydroxyl group). In an embodiment, the organic layer or the polymeric material may include a copolymer including the first repeating unit and the second repeating unit.

[0156] The electroluminescent device may further include hole auxiliary layers 2, 20. The hole auxiliary layer may include a hole transport layer (HTL, e.g., including an organic compound), a hole injection layer (HIL), or a combination thereof. (See: Figure 1A and 1B 、 Figure 2A 、 2B and 2C)

[0157] In the electroluminescent device of the embodiment, the organic layer 6 may be disposed on the electron transport layer 4 and / or optionally on the second electrode 5. The organic layer 6 may be disposed adjacent to the electron transport layer and the second electrode (see Figure 1A 、 1B 、and Figure 3A 、 3B and Figure 3C ). The organic layer 6 may be included (disposed) (see Figure 2A 、 2B and Figure 8 ) to be spaced apart from the electron transport layer and the second electrode, e.g., in a non-contact manner or a remote manner (see Figure 2A 、 Figure 2C 、 Figure 4 、 Figure 5A and Figure 8 ).

[0158] The electroluminescent device of the embodiment may further include a container (e.g., a light-transmissive member) configured to accommodate the electron transport layer and the conductor thin film or the second electrode. In addition to the electron transport layer and the conductor thin film, the container may further include at least a part of the stacked structure including the first electrode and the light-emitting layer (including at least a part of the stacked structure including the first electrode and the light-emitting layer). The container may include a light-transmissive member and may further include additional components, seals, etc. The container may include a transparent member, an opaque member (e.g., additional components such as a sealing member), or a combination thereof. The first surface of the container may face the second electrode, and the organic layer may be disposed on the first surface of the container adjacent to or in contact with the container or the light-transmissive member. The first surface of the organic layer may be adjacent to the container, and the second surface opposite to the first surface may face the second electrode and / or the electron transport layer. (See Figure 2A , Figure 2B and Figure 2C , Figure 4 , Figure 5A , Figure 8 )

[0159] In an embodiment, there is provided an electroluminescent device capable of simultaneously exhibiting improved lifetime and electroluminescent characteristics (e.g., device efficiency and brightness). In the electroluminescent device of the embodiment, hole leakage through the electron assisting layer (e.g., the electron transport layer) can be substantially blocked, and thus, the electroluminescent device of the embodiment can exhibit increased electron transport properties, achieve an improved electron-hole balance in the light-emitting layer, and can suppress or prevent the deterioration of the device due to charging.

[0160] In the electroluminescent device of the embodiment, the organic layer or the polymer 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 can be used, for example, in a case where there is substantially no limitation on the light-emitting mode for a display device (e.g., it can be used for both bottom-emission type devices and top-emission type devices). In the light-emitting device of the embodiment, the electron transport layer (ETL) may exhibit improved electron mobility, which can contribute to an improved hole-electron balance in the light-emitting layer and / or can effectively transfer electrons from the electrode to the light-emitting layer.

[0161] In the electroluminescent device of the embodiment, the electron assisting layer (e.g., the electron transport layer) may have a HOMO energy level having a desired depth and may suppress the appearance of trap energy levels, thereby effectively blocking the undesired hole movement from the light-emitting layer including semiconductor nanoparticles (e.g., quantum dots) to the second electrode.

[0162] In the electroluminescent 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 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.

[0163] 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 (see Figure 3A ), or on the substrate and the driving circuit. 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. The light-emitting layer can be disposed in pixels (or sub-pixels) in a display device (display panel) to be described later.

[0164] In the electroluminescent device of the embodiment, the light-emitting layers 3, 30 can be disposed between the first electrode (e.g., anode) 1, 10 and the second electrode (e.g., cathode) 5, 50. The conductor thin film can be the second electrode, or the second electrode can include the conductor thin film. The second electrode or the cathode 5, 50 can include an electron injection conductor. The anode 1, 10 can include a hole injection conductor. 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.

[0165] The electron / hole injection conductor can include metal-based materials (e.g., metals, metal compounds, alloys, or combinations thereof), such as aluminum, magnesium, tungsten, nickel, cobalt, platinum, palladium, calcium, LiF, etc.; metal oxides, such as indium gallium oxide or indium tin oxide (ITO); or conductive polymers (e.g., having a relatively high work function), such as polyethylenedioxythiophene, but is not limited thereto.

[0166] 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.

[0167] The first electrode, the second electrode, or a combination thereof may be disposed on (e.g., an insulating) substrate 100 and optionally on a driving circuit such as a TFT. Substrate 100 may be a substrate including an insulating material. The substrate may include glass; polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), etc., polycarbonates, and polyacrylates; polysiloxanes (e.g., polydimethylsiloxane (PDMS)); inorganic materials such as Al2O3 or ZnO; or a combination thereof, but is not limited thereto. The thickness of the substrate may be appropriately selected considering the substrate material, but there is no particular limitation. The substrate may be a flexible substrate. The substrate may further include a region for blue pixels, a region for red pixels, a region for green pixels, or a combination thereof.

[0168] 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 as follows: greater than or equal to about 50%, greater than or equal to about 60%, greater than or equal to about 70%, greater than or equal to about 80%, greater than or equal to about 85%, or greater than or equal to about 90% and less than or equal to about 100%, e.g., less than or equal to about 99%, or less than or equal to about 95%. For light emitted from, e.g., semiconductor nanoparticles included in the light-emitting layer, substrate or container (or the light-transmissive component included in the container) may have a light transmittance as follows: greater than or equal to about 50%, greater than or equal to about 60%, greater than or equal to about 70%, greater than or equal to about 80%, greater than or equal to about 85%, greater than or equal to about 90%, greater than or equal to about 95%, or greater than or equal to about 99% and less than or equal to about 100%, 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.

[0169] In an embodiment, thin-film transistors may be disposed in each region of the substrate, but are not limited thereto. In an embodiment, the source electrode or the drain electrode of the thin-film transistor may be electrically connected to the first electrode or the second electrode. In an embodiment, a light-transmissive electrode may be disposed on (e.g., an insulating) transparent substrate. Substrate 100 may be a rigid or flexible substrate.

[0170] 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 zinc tin oxide; metal nitrides such as titanium nitride; conductive polymers such as polyaniline; LiF / Mg:Ag; a single layer or multiple layers of 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 may be appropriately selected and is not particularly limited. The electrode may be formed by vacuum deposition, thermal deposition, sputtering deposition, etc.

[0171] There is no particular limitation on the thickness of each of the electrodes (the first electrode, the second electrode, or a combination thereof) or the thickness of the thin film conductor, and it may be appropriately selected considering device efficiency and the emission type of the device (e.g., top emission or bottom emission). For example, the thickness of the electrode (or thin film conductor) may 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) may be less than or equal to about 100 micrometers (μm), less than or equal to about 90 μm, less than or equal to about 80 μm, less than or equal to about 70 μm, less than or equal to about 60 μm, less than or equal to about 50 μm, less than or equal to about 40 μm, less than or equal to about 30 μm, less than or equal to about 20 μm, less than or equal to about 10 μm, less than or equal to about 1 μm, less than or equal to about 900 nm, less than or equal to about 500 nm, less than or equal to about 100 nm, less than or equal to about 90 nm, less than or equal to about 80 nm, less than or equal to about 70 nm, less than or equal to about 60 nm, less than or equal to about 50 nm, less than or equal to about 40 nm, less than or equal to about 30 nm, or less than or equal to about 25 nm.

[0172] A light-transmissive electrode or a non-light-transmissive or non-transmissive electrode (e.g., a reflective electrode) may be formed by adjusting the composition and / or thickness of the electrode. In an embodiment, the non-transmissive electrode may comprise a metal layer (e.g., aluminum, silver, etc.) disposed between metal oxides (e.g., light-transmissive metal oxides), such as indium tin oxide. In an embodiment, the light-transmissive electrode may comprise a light-transmissive metal oxide, a thin metal or alloy thin film, or combinations thereof. The light-transmissive electrode may include a transparent electrode and a semi-transparent electrode.

[0173] In the electroluminescent device of the embodiment, the second electrode or the thin film conductor may have the following thickness: greater than or equal to about 1 nm, such as greater than or equal to about 5 nm, or greater than or equal to about 9 nm and less than 100 nm, less than or equal to about 99 nm, or less than or equal to about 95 nm. The thickness of the second electrode or the thin film conductor may be greater than about 10 nm, greater than or equal to about 11 nm, greater than or equal to about 12 nm, greater than or equal to about 13 nm, greater than or equal to about 14 nm, greater than or equal to about 15 nm, greater than or equal to about 16 nm, greater than or equal to about 17 nm, greater than or equal to about 18 nm, greater than or equal to about 19 nm, or greater than or equal to about 20 nm. The thin film conductor 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.

[0174] In the electroluminescent device of the embodiment, the second electrode or the thin film conductor may have the following light transmittance for the first light: greater than or equal to about 20%, greater than or equal to about 25%, greater than or equal to about 30%, greater than or equal to about 35%, greater than or equal to about 40%, greater than or equal to about 45%, greater than or equal to about 50%, greater than or equal to about 55%, greater than or equal to about 57%, greater than or equal to about 59%, greater than or equal to about 60%, greater than or equal to about 63%, greater than or equal to about 65%, greater than or equal to about 67%, greater than or equal to about 69%, greater than or equal to about 70%, greater than or equal to about 75%, greater than or equal to about 78%, greater than or equal to about 80%, greater than or equal to about 82%, greater than or equal to about 85%, or greater than or equal to about 89%. The light transmittance for the first light may be less than or equal to about 100%, less than or equal to about 99%, less than or equal to about 98%, less than or equal to about 97%, less than or equal to about 96%, less than or equal to about 95%, less than or equal to about 94%, less than or equal to about 93%, less than or equal to about 92%, less than or equal to about 91%, less than or equal to about 90%, less than or equal to about 89%, less than or equal to about 88%, less than or equal to about 87%, less than or equal to about 86%, less than or equal to about 85%, less than or equal to about 84%, less than or equal to about 83%, less than or equal to about 82%, less than or equal to about 80%, less than or equal to about 79%, less than or equal to about 76%, less than or equal to about 73%, less than or equal to about 68%, less than or equal to about 66%, less than or equal to about 64%, less than or equal to about 61%, less than or equal to about 60%, less than or equal to about 55%, less than or equal to about 50%, less than or equal to about 49%, less than or equal to about 48%, or less than or equal to about 47%.

[0175] 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, for example, a structure having 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.

[0176] 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.

[0177] In an electroluminescent device of an embodiment and a method of manufacturing the device, the thin film conductor may provide conductivity sufficient to be used as an electrode, and at the same time, under the post-treatment conditions described herein, moisture and optionally acid supplied from the organic layer or the polymeric material may pass through the thin film conductor and reach the electron transport layer including metal oxide nanoparticles. Without wishing to be bound by theory, it is believed that the moisture and optionally acid reaching the electron transport layer may modify the surface of the metal oxide nanoparticles in the electron transport layer, whereby hydroxide ions (OH - ) and / or hydrogen ions (H + ) may be supplied to the metal oxide nanoparticles in the electron transport layer to passivate surface defects. Including a post-treated electron transport layer in an electroluminescent device of an embodiment may reduce the hole leakage current, which can be confirmed by a lower driving voltage and higher efficiency of the device compared to the device before post-treatment. Including a post-treated electron transport layer in an electroluminescent device of an embodiment may increase the hole blocking performance and electron mobility of the electron transport layer, and this may contribute to an improvement in the brightness of the device. Including a post-treated electron transport layer in an electroluminescent device of an embodiment 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 degradation and increased lifetime.

[0178] The light-emitting layers 3, 30 may be disposed between the first electrode 1 and the second electrode 5 (e.g., the anode 10 and the cathode 50). The light-emitting layer may include semiconductor nanoparticles (e.g., blue light-emitting nanoparticles, red light-emitting nanoparticles, or green light-emitting nanoparticles). The light-emitting layer may include a single layer of one or more (e.g., 2 or more or 3 or more and 10 or less) semiconductor nanoparticles.

[0179] The light-emitting layer may be patterned. In an embodiment, the patterned light-emitting layer may include a blue light-emitting layer 30B disposed in a blue pixel, a red light-emitting layer 30R disposed in a red pixel, a green light-emitting layer 30G disposed in a green pixel, or a combination thereof. In an embodiment, the light-emitting layer may include a red light-emitting layer disposed in a red pixel and a green light-emitting layer disposed in a green pixel. Each of the (e.g., red, green, or blue) light-emitting layers may be (e.g., optically) separated from an adjacent light-emitting layer by a partition wall. In an embodiment, a partition wall or a dam (e.g., a black matrix or a pixel defining layer, PDL) may be disposed between the red light-emitting layer 30R, the green light-emitting layer 30G, and the blue light-emitting layer 30B (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.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] II-VI compounds may be: binary compounds such as ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS or combinations thereof; ternary compounds such as ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS or combinations thereof; quaternary compounds such as HgZnTeS, HgZnSeS, HgZnSeTe, HgZnSTe or combinations thereof; or combinations thereof. The II-VI compounds may further include group III metals.

[0184] III-V compounds may be: binary compounds such as GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb or combinations thereof; ternary compounds such as GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb or combinations thereof; quaternary compounds such as GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb or combinations thereof; or combinations thereof. The III-V compounds may further include group II metals (such as InZnP).

[0185] IV-VI compounds may be: binary compounds such as SnS, SnSe, SnTe, PbS, PbSe, PbTe or combinations thereof; ternary compounds such as SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe or combinations thereof; quaternary compounds such as SnPbSSe, SnPbSeTe, SnPbSTe or combinations thereof; or combinations thereof.

[0186] Examples of I-III-VI compounds may be CuInSe2, CuInS2, CuInGaSe and CuInGaS, but are not limited thereto.

[0187] 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.

[0188] Examples of I-II-IV-VI group compounds include, but are not limited to, CuZnSnSe and CuZnSnS.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] In an embodiment, the semiconductor nanoparticles may emit blue light or green light and may include a core and a shell, the core including ZnSeTe, ZnSe, or a combination thereof, and the shell including a zinc chalcogenide (e.g., ZnS, ZnSe, ZnSeS, or a combination thereof). The amount of sulfur in the shell may increase or decrease in the radial direction (from the core towards the surface), e.g., the amount of sulfur may have a concentration gradient where the concentration of sulfur varies radially (e.g., decreases or increases in the direction towards the core).

[0194] In an embodiment, the semiconductor nanoparticles may emit red light or green light, the core may include InP, InZnP, or a combination thereof, and the shell may include a Group II metal and a non-metal, the Group II metal including zinc and the non-metal including sulfur, selenium, or a combination thereof.

[0195] 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 may include a homogeneous alloy or may have a concentration gradient. The gradient alloy may 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).

[0196] In an embodiment, the shell may have a composition that varies in the radial direction. In an embodiment, the shell may be a multi-layer shell including two or more layers. In the multi-layer shell, two adjacent layers may have different compositions from each other. In the multi-layer shell, a layer, e.g., at least one layer, may independently include semiconductor nanocrystals having a single composition. In the multi-layer shell, a layer, e.g., at least one layer, may independently have alloyed semiconductor nanocrystals. In the multi-layer shell, a layer, e.g., at least one layer, may have a concentration gradient that varies radially in terms of the composition of the semiconductor nanocrystals.

[0197] In an embodiment, in semiconductor nanoparticles having a core-shell structure, the shell material may have a larger (e.g., higher) bandgap energy than the core. The material of the shell may have a smaller (e.g., lower) bandgap energy than the core. In the case of a multi-layer shell, the bandgap energy of the outermost layer material of the shell may 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.

[0198] The semiconductor nanoparticles according to an embodiment may include, e.g., organic ligands bound or coordinated to their surface.

[0199] 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.

[0200] In an embodiment, the maximum emission peak wavelength of the semiconductor nanoparticles or the light-emitting layer (or the light emitted from the electroluminescent device) can be in the ultraviolet to infrared or longer wavelength range, or in the visible light range such as the green light range, the red light range, or the blue light range.

[0201] In an embodiment, the emission peak wavelength of the semiconductor nanoparticles or the light-emitting layer (or the light emitted from the electroluminescent device) can be greater than or equal to about 300 nm, greater than or equal to about 500 nm, greater than or equal to about 510 nm, greater than or equal to about 520 nm, greater than or equal to about 530 nm, greater than or equal to about 540 nm, greater than or equal to about 550 nm, greater than or equal to about 560 nm, greater than or equal to about 570 nm, greater than or equal to about 580 nm, greater than or equal to about 590 nm, greater than or equal to about 600 nm, or greater than or equal to about 610 nm. The emission peak wavelength of the semiconductor nanoparticles or the light-emitting layer (or the light emitted from the electroluminescent device) can be less than or equal to about 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 emission peak wavelength of the semiconductor nanoparticles or the light-emitting layer (or the light emitted from the electroluminescent device) can be from about 500 nm to about 650 nm.

[0202] The semiconductor nanoparticles (or the light emitted from the electroluminescent device) can emit green light (e.g., when a voltage is applied or when irradiated with light), and its maximum emission peak wavelength can be in the range of greater than or equal to about 500 nm (e.g., greater than or equal to about 510 nm, or greater than or equal to about 515 nm) and less than or equal to about 560 nm, such as less than or equal to about 540 nm, or less than or equal to about 530 nm.

[0203] Semiconductor nanoparticles (or the light emitted from an electroluminescent device) can emit red light (e.g., when a voltage is applied or irradiated with light), and the wavelength of its maximum emission peak can be in the range of greater than or equal to about 600 nm, such as greater than or equal to about 610 nm and less than or equal to about 650 nm, or less than or equal to about 640 nm.

[0204] Semiconductor nanoparticles (or the light emitted from an electroluminescent device) can emit blue light (e.g., when a voltage is applied or irradiated with light), and the wavelength of its maximum emission peak can be greater than or equal to about 430 nm (e.g., greater than or equal to about 450 nm, greater than or equal to about 455 nm, greater than or equal to about 460 nm, greater than or equal to about 465 nm) and less than or equal to about 480 nm (e.g., less than or equal to about 475 nm, less than or equal to about 470 nm, or less than or equal to about 465 nm).

[0205] In an embodiment, the semiconductor nanoparticles can exhibit a luminescence spectrum (e.g., a photoluminescence or electroluminescence spectrum) with a relatively narrow full width at half maximum. In an embodiment, in the photoluminescence or electroluminescence spectrum, the semiconductor nanoparticles can exhibit a full width at half maximum of less than or equal to about 45 nm, less than or equal to about 44 nm, less than or equal to about 43 nm, less than or equal to about 42 nm, less than or equal to about 41 nm, less than or equal to about 40 nm, less than or equal to about 39 nm, less than or equal to about 38 nm, less than or equal to about 37 nm, less than or equal to about 36 nm, or less than or equal to about 35 nm. The full width at half maximum can be greater than or equal to about 10 nm, greater than or equal to about 15 nm, greater than or equal to about 20 nm, or greater than or equal to about 25 nm.

[0206] The semiconductor nanoparticles can exhibit (or can be configured to exhibit) a quantum efficiency (or quantum yield) of greater than or equal to about 10%, such as greater than or equal to about 30%, greater than or equal to about 50%, greater than or equal to about 60%, greater than or equal to about 70%, greater than or equal to about 80%, greater than or equal to about 90%, or about 100%.

[0207] 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.

[0208] 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.

[0209] The semiconductor nanoparticles can be prepared by appropriate methods. The semiconductor nanoparticles can be prepared, for example, by chemical wet methods, in which nanocrystalline particles can grow through reactions between precursors in a reaction system including an organic solvent and an organic ligand. The organic ligand or organic solvent can coordinate to the surface of the semiconductor nanocrystal (coordinate with the surface of the semiconductor nanocrystal or coordinate to the surface of the semiconductor nanocrystal) to control its growth.

[0210] 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. 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.

[0211] In an embodiment, to form the shell, the solvent and optionally the first shell precursor and the ligand compound may be heated under vacuum at a predetermined temperature (such as greater than or equal to about 100 °C) (also referred to herein as vacuum treatment), and then after introducing an inert gas into the reaction vessel, the mixture may be heat-treated again at a predetermined temperature (such as greater than or equal to 100 °C). Then, the core and the second shell precursor may be added to the mixture and heated at the reaction temperature. The shell precursors may be added simultaneously or sequentially in different proportions during the reaction time.

[0212] In the semiconductor nanoparticles of an embodiment, the core may be prepared in a suitable manner. In an embodiment, the organic solvent may include C6-C22 primary amines such as hexadecylamine, C6-C22 secondary amines such as dioctylamine, C6-C40 tertiary amines such as trioctylamine, nitrogen-containing heterocyclic compounds such as pyridine, C6-C40 olefins such as octadecene, C6-C40 aliphatic hydrocarbons such as hexadecane, octadecane, or squalane, aromatic hydrocarbons substituted with C6-C30 alkyl groups such as phenyldodecane, phenyltetradecane, or phenylhexadecane, primary, secondary, or tertiary phosphines substituted with C6 to C22 alkyl groups, such as at least one (such as 1, 2, or 3) C6 to C22 alkyl groups (such as trioctylphosphine), phosphine oxides substituted with C6 to C22 alkyl groups (such as 1, 2, or 3 C6 to C22 alkyl groups) (such as trioctylphosphine oxide), C12-C22 aromatic ethers such as phenyl ether or benzyl ether, or a combination thereof. Combinations including more than one type of organic solvent may be used.

[0213] The organic ligand may include RCOOH, RNH2, R2NH, R3N, RSH, RH2PO, R2HPO, R3PO, RH2P, R2HP, R3P, ROH, RCOOR', RPO(OH)2, R2POOH, or a combination thereof. Here, R and R' are each independently a substituted or unsubstituted aliphatic hydrocarbon group having 3 or more, 6 or more, or 10 or more carbon atoms and about 40 or fewer, 35 or fewer, or 25 or fewer carbon atoms (e.g., alkyl, alkenyl, alkynyl, etc.), a substituted or unsubstituted aromatic hydrocarbon group having 6 to 40 carbon atoms (e.g., aryl), or a combination thereof. In an embodiment, at least two different organic ligands may be used.

[0214] In an embodiment, after completion of the reaction (for forming a core or for forming a 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 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.

[0215] The semiconductor nanoparticles of the embodiment may be non-dispersible or insoluble in water, the foregoing non-solvent, or a combination thereof. The semiconductor nanoparticles of the embodiment may be dispersed in the foregoing organic solvents. In an embodiment, the foregoing semiconductor nanoparticles may be dispersed in a substituted or unsubstituted aliphatic hydrocarbon having 6 to 40 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon having 6 to 40 carbon atoms, or a combination thereof.

[0216] 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.

[0217] In the electroluminescent device or display device of the embodiment, the thickness of the light-emitting layer can be appropriately selected. The light-emitting layer can have a thickness greater than or equal to about 5 nm, such as greater than or equal to about 10 nm, greater than or equal to about 20 nm, or greater than or equal to about 30 nm and less than or equal to about 200 nm, less than or equal to about 150 nm, less than or equal to about 100 nm, less than or equal to about 90 nm, less than or equal to about 80 nm, less than or equal to about 70 nm, less than or equal to about 60 nm, or less than or equal to about 50 nm. The light-emitting layer can have a thickness of, for example, about 10 nm to about 150 nm, about 20 nm to about 100 nm, or about 30 nm to about 50 nm.

[0218] In an embodiment, the formation of the light-emitting layer including semiconductor nanoparticles can be carried out as follows: obtaining a coating solution including semiconductor nanoparticles and an organic solvent (e.g., 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 (e.g., a hole assisting layer) in an appropriate manner (e.g., by spin coating, inkjet printing, etc.). The type of the organic solvent for the coating solution is not particularly limited and can be appropriately selected. In an embodiment, the organic solvent can include a substituted or unsubstituted aliphatic hydrocarbon, a substituted or unsubstituted aromatic hydrocarbon, a substituted or unsubstituted alicyclic hydrocarbon, an acetate solvent, or a combination thereof.

[0219] In an embodiment, the formation of the light-emitting layer can further include contacting a film of semiconductor nanoparticles with an organic solution containing a metal halide (e.g., zinc chloride). In an embodiment, the light-emitting layer can include: a first light-emitting layer including first semiconductor nanoparticles and a second light-emitting layer including second semiconductor nanoparticles, wherein the first semiconductor nanoparticles have a surface with halogen (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 an appropriate manner (e.g., post-treatment of the formed layer). In an embodiment, a thin film of semiconductor nanoparticles having an organic ligand (e.g., having a carboxylic acid group) is formed, which is then treated with a solution containing a metal halide (e.g., zinc chloride in an alcohol solvent) to control the amount of the organic ligand of the semiconductor nanoparticles in the thin film. The treated thin film can have an increased amount of halogen and can display (e.g., exhibit) changed properties (e.g., solubility) with respect to, for example, the organic solvent, and subsequently, it may be possible to form a layer of semiconductor nanoparticles having a different amount of organic ligands (e.g., halogen-treated semiconductor nanoparticles or semiconductor nanoparticles having ligands with carboxylic acid groups) on the treated thin film.

[0220] In an embodiment, the light-emitting layer may be a single layer or a multilayer structure having at least two layers. In the multilayer structure, adjacent layers (e.g., a first light-emitting layer and a second light-emitting layer) may be configured to emit a first light (e.g., green light, blue light, or red light). In the multilayer structure, adjacent layers (e.g., a first light-emitting layer and a second light-emitting layer) may have the same or different compositions, ligands, or combinations thereof. In an embodiment, the (multilayer) light-emitting layer may exhibit a 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 the organic ligand may decrease in the direction toward the electron assisting layer. In the (multilayer) light-emitting layer, the content of the organic ligand may increase in the direction toward the electron assisting layer.

[0221] 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.

[0222] The light-emitting layer may be heat-treated. The heat treatment may be performed in air or in an inert gas atmosphere. The temperature of the heat treatment may be greater than or equal to about 50 °C, greater than or equal to about 70 °C, greater than or equal to about 90 °C, greater than or equal to about 100 °C, greater than or equal to about 120 °C, greater than or equal to about 150 °C, greater than or equal to about 170 °C, or greater than or equal to about 200 °C. The temperature of the heat treatment may be less than or equal to about 250 °C, less than or equal to about 230 °C, less than or equal to about 200 °C, less than or equal to about 180 °C, less than or equal to about 160 °C, less than or equal to about 140 °C, or less than or equal to about 130 °C.

[0223] The light-emitting device of the embodiment includes an electron assisting layer 4, 40 provided on the light-emitting layer 3, 30, e.g., between the light-emitting layer and the second electrode or thin film conductor (hereinafter, "second electrode") 5, 50. In the electron assisting layer 4, 40, the transport, injection, or transport and injection of electrons may occur. The electron assisting layer 4, 40 includes an electron transport layer (ETL). The electron transport layer includes (a plurality of) metal oxide nanoparticles. The electron assisting layer 4, 40 may further include an electron injection layer, a hole blocking layer, or a combination thereof. The electron injection layer, the hole blocking layer, or a combination thereof may be provided between the electron transport layer and the second electrode, but is not limited thereto. In an embodiment, the electron transport layer may be provided between the electron injection layer and the hole blocking layer. In an embodiment, the hole blocking layer may be provided between the electron injection layer and the electron transport layer. The electron transport layer may be adjacent to the light-emitting layer (e.g., directly adjacent to the light-emitting layer or directly provided on the light-emitting layer). In an embodiment, the light-emitting layer 3, 30 may contact the electron transport layer.

[0224] The metal oxide (nanoparticle) may include zinc oxide. The metal oxide (nanoparticle) or zinc oxide may include: zinc; and optionally a Group IIA metal, Zr, W, Li, Ti, Y, Al, gallium, indium, tin (Sn), cobalt (Co), vanadium (V), or a combination thereof. The metal oxide (nanoparticle) or zinc oxide may include zinc, a Group IIA metal, and optionally an alkali metal.

[0225] The metal oxide (nanoparticle) or zinc oxide may include a compound represented by Zn 1-x M x O, where M is Mg, Ga, Ca, Zr, Co, W, Li, Ti, Y, Al, or a combination thereof, and 0 ≤ x ≤ 0.5. x may be greater than or equal to about 0.01, greater than or equal to about 0.03, greater than or equal to about 0.05, greater than or equal to about 0.07, greater than or equal to about 0.1, greater than or equal to about 0.13, greater than or equal to about 0.15, greater than or equal to about 0.17, greater than or equal to about 0.2, greater than or equal to about 0.23, or greater than or equal to about 0.25. x may be less than or equal to about 0.47, less than or equal to about 0.45, less than or equal to about 0.43, less than or equal to about 0.4, less than or equal to about 0.37, less than or equal to about 0.35, or less than or equal to about 0.3. The metal oxide or zinc oxide may further include magnesium. The electron transport layer or zinc oxide may include Zn 1-x Mg x O (x is greater than or equal to 0, or greater than 0 and less than or equal to about 0.5, where x is as defined herein), ZnO, or a combination thereof. The zinc oxide may further include magnesium.

[0226] The size or average size (hereinafter referred to as "size") of the metal oxide nanoparticles may be greater than or equal to about 1 nm, greater than or equal to about 2 nm, greater than or equal to about 2.5 nm, greater than or equal to about 3 nm, or greater than or equal to about 3.5 nm and less than or equal to about 10 nm, less than or equal to about 9 nm, less than or equal to about 8 nm, less than or equal to about 7 nm, less than or equal to about 6 nm, less than or equal to about 5 nm, or less than or equal to about 4.5 nm. The size of the metal oxide nanoparticles may be the diameter or the equivalent diameter. The equivalent diameter is a value obtained by converting the size of a non-spherical particle into the diameter of a spherical particle. The size of the nanoparticles may be analyzed by appropriate means such as electron microscopy methods like TEM or XRD measurement. In this specification, the size may refer to the size of a single particle or the average size of a group of particles.

[0227] 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 metal oxide nanoparticles can include a sol-gel reaction. In an embodiment, zinc oxide (e.g., zinc magnesium oxide) nanoparticles can be prepared by: placing a zinc compound (e.g., an organic zinc 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 retrieved from the reaction solution, e.g., by centrifugation.

[0228] In an embodiment, the electron assisting layer or the electron transporting layer can be prepared by a solution process. In an embodiment, the electron assisting layer or the electron transporting layer can be prepared by: dispersing a plurality of metal oxide nanoparticles in an organic solvent (e.g., a polar solvent, a non-polar solvent, or a combination thereof) to obtain a precursor dispersion of the electron transporting layer, and then applying it to a surface to form a film. The precursor dispersion of the electron transporting layer can be applied to the light-emitting layer. The solution process can further include removing the organic solvent from the formed film, e.g., by evaporation. The organic solvent can include a C1 to C10 alcohol solvent or a combination thereof.

[0229] 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.

[0230] The thickness of the electron injection layer, the hole blocking layer, or a combination thereof is not particularly limited and can be appropriately selected. The thickness of the electron injection layer, the hole blocking layer, or a combination thereof can be greater than or equal to about 5 nm, greater than or equal to about 6 nm, greater than or equal to about 7 nm, greater than or equal to about 8 nm, greater than or equal to about 9 nm, greater than or equal to about 10 nm, greater than or equal to about 11 nm, greater than or equal to about 12 nm, greater than or equal to about 13 nm, greater than or equal to about 14 nm, greater than or equal to about 15 nm, greater than or equal to about 16 nm, greater than or equal to about 17 nm, greater than or equal to about 18 nm, greater than or equal to about 19 nm, or greater than or equal to about 20 nm and less than or equal to about 500 nm, less than or equal to about 120 nm, less than or equal to about 110 nm, less than or equal to about 100 nm, less than or equal to about 90 nm, less than or equal to about 80 nm, less than or equal to about 70 nm, less than or equal to about 60 nm, less than or equal to about 50 nm, less than or equal to about 40 nm, less than or equal to about 30 nm, or less than or equal to about 25 nm, but is not limited thereto.

[0231] In an embodiment, materials for an electron injection layer, a hole blocking layer, or a combination thereof may include 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA), bathocuproine (BCP), tris[3-(3-pyridyl)-mesityl]borane (3TPYMB), LiF, tris(8-hydroxyquinoline)aluminum (Alq3), tris(8-hydroxyquinoline)gallium (Gaq3), tris(8-hydroxyquinoline)indium (Inq3), bis-(8-hydroxyquinoline)zinc (Znq2), bis[2-(2-hydroxyphenyl)benzothiazole]zinc (Zn(BTZ)2), bis(10-hydroxybenzo[h]quinolinato)beryllium (BeBq2), 8-(4-(4,6-bis(naphthalen-2-yl)-1,3,5-triazin-2-yl)phenyl)quinolone (ET204), lithium 8-hydroxyquinolate (Liq), 2,2',2''-(1,3,5-benzenetriyl)-tris(1-phenyl-1H-benzoimidazole) (TPBi), n-type metal oxides (e.g., ZnO, HfO2, etc.), 8-(4-(4,6-bis(naphthalen-2-yl)-1,3,5-triazin-2-yl)phenyl)quinolone:lithium 8-hydroxyquinolate (ET204:Liq), or a combination thereof, but not limited thereto.

[0232] In the electron transport layer, metal oxide nanoparticles may provide higher electron mobility than an organic semiconductor material, and a light emitting layer (e.g., in combination with an electron transport layer including metal oxide nanoparticles) may exhibit desired levels of electroluminescent properties. Further, 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.

[0233] However, the 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 simultaneously 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. Without wishing to be bound by any theory, it is believed that, as a result of the synthesis, various surface chemical species such as metal ions, e.g., (Zn 2+ , Mg 2+ ), O 2- , OH - , CH3COO -They can exist on the surface of metal oxide nanoparticles, and these surface chemical species can be the source of surface defects of the nanoparticles and act as defect energy levels in the ETL. Without wishing to be bound by any theory, it is believed that the surface defects present on metal oxide (e.g., ZnMgO) particles can have energy levels close to the HOMO energy level of quantum dots or semiconductor nanoparticles, and thus, can be used as trapping (trap) sites for holes and can lead to an increase in leakage current.

[0234] Metal oxide nanoparticles in the electron auxiliary layer or electron transport layer can include various defects generated during their manufacturing process and film formation process, and these defects can provide various energy levels within the nanoparticles to be used as channels for hole movement. Thus, the electron transport layer based on metal oxide nanoparticles can exhibit reduced hole blocking performance or relatively high hole leakage current, which can adversely affect the electroluminescent properties (e.g., luminous efficiency) of the device.

[0235] In addition, without wishing to be bound by any theory, 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. The accumulation of this charge can lead to unwanted charging (e.g., within the electron transport layer or at the interface between the light-emitting layer and the electron transport layer), and can result in a reduction in the brightness or lifetime of the QD-LED device.

[0236] The electroluminescent device or method of manufacturing the same according to an embodiment includes using an organic layer or polymer material as described herein, and the electron transport layer based on metal oxide nanoparticles can be post-treated as described herein. The electroluminescent device according to an embodiment including the post-treated electron transport layer can exhibit improved electroluminescent properties and lifetime characteristics. In the post-treatment of the method according to an embodiment, since moisture and acid components can easily diffuse into the electron transport layer (in a contact or remote manner), it can be easily used for both bottom-emission type and front-emission type devices.

[0237] Without wishing to be bound by any theory, it is believed that the post-treatment of the embodiment using the organic layer (or polymer material) and the conductor thin film (or the second electrode) can induce modification (e.g., surface modification or surface chemical reaction) of the metal oxide nanoparticles contained in the electron transport layer by (e.g., diffused) acid and moisture. This surface modification can passivate the defects on the nanoparticle surface, and by improving the electrical properties of the metal oxide, the modified metal oxide nanoparticles can exhibit increased conductivity to the desired extent. Therefore, it is believed that when applied to the electron transport layer, the post-treated electron transport layer can exhibit effectively reduced hole leakage current and effectively reduced charge accumulation, and thus can alleviate the charging problem. Therefore, the electroluminescent device according to an embodiment can exhibit an extended lifetime and improved efficiency.

[0238] The present inventors have also found that when the post-treatment is carried out only with the acid component, the electroluminescent device may exhibit a (significant or substantial) change (e.g., decrease) in electroluminescent performance, e.g., after an extended period of time and / or after the treated device is maintained at a relatively high temperature. For example, if an electroluminescent device post-treated with an acid component is maintained at a high temperature of 120 °C for a predetermined time (e.g., about 2 hours) or even at a temperature of 70 °C or even at room temperature for a relatively long time (e.g., about 1 to 2 days), there may be a negative (e.g., undesirable) change in the performance of the post-treated device. In addition, if the post-treatment time using only the acid component exceeds an appropriate time, the post-treated device may exhibit a decrease in performance.

[0239] Without wishing to be bound by any theory, it is believed that this performance degradation may occur when the effective component that modifies the metal oxide nanoparticles in the electron transport layer further migrates through the electron transport layer to other layers (e.g., the hole transport layer) during the post-treatment and adversely affects the properties of the device. The devices of the embodiments solve this technical problem. Even when treated at a relatively high temperature (e.g., above 120 °C) and / or for a long time at a predetermined temperature (e.g., room temperature or 70 °C), the method of the embodiments can minimize potential damage to the device.

[0240] In an embodiment, the electroluminescent device may or may not include an organic layer on the electron transport layer and / or the second electrode. The organic layer includes a polymer material, and in the organic layer or the polymer material, it includes a repeating unit having an acid functional group (first repeating unit) and a repeating unit having a hydroxyl group (second repeating unit). In an embodiment, the polymer material (hereinafter may be referred to as "polymer") may include: a first (homo)polymer including the first repeating unit and a second (homo)polymer including the second repeating unit. In an embodiment, the polymer may include or be: a copolymer including the first repeating unit and the second repeating unit.

[0241] In the organic layer or polymer material, the molar ratio (acid:hydroxyl) between the first repeating unit (acid functional group) of the first polymer or the copolymer and the second repeating unit (hydroxyl group) of the second polymer or the copolymer can be 1:0.01 to 1:100, 1:0.02 to 1:50, 1:0.03 to 1:30, 1:0.04 to 1:25, 1:0.05 to 1:20, 1:0.06 to 1:16, 1:0.07 to 1:15, 1:0.075 to 1:13, 1:0.09 to 1:11, 1:0.1 to 1:10, 1:0.2 to 1:5, 1:0.25 to 1:4, 1:0.3 to 1:3, 1:0.35 to 1:2.8, 1:0.4 to 1:2.5, 1:0.45 to 1:2.3, 1:0.48 to 1:2.1, 1:0.5 to 1:2.0, 1:0.53 to 1:1.9, 1:0.55 to 1:1.8, 1:0.6 to 1:1.7, 1:0.65 to 1:1.5, 1:0.68 to 1:1.47, 1:0.7 to 1:1.4, 1:0.75 to 1:1.33, 1:0.77 to 1:1.3, 1:0.78 to 1:1.28, 1:0.79 to 1:1.26, 1:0.8 to 1:1.25, 1:0.85 to 1:1.17, 1:0.9 to 1:1.1, or 1:1 to 1:1.05, or a combination thereof.

[0242] In the first repeating unit having an acid functional group, the acid functional group can include a carboxyl group (COOH), a phosphonic acid (PO(OH)2) group, a sulfonic acid (SO3H) group, or a combination thereof. In an embodiment, introducing the organic layer and / or post-treatment as described herein can prevent substantial or significant deterioration of the electroluminescent properties and / or a sharp increase in the driving voltage due to the presence of the organic layer, even after the electroluminescent device is maintained or stored for an extended or relatively long period of time at room temperature or a relatively elevated temperature.

[0243] In an embodiment, the electron transport layer or the electron assisting layer can include a first surface facing the light emitting layer and a second surface opposite the first surface, and the organic layer can be disposed on at least a part or all of the second surface of the electron transport layer or the electron assisting layer. In an embodiment, the second electrode includes a first surface facing the electron transport layer and a second surface opposite the first surface, and the organic layer can be disposed on at least a part or all of the second surface of the second electrode.

[0244] In an embodiment, the organic layer or the polymer material can be in contact with the second surface of the electron transport layer and the second surface of the second electrode. (See Figure 1A 、 Figure 1B 、 Figure 3A 、 Figure 3B 、 Figure 3C andFigure 6B )。In an embodiment, the organic layer may be spaced apart from the electron transport layer or the second electrode and may be disposed to face the electron transport layer or the second electrode. The electroluminescent device of the embodiment may further include a container configured to receive at least a part or all of a stacked structure including a first electrode, an emission layer, an electron transport layer, and a second electrode (or a conductor thin film), and the organic layer may be disposed on the surface of the container (see Figure 2A , Figure 2B , Figure 2C , Figure 4 , Figure 5A and Figure 8 ).

[0245] The organic layer or the polymer material may be disposed to face the (surface of the) thin film conductor. The organic layer or the polymer material may be disposed to face the electron transport layer. The second electrode or the thin film conductor may be disposed between the organic layer and the electron transport layer.

[0246] Without wishing to be bound by any theory, hydrogen ions and / or moisture supplied from the organic material or the polymer material of the embodiment may passivate defects on the surface of the metal oxide nanoparticles, for example, via a chemical reaction therebetween, to remove trapping (trap) sites, suppress leakage current of holes generated through the trapping sites of the metal oxide (e.g., ZnMgO) nanoparticles, and enhance the hole blocking ability of the metal oxide-based electron transport layer. Without wishing to be bound by any particular theory, it is considered that the electroluminescent 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.

[0247] In addition, the post-treatment may provide surface modification of the metal oxide nanoparticles, thereby reducing trapping sites, and may prevent or suppress charge accumulation at the trapping sites or undesired charging in the device. Further, when driven at a desired voltage for a long time, the device of the embodiment may exhibit reduced / suppressed deterioration of the semiconductor nanoparticles or the ETL material (e.g., metal oxide nanoparticles), and thus may exhibit improved (e.g., extended) device lifetime.

[0248] In an embodiment, the polymer material (referred to as "polymer") or the first polymer may include or be a polymeric acid compound. The polymer or the first polymer may include, for example, a carboxyl group (COOH), a phosphonic acid group (PO(OH)2), a sulfonic acid group (SO3H), or a combination thereof in its repeating unit.

[0249] The polymer or the first polymer may be water-soluble and / or alcohol-soluble. In an embodiment, the polymer or the first polymer may have the following solubility in water or a C1 to C10 alcohol such as 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 polymer or the first polymer in water or a C1 to C10 alcohol such as ethanol (e.g., at room temperature or at a temperature of 20 °C or at 25 °C) 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, 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.

[0250] In an embodiment, the polymer or the first polymer 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 polymer or the first polymer 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 the aqueous solution or alcohol solution of the polymer or the first polymer, the concentration of the polymeric acid compound may be about 5 wt% to about 80 wt%, about 10 wt% to about 75 wt%, about 15 wt% to about 70 wt%, about 18 wt% to about 65 wt%, about 20 wt% to about 60 wt%, about 25 wt% to about 55 wt%, about 30 wt% to about 50 wt%, or a combination thereof.

[0251] The first polymer may include polyacrylic acid, polymethacrylic acid, polyacrylic acid-methacrylic acid, (partially) alkali metal salts of polyacrylic acid, copolymers including (meth)acrylic acid repeating units, polyvinylphosphonic acid, poly(aromatic sulfonic acid) compounds, poly(vinylsulfonic acid), polymaleic acid, or a combination thereof (e.g., copolymer or mixture). The first polymer may further include corresponding ester groups (-COOR, where R is an alkyl or aryl group) of the acid groups. The poly(aromatic sulfonic acid) compound may include polystyrene sulfonic acid, polystyrene sulfonic acid-maleic acid, its alkali metal salts (e.g., sodium salt), or a combination thereof.

[0252] The polymer or the second polymer may include repeating units represented by Chemical Formula 1:

[0253] Chemical Formula 1

[0254]

[0255] Wherein A is a direct bond, -CO-, -O-, an ester linkage (e.g., -COO- or -OCO-), -CONH-, -NH-, -S-, -SO- or a combination thereof, L is a direct bond, a substituted or unsubstituted C1-C30, C2-C15, C3-C10 aliphatic hydrocarbon group (e.g., an alkylene, an alkenylene), a substituted or unsubstituted C6-C20 or C8-C15 arylene group (e.g., a phenylene), and R is the same or different and is hydrogen or a substituted or unsubstituted C1-C30 (or C1-C5) alkyl group, and * is the moiety that connects to an adjacent atom (or adjacent repeating unit) (e.g., in the main chain).

[0256] In the polymer or the second polymer of an embodiment, both A and L in Formula 1 can be a direct bond. In the polymer or the second polymer of an embodiment, A in Formula 1 can be an ester linkage (e.g., -COO- or -OCO-), -CO- or CONH, and L in Formula 1 can be a substituted or unsubstituted C1-C30, C2-C15 or C3-C10 aliphatic hydrocarbon group (e.g., a propylene, an ethylene, a methylene, a butylene, a pentylene, etc.). In the polymer or the second polymer of an embodiment, A in Formula 1 can be a direct bond, and L in Formula 1 can be a substituted or unsubstituted C6-C20 arylene group (e.g., a phenylene).

[0257] The polymer or the second polymer can be a hydrophilic polymer. The polymer or the second polymer can include polyvinyl alcohol. The polymer or the second polymer can be a non-gelling polymer. The polymer or the second polymer can be a linear polymer. The polymer or the second polymer can be a copolymer. The second polymer can include a second repeating unit represented by Formula 2 or Formula 2-1 (a unit derived from vinyl alcohol) and optionally a third repeating unit represented by Formula 3 or Formula 3-1 (a unit derived from vinyl acetate):

[0258] Formula 2

[0259]

[0260] Formula 2-1

[0261]

[0262] Formula 3

[0263]

[0264] Formula 3-1

[0265]

[0266] In the above formula, * is the part connected to the adjacent repeating unit, R is the same or different and each independently is hydrogen or a substituted or unsubstituted C1-C30 (or C5-C10) alkyl group, and R' is a substituted or unsubstituted C1-C10 (C2-C5) alkyl group.

[0267] The percentage (e.g., degree of hydrolysis) of the second repeating unit to the sum (in moles) of the second repeating unit and the third repeating unit can be greater than or equal to about 50%, greater than or equal to about 55%, greater than or equal to about 60%, greater than or equal to about 65%, greater than or equal to about 70%, greater than or equal to about 75%, greater than or equal to about 80%, greater than or equal to about 85%, greater than or equal to about 90%, greater than or equal to about 95%, greater than or equal to about 99%, or a combination thereof. The degree of hydrolysis of the second polymer can be in the range of about 78% to 100%, 80% to 99%, 82% to 98%, 85% to 95%, or a combination thereof.

[0268] Polyvinyl alcohol can be a polymer having a hydroxyl group in the repeating unit. Polyvinyl alcohol can be synthesized by various synthetic methods or can be commercially available.

[0269] The polymer or the second polymer can include a repeating unit represented by Chemical Formula 4 or Chemical Formula 4-1; or can include polyvinylphenol or a copolymer thereof including the same:

[0270] Chemical Formula 4

[0271]

[0272] Chemical Formula 4-1

[0273]

[0274] In the above formula, R is the same or different and each independently is hydrogen or a substituted or unsubstituted C1-C30 (or C5-C10) alkyl group, and * is the part connected to the adjacent repeating unit. The phenyl group of Chemical Formula 4 or Chemical Formula 4-1 can have additional substituents in addition to the hydroxyl group. For the substituents, reference can be made to the substituents described herein.

[0275] Polyvinylphenol or a copolymer thereof can be synthesized by various synthetic methods or can be commercially available.

[0276] The polymer or the second polymer can include a repeating unit represented by Chemical Formula 5 or Chemical Formula 5-1; or can be poly(hydroxyalkyl) (meth)acrylate or a copolymer thereof including the same:

[0277] Chemical Formula 5

[0278]

[0279] Chemical formula 5-1

[0280]

[0281] wherein R is hydrogen or a substituted or unsubstituted C1-C10 alkyl group, and L is a substituted or unsubstituted C1-10 alkylene group (e.g., methylene, ethylene, propylene, butylene, pentylene, etc.), and * is the moiety that connects to the adjacent repeating unit.

[0282] Poly(hydroxyalkyl) (meth)acrylate or its copolymer can be synthesized by various synthetic methods or obtained commercially.

[0283] The polymer or the second polymer has the following solubility in water or alcohol: greater than or equal to about 1 g / L, greater than or equal to about 5 g / L, greater than or equal to about 10 g / L, greater than or equal to about 15 g / L, greater than or equal to about 20 g / L, greater than or equal to about 33 g / L, greater than or equal to about 50 g / L, greater than or equal to about 55 g / L, greater than or equal to about 65 g / L, greater than or equal to about 70 g / L, greater than or equal to about 85 g / L, greater than or equal to about 100 g / L, greater than or equal to about 150 g / L, greater than or equal to about 200 g / L, greater than or equal to about 250 g / L, or greater than or equal to about 300 g / L. The polymer or the second polymer has the following solubility in water or alcohol: less than or equal to about 5000 g / L, less than or equal to about 4000 g / L, less than or equal to about 3000 g / L, less than or equal to about 1000 g / L, less than or equal to about 800 g / L, less than or equal to about 600 g / L, less than or equal to about 500 g / L, less than or equal to about 400 g / L, less than or equal to about 350 g / L, less than or equal to about 200 g / L, less than or equal to about 130 g / L, less than or equal to about 90 g / L, or less than or equal to about 80 g / L. The polymer or the second polymer can be a water-soluble polymer.

[0284] The polymer or the second polymer can be a water-soluble or alcohol-soluble polymer. In an embodiment, the water-soluble or alcohol-soluble polymer can form a solution (e.g., an aqueous solution or an alcohol solution) at the following polymer concentrations: greater than or equal to about 3 wt%, greater than or equal to about 5 wt%, or greater than or equal to about 10 wt%, based on the total weight of the solution (e.g., at 25 °C or at a temperature below 80 °C).

[0285] In solution, the polymer concentration can be less than about 100 wt%, less than or equal to about 80 wt%, less than or equal to about 60 wt%, less than or equal to about 50 wt%, less than or equal to about 40 wt%, less than or equal to about 30 wt%, less than or equal to about 20 wt%, less than or equal to about 15 wt%, less than or equal to about 9 wt%, less than or equal to about 7 wt%, or less than or equal to about 5 wt%.

[0286] The polymer or second polymer contains hydroxyl groups within its repeating units, which can be confirmed by appropriate analysis. In an embodiment, the second polymer can exhibit a hydroxyl peak between about 4 ppm and about 5 ppm (e.g., three peaks), as confirmed by NMR analysis.

[0287] When dissolved in water or an alcohol, the second polymer can exhibit a pH greater than or equal to about 4.5, greater than or equal to about 5, greater than or equal to about 5.5, greater than or equal to about 6, greater than or equal to about 6.5, greater than or equal to about 7, greater than or equal to about 7.5, or greater than or equal to about 7.8, greater than or equal to about 8, greater than or equal to about 8.2 and less than or equal to about 9, less than or equal to about 8.7, less than or equal to about 8.5, less than or equal to about 8.3, less than or equal to about 8, less than or equal to about 7.6, less than or equal to about 7.2, or less than or equal to about 6.8. In solution (e.g., an aqueous solution or an alcohol solution), the concentration of the second polymer can 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.

[0288] The second polymer can be soluble or insoluble in C1 - C5 alcohols (e.g., ethanol). In an embodiment, the second polymer can be soluble in C1 - C5 alcohols (e.g., ethanol), DMSO, water, or a combination thereof.

[0289] In an embodiment, the polymer (or copolymer), the first polymer, or the second polymer may have an average molecular weight (unit: g / mol) as follows: greater than or equal to about 50, greater than or equal to about 80, greater than or equal to about 100, greater than or equal to about 150, greater than or equal to about 200, greater than or equal to about 250, greater than or equal to about 300, greater than or equal to about 350, greater than or equal to about 400, greater than or equal to about 450, greater than or equal to about 500, greater than or equal to about 550, greater than or equal to about 600, greater than or equal to about 650, greater than or equal to about 700, greater than or equal to about 750, greater than or equal to about 800, greater than or equal to about 900, greater than or equal to about 1000, greater than or equal to about 1100, greater than or equal to about 1200, greater than or equal to about 1300, greater than or equal to about 1400, greater than or equal to about 1500, greater than or equal to about 1600, greater than or equal to about 1700, greater than or equal to about 1800, greater than or equal to about 1900, greater than or equal to about 2000, greater than or equal to about 2100, greater than or equal to about 2200, greater than or equal to about 2300, greater than or equal to about 2400, greater than or equal to about 2500, greater than or equal to about 3000, greater than or equal to about 3500, greater than or equal to about 4000, greater than or equal to about 4500, greater than or equal to about 5000, greater than or equal to about 5500, greater than or equal to about 6000, greater than or equal to about 7000, greater than or equal to about 8000, greater than or equal to about 9000, greater than or equal to about 10,000, greater than or equal to about 15000, greater than or equal to about 20,000, greater than or equal to about 25000, greater than or equal to about 30,000, greater than or equal to about 35,000, greater than or equal to about 40,000, greater than or equal to about 45,000, greater than or equal to about 50,000, greater than or equal to about 55,000, greater than or equal to about 60,000, greater than or equal to about 65,000, greater than or equal to about 70,000, greater than or equal to about 75,000, greater than or equal to about 80,000, greater than or equal to about 85,000, greater than or equal to about 90,000, greater than or equal to about 95,000, greater than or equal to about 100,000, greater than or equal to about 120,000, greater than or equal to about 140,000, greater than or equal to about 160,000, greater than or equal to about 180,000, greater than or equal to about 200,000, greater than or equal to about 220,000, greater than or equal to about 240,000, greater than or equal to about 260,000, greater than or equal to about 280,000, greater than or equal to about 300,000, greater than or equal to about 350,000, greater than or equal to about 400,000, greater than or equal to about 450,000, greater than or equal to about 500,000, or greater than or equal to about 550,000.The average molecular weight of the polymer (or copolymer), the first polymer, or the second polymer may be less than or equal to about 8,000,000, less than or equal to about 7,000,000, less than or equal to about 6,000,000, less than or equal to about 5,000,000, less than or equal to about 4,000,000, less than or equal to about 3,000,000, less than or equal to about 2,000,000, less than or equal to about 1,500,000, less than or equal to about 1,200,000, less than or equal to about 1,000,000, less than or equal to about 900,000, less than or equal to about 800,000, less than or equal to about 700,000, less than or equal to about 600,000, less than or equal to about 500,000, less than or equal to about 450,000, less than or equal to about 200,000, less than or equal to about 150,000, less than or equal to about 100,000, less than or equal to about 90,000, less than or equal to about 80,000, less than or equal to about 70,000, less than or equal to about 50,000, less than or equal to about 30,000, less than or equal to about 23,000, or less than or equal to about 20,000.

[0290] The molecular weight of the polymer (or copolymer), the first polymer, or the second polymer (hereinafter, may be simply referred to as "polymer") can be obtained considering the degree of polymerization and molecular weight (e.g., g / mol) of the repeating unit, and can exhibit a molecular weight distribution. The molecular weight of the polymer can be the average molecular weight of the polymer, and can be the number-average molecular weight, weight-average molecular weight, or viscosity-average molecular weight.

[0291] In an embodiment, the average molecular weight of the polymer can be measured by using a solution of the polymer. To reduce the interaction between the molecules of the polymer, the molecular weight can be measured by a dilute solution. The concentration of the polymer solution can be appropriately selected, and a solution in which 1 gram or less of the polymer is dissolved per 100 mL, for example, can be used for measurement. The average molecular weight of the polymer can be measured by an appropriate method, such as gel permeation chromatography, end-group analysis, osmotic pressure method, capillary viscometry, etc. In gel permeation chromatography, the polymer dissolved in a solvent can be separated according to its size, and the results obtained can be calibrated using a standard material with a determined molecular weight. In the end-group analysis method, the molecular weight can be measured as follows: by dissolving the polymer in a solvent to quantify the functional group (e.g., carboxyl group). According to the established standards, using commercially available devices, each measurement method can easily and reproducibly provide substantially the same information about the molecular weight.

[0292] The number-average molecular weight, weight-average molecular weight, and viscosity-average molecular weight of the polymer can be related to each other.

[0293] The polymer (or copolymer), first polymer, or second polymer may be commercially available from various manufacturers. The manufacturers provide information about the polymer (e.g., number average molecular weight, weight average molecular weight, etc.), and thus polymers with desired levels and types of molecular weight values may be commercially available.

[0294] The organic layer or polymer material may include a copolymer that includes the first repeating unit and the second repeating unit. The copolymer may be an alternating copolymer, a block copolymer, a random copolymer, or a combination thereof. The organic layer or polymer material may include a mixture of the first polymer and the second polymer.

[0295] In an embodiment, the polymer (e.g., the first polymer and / or the second polymer) may have a relatively high level of solubility in water or a water-miscible organic solvent (e.g., alcohol, DMSO, etc.), and when manufacturing the organic layer, the viscosity of the solution for coating can be relatively freely adjusted. Therefore, compared with an adhesive composition having a high viscosity (e.g., a composition based on a curable resin), a high degree of freedom can be provided when forming a film.

[0296] The organic layer or polymer 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; C2-50 carboxylic acid compounds (e.g., represented by R(COOH) n ), sulfinic acid compounds (e.g., represented by R(SO2H) n ), sulfonic acid compounds (e.g., represented by R(SO3H) n ), or a combination 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, 2 to 8, or 3 to 6. The carboxylic acid compound, sulfinic acid compound, sulfonic acid compound, or a combination thereof may further include a hydroxyl group.

[0297] The additives may include a polycarboxylic acid compound having two or more carboxylic acid groups. The polycarboxylic acid compound may be a non-polymeric compound. The polycarboxylic acid compound may be a compound having 2 to 10 carboxylic acid groups. The polycarboxylic acid compound may have 1 to 10, 2 to 5, 3 to 4 C 1-100 、C 2-60 or C 6-15 aliphatic hydrocarbon groups, 1 to 10, 2 to 5, 3 to 4 C 6-50 or C 6-15 aromatic hydrocarbon groups, or a combination thereof. The polycarboxylic acid compound may further include a hydroxyl group.

[0298] The polycarboxylic acid compound may include a compound represented by HOOC-A-(COOH) m wherein A is a single bond, a carbon atom, a substituted or unsubstituted C1 to C100 (C1-C50, C5-C15, C6-C12) aliphatic hydrocarbon group such as an alkylene group, an alkenylene group, or an alkynylene group, a substituted or unsubstituted C6 to C40 aromatic hydrocarbon group, or a combination thereof, and 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, or 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 polycarboxylic acid compound may have the following 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 polycarboxylic acid compound may have the following 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.

[0299] The additive 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 a combination thereof.

[0300] In the organic layer or polymer material, based on the total weight of the organic layer, the amount of the crosslinked polymer (e.g., crosslinked poly(meth)acrylate, crosslinked epoxy resin, crosslinked polysiloxane, crosslinked 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 organic layer may substantially not include a crosslinked polymer (or poly(meth)acrylate).

[0301] The organic layer may be configured to dissolve at least a portion thereof 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 20 °C, greater than or equal to about 25 °C, or greater than or equal to about 30 °C. The temperature of the water (or the temperature of the C1 to C5 alcohol) may be less than or equal to its boiling point (e.g., about 50 °C or lower, or about 30 °C or lower).

[0302] In an embodiment, the thickness of the organic layer may be greater than or equal to about 10 nm, greater than or equal to about 30 nm, greater than or equal to about 50 nm, greater than or equal to about 70 nm, greater than or equal to about 90 nm, greater than or equal to about 100 nm, greater than or equal to about 120 nm, greater than or equal to about 140 nm, greater than or equal to about 160 nm, greater than or equal to about 180 nm, greater than or equal to about 200 nm, greater than or equal to about 250 nm, greater than or equal to about 300 nm, greater than or equal to about 350 nm, greater than or equal to about 400 nm, greater than or equal to about 450 nm, greater than or equal to about 500 nm, greater than or equal to about 550 nm, greater than or equal to about 600 nm, greater than or equal to about 650 nm, greater than or equal to about 700 nm, greater than or equal to about 750 nm, greater than or equal to about 800 nm, greater than or equal to about 850 nm, greater than or equal to about 900 nm, greater than or equal to about 950 nm, greater than or equal to about 1 micrometer (μm), or greater than or equal to about 1.5 μm.

[0303] The thickness of the organic layer may be less than or equal to about 1 centimeter, such as less than or equal to about 50 millimeters (mm), less than or equal to about 10 mm, less than or equal to about 1 mm, less than or equal to about 0.5 mm, less than or equal to about 0.15 mm, less than or equal to about 100 μm, less than or equal to about 90 μm, less than or equal to about 80 μm, less than or equal to about 70 μm, less than or equal to about 60 μm, less than or equal to about 50 μm, less than or equal to about 40 μm, less than or equal to about 30 μm, less than or equal to about 20 μm, less than or equal to about 10 μm, less than or equal to about 9 μm, less than or equal to about 8 μm, less than or equal to about 7 μm, less than or equal to about 6 μm, less than or equal to about 5 μm, less than or equal to about 4 μm, less than or equal to about 3 μm, less than or equal to about 2 μm, or less than or equal to about 1 μm. The thickness of the organic layer may be greater than or equal to about 10 nm, greater than or equal to about 100 nm, greater than or equal to about 500 nm, greater than or equal to about 1 µm, or greater than or equal to about 1.5 µm.

[0304] The electroluminescent device of the embodiment may further include a container configured to accommodate at least a part of a stacked structure including a first electrode, a light-emitting layer, an electron transport layer, and a conductor thin film (or a second electrode). The container may include a light-transmissive component. Additional components (e.g., light-transmissive or non-light-transmissive materials, sealing materials) connected to the light-transmissive component may be further included. In an embodiment, the container may be an integrated material or structure. In an embodiment, the container may be formed by combining multiple components. In an embodiment, the container may be an integrated light-transmissive component (e.g., an element or material, see Figure 2B and Figure 8 encapsulation glass). In an embodiment, the container may include a light-transmissive component and a sealant. The container may be an encapsulation element for the 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 details of the substrate described herein. In an embodiment, the furnace may be a device or apparatus configured to expose a given material to a high-temperature environment (e.g., the post-treatment temperature described herein, such as a temperature of 50 °C or higher, 70 °C or higher, 90 °C or higher), and the heating method is not particularly limited. The furnace includes a hollow chamber and includes a heating element configured to heat the chamber in a controlled manner. The hollow chamber may provide the defined space.

[0305] In the electroluminescent device of the embodiment, the organic layer may be disposed adjacent to or in contact with the container or the light-transmissive component. The organic layer may be applied or coated on the surface of the container or the light-transmissive component. In the electroluminescent device of the embodiment, the container including the organic layer may be replaced with a new container after post-treatment, and thus, the electroluminescent device of the embodiment may not include the organic layer.

[0306] In an embodiment, the electroluminescent device may further include a hole assisting layer 2, 20 between the first electrodes 1, 10 and the light-emitting layers 3, 30. The hole assisting layer 2, 20 may include a hole injection layer, a hole transport layer, an electron blocking layer, or a combination thereof. The hole assisting layer 2, 20 may be a single layer or a multilayer structure in which adjacent layers include different components. (Refer to Figure 1A , 1B , 2A and 2B)

[0307] The hole auxiliary layers 2 and 20 may have the following HOMO energy levels: they can match the HOMO energy levels of the light-emitting layers 3 and 30 to enhance the mobility of holes transferred from the hole auxiliary layers 2 and 20 to the light-emitting layers 3 and 30. In an embodiment, the hole auxiliary layers 2 and 20 may include a hole injection layer close to the first electrode 1 and 10 (e.g., adjacent thereto) and a hole transport layer close to the light-emitting layers 3 and 30 (e.g., adjacent thereto).

[0308] In an embodiment, the materials included in the hole auxiliary layers 2 and 20 (e.g., hole transport layer, hole injection layer, or electron blocking layer) are not particularly limited and may include, for example, poly(9,9-dioctyl-fluorene-co-N-(4-butylphenyl)-diphenylamine) (TFB), polyarylamine (polyaryl amine), poly(N-vinylcarbazole), poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), polyaniline, polypyrrole, N,N,N',N'-tetrakis(4-methoxyphenyl)-benzidine (TPD), 4,4'-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), m-MTDATA (4,4',4''-tris[phenyl(m-tolyl)amino]triphenylamine), 4,4',4''-tris(N-carbazolyl)-triphenylamine (TCTA), 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), p-type metal oxides (e.g., NiO, WO3, MoO3, etc.), carbon-based materials such as graphene oxide, or a combination thereof, but not limited thereto.

[0309] 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.

[0310] According to as Figure 3A 、 3B, the devices of the embodiments shown in 3C, 5A, and 8 may have a normal structure. In the devices of the embodiments, the anode 10 disposed on the transparent substrate 100 may include a metal oxide-based transparent electrode (e.g., ITO electrode), and the cathode 50 facing the anode 10 may include a conductive metal (e.g., having a relatively low work function, such as Mg, Al, etc.). The hole auxiliary layer 20 (e.g., a hole injection layer such as PEDOT:PSS, a p-type metal oxide, or a combination thereof; a hole transport layer such as TFB, polyvinylcarbazole (PVK), or a combination thereof; or a combination thereof) may be disposed between the transparent electrode 10 and the light-emitting layer 30. The hole injection layer may be disposed adjacent to the transparent electrode (e.g., adjacent thereto), and the hole transport layer may be disposed adjacent to the light-emitting layer (e.g., adjacent thereto). The electron transport layer or an electron auxiliary layer including the same (e.g., an electron injection / transport layer) 40 may be disposed between the light-emitting layer 30 and the cathode 50.

[0311] In an embodiment, the electroluminescent device of the embodiment may be manufactured by a method including the following:

[0312] Form a light-emitting (e.g., patterned) layer including semiconductor nanoparticles on or above the first electrode, form an electron transport layer on the light-emitting layer, and form a second electrode or a thin film conductor on or above the electron transport layer to obtain a stacked structure. The method further includes forming an organic layer on or above the electron transport layer and performing post-treatment on the stacked structure.

[0313] In an embodiment, the method may further include forming a hole auxiliary layer on the first electrode (e.g., disposed on the 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 the patterned layer) of semiconductor nanoparticles is the same as that described herein.

[0314] The post-treatment may be performed using the organic layer or polymer material described herein and optionally a container. In an embodiment, the post-treatment may include:

[0315] Place at least a part of the stacked structure (e.g., the electron transport layer and the thin film conductor) and the organic layer or polymer material together in a first space, and maintain (e.g., heat) the first space at a post-treatment temperature greater than or equal to about 40 °C and less than or equal to about 200 °C.

[0316] The method may further include providing a container to the stacked structure, wherein the container may be configured to define at least a part of the first space. Details regarding the container are the same as those described herein.

[0317] The space may be an enclosed space, e.g., a sealed space or an airtight or gas-impermeable space. The method may include removing the container after the post-treatment or separating the stacked structure from the container. The post-treatment may be carried out for a predetermined time.

[0318] The container may include a light-transmissive component, e.g., a light-transmissive material or component. The container may be or include an encapsulation 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, e.g., a furnace or a chamber, and provides a space (e.g., an enclosed space).

[0319] Details of the container and the post-treatment are the same as those described herein.

[0320] In the method of an embodiment, a stacked structure can be obtained by forming a light-emitting layer and an electron-transporting layer on a first electrode and, e.g., between a pixel-defining layer PDL, and then forming a thin-film conductor on the electron-transporting layer (see Figure 5A and 5B ). The method may further include forming a hole-assist layer on the first electrode, e.g., before forming the light-emitting layer. The organic layer (or polymer material) and the container are provided to the stacked structure thus obtained such that at least a part of the organic layer (or polymer material) and the stacked structure (e.g., the electron-transporting layer and the thin-film conductor) can be disposed in the space defined by the container. (See Figure 5A , Figure 6A and Figure 8 ). In an embodiment, the container may be a furnace or a chamber (see Figure 7 ).

[0321] Surprisingly, the inventors have found that by maintaining the organic layer (or polymer material) and the stacked structure in a first space at a predetermined post-treatment temperature greater than or equal to about 40 °C (and optionally less than or equal to about 180 °C (e.g., less than or equal to about 150 °C)), the properties of the light-emitting device can be significantly improved. Without wishing to be bound by any theory, it is believed that the organic layer or polymer material can 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-transporting layer, thereby improving the properties of the light-emitting device.

[0322] The thin-film conductor or the second electrode may have a specified thickness such that it can have conductivity capable of serving as an electron-injection conductor and can allow the acid / moisture released from the organic layer or polymer material to diffuse or spread (e.g., downward) and transfer to the electron-transporting layer provided under the thin-film conductor. Providing an acid / moisture vapor environment and generating a relatively high-temperature environment can promote the surface modification reaction.

[0323] The method may include preparing an organic layer-forming composition including the polymeric material (e.g., a copolymer including a first repeating unit and a second repeating unit, or a first polymer and a second polymer each having their respective first repeating unit and second repeating unit) and a liquid carrier. The organic layer-forming composition may further or may not further include additives. Details of the polymer, the first polymer, the second polymer, and the additives are the same as those described herein. The concentrations of the polymer, the first polymer, the second polymer, and the additives may be appropriately selected considering the type of the compound and the thickness of the organic layer to be formed.

[0324] The method may include applying the organic layer-forming composition on an electron transport layer (and optionally a second electrode). The method may include applying the organic layer-forming composition on the surface of a container (e.g., applying onto the surface of the container) such that the container faces the electron transport layer or the second electrode. In an embodiment of the method, the organic layer-forming composition may be applied onto the electron transport layer (and the second electrode) or the surface of the container to form an organic layer. The method may include removing (e.g., evaporating) at least a portion of the liquid carrier from the applied composition to form an organic layer.

[0325] The above liquid carrier may include: water; C1-10 alcohols such as ethanol, methanol, propanol, isopropanol, (iso)propanol, (iso)butanol, (iso)pentanol, hexanol, heptanol, octanol, nonanol, etc.; nitrile solvents such as acetonitrile, etc.; sulfoxide solvents such as dimethyl sulfoxide, diethyl sulfoxide, ethyl methyl sulfoxide; ester solvents such as ethyl acetate, or a combination thereof. The liquid carrier may include a mixture of water and a C1-10 alcohol.

[0326] The method may include: preparing a first solution by dissolving a first polymer in a C1-10 alcohol, preparing a second solution by dissolving a second polymer in water, and preparing an organic layer-forming composition by mixing the first solution and the second solution. The method may include preparing an organic layer-forming composition by dissolving a polymer having a first repeating unit and a second repeating unit in a C1-10 alcohol. When observed with the naked eye, the organic layer-forming composition may be a transparent solution. The mixing ratio of the first solution and the second solution may be appropriately adjusted considering the solubility and concentration of the first polymer and the second polymer. In an embodiment, the mixing ratio (e.g., weight ratio or volume ratio) of the first solution and the second solution may be in the range of 1:0.1 to 1:10, 1:0.3 to 1:3, 1:0.5 to 1:2, or a combination thereof, but not limited thereto. The molar ratio between the acid functional group and the hydroxyl functional group in the organic layer-forming composition is as described herein.

[0327] The first polymer and the second polymer can be well dissolved in water or an organic solvent (e.g., alcohol), for example, having a desired level of solubility in water or an organic solvent to relatively easily form a (transparent) organic layer-forming composition having an appropriate viscosity. The viscosity of the organic layer-forming composition at room temperature (e.g., about 20 - 30 °C or about 25 °C) can be in the range of about 2 centipoise (cPs) to about 2000 cPs, about 3 cPs to about 1500 cPs, about 7 cPs to about 1200 cPs, about 10 cPs to about 1000 cPs, about 15 cPs to about 800 cPs, about 20 cPs to about 700 cPs, about 30 cPs to about 500 cPs, about 40 cPs to about 150 cPs, about 50 cPs to about 100 cPs, or a combination thereof, but not limited thereto.

[0328] In the organic layer-forming composition, the concentration of the polymer (or the concentration of the first polymer and / or the second polymer) can be appropriately selected in consideration of the type of the polymer, the desired thickness of the organic layer, etc. In an embodiment, the concentration of the polymer in the organic layer-forming composition, or the concentration of the first polymer, the concentration of the second polymer, or the concentration of the mixture of the first and second polymers can be respectively greater than or equal to about 0.01 wt%, greater than or equal to about 0.05 wt%, greater than or equal to about 0.1 wt%, greater than or equal to about 0.5 wt%, greater than or equal to about 1 wt%, greater than or equal to about 2 wt%, greater than or equal to about 3 wt%, greater than or equal to about 3.3 wt%, greater than or equal to about 4 wt%, greater than or equal to about 5 wt%, greater than or equal to about 6 wt%, greater than or equal to about 7 wt%, greater than or equal to about 8 wt%, greater than or equal to about 9 wt%, greater than or equal to about 10 wt%, greater than or equal to about 11 wt%, greater than or equal to about 12 wt%, greater than or equal to about 13 wt%, greater than or equal to about 14 wt%, greater than or equal to about 15 wt%, greater than or equal to about 16 wt%, greater than or equal to about 17 wt%, greater than or equal to about 18 wt%, greater than or equal to about 19 wt%, greater than or equal to about 20 wt%, greater than or equal to about 21 wt%, greater than or equal to about 22 wt%, greater than or equal to about 23 wt%, greater than or equal to about 24 wt%, greater than or equal to about 25 wt%, greater than or equal to about 26 wt%, greater than or equal to about 27 wt%, greater than or equal to about 28 wt%, greater than or equal to about 29 wt%, greater than or equal to about 30 wt%, greater than or equal to about 31 wt%, greater than or equal to about 32 wt%, greater than or equal to about 33 wt%, greater than or equal to about 34 wt%, greater than or equal to about 35 wt%, greater than or equal to about 36 wt%, greater than or equal to about 37 wt%, greater than or equal to about 38 wt%, greater than or equal to about 39 wt%, or greater than or equal to about 40 wt%, based on the total weight of the composition. The concentration of the polymer in the organic layer-forming composition, or the concentration of the first polymer and / or the second polymer can be respectively less than or equal to about 99 wt%, less than or equal to about 90 wt%, less than or equal to about 85 wt%, less than or equal to about 80 wt%, less than or equal to about 75 wt%, less than or equal to about 70 wt%, less than or equal to about 65 wt%, less than or equal to about 60 wt%, less than or equal to about 55 wt%, less than or equal to about 50 wt%, less than or equal to about 45 wt%, less than or equal to about 40 wt%, less than or equal to about 35 wt%, less than or equal to about 30 wt%, less than or equal to about 25 wt%, less than or equal to about 20 wt%, less than or equal to about 15 wt%, less than or equal to about 10 wt%, or less than or equal to about 5 wt%, based on the total weight of the composition.

[0329] In an embodiment, the organic layer-forming composition may further include an additive, and the concentration of the additive in the organic layer-forming composition may be in the range of from about 0.0001 mole / L (M) to about 10 M, from about 0.0005 M to about 5 M, from about 0.001 M to about 4 M, from about 0.005 M to about 3 M, from about 0.01 M to about 2 M, from about 0.05 M to about 1.5 M, from about 0.1 M to about 1.3 M, from about 0.1 M to about 1.2 M, from about 0.15 M to about 1 M, from about 0.15 M to about 0.9 M, from about 0.2 M to about 0.8 M, from about 0.3 M to about 0.7 M, from about 0.4 M to about 0.6 M, from about 0.45 M to about 0.55 M, or a combination thereof.

[0330] The organic layer-forming composition may exhibit a pH greater than or equal to about 1, greater than or equal to about 1.5, greater than or equal to about 2, greater than or equal to about 3, greater than or equal to about 3.5, greater than or equal to about 4, greater than or equal to about 4.5, greater than or equal to about 5, or greater than or equal to about 5.5 and less than or equal to about 8, less than or equal to about 7.5, less than or equal to about 7, less than or equal to about 6.5, less than or equal to about 6, less than or equal to about 5.5, less than or equal to about 5.2, less than or equal to about 5, or less than or equal to about 4.8, or less than or equal to about 4. The concentration of the organic layer-forming composition at these pH levels may be the same as those described herein.

[0331] The method of applying the organic layer-forming composition is not particularly limited and may be appropriately selected. The application may involve spin coating, drop coating, or a combination thereof. After applying the organic layer-forming composition, the excess composition may be removed by rotation or the like.

[0332] The formation of the organic layer may not involve polymerization and / or crosslinking reactions. Thus, based on the total weight of the organic layer or the polymer, the amount of the crosslinked polymer in the organic layer may be less than 1 wt%. Without wishing to be bound by a particular theory, it is believed that providing a layer containing a crosslinked polymer (e.g., as a main component) on or above the electron transport layer may result in significant light absorption in a certain wavelength range, which may make it difficult to use the fabricated light-emitting device, for example, in a front-emission type display panel having a second electrode as a transparent electrode.

[0333] In addition, the present inventors have found that an organic layer-forming composition including a crosslinked resin easily leads to a significantly increased viscosity, and thus it may become more difficult to form an organic layer having a desired or controlled thickness. The present inventors have found that in the method of the embodiment, the organic layer including a crosslinked resin as a main component does not sufficiently provide an acid component and moisture.

[0334] In an embodiment, the post-treatment may be carried out in a suitable atmosphere (e.g., in an inert gas atmosphere, in an oxygen-free atmosphere, or in air).

[0335] In the organic layer of the embodiment, the polymer material (e.g., a first polymer and a second polymer, or a copolymer having a first repeating unit and a second repeating unit) (e.g., having a molecular weight as described herein) may exhibit hydrophilicity, and thus, a limited amount of moisture may be present in the organic layer or the polymer material together with relatively unstable acid moieties (e.g., COOH groups). In an embodiment, the organic layer or the polymer material may relatively easily and gradually release moisture and acid components under a predetermined atmosphere (e.g., an inert gas atmosphere or ambient atmosphere) and at the post-treatment temperature described herein. The released moisture and the released acid components may diffuse (e.g., through a thin film conductor of a predetermined thickness) to reach the metal oxide nanoparticles present in the electron assisting layer, promoting surface modification. For example, the moisture and the acid components may relatively easily and gradually move to the electron assisting layer and may interact or react (e.g., participate in a dehydration condensation reaction) with the metal oxide nanoparticles (e.g., with hydroxyl groups or defect sites that may be present on the surface of the metal oxide nanoparticles). It is believed that the interaction and reaction may modify the surface of the metal oxide nanoparticles, possibly eliminating defects and resulting in the growth of the metal oxide nanoparticles.

[0336] The post-treatment temperature may 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 may be less than or equal to about 200 °C, less than or equal to about 190 °C, less than or equal to about 180 °C, less than or equal to about 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.

[0337] The post-treatment time can be greater than or equal to about 30 minutes, greater than or equal to about 1 hour, greater than or equal to about 2 hours, greater than or equal to about 3 hours, greater than or equal to about 5 hours, greater than or equal to about 7 hours, greater than or equal to about 12 hours, greater than or equal to about 20 hours, greater than or equal to about 24 hours, greater than or equal to about 36 hours, greater than or equal to about 48 hours, or greater than or equal to about 50 hours. The post-treatment time can be less than or equal to about 30 days, less than or equal to about 20 days, less than or equal to about 10 days, less than or equal to about 5 days, less than or equal to about 3 days, less than or equal to about 70 hours, less than or equal to about 50 hours, less than or equal to about 2 days, less than or equal to about 30 hours, less than or equal to about 1 day, less than or equal to about 18 hours, less than or equal to about 14 hours, less than or equal to about 8 hours, less than or equal to about 6 hours, less than or equal to about 5 hours, less than or equal to about 4 hours, less than or equal to about 3 hours, less than or equal to about 2 hours, or less than or equal to about 1 hour.

[0338] The method of the embodiment can further include removing the container after the post-treatment and providing a conductive layer on the thin film conductor to increase the thickness of the thin film conductor or the second electrode. After the thin film conductor or the second electrode obtains an increased thickness as needed, a new container can be further provided. (See Figure 6A and Figure 6B ).

[0339] In an embodiment, a light-emitting device or an electroluminescent device (hereinafter referred to as "light-emitting device") includes a first electrode (e.g., a hole injection conductor or an anode), 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.

[0340] Wherein the light-emitting layer includes semiconductor nanoparticles, and the light-emitting layer is configured to emit a first light,

[0341] 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,

[0342] Wherein the second electrode has a thickness greater than or equal to about 1 nm (or greater than or equal to about 11 nm) and less than or equal to about 50 nm, and the second electrode has a light transmittance for the first light greater than or equal to about 50% and less than or equal to about 100%, and

[0343] Wherein the first electrode is configured to reflect at least a portion of the first light.

[0344] The first electrode may include a hole injection conductor, and the second electrode may include an electron injection conductor.

[0345] The semiconductor nanoparticles or the light-emitting layer may not contain cadmium, lead, mercury, or a combination thereof.

[0346] The second electrode may have a thickness greater than or equal to about 15 nm and less than or equal to about 40 nm.

[0347] The first electrode may be configured to reflect at least a portion of the first light.

[0348] 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.

[0349] The light-emitting device may further include an organic layer or a polymer material disposed on the electron transport layer. The organic layer and the polymer material are the same as those described herein.

[0350] The organic layer or the polymer material may be disposed to be spaced apart from the electron transport layer and the second electrode. The organic layer may be disposed to face the electron transport layer and the second electrode or the conductor thin film.

[0351] The electron transport layer may have a first surface facing the emission layer and a second surface opposite to the first surface, and the organic layer or the polymer material may be disposed on the second surface. The organic layer or the polymer material may be disposed to be spaced apart from the electron transport layer (e.g., separated from the electron transport layer).

[0352] The organic layer or the polymer material may have a thickness greater than or equal to about 10 nm, or greater than or equal to about 100 nm. The thickness of the organic layer or the polymer material may be less than or equal to about 100 micrometers (μm), or less than or equal to about 10 μm.

[0353] The thin film conductor or the second electrode may have a first surface facing the surface of the electron assisting layer and a second surface opposite to the first surface, and the organic layer or the polymer material may be disposed to be spaced apart from the electron transport layer and / or the second electrode and may be disposed to face at least a portion (e.g., all) of the surface of the electron transport layer and / or at least a portion (e.g., all) of the second surface of the second electrode.

[0354] Details of the light-emitting device (e.g., its elements such as semiconductor nanoparticles, metal oxide nanoparticles, first / second electrodes, thin film conductors, organic layers or polymer materials) are the same as those described herein. For details of the second electrode, reference may also be made to the description of the conductor thin film.

[0355] The light-emitting device of the embodiment can be configured to emit red light, green light, or blue light. Details of the red light, green light, or blue light (e.g., wavelength) are the same as those described herein.

[0356] In an embodiment, the light-emitting (or electroluminescent) device can have a maximum external quantum efficiency (EQE) as follows: greater than or equal to about 4%, greater than or equal to about 5%, greater than or equal to about 5.5%, greater than or equal to about 6%, greater than or equal to about 6.5%, greater than or equal to about 7%, greater than or equal to about 7.5%, greater than or equal to about 7.7%, greater than or equal to about 8%, greater than or equal to about 8.5%, greater than or equal to about 9%, greater than or equal to about 9.5%, greater than or equal to about 10%, greater than or equal to about 10.5%, greater than or equal to about 11%, greater than or equal to about 11.5%, greater than or equal to about 12%, greater than or equal to about 12.5%, greater than or equal to about 13%, greater than or equal to about 13.5%, or greater than or equal to about 14%. The maximum external quantum efficiency (EQE) can be less than or equal to about 60%, less than or equal to about 50%, less than or equal to about 40%, less than or equal to about 30%, or less than or equal to about 20%.

[0357] The light-emitting (or electroluminescent) device of the embodiment can exhibit a maximum luminance greater than or equal to about 10,000 candela per square meter (cd / m 2 )、greater than or equal to about 30,000 cd / m 2 、greater than or equal to about 40,000 cd / m 2 、greater than or equal to about 60,000 cd / m 2 、greater than or equal to about 65,000 cd / m 2 、greater than or equal to about 70,000 cd / m 2 、greater than or equal to about 80,000 cd / m 2 、greater than or equal to about 90,000 cd / m 2 、greater than or equal to about 100,000 cd / m 2 、greater than or equal to about 110,000 cd / m 2 、or greater than or equal to about 120,000 cd / m 2 .

[0358] The luminescent (or electroluminescent) device of the embodiment may exhibit a maximum luminous efficiency greater than or equal to about 5 candela per ampere (cd / A), greater than or equal to about 5.5 cd / A, greater than or equal to about 6 cd / A, greater than or equal to about 7 cd / A, greater than or equal to about 8 cd / A, greater than or equal to about 9 cd / A, greater than or equal to about 10 cd / A, greater than or equal to about 15 cd / A, greater than or equal to about 20 cd / A, or greater than or equal to about 30 cd / A.

[0359] In an embodiment, when measured by driving the device at a predetermined initial luminance (e.g., about 650 nits or about 146 nits), the luminescent (or electroluminescent) device may exhibit a T50 greater than or equal to about 10 hours, greater than or equal to about 20 hours, greater than or equal to about 25 hours, greater than or equal to about 30 hours, greater than or equal to about 40 hours, greater than or equal to about 50 hours, greater than or equal to about 60 hours, greater than or equal to about 65 hours, greater than or equal to about 70 hours, greater than or equal to about 80 hours, greater than or equal to about 90 hours, greater than or equal to about 100 hours, greater than or equal to about 120 hours, greater than or equal to about 150 hours, greater than or equal to about 180 hours, greater than or equal to about 200 hours, or greater than or equal to about 250 hours.

[0360] In an embodiment, when measured by driving the device at a predetermined initial luminance (e.g., about 650 nits or about 146 nits), the luminescent 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.

[0361] The light-emitting (or electroluminescent) device may exhibit increased stability. After heat treatment at about 70 °C for about 2 days in air or an inert atmosphere and driving at about 146 nits, the light-emitting (or electroluminescent) device of the embodiment may exhibit a voltage increase of less than or equal to about 30%, or less than or equal to about 25% of the initial voltage, compared to a comparable device without heat treatment.

[0362] In an embodiment, the display device includes the light-emitting (e.g., electroluminescent) device described herein.

[0363] The display device (e.g., display panel) may include a first pixel and a second pixel configured to emit light different from that of the first pixel.

[0364] Referring Figure 9 , the display panel 1000 according to an embodiment includes a display area 1000D for displaying an image and a non-display area 1000P provided around the display area 1000D, and the bonding elements may be located in the non-display area 1000P.

[0365] The display area 1000D may include a plurality of pixels PX arranged along rows (e.g., X direction) and / or columns (e.g., 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.

[0366] The sub-pixels PX1, PX2, and PX3 may each be configured to display colors such as primary colors or combinations of primary colors, e.g., red, green, blue, or combinations 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.

[0367] In the figure, the sub-pixels are each 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 have a different shape from the other sub-pixels.

[0368] In an embodiment, the display panel of the embodiment may include a light-emitting panel 100, and the light-emitting panel 100 may include a lower substrate 110, a buffer layer 111, thin film transistors TFT, and light-emitting elements 180. The display panel may further include circuit elements for switching (or toggling) and / or driving the light-emitting elements respectively.

[0369] Reference Figure 10 In the light-emitting panel of the embodiment, light-emitting elements 180 may be provided for each of the sub-pixels PX1, PX2, and PX3. The light-emitting elements 180 provided in each of the sub-pixels PX1, PX2, and PX3 may be independently driven. The sub-pixels may include blue sub-pixels, red sub-pixels, or green sub-pixels. At least one of the light-emitting elements 180 may be an electroluminescent element according to the embodiment described herein.

[0370] Details of the substrate are the same as those described herein. The buffer layer 111 may include an organic material, an inorganic material, or an organic-inorganic material. The buffer layer 111 may include, for example, an oxide, a nitride, or a oxynitride, and may include, for example, silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof, but is not limited thereto. The buffer layer 111 may be one layer, two layers, or more layers, and may cover a part or the entire surface of the lower substrate 110. The buffer layer 111 may be omitted.

[0371] The thin-film transistor TFT may be a three-terminal element for switching and / or driving the light-emitting element 180, and one, two, or more may be included for each sub-pixel. The thin-film transistor TFT may include a gate electrode 124, a semiconductor layer 154 overlapping the gate electrode 124, a gate insulating layer 140 between the gate electrode 124 and the semiconductor layer 154, and a source electrode 173 and a drain electrode 175 electrically connected to the semiconductor layer 154. A coplanar top-gate structure is shown as an example, but the structure is not limited thereto and may have various structures.

[0372] The gate electrode 124 is electrically connected to a gate line (not shown) and may include, for example, a low-resistance metal such as aluminum (Al), molybdenum (Mo), copper (Cu), titanium (Ti), silver (Ag), gold (Au), an alloy thereof, or a combination thereof, but is not limited thereto.

[0373] The semiconductor layer 154 may be an inorganic semiconductor such as amorphous silicon, polycrystalline silicon, or an oxide semiconductor; an organic semiconductor; an organic-inorganic semiconductor; or a combination thereof. For example, the semiconductor layer 154 may include an oxide semiconductor including at least one of indium (In), zinc (Zn), tin (Sn), and gallium (Ga), and the oxide semiconductor may include, for example, indium-gallium-zinc oxide, zinc-tin oxide, or a combination thereof, but they are not limited thereto. The semiconductor layer 154 may include a channel region and doping regions provided on both sides of the channel region and electrically connected to the source electrode 173 and the drain electrode 175, respectively.

[0374] The gate insulating layer 140 may include an organic material, an inorganic material, or an organic-inorganic material, and may include, for example, an oxide, a nitride, or a oxynitride, and may include, for example, silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof, but is not limited thereto. In the drawings, an example is shown in which the gate insulating layer 140 is formed on the entire surface of the lower substrate 110, but the present disclosure is not limited thereto, and may be selectively formed between the gate electrode 124 and the semiconductor 154. The gate insulating layer 140 may be formed of one layer, two layers, or more layers.

[0375] The source electrode 173 and the drain electrode 175 may include, for example, a low-resistance metal such as aluminum (Al), molybdenum (Mo), copper (Cu), titanium (Ti), silver (Ag), gold (Au), an alloy thereof, or a combination thereof, but is not limited thereto. The source electrode 173 and the drain electrode 175 may be electrically connected to the doped regions of the semiconductor layer 154, respectively. The source electrode 173 is electrically connected to a data line (not shown), and the drain electrode 175 is electrically connected to the light-emitting element 180.

[0376] An interlayer insulating layer 145 is further formed between the gate electrode 124 and the source / drain electrodes 173 and 175. The interlayer insulating layer 145 may include an organic material, an inorganic material, or an organic-inorganic material, such as an oxide, a nitride, or a oxynitride, such as silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof, but is not limited thereto. The interlayer insulating layer 145 may be formed of one layer, two layers, or more layers.

[0377] A protective layer 160 is formed on the thin-film transistor TFT. The protective layer 160 may be, for example, a passivation layer. The protective layer 160 may include an organic material, an inorganic material, or an organic-inorganic material, such as polyacrylic acid, polyimide, polyamide, poly(amide-imide), or a combination thereof, but is not limited thereto. The protective layer 160 may be formed of one layer, two layers, three layers, or more layers.

[0378] 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.

[0379] In an embodiment, the light-emitting device or the display device including the same may be used in a top-emission type, a bottom-emission type, a double-emission type, or a combination thereof.

[0380] In an embodiment, the first electrodes 1 and 10 may be light-transmissive electrodes and the second electrodes 5 and 50 may be reflective electrodes, and the display panel may be a bottom-emission type display panel that emits light toward the first electrode 10 and the substrate 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 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 the substrate side and on the opposite side of the substrate.

[0381] The display device or the electronic device may include (or may be) a television, a virtual reality / augmented reality (VR / AR) device, a handheld terminal, a monitor, a laptop computer, an electronic display board, a camera, or a component for an automatic (e.g., self-driving) vehicle.

[0382] 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.

[0383] Embodiment

[0384] 1. Electroluminescence measurement

[0385] 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.

[0386] 2. Lifetime characteristics

[0387] T90 and T50 were measured at an initial luminance of 146 nits.

[0388] 3. Electron microscope analysis

[0389] Transmission electron microscopy analysis was performed using a UTF30 Tecnai electron microscope.

[0390] 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 stated as molar contents.

[0391] Synthesis Example 1:

[0392] A 2 molar / liter (M) Se / trioctylphosphine (TOP) stock solution, a 1 M S / TOP stock solution, and a 0.1 M Te / TOP stock solution were prepared by dispersing selenium (Se), sulfur (S), and tellurium (Te) in trioctylphosphine (TOP), respectively.

[0393] In a reactor containing trioctylamine, 0.125 millimoles (mmol) of zinc acetate and oleic acid were added to the reactor, and the mixture was heated at 120 °C under vacuum. After 1 hour, nitrogen was introduced into the reactor. The reactor was heated to 300 °C, and a Se / TOP stock solution and a Te / TOP stock solution with a Te:Se molar ratio of 1:15 were rapidly added to the reactor (e.g., injected into the reactor). After 40 minutes, the reaction was completed, and the reaction solution was rapidly cooled to room temperature, and acetone was added to the reactor. The resulting product mixture was centrifuged, and the precipitate was separated and dispersed in toluene to prepare a ZnSeTe core particle dispersion.

[0394] An amount of 1.8 mmol of zinc acetate and oleic acid were added to a flask containing trioctylamine, and the prepared mixture was heated at 120 °C under vacuum for 10 minutes. Then nitrogen (N2) was introduced into the reactor, the reactor was heated to 180 °C, and the prepared ZnTeSe core particle dispersion was rapidly added to the reactor. A Se / TOP stock solution and an S / TOP stock solution were also added to the reactor, and the reactor temperature was raised to about 280 °C. After 2 hours, the reaction was completed, the reactor was cooled to room temperature and ethanol was added to promote the precipitation of the semiconductor nanoparticles, which were then separated by centrifugation. The prepared semiconductor nanoparticles emit blue light, and photoluminescence spectroscopy analysis using a Hitachi F-7000 spectrophotometer confirmed that the blue light has a maximum emission peak wavelength of about 455 nanometers (nm).

[0395] The synthesized semiconductor nanoparticles (optical density of 0.25 at 420 nm, 6 milliliters (mL)) were precipitated with ethanol, separated by centrifugation, and the separated nanoparticles were dispersed in octane to prepare an octane dispersion.

[0396] Synthesis Example 2: Synthesis of ZnMgO Nanoparticles

[0397] 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 in 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 an ethanol dispersion of Zn 1-x Mg x O (x = 0.15) nanoparticles.

[0398] 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.

[0399] Example 1:

[0400] A dispersion of zinc magnesium oxide nanoparticles prepared in Synthesis Example 2 was used as an electron transport layer dispersion (hereinafter, ETL dispersion).

[0401] Polyacrylic acid (weight average molecular weight: 450,000, product name: poly(acrylic acid), PAA, Sigma-Aldrich (181285)) was dissolved in ethanol to prepare a first solution (PAA concentration: 5 wt%). Polyvinyl alcohol (weight average molecular weight: 22,000, manufacturer: Daejung Chemicals, degree of hydrolysis: 86 - 88%, product name: polyvinyl alcohol 500) was dissolved in water to prepare a second solution (PVA concentration: 3.3 wt%). The first solution and the second solution were mixed at a weight ratio of 2:1 to obtain an organic layer forming composition (pH 4 to 5).

[0402] A glass substrate deposited with indium tin oxide (ITO) was surface-treated with ultraviolet (UV)-ozone for 15 minutes, then spin-coated with a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) solution (H.C. Starks) and heated at 150 °C for 10 minutes in an air atmosphere and then heated again at 150 °C for 20 to 30 minutes in an air atmosphere to provide a hole injection layer (HIL) with a thickness of 120 nm.

[0403] 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 35 nm.

[0404] An octane dispersion of semiconductor nanoparticles prepared in Synthesis Example 1 was spin-coated on the prepared hole transport layer to prepare a light-emitting layer with a thickness of 50 nm, and then it was heat-treated in an air atmosphere at a temperature of about 140 °C for 30 minutes.

[0405] The ETL dispersion was spin-coated on the heat-treated light-emitting layer and heat-treated at 140 °C to form an electron transport layer with a thickness of about 50 nm.

[0406] On the obtained electron transport layer, magnesium and silver (molar ratio = 10:1) were thermally evaporated to form a second electrode with a thickness of 20 nm, thereby obtaining a stacked structure (hereinafter, may be referred to as a QD stack).

[0407] As Figure 5AAs shown in [Figure 0], the prepared organic layer-forming composition is placed in the form of drops and then spin-coated on the surface of an open box-shaped container (e.g., encapsulation glass), and then the solvent is removed to form an organic layer 60 with a thickness of about 3 μm.

[0408] In the sealed space defined by the container (i.e., encapsulation glass), the stacked structure is placed such that the organic layer is spaced apart from and faces the thin film conductor, as shown in [Figure 0], and then it is kept in an oven at 70 °C for 1 day to obtain a light-emitting device. Figure 5A As shown in [Figure 0], and then it is kept in an oven at 70 °C for 1 day to obtain a light-emitting device.

[0409] The electroluminescence properties of the prepared light-emitting device are measured, and the results are shown in Table 1.

[0410] It is confirmed that the external quantum efficiency of the fabricated light-emitting device at 146 nits is 6% or more.

[0411] Comparative Example 1

[0412] A light-emitting device is prepared in the same manner as in Example 1, except that: only the first solution is used as the composition for forming the organic layer, without using the second solution, that is, without using polyvinyl alcohol 500 (PVA concentration 3.3 wt%). The electroluminescence properties of the prepared light-emitting device are measured, and the results are shown in Table 1.

[0413] It is confirmed that the external quantum efficiency of the fabricated light-emitting device at 146 nits is 6% or more.

[0414] Comparative Example 2

[0415] A light-emitting device is prepared in the same manner as in Example 1, except that: malic acid (MA, concentration 0.1 M) is added to the first solution instead of the second solution to prepare the composition for forming the organic layer. The electroluminescence properties of the prepared light-emitting device are measured, and the results are shown in Table 1.

[0416] It is confirmed that the external quantum efficiency of the fabricated light-emitting device at 146 nits is 6% or more.

[0417] Table 1

[0418]

[0419] PAA: Polyacrylic acid

[0420] MA: Malic acid

[0421] PVA: Polyvinyl alcohol

[0422] Relative T50: T50 (hours) of a given device / T50 (hours) of Comparative Example 1

[0423] Relative luminance (%): Luminance of a given device / Luminance of Comparative Example 1

[0424] The results in Table 1 confirm that the light-emitting device of Example 1 not only exhibits significantly higher luminance and lifetime compared to the light-emitting device of Comparative Example 1, but also shows higher luminance and extended lifetime compared to Comparative Example 2.

[0425] Experimental Example 1

[0426] The light-emitting device fabricated in Example 1 was heat-treated on a hot plate at 120 °C for 2 hours. The electroluminescent properties of the device after heat treatment were measured, and the results are summarized in Table 2. The lifetime of the light-emitting device after heat treatment was measured. It was confirmed that the EQE value of the device of Example 1 at 146 nits remained at about 6% or higher. It was confirmed that the device of Example 1 had a maximum external quantum efficiency of 11% (before heat treatment) and 10.9% (after heat treatment) up to a driving voltage of 5 V. It was confirmed that the device of Example 1 had a current density of 38.4 mA / cm 2 (before heat treatment) and 22.6 mA / cm 2 (after heat treatment).

[0427] The light-emitting device fabricated in Comparative Example 1 was heat-treated on a hot plate at 120 °C for 2 hours. The electroluminescent properties and lifetime of the light-emitting device of Comparative Example 1 after heat treatment were measured. It was confirmed that the light-emitting device of Comparative Example 1 had a maximum external quantum efficiency of 8.5% (before heat treatment) and 2.6% (after heat treatment) up to a driving voltage of 5 V. It was confirmed that the light-emitting device of Comparative Example 1 had a current density of 13.4 mA / cm 2 (before heat treatment) and 0.3 mA / cm 2 (after heat treatment).

[0428] The light-emitting device fabricated in Comparative Example 2 was heat-treated on a hot plate at 120 °C for 2 hours. The electroluminescent properties and lifetime of the light-emitting device after heat treatment were measured, and the results are summarized in Table 2. It was confirmed that the light-emitting device of Comparative Example 2 had an EQE value of 0.5% (leakage) at 146 nits. It was confirmed that the maximum external quantum efficiency of the light-emitting device of Comparative Example 2 was about 13% (before heat treatment) and 3.6% (after heat treatment) up to a driving voltage of 5 V. It was confirmed that the light-emitting device of Comparative Example 2 had a current density of 28.5 mA / cm 2 (before heat treatment) or "leakage" after heat treatment.

[0429] In the case of a normal device, current flows above the emission voltage. However, in the device of Comparative Example 2, current flow was observed at a low voltage below the emission voltage before emission. This may indicate acid-induced damage in the hole transport layer of the device. Damage to the hole assist layer can cause phenomena or leakage such as, as observed in Comparative Example 1, a substantial or significant increase in the driving voltage, or leakage as occurred in Comparative Example 2 and can lead to a reduction in efficiency.

[0430] Table 2

[0431]

[0432] From the results in Table 2, it was confirmed that even when undergoing heat treatment at a relatively high temperature, the device of Example 1 could exhibit significantly higher luminance and a significantly extended lifespan compared to the comparative examples.

[0433] Experimental Example 2:

[0434] After post-treatment for 1 day, 2 days, and 5 days at 70 °C for the device of Example 1 and the device of Comparative Example 1, the driving voltage (at 146 nits) for each device was measured, and the results are summarized in Table 3 below.

[0435] Table 3. Driving Voltage

[0436]

[0437] In the case of the device of Comparative Example 1, the driving voltage increased significantly with the post-treatment time, while the driving voltage of the device of Example 1 showed a small or limited change compared to the driving voltage of the device of Comparative Example 1.

[0438] 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. An electroluminescent device, comprising a first electrode; a second electrode; a light-emitting layer disposed between the first electrode and the second electrode; an electron transport layer disposed between the light-emitting layer and the second electrode; and an organic layer, wherein the light-emitting layer comprises semiconductor nanoparticles, wherein the electron transport layer comprises metal oxide nanoparticles, and the metal oxide nanoparticles have a size greater than or equal to 1 nm and less than or equal to 50 nm, wherein the organic layer comprises a polymer material, and in the organic layer, there are a first repeating unit having an acid functional group and a second repeating unit having a hydroxyl group, and wherein the acid functional group includes a carboxylic acid group (COOH), a phosphonic acid (PO(OH)2) group, a sulfonic acid (SO3H) group, or a combination thereof.

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

3. The electroluminescent device according to claim 1, wherein the polymeric material in the organic layer comprises: a first polymer including the first repeating unit and a second polymer including the second repeating unit; or wherein the polymer material in the organic layer comprises a copolymer, the copolymer including the first repeating unit and the second repeating unit.

4. The electroluminescent device according to claim 3, wherein the weight-average molecular weight of the first polymer is greater than or equal to 1200 g / mol and less than or equal to 1,500,000 g / mol; or wherein the first polymer has a solubility in water greater than or equal to 1 g / L and less than or equal to 1000 g / L; or wherein the first polymer is configured to exhibit a pH less than or equal to 5.

5. The electroluminescent device according to claim 3, wherein the first polymer includes polyacrylic acid, polymethacrylic acid, polyacrylic acid-methacrylic acid, an alkali metal salt of poly(meth)acrylic acid, polyvinylphosphonic acid, a poly(aromatic sulfonic acid) compound, poly(vinyl sulfonic acid), polymaleic acid, alginic acid, or a combination thereof.

6. The electroluminescent device according to claim 3, wherein the second polymer includes polyvinyl alcohol.

7. The electroluminescent device according to claim 3, wherein the weight-average molecular weight of the second polymer is greater than or equal to 500 g / mol and less than or equal to 500,000 g / mol, or wherein the second polymer has a solubility in water or alcohol greater than or equal to 1 g / L and less than or equal to 1000 g / L, or wherein the second polymer is configured to exhibit a pH greater than or equal to 4 and less than or equal to 8.

5.

8. The electroluminescent device according to claim 3, wherein the weight-average molecular weight of the second polymer is greater than or equal to 1000 g / mol and less than or equal to 100,000 g / mol, or wherein the second polymer has a solubility in water or alcohol greater than or equal to 10 g / L and less than or equal to 500 g / L, or wherein the second polymer is configured to exhibit a pH greater than or equal to 5 and less than or equal to 8.

9. The electroluminescent device according to claim 1, wherein the polymeric material in the organic layer comprises: A mixture of a first polymer including the first repeating unit and a second polymer including the second repeating unit.

10. The electroluminescent device according to claim 1, wherein the organic layer is configured to be soluble in a mixed solvent of water and a C1 to C10 alcohol, and when dissolved in the mixed solvent, the organic layer is configured to exhibit a pH greater than or equal to 2 and less than or equal to 7.

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

12. The electroluminescent device according to claim 1, wherein the organic layer is spaced apart from the electron transport layer and the second electrode, and is arranged such that the surface of the organic layer faces the electron transport layer and the second electrode.

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

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

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

16. A method of manufacturing the electroluminescent device according to any one of claims 1-14, the method including: 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 to obtain a stacked structure; and performing post-treatment on the stacked structure, wherein the post-treatment includes: placing at least a part of the stacked structure and the polymer material together in a first space, and heating the first space at a post-treatment temperature greater than or equal to 40 °C and less than or equal to 150 °C; wherein the at least a part of the stacked structure includes the electron transport layer and the thin film conductor.

17. The method according to claim 16, wherein the method further includes applying an organic layer forming composition including the polymer material and a liquid carrier to the electron transport layer or the second electrode; or wherein the first space is defined by a container, and the method further includes applying an organic layer forming composition including the polymer material and a liquid carrier to the surface of the container, and the surface of the container faces the electron transport layer or the second electrode.

18. The method according to claim 17, wherein the liquid carrier includes water, a C1-10 alcohol, a sulfoxide solvent, a nitrile solvent, an ester solvent, or a combination thereof.

19. The method according to claim 16, wherein the polymeric material comprises: A first polymer including the first repeating unit having an acid functional group and a second polymer including the second repeating unit having a hydroxyl group.

20. The method according to claim 19, wherein the second polymer has a weight average molecular weight greater than or equal to 500 g / mol and less than or equal to 500,000 g / mol, or the second polymer has a solubility in water or alcohol greater than or equal to 1 g / L and less than or equal to 1000 g / L, or the second polymer is configured to exhibit a pH greater than or equal to 4.5 and less than or equal to 8.5; and wherein the first polymer has a weight average molecular weight greater than or equal to 1200 g / mol and less than or equal to 1,500,000 g / mol, or the first polymer has a solubility in water greater than or equal to 1 g / L and less than or equal to 1000 g / L, or the first polymer is configured to exhibit a pH less than or equal to 5.

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