Ink composition, method of preparing the same, quantum dot complex, and color conversion apparatus

Abstract

The present invention provides an ink composition and a method of making the same, a quantum dot composite, and a color conversion apparatus. The ink composition includes a plurality of quantum dots, a liquid monomer, an initiator, and optionally an organic solvent, wherein the plurality of quantum dots includes first quantum dots including a first ligand and second quantum dots including a second ligand different from the first ligand, and the ink composition is configured to emit first light.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2021-0015666, filed on February 3, 2021, which is incorporated herein by reference for all purposes, as fully set forth herein. Technical Field

[0003] Embodiments of the present invention generally relate to display devices, and more particularly to ink compositions comprising quantum dots, methods for preparing the same, quantum dot composites prepared therefrom, and color conversion panels and display devices comprising quantum dot composites. Background Technology

[0004] Quantum dots are nanoscale semiconductor nanocrystal materials whose optical properties (e.g., luminescence properties) can be controlled, for example, by changing their size and / or composition. The luminescence properties of quantum dots can be applied to various electronic devices (e.g., display devices). For application in devices, quantum dots or composites comprising quantum dots can be in the form of films or patterns, which is under further investigation.

[0005] The information disclosed in this background section is only for understanding the background technology of the present invention, and therefore may contain information that does not constitute prior art. Summary of the Invention

[0006] As detailed herein, the applicant has identified numerous issues related to the preparation of ink compositions comprising quantum dot composites and solutions.

[0007] For example, an ink composition comprising quantum dots, a method for preparing the ink composition, a quantum dot composite made from the ink composition, a color conversion panel or display panel comprising the quantum dot composite, and an electronic device (e.g., a display device) comprising the color conversion panel, constructed according to the principles and illustrative implementation of the present invention, can provide improved physical properties, such as improved jetting performance, and when applied, for example, in an inkjet printing method, can provide a large-area quantum dot (composite) monolayer film or pattern.

[0008] Further features of the inventive concept will be set forth in the description which follows, and will be apparent in part from the description or may be recognized by practice of the inventive concept.

[0009] According to one aspect of the invention, the ink composition includes a plurality of quantum dots, a liquid monomer, an initiator, and an optional organic solvent, wherein the plurality of quantum dots include: a first quantum dot containing a first ligand, and a second quantum dot containing a second ligand different from the first ligand, and the ink composition is configured to emit a first light.

[0010] The first light can be green light, red light, or blue light, and a maximum emission peak of the first light can have a full width at half maximum of less than or equal to about 45 nm.

[0011] The first ligand or the second ligand, independently of one another, can include RCOOH, RNH2, R2NH, R3N, RSH, R3PO, R3P, ROH, RCOOR', RPO(OH)2, RHPOOH, R2POOH, a polymeric organic ligand, or any combination thereof, where R and R' are defined herein.

[0012] The first ligand can include a monocarboxylic acid compound having a substituted or unsubstituted C 10 to a C 40 hydrocarbyl group.

[0013] The second ligand can include an organic compound having a functional group of an amine group, a mercaptan group, a carboxylic acid group, a phosphine group, or any combination thereof, and a moiety connected to the functional group and having the following formula:

[0014] * - L - A,

[0015] where the variables are defined herein.

[0016] The liquid monomer can include a compound having a carbon-carbon double bond and a vapor pressure of less than or equal to about 10 -5 mmHg.

[0017] The organic solvent can include a substituted or unsubstituted C3to C 40 aliphatic hydrocarbon solvent, a substituted or unsubstituted C6to C 40 aromatic hydrocarbon solvent, a substituted or unsubstituted C3to C 40 aliphatic hydrocarbon solvent, an alkylene glycol alkyl ether acetate solvent, an alkyl acetamide solvent, or any combination thereof.

[0018] The liquid monomer can include a monoacrylate compound, a diacrylate compound (e.g., hexamethylene diacrylate, tetraethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, triethylene glycol diacrylate, or any combination thereof), a triacrylate compound, a tetraacrylate compound, a pentaacrylate compound, a hexaacrylate compound, or any combination thereof, or the organic solvent can include propylene glycol monomethyl ether acetate, dimethylacetamide, cyclohexyl acetate, or any combination thereof.

[0019] The ink composition can have a viscosity of less than or equal to about 40 cP and a vapor pressure of less than or equal to about 10 -3 mmHg.

[0020] The ink composition can have both an acid value and an amine value, and the acid value and the amine value can each be greater than or equal to about 35 mg KOH / g, or the difference between the acid value and the amine value can be less than or equal to about 5 mg KOH / g.

[0021] The ink composition can exhibit a film retention of greater than or equal to about 90% after 30 minutes after forming a film, for example.

[0022] The ink composition can be configured to have a relative external quantum efficiency (EQE) of less than or equal to about 104% relative to an initial value of about 100% EQE after forming a solid state after polymerization thereof, during irradiation with excitation light having a wavelength of about 450 nm at a temperature of about 60 °C for about 100 hours.

[0023] According to another aspect of the present application, a method of preparing an ink composition can include preparing a first solution including first quantum dots and an organic solvent, preparing a second solution including second quantum dots and a liquid monomer; and mixing the first solution and the second solution to maintain a colloidal dispersion state.

[0024] The first solution and the second solution can satisfy one of the following conditions: at least one of the first solution and the second solution can not exhibit both an acid value and an amine value; when the first solution can exhibit one of an acid value or an amine value, then the second solution exhibits the other one of the acid value or the amine value; when the first solution can be amphoteric exhibiting both an acid value and an amine value, then the second solution can also be amphoteric; or when one of the first solution and the second solution can be amphoteric, and the other can exhibit one of an acid value or an amine value, then in the solution having amphoteric, the difference between the acid value and the amine value can be less than about 5 mg KOH / g, or all of the acid value and the amine value can be greater than or equal to about 35 mg KOH / g.

[0025] According to another aspect of the present application, an ink composition includes a liquid carrier including an organic solvent and a liquid monomer; and a plurality of quantum dots and optional metal oxide particles dispersed in the liquid carrier, in the ink composition, an amount of the organic solvent is less than or equal to about 20 wt% based on a total weight of the ink composition, and the ink composition is configured to have a relative external quantum efficiency (EQE) of less than or equal to about 104% relative to an initial EQE of about 100% during irradiation with excitation light having a wavelength of about 450 nm at a temperature of about 60 °C for 100 hours after forming a solid state after polymerization thereof.

[0026] The ink composition can be configured to emit first light, and a maximum emission peak of the first light can have a full width at half maximum of less than or equal to about 45 nm.

[0027] In the ink composition, an amount of the organic solvent can be greater than or equal to about 1 wt% and less than or equal to about 10 wt% based on a total weight of the ink composition.

[0028] According to another aspect of the invention, the quantum dot composite comprises a matrix and a plurality of quantum dots dispersed in the matrix, wherein the plurality of quantum dots include a first quantum dot containing a first ligand and a second quantum dot containing a second ligand different from the first ligand, the quantum dot composite emits light of a predetermined wavelength, and the quantum dot composite is configured such that, after its polymerization, it forms a solid state and is irradiated with excitation light of a wavelength of about 450 nm at a temperature of about 60°C for 100 hours, the relative EQE relative to about 100% of the initial EQE is less than or equal to about 104%.

[0029] The matrix can exhibit both acid value and amine value, or the matrix can exhibit an acid value of less than about 50 mg KOH / g.

[0030] According to another aspect of the invention, the color conversion device may include a layer comprising a region for color conversion, and the region comprising a first region for emitting a first light, the first region comprising a quantum dot composite as defined above; and an isolation wall defining each region of the layer.

[0031] The color conversion device may include a color conversion panel, which may further include a second region to emit a second light different from the first light, and the second region may include a quantum dot complex.

[0032] According to another aspect of the invention, the display device includes a light emitter, a color conversion device as defined above, and a layer disposed between the light emitter and the color conversion device for transmitting light.

[0033] A light emitter may include a light-emitting element or a panel.

[0034] It should be understood that the foregoing general description and the following detailed description are illustrative and explanatory, and are intended to provide further explanation of the claimed invention. Attached Figure Description

[0035] The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification. The drawings illustrate illustrative embodiments of the invention and, together with the description, serve to explain the inventive concept.

[0036] Figure 1 This is a perspective view of an embodiment of a display panel constructed according to the principles of the present invention.

[0037] Figure 2 for Figure 1 A cross-sectional view of the display panel.

[0038] Figure 3 for Figure 1 A plan view of an implementation of the pixel arrangement of a display panel.

[0039] Figure 4For along Figure 3 A cross-sectional view of the display panel taken from line IV-IV.

[0040] Figure 5 A cross-sectional view of an embodiment of a light-emitting element constructed according to the principles of the present invention.

[0041] Figure 6A Inkjet photographs depicting the ink composition of Comparative Example 1.

[0042] Figure 6B This shows an inkjet photograph of the ink composition of Example 1 prepared according to the principles of the present invention.

[0043] Figure 7 A graph showing the change in film residue over time of films prepared from the quantum dot solution (first solution) of Reference Example 1, the ink composition of Comparative Example 1, and the ink composition of Example 1 prepared according to the principles of the present invention.

[0044] Figure 8 A graph showing the change in external quantum efficiency over time for the quantum dot composite prepared from the ink composition of Comparative Example 1 and the quantum dot composite prepared from the ink composition of Example 1. Detailed Implementation

[0045] In the following description, numerous specific details are set forth for purposes of explanation in order to provide a thorough understanding of various embodiments or implementations of the invention. As used herein, “embodiment” and “implementation” are interchangeable terms and are non-limiting examples of apparatus or methods employing one or more of the inventive concepts disclosed herein. However, it will be apparent, however, that various embodiments may be implemented without these specific details or with one or more equivalent arrangements. In other instances, well-known structures and apparatuses are shown in block diagram form to avoid unnecessarily obscuring the various embodiments. Furthermore, the various embodiments may be different, but not necessarily exclusive. For example, a particular shape, configuration, and characteristic of one embodiment may be used or implemented in another embodiment without departing from the inventive concept.

[0046] Unless otherwise indicated, the illustrated exemplary embodiments should be understood as providing exemplary features that detail changes to some ways in which the inventive concept can be implemented in practice. Therefore, unless otherwise indicated, features, components, modules, layers, films, panels, regions, substrates and / or aspects (hereinafter individually or collectively referred to as “elements”) of various embodiments may be combined, separated, interchanged and / or rearranged in other ways without departing from the inventive concept.

[0047] The use of cross-hatching and / or shading in the drawings is generally for clarification purposes only. As such, unless specified to the contrary, the presence or absence of cross-hatching or shading is not intended to convey or indicate any bias or requirement for any particular material, material property, dimension, scale, commonality of illustrated elements, and / or any other characteristic, attribute, property, etc. of an element. Further, in the drawings, the size and relative sizes of elements can be exaggerated for clarity and / or descriptive purposes. As used herein, the term "plan view phase" refers to a situation where a target portion is viewed from the top, and the term "cross-sectional view phase" refers to a situation where a cross-section of a target portion cut in a vertical direction is viewed from the side. While exemplary implementations can be performed differently, a particular process sequence can be performed differently from the sequence described. For example, two consecutively described processes can be performed at substantially the same time or in an order opposite to the described sequence. Also, like reference numerals denote like elements, and redundant explanations are omitted to avoid redundancy.

[0048] When an element, such as a layer, is referred to as being "on" or "connected to" or "coupled to" another element or layer, it can be directly on, connected to, or coupled to the other element or layer, or intervening elements or layers can be present. In contrast, when an element or layer is referred to as being "directly on," or "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers present. For the purposes of this disclosure, the term "connected" can include physical or electrical and / or fluid connection with or without intervening elements. Further, the D1 axis, the D2 axis, and the D3 axis are not limited to three axes of a rectangular coordinate system, such as, for example, the x-axis, the y-axis, and the z-axis, and can be interpreted in a broader sense. For example, the D1 axis, the D2 axis, and the D3 axis can be perpendicular to each other, or can represent different directions that are not perpendicular to each other. For the purposes of this disclosure, "at least one of X, Y, and Z" and "at least one selected from the group consisting of X, Y, and Z" can be interpreted to be only X, only Y, only Z, or any combination of two or more of X, Y, and Z, such as, for example, XYZ, XYY, YZ, and ZZ. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0049] Although the terms "first," "second," etc. can be used herein to describe various types of elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another. Thus, a first element discussed below could be termed a second element without departing from the teachings of the present disclosure.

[0050] Spatially relative terms, such as "beneath", "below", "lower", "under", "above", "upper", "on", "over", "side" (as in "sidewall"), and the like, can be used herein for descriptive purposes, and, thereby, to describe one element's relationship to another element(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use, operation, and / or manufacture in use, for example, the devices can be inverted along the vertical axis relative to the orientation depicted in the figures. The terms "below" and "above" can encompass both orientations when the devices are turned over. Thus, the term "below" can encompass both an orientation of above and below. The devices can be otherwise oriented (e.g., rotated 90 degrees or at other orientations) and, as such, the spatially relative descriptors used herein are interpreted in like fashion. It is to be understood that the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. It is to be further understood that the terms "comprises", "comprising", "includes", and / or "including", as used herein, are intended to mean the statement encompassing the presence of the recited features, integers, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It is to be further understood that the term "substantially" and other similar terms, as used herein, are used as terms of approximation and / or estimation and not as terms of degree, unless the context clearly indicates otherwise.

[0051] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, the terms "comprises", "comprising", "includes", and / or "including" when used herein, specify the presence of stated features, integers, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should also be noted that, as used herein, the terms "substantially", "approximately", and other like terms, are used as terms of approximation and / or estimation and not as terms of degree, and as such, are used to account for inherent deviations in measurements, calculations, and / or provided values that would be recognized by those of ordinary skill in the art.

[0052] Various exemplary embodiments are described herein with reference to schematic cross-sectional and / or exploded illustrations that are idealized illustrations and / or intermediate structures of idealized exemplary embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and / or tolerances, are to be expected. Therefore, the exemplary embodiments disclosed herein are not to be construed as being limited to the particular shapes of regions illustrated in the figures but are to include deviations in shapes that result from, for example, manufacturing. Thus, the regions illustrated in the figures are schematic and the shapes of the regions disclosed herein should not be viewed as being restrictive, but are to be understood as being exemplary.

[0053] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Terms, such as those defined in common dictionaries, shall be interpreted as having the same meaning as they have in the context of the relevant field and shall not be interpreted in an idealized or overly formal sense unless expressly so specified herein.

[0054] definition

[0055] In the following text, as used herein, unless otherwise defined, “substituted” means that the hydrogen atoms of a compound, group, or part thereof are substituted by substituents selected from C1 to C2. 30 Alkyl, C2 to C 30 alkenyl, C2 to C 30 alkynyl group, C2 to C 30 Epoxy groups, C2 to C 30 alkenyl, C2 to C 30 Alkyl ester group, C3 to C 30 Alkenyl ester group (e.g., acrylate group, methacrylate group), C6 to C 30 Aryl, C7 to C 30 alkylaryl, C1 to C 30 Alkoxy, C1 to C 30 Heteroalkyl, C3 to C 30 Heteroalkylaryl, C3 to C 30 cycloalkyl, C3 to C 15 Cycloalkenyl, C6 to C 30 Cycloalkynyl, C2 to C 30 Heterocyclic alkyl, halogen (-F, -Cl, -Br or -I), hydroxyl (-OH), nitro (-NO2), cyano (-CN), amino (-NRR', where R and R' are independently hydrogen or C1 to C6 alkyl), azide (-N3), amidine (-C(=NH)NH2), hydrazine (-NHNH2), hydrazone (=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 C6 alkyl. 12 Aryl), carboxyl (-COOH) or its salt (-C(=O)OM, wherein M is an organic or inorganic cation), sulfonic acid (-SO3H) or its salt (-SO3M, wherein M is an organic or inorganic cation), phosphate (-PO3H2) or its salt (-PO3MH or -PO3M2, wherein M is an organic or inorganic cation) and any combination thereof.

[0056] In addition, unless otherwise defined below, “mixed” means including 1 to 3 heteroatoms selected from N, O, S, Si and P.

[0057] As used herein, the term "alkylene" is a straight-chain or branched saturated aliphatic hydrocarbon radical that optionally includes at least one substituent and has two or more valences. As used herein, the term "arylene" can be a functional group that optionally includes at least one substituent and has two or more valences formed by removing at least two hydrogens from at least one aromatic ring. As used herein, the term "alkyl" refers to a monovalent straight-chain or branched saturated aliphatic hydrocarbon radical (e.g., which can optionally include one or more substituents). At least one methylene group in an alkyl or alkylene group can be replaced by a sulfonyl (-SO2-), carbonyl (-CO-), ether (-0-), sulfido (-S-), sulfoxido (-SO-), ester (-C(=0)0-), amido (-C(=0)NR"-) (where R" is hydrogen or a Ci to C6alkyl group), or any combination thereof. 10 alkyl) or any combination thereof.

[0058] In embodiments, "aliphatic hydrocarbon radical" can refer to a substituted or unsubstituted Ci to C 100 straight-chain or branched alkyl radical (e.g., Ci to C 30 alkyl, C2 to C 30 alkenyl, C2 to C 30 alkynyl). In embodiments, "aromatic hydrocarbon radical" can refer to a substituted or unsubstituted C6to C 60 aryl or a substituted or unsubstituted C2to C 60 heteroaryl.

[0059] As used herein, the term "(meth)acrylate" refers to an acrylate and / or a methacrylate. As used herein, the "solid content" of a composition refers to the amount of non-volatile matter (i.e., components in the ink composition other than organic solvents that will evaporate in the course of a process such as a pattern forming process). The non-volatile matter (such as a polymer or a monomer) can remain in which once the volatile solvent is evaporated. There can be no organic solvents that will evaporate in the course of a process in the solution when the total solid content of the solution is 100%.

[0060] As used herein, "group" refers to a group of the periodic table.

[0061] As used herein, "Group II" refers to Group IIA and Group IIB, and examples of Group II metals can include Cd, Zn, Hg, and Mg, but are not limited thereto.

[0062] As used herein, "Group III" refers to Group IIIA and Group IIIB, and examples of Group III metals can include Al, In, Ga, and Tl, but are not limited thereto.

[0063] As used herein, "Group IV" refers to Group IVA and Group IVB, and examples of Group IV metals can include Si, Ge, and Sn, but are not limited thereto. As used herein, the term "metal" also includes semimetals such as Si.

[0064] As used herein, "Group I" refers to Group IA and Group IB, and can include Li, Na, K, Rb, and Cs, but is not limited thereto.

[0065] As used herein, "Group V" can refer to Group VA, and examples can include nitrogen, phosphorus, arsenic, antimony, and bismuth, but are not limited thereto.

[0066] As used herein, "Group VI" can refer to Group VIA, and examples can include sulfur, selenium, and tellurium, but are not limited thereto.

[0067] As used herein, "cadmium-free" or "non-cadmium" can refer to an amount of cadmium included in a corresponding structure that is less than or equal to about 100 parts per million by weight (ppmw). The Restriction of Hazardous Substances (RoHS) compliance definition requires that cadmium must not exceed 0.01% (100 ppm) by weight in the original homogeneous precursor material. As used herein, the level of cadmium in a "cadmium-free" or "non-cadmium" quantum dot is limited by the trace metal concentration in the precursor material. The trace metal concentration (including cadmium) of a cadmium-free or non-cadmium quantum dot or precursor thereof can be measured by inductively coupled plasma mass spectrometry (ICP-MS), which can be at the ppb (parts per billion) level. In embodiments, the amount of cadmium (or a corresponding atom) in a "cadmium-free" (or a corresponding atom) quantum dot can be less than about 50 ppm, less than about 20 ppm, less than about 10 ppm, or less than about 1 ppm.

[0068] As used herein, a quantum dot is a nanometer-sized semiconductor nanocrystal and exhibits a quantum confinement effect. By receiving light from an excitation source and reaching an energy excited state, a quantum dot can emit energy (e.g., light) according to a band gap energy. Quantum dots can control electrical, optical properties by adjusting their size and / or composition. Quantum dots can be applied to various devices, such as light receiving elements and light emitting elements, etc. To be applied to devices, quantum dots can be in the form of a composite film (or a pattern thereof) dispersed in a liquid carrier (e.g., including an organic monomer or a polymer). Inkjet is expected to provide a quantum dot composite film or a pattern having a large area with high efficiency. However, since the properties (e.g., light emitting properties) of quantum dots are significantly affected by an external environment, it can be a technically challenging task to provide a film or a pattern thereof capable of exhibiting desired properties (e.g., light emitting efficiency, reliability, etc.) through a solution process such as an inkjet process.

[0069] Illustrative Embodiments

[0070] The ink composition according to embodiments can provide (e.g., by a solution process) a quantum dot composite monolayer film (or a pattern thereof) that can exhibit improved physical properties.

[0071] In embodiments, the ink composition includes a plurality of quantum dots, a liquid monomer, an initiator, and optionally (limited amounts of) an organic solvent. The plurality of quantum dots includes first quantum dots including a first ligand and second quantum dots including a second ligand different from the first ligand.

[0072] In embodiments, the ink composition can include a liquid carrier including an organic solvent and a liquid monomer, a plurality of quantum dots dispersed in the liquid carrier, and optionally metal oxide fine particles, and the ink composition can include the organic solvent in an amount less than or equal to about 20 weight percent (wt%) based on a total weight of the ink composition, for example, less than or equal to about 15 wt%. The ink composition can exhibit improved stability (e.g., improved reliability when applied to a device).

[0073] The ink composition is configured to emit first light (or light of a predetermined wavelength, hereinafter referred to as first light) by photoexcitation. The first light can be green light, red light, or blue light (depending on the plurality of quantum dots). The green light can have a peak emission wavelength in a range of about 500 nanometers (nm) to about 580 nm. The red light can have a peak emission wavelength in a range of about 650 nm to about 670 nm. The blue light can have a peak emission wavelength in a range of about 440 nm to about 490 nm. The first light has one peak emission (e.g., is monochromatic light), and a full width at half maximum (FWHM) of the peak emission can be less than or equal to about 45 nm, less than or equal to about 40 nm, less than or equal to about 35 nm, less than or equal to about 30 nm, or less than or equal to about 25 nm. The ink composition is configured to have a relative external quantum efficiency (EQE) of less than or equal to about 104% relative to 100% of an initial EQE at a temperature of 60 °C for a period of 100 hours of irradiation with excitation light having a wavelength of 450 nm in a solid state after polymerization.

[0074] The plurality of quantum dots (e.g., the first quantum dots and / or the second quantum dots, hereinafter, referred to as quantum dots) can include a Group II-VI compound, a Group III-V compound, a Group IV-VI compound, a Group IV element or compound, a Group I-III-VI compound, a Group II-III-VI compound, a Group I-II-IV-VI compound, or any combination thereof. The plurality of quantum dots can not include cadmium. The plurality of quantum dots can not include lead, mercury, or a combination thereof. The first quantum dots and the second quantum dots can be configured to emit the first light.

[0075] The Group II-VI compound can be selected from: binary compounds selected from CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, and mixtures thereof; ternary compounds selected from CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, and mixtures thereof; and quaternary compounds selected from HgZnTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, and mixtures thereof. The Group II-VI compound can further include a Group III metal.

[0076] The Group III-V compound can be selected from: binary compounds selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, and mixtures thereof; ternary compounds selected from GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, and mixtures thereof; and quaternary compounds selected from GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, InZnP, and mixtures thereof. The Group III-V compound can further include a Group II metal (e.g., InZnP).

[0077] The Group IV-VI compound can be selected from: binary compounds selected from SnS, SnSe, SnTe, PbS, PbSe, PbTe, and mixtures thereof; ternary compounds selected from SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, and mixtures thereof; and quaternary compounds selected from SnPbSSe, SnPbSeTe, SnPbSTe, and mixtures thereof.

[0078] Examples of Group I-III-VI compounds can include CuInSe2, CuInS2, CuInGaSe, and CuInGaS, but are not limited thereto. Examples of Group I-II-IV-VI compounds can include CuZnSnSe and CuZnSnS, but are not limited thereto.

[0079] The Group IV element or compound can be selected from the group consisting of a single substance selected from Si, Ge, and mixtures thereof; and a binary compound selected from SiC, SiGe, and mixtures thereof.

[0080] The binary, ternary, or quaternary compound is present in the particle at a uniform concentration or at a partially different concentration in the same particle. The quantum dot can have a core / shell structure, in which a first semiconductor nanocrystal surrounds a second semiconductor nanocrystal. The core and shell can have an interface, and the element of at least one of the core and shell at the interface can have a concentration gradient, in which the concentration of the element of the shell decreases toward the core. The semiconductor nanocrystal can have a structure comprising one semiconductor nanocrystal core and a multi-layer shell surrounding the core. Herein, the multi-layer shell has at least two shells, in which each shell can be a single component, an alloy, and / or a component with a concentration gradient.

[0081] In the quantum dot, the shell material and the core material can have different band gap energies. For example, the band gap energy of the shell material can be greater than the band gap energy of the core material. In another embodiment, the band gap energy of the shell material can be less than the band gap energy of the core material. The quantum dot can have a multi-layer shell. In the multi-layer shell, the energy band gap of the outer layer can be greater than that of the inner layer, i.e., the layer closer to the core. In the multi-layer shell, the energy band gap of the outer layer can be less than that of the inner layer. The quantum dot can control the absorption / emission wavelength by adjusting the composition and size. The quantum dot can emit green light, red light, or blue light. The maximum light emission peak wavelength of the quantum dot can be from ultraviolet (UV) to infrared wavelengths, or wavelengths greater than the above wavelength range.

[0082] In embodiments, the quantum dots can have a maximum luminescence peak wavelength greater than or equal to about 300 nm, for example 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 quantum dots can have a maximum luminescence peak wavelength less than or equal to about 800 nm, for example 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 quantum dots can have a maximum luminescence peak wavelength in a range of about 500 nm to about 650 nm.

[0083] The quantum dots can have a maximum luminescence peak wavelength (or a central wavelength of the green light when the first light is green) in a range of about 500 nm to about 580 nm, about 510 nm to about 560 nm, or about 520 nm to about 540 nm. The quantum dots can have a maximum luminescence peak wavelength (or a wavelength of the red light when the first light is red) in a range of about 600 nm to about 670 nm, about 610 nm to about 650 nm, or about 620 nm to about 640 nm. The quantum dots can have a maximum luminescence peak wavelength (or a central wavelength of the blue light when the first light is blue) greater than or equal to about 440 nm, or greater than or equal to about 450 nm and less than or equal to about 480 nm, or less than or equal to about 470 nm.

[0084] The quantum dots can have a quantum efficiency greater than or equal to about 10%, for example 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 90%, or even about 100%. The quantum dots can have a full width at half maximum (FWHM) of an emission wavelength spectrum less than or equal to about 50 nm, for example less than or equal to about 45 nm, less than or equal to about 40 nm, or less than or equal to about 30 nm.

[0085] The quantum dots can have a (mean) size greater than or equal to about 1 nm and less than or equal to about 100 nm. The quantum dots can have a (mean) size of about 1 nm to about 20 nm, for example, greater than or equal to about 2 nm, greater than or equal to about 3 nm, or greater than or equal to about 4 nm and less than or equal to about 50 nm, for example, less than or equal to about 40 nm, less than or equal to about 30 nm, less than or equal to about 20 nm, less than or equal to about 15 nm, or less than or equal to about 10 nm. The shape of the quantum dots is not particularly limited. For example, the shape of the quantum dots can be substantially spherical, substantially polyhedral, substantially pyramidal, substantially prismatic, substantially cubic, substantially cuboid, substantially nanotubular, substantially nanorod, substantially nanowire, substantially nanoplate, or any combination thereof, but is not limited thereto. The quantum dots can be commercially available or can be synthesized appropriately. The plurality of quantum dots can not include perovskite quantum dots.

[0086] In embodiments, the quantum dots can be synthesized by a wet synthesis method, and can include, for example, organic ligands (hereinafter, also referred to as native ligands) bound to the surface. The organic ligands coordinate the surface of the nanocrystals (quantum dots) prepared, and can disperse the quantum dots in a medium, for example, an organic solution or a liquid monomer. The organic ligands can affect the physical properties (e.g., light emission and electrical properties) of the quantum dots.

[0087] In the ink composition of embodiments, the organic ligands of the plurality of quantum dots can have a functional group for binding the quantum dots and a portion for dispersion in a medium, for example, a liquid carrier, an organic solvent, or a liquid monomer. Among the plurality of quantum dots, a first ligand included in a first quantum dot can facilitate dispersion of the quantum dots in a predetermined organic solvent. The first ligand can be a native ligand. However, the applicants have found that the first ligand does not easily provide a desired degree or level of dispersibility for a desired liquid monomer. The liquid monomer can be required for forming a solid quantum dot film in the ink composition (e.g., by polymerization, etc.). Thus, when the liquid carrier includes a large amount of the liquid monomer, the first quantum dot can have difficulty in exhibiting a level of dispersibility required for film formation.

[0088] The first ligand can be bound to or on the surface of the first quantum dot. The first ligand can be configured to disperse the first quantum dot in an organic solvent. The second ligand can be bound to or on the surface of the second quantum dot. The second ligand can be configured to disperse the second quantum dot in a liquid monomer.

[0089] In the ink composition of embodiments, the plurality of quantum dots further includes a second quantum dot having a second ligand bound thereto. The second ligand can be configured to disperse the second quantum dot in a liquid monomer. The second quantum dot having the second ligand can be dispersed in the liquid monomer to form, for example, a liquid monomer-quantum dot composition exhibiting colloidal dispersibility.

[0090] However, Applicants have discovered that when a quantum dot film obtained by polymerizing a liquid monomer-quantum dot composition is placed under short wavelength (e.g., about 440 nm to about 480 nm, or about 450 nm to about 460 nm) light and elevated temperatures (e.g., greater than or equal to about 50 °C, or greater than or equal to about 60 °C) for an extended period of time (e.g., greater than or equal to about 10 hours, greater than or equal to about 50 hours, or greater than or equal to about 150), it can exhibit a significantly changed (e.g., significantly higher) luminescent efficiency than the initial luminescent efficiency of the quantum dots (hereinafter, referred to as an overshoot for this phenomenon). Without being bound by any particular theory, the efficiency change is believed to be because the original efficiency of the quantum dots can be recovered by rearrangement of the organic ligands in the matrix. The efficiency change can have an adverse effect on the driving reliability of a corresponding device (e.g., a final device).

[0091] Surprisingly and unexpectedly, an ink composition obtained by mixing the above-described liquid monomer-quantum dot composition with an organic solution including first quantum dots having first ligands can solve the above-described overshoot problem while exhibiting desirable dispersibility. In addition, Applicants have discovered that the addition of the organic solution including the first quantum dots can enable an increased amount of organic material while enabling the final quantum dot ink composition to exhibit desirable, e.g., reduced, levels of viscosity.

[0092] In embodiments, the viscosity can be measured by any known method. The viscosity can be measured using a commercially available rheometer (or viscometer) (e.g., a viscometer sold under the trademark HAAKE series, manufactured by Thermo Fisher Scientific, Waltham, MA, or the like). For example, the viscosity can be measured using a rotational rheometer, extensional rheometer, falling ball viscometer, rotational viscometer, or the like.

[0093] The first ligand or the second ligand can include a group of RCOOH, RNH2, R2NH, R3N, RSH, R3PO, R3P, ROH, RCOOR', RPO(OH)2, RHPOOH, R2POOH, a polymeric organic ligand, or any combination thereof. Herein, R and R' can independently include a substituted or unsubstituted C1to C 100 (e.g., C3to C 50 or C5to C 24 )aliphatic hydrocarbon group, a substituted or unsubstituted C6to C 50 (e.g., C6to C 24) aromatic hydrocarbon group or a combination thereof. At least one methylene group in the aliphatic hydrocarbon group can be optionally substituted with a sulfonyl (-SO2-), a carbonyl (-CO-), an ether linkage (-O-), a sulfide (-S-), a sulfoxide (-SO-), an ester (-C(=O)O-), an amide (-C(=O)NR"-) (where R" is hydrogen or a C1to C 10 alkyl) or any combination thereof. The polymeric organic ligand can have a polyurethane moiety.

[0094] The first ligand (or the second ligand) can include a substituted or unsubstituted C1to C 100 alkylamine (ethylamine, propylamine, butylamine, pentylamine, hexylamine, octylamine, dodecylamine, hexadecylamine, octadecylamine, dimethylamine, diethylamine, dipropylamine, or trioctylamine); a substituted or unsubstituted C1(or C2) to C 40 carboxylic acid compound (e.g., formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, dodecanoic acid, hexadecanoic acid, octadecanoic acid, oleic acid, or benzoic acid); a mono-, di-, or tri-alkyl or aryl phosphine or oxide compound (or phosphine oxide compound), such as a methyl phosphine, ethyl phosphine, propyl phosphine, butyl phosphine, pentyl phosphine, diphenyl phosphine, triphenyl phosphine compound, C5to C 20 phosphonic acid, C5to C 20 phosphinic acid, and the like. The first ligand or the second ligand can be used alone or as a mixture of two or more.

[0095] The first ligand and the second ligand can not exhibit an acid value or an amine value. Depending on the selection, the first ligand and the second ligand can each independently exhibit an acid value or an amine value (as described below). When the first ligand exhibits both an acid value and an amine value (e.g., amphoteric), the second ligand can also exhibit amphoteric. The acid value, the amine value, and amphoteric will be described in more detail below with reference to the dispersant and the ink preparation method, and the description can apply to the first ligand and the second ligand.

[0096] In embodiments, the second ligand can be a multifunctional organic compound having two or more functional groups as described herein. In embodiments, the first ligand can be a C 10 to C 40 carboxylic acid compound of a hydrocarbon group (e.g., an alkyl, an alkenyl, or an alkynyl) having a C 10 to C 40 amine compound of a hydrocarbon group (e.g., an alkyl, an alkenyl, or an alkynyl) or a combination thereof. The first ligand can include oleic acid, oleylamine, or a combination thereof.

[0097] In embodiments, the second ligand can include a C1to C 100 (e.g., C5to C 60 , or C7to C20 ) an organic compound (e.g., a (poly)functional organic compound).

[0098] The second ligand can include a moiety connected to the functional group and having the following formula:

[0099] * -L-A,

[0100] wherein, in the above formula, L is a substituted or unsubstituted C1to C 30 alkylene, a substituted or unsubstituted C2to C 30 alkenylene, a substituted or unsubstituted C3to C 30 cycloalkylene, a substituted or unsubstituted C3to C 30 heterocycloalkylene, a substituted or unsubstituted C6to C 30 arylene, a substituted or unsubstituted C3to C 30 heteroarylene, sulfonyl (-SO2-), carbonyl (-CO-), ether bond (-O-), sulfido (-S-), sulfoxido (-SO-), ester (-C(=O)O-), amido (-C(=O)NR"-) (where R" is hydrogen or C1to C 10 alkyl), or any combination thereof,

[0101] A is hydrogen, -COOH, -NR"2(where R" is hydrogen or C1to C 10 alkyl), or any combination thereof, and

[0102] * is a moiety connected to a functional group (e.g., an amine group, a thiol group, a carboxylic acid group, a phosphine group, or any combination thereof).

[0103] If desired, the second ligand can be bound to the second quantum dot (e.g., by an organic ligand exchange process). The organic ligand exchange process can be performed by, for example, reacting the organic ligand and the quantum dot in an organic solvent under elevated temperature conditions to exchange. The organic solvent used for the ligand exchange reaction is not particularly limited, and can be selected from suitable solvents used for the colloidal synthesis of quantum dots. Examples of the organic solvent can be selected from C6to C 22 primary alkyl amines such as hexadecylamine; C6to C 22 secondary alkyl amines such as dioctylamine; C6to C 40 tertiary alkyl amines such as trioctylamine; nitrogen-containing heterocyclic compounds such as pyridine; C6to C 40 aliphatic hydrocarbons (e.g., alkanes, alkenes, alkynes, etc.) such as hexadecane, octadecane, octadecene, and squalene; C6to C 30 aromatic hydrocarbons such as phenyldodecane, phenyltetradecane, and phenylhexadecane; C6to C 22 alkyl-substituted phosphines such as trioctylphosphine; C6to C 22 alkyl-substituted phosphine oxides such as trioctylphosphine oxide; C6to C12 to C 22 Aromatic ethers, such as phenyl ethers and dibenzyl ethers, and combinations thereof. The temperature for the ligand exchange reaction can be suitably selected, and can be greater than or equal to about 40 °C, greater than or equal to about 50 °C, or greater than or equal to about 60 °C, and less than or equal to about 150 °C, less than or equal to about 140 °C, or less than or equal to about 100 °C, but is not limited thereto.

[0104] In the ink composition, the amount of the plurality of quantum dots can be greater than or equal to about 1 wt%, greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 15 wt%, greater than or equal to about 20 wt%, greater than or equal to about 25 wt%, greater than or equal to about 30 wt%, greater than or equal to about 35 wt%, greater than or equal to about 40 wt%, greater than or equal to about 45 wt%, or greater than or equal to about 48 wt%, based on the total solids content of the ink composition. In the ink composition, the amount of the plurality of quantum dots can be greater than or equal to about 1 wt%, greater than or equal to about 20 wt%, greater than or equal to about 30 wt%, greater than or equal to about 40 wt%, or greater than or equal to about 45 wt% and less than or equal to about 70 wt%, less than or equal to about 60 wt%, or less than or equal to about 55 wt%, based on the total solids content of the ink composition.

[0105] In the ink composition, the amount of the plurality of quantum dots can be 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%, or less than or equal to about 35 wt%, based on the total solids content of the ink composition. The ink composition of embodiments can exhibit increased inorganic material content by improved dispersion properties.

[0106] In the ink composition, the amount ratio between the second quantum dots and the first quantum dots can be suitably selected. In embodiments, the weight ratio between the first quantum dots: second quantum dots can be about 1 :99 to about 99: 1, about 5:95 to about 95:5, about 10:90 to about 90: 10, about 15:85 to about 85: 15, about 20:80 to about 80:20, about 25:75 to about 75:25, about 30:70 to about 70:30, about 35:65 to about 65:35, about 40:60 to about 60:40, about 45:55 to about 55:45, or any combination thereof. In the ink composition, the weight ratio between the first quantum dots and the second quantum dots (first quantum dot weight: second quantum dot weight) can be about 1 :99 to about 99: 1.

[0107] In the ink composition of embodiments, the liquid monomer can include a carbon-carbon double bond and be less than or equal to about 10 - 4 mmHg, for example, less than or equal to about 10-5 mmHg. As used herein, vapor pressure, viscosity, or surface tension can be a value measured at room temperature, e.g., about 20 °C to about 25 °C, e.g., about 20 °C, about 23 °C, or about 25 °C.

[0108] The liquid monomer can include C3 to C 100 monoacrylate compound, C6 to C 150 diacrylate compound, C9 to C 200 triacrylate compound, C 12 to C 250 tetraacrylate compound, C 15 to C 250 pentaacrylate compound, or C 18 to C 300 hexaacrylate compound, or any combination thereof. The liquid monomer can form (e.g., electrically insulating) polymer by polymerization, and the quantum dot composite to be described below can include, for example, the polymer as a matrix.

[0109] The liquid monomer can include an acrylate compound. The acrylate compound can include alkyl (meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol di(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, bisphenol A di(meth)acrylate, bisphenol A epoxy acrylate, trimethylolpropane tri(meth)acrylate, ethylene glycol monomethyl ether (meth)acrylate, phenol novolac epoxy (meth)acrylate, propylene glycol di(meth)acrylate, tri(meth)acryloyloxyethyl phosphate, or any combination thereof. In an embodiment, the liquid monomer can include di(meth)acrylate compound, tri(meth)acrylate compound, tetra(meth)acrylate compound, penta(meth)acrylate compound, hexa(meth)acrylate compound, or any combination thereof, but is not limited thereto.

[0110] In an embodiment, the liquid monomer can include hexamethylene di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, or any combination thereof.

[0111] In the ink composition, the amount of liquid monomer can be greater than or equal to about 1 wt%, greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 15 wt%, greater than or equal to about 20 wt%, greater than or equal to about 25 wt%, greater than or equal to about 30 wt%, greater than or equal to about 35 wt%, or greater than or equal to about 40 wt%, based on the total solids content of the ink composition. In the ink composition, the amount of liquid monomer can be 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%, or less than or equal to about 15 wt%, based on the total solids content of the ink composition. In the ink composition, the amount of liquid monomer can be greater than or equal to about 1 wt%, greater than or equal to about 5 wt%, or greater than or equal to about 10 wt% and 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%, or less than or equal to about 25 wt%, based on the total solids content of the ink composition.

[0112] The ink composition can further include an organic solvent. The organic solvent can be a solvent capable of dispersing the first quantum dots. The organic solvent can include a substituted or unsubstituted C3 to C 40 aliphatic hydrocarbon solvent, a substituted or unsubstituted C6 to C 40 aromatic hydrocarbon solvent, a substituted or unsubstituted C3 to C 40 aliphatic hydrocarbon solvent, an alkylene glycol alkyl ether acetate solvent, an alkyl acetamide solvent, or any combination thereof. The organic solvent can have a vapor pressure of less than or equal to about 5 mmHg, less than or equal to about 4 mmHg, less than or equal to about 3.5 mmHg, less than or equal to about 3 mmHg, less than or equal to about 2.5 mmHg, or less than or equal to about 1 mmHg. The organic solvent can include dipropylene glycol monomethyl ether acetate (DPMA), polyglycidyl methacrylate (PGMA), diethylene glycol monoethyl ether acetate (EDGAC), propylene glycol methyl ether acetate (PGMEA, 3.7 mm Hg vapor pressure at 20 °C), a dialkyl acetamide (e.g., dimethylacetamide (DMA)), cyclohexyl acetate (CHA), or any combination thereof. The organic solvent can or can not include chloroform, a halogenated aromatic compound such as chlorobenzene, cyclohexane, hexane, heptane, octane, hexadecane, undecane, decane, dodecane, xylene, toluene, benzene, octadecane, tetradecane, butyl ether, ethanol, or any combination thereof.

[0113] In the ink composition, the amount of organic solvent can be greater than or equal to about 0.01 wt%, greater than or equal to about 0.05 wt%, greater than or equal to about 0.1 wt%, greater than or equal to about 0.5 wt%, greater than or equal to about 1 wt%, greater than or equal to about 2 wt%, greater than or equal to about 3 wt%, greater than or equal to about 4 wt%, greater than or equal to about 5 wt%, greater than or equal to about 6 wt%, greater than or equal to about 7 wt%, greater than or equal to about 8 wt%, greater than or equal to about 9 wt%, greater than or equal to about 10 wt%, greater than or equal to about 12 wt%, or greater than or equal to about 15 wt%, based on the total weight of the ink composition. In the ink composition, the amount of organic solvent can be greater than or equal to about 0.01 wt%, greater than or equal to about 1 wt%, greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 15 wt%, or greater than or equal to about 20 wt% and 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 25 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 ink composition.

[0114] In the ink composition, the amount of organic solvent can be greater than or equal to about 0.01 wt%, greater than or equal to about 0.05 wt%, greater than or equal to about 0.1 wt%, greater than or equal to about 0.5 wt%, greater than or equal to about 1 wt%, greater than or equal to about 2 wt%, greater than or equal to about 3 wt%, greater than or equal to about 4 wt%, greater than or equal to about 5 wt%, greater than or equal to about 6 wt%, greater than or equal to about 7 wt%, greater than or equal to about 8 wt%, greater than or equal to about 9 wt%, greater than or equal to about 10 wt%, greater than or equal to about 12 wt%, or greater than or equal to about 15 wt%, based on the total weight of the ink composition. In the ink composition, the amount of organic solvent can be greater than or equal to about 0.01 wt%, greater than or equal to about 1 wt%, greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 15 wt%, or greater than or equal to about 20 wt% and 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 25 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 ink composition.

[0115] In the ink composition of the embodiments, the initiator can be a compound capable of initiating polymerization (e.g., radical polymerization) of the liquid monomer described above, etc. by energy (e.g., heat or light). The initiator can include a thermal initiator and / or a photoinitiator. The type of the thermal initiator can include azobisisobutyronitrile, etc., but is not limited thereto. The photoinitiator can include a triazine compound, a phenylethanone compound, a benzophenone compound, a thioxanthone compound, a benzoin compound, an oxime ester compound, an aminoketone compound, a phosphine or phosphine oxide compound, a carbazole compound, a diketone compound, a sulfonium borate compound, a diazonium compound, a bisimidazole compound, or any combination thereof, but is not limited thereto. The type of each of the initiators described above is known and is not particularly limited. In the ink composition, the amount of the initiator can be greater than or equal to about 0.01 wt% and less than or equal to about 10 wt% based on the total solid content of the ink composition. In the ink composition, the amount of the initiator can be 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 1.5 wt%, greater than or equal to about 2 wt%, greater than or equal to about 2.5 wt%, or greater than or equal to about 3 wt% based on the total solid content of the ink composition. In the ink composition, the amount of the initiator can be less than or equal to about 10 wt%, less than or equal to about 5 wt%, less than or equal to about 4 wt%, less than or equal to about 3 wt%, less than or equal to about 2 wt%, less than or equal to about 1 wt%, or less than or equal to about 0.5 wt% based on the total solid content of the ink composition.

[0116] The ink composition can further include a dispersant. The dispersant can disperse the quantum dots and / or the metal oxide fine particles to be described below in an amount. The dispersant can include a polymer. The dispersant can include a substituted or unsubstituted urethane polymer (e.g., polyurethane), a substituted or unsubstituted alkylene polymer (e.g., polyethylene (PE), polypropylene (PP), etc.), a substituted or unsubstituted poly(meth)acrylate, a substituted or unsubstituted epoxy resin polymer, a substituted or unsubstituted polyester, or any combination thereof. The dispersant or polymer can include, for example, a carboxylic acid group, an amine group, or a combination thereof in its main chain. The dispersant can include a carbon-carbon double bond and can participate in polymerization as described below. The dispersant can be a compound (e.g., a polymer such as polyurethane) containing a repeating unit of Chemical Formula A-1, Chemical Formula A-2, or Chemical Formula A-3:

[0117] Chemical Formula A-1

[0118]

[0119] Chemical Formula A-2

[0120]

[0121] Chemical Formula A-3

[0122]

[0123] In the above formula, R1and R2are each independently substituted or unsubstituted alkylene, and R 3 is an organic group comprising an amine group, a carboxylic acid group, or a combination thereof.

[0124] The dispersant can exhibit an acid value and / or an amine value. As disclosed herein, the acid value refers to the number of milligrams (mg) of potassium hydroxide (KOH) required to neutralize the free fatty acids contained in 1 gram (g) of a given compound. Methods for obtaining acid values are known. As disclosed herein, the amine value refers to the amine content contained in a given compound. The amine value can be a value exhibiting the titration amount of potassium hydroxide consumed per 1 g of amine in milligrams (mg). The amine value can be determined by known methods. The ink composition of embodiments can exhibit a desired acid value and / or amine value by including the dispersant and / or the first and second ligands described above. In embodiments, the acid value of the polymer can be obtained (e.g., calculated) from the “titration volume” of potassium hydroxide (KOH) solution. In embodiments, the acid value can be measured by a titration method, in which a known amount (e.g., 100 grams) of sample is dissolved in an organic solvent and titrated with a known concentration of KOH solution in alcohol (e.g., ethanol) using a commercially available titrator or using a color indicator (e.g., phenolphthalein).

[0125] In embodiments, the dispersant (or first or second ligand, or ink composition) can have an acid value of less than or equal to about 5 mg KOH / g. In embodiments, the dispersant can have an acid value of greater than or equal to about 10 mg KOH / g or greater than or equal to about 20 mg KOH / g. In embodiments, the dispersant (or first or second ligand, or ink composition) can have an acid value of greater than or equal to about 35 mg KOH / g, greater than or equal to about 40 mg KOH / g, greater than or equal to about 45 mg KOH / g, greater than or equal to about 50 mg KOH / g, greater than or equal to about 55 mg KOH / g, greater than or equal to about 60 mg KOH / g, greater than or equal to about 65 mg KOH / g, greater than or equal to about 70 mg KOH / g, greater than or equal to about 75 mg KOH / g, greater than or equal to about 80 mg KOH / g, greater than or equal to about 85 mg KOH / g, greater than or equal to about 90 mg KOH / g, greater than or equal to about 95 mg KOH / g, or greater than or equal to about 100 mg KOH / g. In embodiments, the dispersant can have an acid value of less than or equal to about 300 mg KOH / g, less than or equal to about 250 mg KOH / g, less than or equal to about 200 mg KOH / g, less than or equal to about 180 mg KOH / g, less than or equal to about 150 mg KOH / g, less than or equal to about 130 mg KOH / g, less than or equal to about 110 mg KOH / g, less than or equal to about 100 mg KOH / g, less than or equal to about 90 mg KOH / g, less than or equal to about 80 mg KOH / g, less than or equal to about 70 mg KOH / g, less than or equal to about 60 mg KOH / g, less than or equal to about 50 mg KOH / g, or less than or equal to about 45 mg KOH / g.

[0126] In embodiments, the dispersant (or first or second ligand, or ink composition) can have an amine value of less than or equal to about 5 mg KOH / g. In embodiments, the dispersant (or first or second ligand, or ink composition) can have an amine value of greater than or equal to about 10 mg KOH / g, greater than or equal to about 20 mg KOH / g, or greater than or equal to about 35 mg KOH / g.

[0127] When the dispersant has both an acid value and an amine value (i.e., if it is amphoteric), the difference between the acid value and the amine value in the dispersant can be less than about 5. When the dispersant is amphoteric, the dispersant can have an acid value and an amine value of greater than or equal to about 35 mg KOH / g.

[0128] In embodiments, the dispersant (or first or second ligand, or ink composition) can have an amine value greater than or equal to about 35 mg KOH / g, greater than or equal to about 40 mg KOH / g, greater than or equal to about 45 mg KOH / g, greater than or equal to about 50 mg KOH / g, greater than or equal to about 55 mg KOH / g, greater than or equal to about 60 mg KOH / g, greater than or equal to about 65 mg KOH / g, greater than or equal to about 70 mg KOH / g, greater than or equal to about 75 mg KOH / g, greater than or equal to about 80 mg KOH / g, greater than or equal to about 85 mg KOH / g, greater than or equal to about 90 mg KOH / g, greater than or equal to about 95 mg KOH / g, or greater than or equal to about 100 mg KOH / g. In embodiments, the dispersant can have an amine value less than or equal to about 300 mg KOH / g, less than or equal to about 250 mg KOH / g, less than or equal to about 200 mg KOH / g, less than or equal to about 180 mg KOH / g, less than or equal to about 150 mg KOH / g, less than or equal to about 130 mg KOH / g, less than or equal to about 110 mg KOH / g, less than or equal to about 100 mg KOH / g, less than or equal to about 90 mg KOH / g, less than or equal to about 80 mg KOH / g, less than or equal to about 70 mg KOH / g, less than or equal to about 60 mg KOH / g, or less than or equal to about 50 mg KOH / g.

[0129] The ink composition can have both an acid value and an amine value, and the difference between the acid value and the amine value can be less than about 5 mg KOH / g. The ink composition can have both an acid value and an amine value, and both the acid value and the amine value can be greater than or equal to about 35 mg KOH / g. The ink composition can exhibit both an acid value and an amine value. The ink composition can have both an acid value and an amine value greater than or equal to about 35 mg KOH / g, for example, greater than or equal to about 40 mg KOH / g. Alternatively, the acid value and the amine value, or the difference therebetween, can be less than or equal to about 5 mg KOH / g (e.g., less than or equal to about 3 mg KOH / g).

[0130] The ink composition can have an acid value in a range of about 5 mg KOH / g to about 200 mg KOH / g, about 10 mg KOH / g to about 180 mg KOH / g, about 15 mg KOH / g to about 170 mg KOH / g, about 20 mg KOH / g to about 160 mg KOH / g, about 25 mg KOH / g to about 150 mg KOH / g, about 30 mg KOH / g to about 140 mg KOH / g, about 35 mg KOH / g to about 130 mg KOH / g, about 40 mg KOH / g to about 120 mg KOH / g, about 45 mg KOH / g to about 110 mg KOH / g, about 50 mg KOH / g to about 100 mg KOH / g, about 55 mg KOH / g to about 90 mg KOH / g, about 60 mg KOH / g to about 80 mg KOH / g, about 65 mg KOH / g to about 70 mg KOH / g, or any combination thereof.

[0131] The ink composition can have an amine value in a range of about 5 mg KOH / g to about 200 mg KOH / g, about 10 mg KOH / g to about 180 mg KOH / g, about 15 mg KOH / g to about 170 mg KOH / g, about 20 mg KOH / g to about 160 mg KOH / g, about 25 mg KOH / g to about 150 mg KOH / g, about 30 mg KOH / g to about 140 mg KOH / g, about 35 mg KOH / g to about 130 mg KOH / g, about 40 mg KOH / g to about 120 mg KOH / g, about 45 mg KOH / g to about 110 mg KOH / g, about 50 mg KOH / g to about 100 mg KOH / g, about 55 mg KOH / g to about 90 mg KOH / g, about 60 mg KOH / g to about 80 mg KOH / g, about 65 mg KOH / g to about 70 mg KOH / g, or any combination thereof.

[0132] The dispersants capable of producing the above-mentioned acid value / amine value can include any dispersants for ink compositions. These dispersants are commercially available (for example, DisperByk series sold by the BYK-Chemie division of Altana, Inc. in Wiesbaden, Germany, EFKA series sold by Ajinomoto-Fine-Techno Co., Ltd. in Kanagawa, Japan, and the like), and can be appropriately selected in consideration of the liquid carrier, quantum dots, metal oxide fine particles, and the like used.

[0133] The amount of dispersant in the ink composition can be selected taking into account the acid value / amine value of the final ink composition, the type of first and second ligands, the quantum dots, etc. In the ink composition, the amount of dispersant can be greater than or equal to about 1 wt%, greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 15 wt%, greater than or equal to about 20 wt%, greater than or equal to about 25 wt%, greater than or equal to about 30 wt%, greater than or equal to about 35 wt%, or greater than or equal to about 40 wt%, based on the total solids content of the ink composition. In the ink composition, the amount of dispersant can be less than or equal to about 70 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 solids content of the ink composition.

[0134] The ink composition can further include a plurality of metal oxide fine particles. The metal oxide fine particles can help improve the optical performance (e.g., brightness improvement) of the quantum dot composite, which will be described below. The metal oxide fine particles can include titanium oxide, silicon oxide, barium oxide, zinc oxide, hafnium oxide, zirconium oxide, aluminum oxide, gallium oxide, indium oxide, germanium oxide, tin oxide, antimony oxide, scandium oxide, yttrium oxide, lanthanum oxide, ruthenium oxide, cerium oxide, tantalum oxide, niobium oxide, or any combination thereof. The average size of the metal oxide fine particles can be greater than or equal to about 150 nm, greater than or equal to about 180 nm, or greater than or equal to about 200 nm. The average size of the metal oxide fine particles can be less than or equal to about 500 nm, less than or equal to about 400 nm, less than or equal to about 350 nm, or less than or equal to about 300 nm. The average size of the metal oxide fine particles can be greater than or equal to about 150 nm and / or less than or equal to about 500 nm.

[0135] In the ink composition, the content of the metal oxide fine particles can be greater than or equal to about 1 wt%, greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 15 wt%, or greater than or equal to about 18 wt%, based on the total solids content of the ink composition. In the ink composition, the content of the metal oxide fine particles can be 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 solids content of the ink composition. In the ink composition, when present, the amount of the metal oxide fine particles can be greater than or equal to about 1 wt%, greater than or equal to about 5 wt%, or greater than or equal to about 10 wt% and less than or equal to about 20 wt%, or less than or equal to about 15 wt%, based on the total solids content of the ink composition. In another embodiment, a method of making an ink composition includes: preparing a first solution including a first quantum dot and an organic solvent, preparing a second solution including a second quantum dot and a liquid monomer; and mixing the first solution and the second solution substantially without precipitation (e.g., while maintaining a colloidal dispersion state).

[0136] The method can further include removing at least a portion of the organic solvent from the ink composition. The first solution and the second solution can satisfy one of the following conditions: at least one of the first solution and the second solution can not exhibit both an acid value and an amine value; when the first solution exhibits an acid value or an amine value, then the second solution exhibits one of an acid value and an amine value; when the first solution is amphoteric exhibiting both an acid value and an amine value, then the second solution is also amphoteric; or when one of the first solution and the second solution is amphoteric and the other exhibits an acid value or an amine value, then the difference between the acid value and the amine value in the solution that is amphoteric can be less than about 5 mg KOH / g, or both the acid value and the amine value can be greater than or equal to about 35 mg KOH / g.

[0137] The initiator, the dispersant, and the metal oxide fine particles can be included in the first solution, the second solution, or both the first solution and the second solution. In particular, the first solution can further include an initiator, a dispersant, a metal oxide fine particle, or any combination thereof, and the second solution can further include an initiator, a dispersant, a metal oxide fine particle, or any combination thereof. At least one of the first solution or the second solution can include an initiator.

[0138] Unlike organic pigments and the like, the dispersion state of the quantum dots (and, if present, the metal oxide fine particles) in the ink composition can have a significant impact on the light emission performance and injection processing performance of the ink composition and the quantum dot composite obtained therefrom. The ink composition of embodiments can achieve a desired dispersion state (e.g., a colloidal dispersion state). Applicants have found that the acid value and the amine value of the first solution and the second solution can have a significant impact on the dispersion state of the final ink composition.

[0139] In embodiments, to maintain the dispersed state of the ink composition, the first solution and the second solution used in the method can be any of the following: at least one of the first solution and the second solution can not exhibit both an acid value and an amine value; when the first solution exhibits either of an acid value and an amine value, then the second solution also exhibits either of an acid value and an amine value; when the first solution exhibits both an acid value and an amine value, then the second solution also exhibits both an acid value and an amine value; or when one of the first and second solutions exhibits both an acid value and an amine value (i.e., is amphoteric), and the other has only an acid value or an amine value, then in the solution having both, the difference between the acid value and the amine value can be less than about 5 mg KOH / g, or both the acid value and the amine value can be greater than or equal to about 35 mg KOH / g.

[0140] The acid value and the amine value of the first solution and the second solution can be controlled to a desired value (e.g., corresponding to one of the above conditions) by the dispersant and / or the first and second ligands contained therein. The content of the first quantum dots (or the second quantum dots) in the first solution (or the second solution), and the content of the initiator, the dispersant, or the metal oxide fine particles, if present, can be appropriately selected in consideration of each component contained in the solution and the final ink composition.

[0141] In the ink composition of embodiments, the quantum dot (complex) film or a pattern thereof can be provided to have the above-described properties according to, for example, an inkjet method, and the obtained film (or pattern) can exhibit improved performance (e.g., light emission efficiency or driving reliability when applied to a device). In the ink composition of embodiments, the quantum dots and the metal oxide fine particles, if present, can exhibit an improved dispersed state. The ink composition can maintain a colloidal dispersed state. In the ink composition (or the quantum dot complex to be described below) of embodiments, the dispersed phase can be solid, and the continuous liquid carrier (continuous medium) can be liquid (or solid). Herein, the term "colloidal dispersion" means a dispersion in which the size of the dispersed phase is greater than or equal to about 1 nm (e.g., greater than or equal to about 10 nm, greater than or equal to about 50 nm, or greater than or equal to about 100 nm) and less than or equal to several micrometers (pm) or less (e.g., less than or equal to about 5 pm, less than or equal to about 4 pm, less than or equal to about 3 pm, less than or equal to about 2 pm, less than or equal to about 1 pm, less than or equal to about 900 nm, less than or equal to about 800 nm, less than or equal to about 700 nm, less than or equal to about 600 nm, or less than or equal to about 500 nm).

[0142] The ink composition of embodiments can be prepared by mixing the first solution and the second solution, such that the final composition can exhibit physical properties (e.g., viscosity) more suitable for the inkjet process. In embodiments, the viscosity of the ink composition can be greater than or equal to about 1 centipoise (cP), greater than or equal to about 3 cP, greater than or equal to about 5 cP, greater than or equal to about 7 cP, greater than or equal to about 9 cP, greater than or equal to about 11 cP, greater than or equal to about 13 cP, or greater than or equal to about 15 cP. The viscosity of the ink composition can be less than or equal to about 43 cP, less than or equal to about 40 cP, less than or equal to about 35 cP, less than or equal to about 30 cP, less than or equal to about 25 cP, less than or equal to about 20 cP, less than or equal to about 18 cP, less than or equal to about 15 cP, less than or equal to about 12 cP, less than or equal to about 10 cP, or less than or equal to about 7 cP. The ink composition can have a viscosity of less than or equal to about 40 cP, less than or equal to about 30 cP, less than or equal to about 25 cP, less than or equal to about 20 cP, less than or equal to about 15 cP, or less than or equal to about 10 cP. The viscosity of the ink composition can be measured at room temperature or ambient temperature (e.g., about 20 °C or about 25 °C).

[0143] The ink composition can have a surface tension of greater than or equal to about 1510 -3 mN / m, greater than or equal to about 20 mN / m, greater than or equal to about 25 mN / m, or greater than or equal to about 30 mN / m. The surface tension can be less than or equal to about 100 mN / m, less than or equal to about 90 mN / m, less than or equal to about 80 mN / m, less than or equal to about 70 mN / m, less than or equal to about 60 mN / m, less than or equal to about 50 mN / m, less than or equal to about 40 mN / m, or less than or equal to about 35 mN / m. The ink composition can have a surface tension of greater than or equal to about 15 mN / m. The surface tension can be measured at 23 °C.

[0144] The ink composition can have a vapor pressure of less than or equal to about 2.5 millimeters of mercury (mmHg), less than or equal to about 2 mmHg, less than or equal to about 1.5 mmHg, or less than or equal to about 1 mmHg. The ink composition can have a vapor pressure of less than or equal to about 5 mmHg, for example, less than or equal to about 1 mmHg, less than or equal to about 10 -1 mmHg, less than or equal to about 10 -2 mmHg, less than or equal to about 10 - 3 mmHg, less than or equal to about 10 -4 mmHg, or less than or equal to about 10 -5 mmHg.

[0145] The film residual rate of the ink composition can be greater than or equal to about 90 percent (%), for example, greater than or equal to about 91%, greater than or equal to about 92%, greater than or equal to about 93%, greater than or equal to about 94%, or greater than or equal to about 95%. The film residual rate can be, for example, a film residual rate after 30 minutes (min) after polymerization (or curing) in an inkjet process. For example, the ink composition can have a film residual rate of greater than or equal to about 90% in the form of a film after 30 minutes. The film residual rate can be a film residual rate after a predetermined time, for example, after 30 minutes, after jetting the ink in an air atmosphere at room temperature.

[0146] The film residual rate is measured by the following equation:

[0147] Film residual rate = [(volume of ink film) / (volume of ink filled in pixel unit)] x 100.

[0148] The volume of the ink film can be measured by a three-dimensional surface profiler. The volume of the ink can be obtained by the volume of the ink to be jetted. The ink composition can exhibit improved quantum efficiency. In embodiments, the quantum dots in the ink composition (or the composite to be described below) can exhibit a quantum efficiency of greater than or equal to about 30%, greater than or equal to about 40%, greater than or equal to about 50%, greater than or equal to about 60%, or greater than or equal to about 65%. The quantum efficiency can be measured using a commercially available spectrophotometer, for example, by an absolute or relative method.

[0149] The film residual rate can be measured at room temperature (RT). The film residual rate can be measured in an air atmosphere. The ink composition can relatively alleviate the overshooting phenomenon of light emission performance (e.g., light emission efficiency) compared to a composition including only ligand-exchanged quantum dots, for example, by including a different ligand described above. Accordingly, the ink composition according to embodiments can be configured such that the relative external quantum efficiency of the quantum dot composite shows less than or equal to about 104%, for example, less than or equal to about, for example, about 103%, or less than or equal to about 102%, relative to an initial external quantum efficiency of 100% during a period of about 100 hours of irradiation at a temperature of about 60°C with excitation light having a wavelength of about 450 nm (in a solid state, for example, in the state of a quantum dot (composite) film or pattern formed by polymerization).

[0150] When applied, for example, in an inkjet printing method, the ink composition of embodiments can exhibit improved jetting performance and provide a large-area quantum dot (composite) single-layer film or pattern. According to the preparation method of embodiments, a composition having a desired level of physical properties, for example, viscosity, etc., can be prepared while inhibiting or preventing phase separation or precipitation. When applied to a device, the formed quantum dot single-layer film or pattern can exhibit driving stability without a sudden change in light emission efficiency.

[0151] The ink composition can have a form of a film (or a pattern thereof) by any coating process, for example, spin coating, slot coating, or inkjet coating. It can provide a quantum dot composite film (or a pattern) according to an inkjet printing (or coating) method. When using an inkjet method, the ink composition according to the embodiments is jetted onto a substrate (or onto a pixel area). The ink composition according to the embodiments can form a film or a pattern using an inkjet apparatus (refer to a manual provided by the manufacturer of the apparatus) (for example, without elevating a temperature, for example, at about 20 to about 30 °C or at room temperature).

[0152] By optionally drying and polymerizing (or curing), the obtained film (or pattern) can provide a solid quantum dot composite or pattern. Apparatuses for an inkjet process are known and are commercially available. Polymerization or curing conditions (temperature, time, atmosphere, etc.) can be appropriately selected in consideration of the types of liquid monomers and initiators included in the ink, but are not limited thereto. In the embodiments, the polymerization or curing can be accompanied by thermal polymerization or photopolymerization.

[0153] The quantum dot composite of the embodiments includes a matrix and a plurality of quantum dots dispersed in the matrix, and the plurality of quantum dots includes first quantum dots including a first ligand and second quantum dots including a second ligand different from the first ligand, and the quantum dot composite emits light of a predetermined wavelength (for example, by photoexcitation), and is configured such that, when the composite is irradiated with excitation light of a wavelength of 450 nm at a temperature of 60 °C for about 100 hours in a solid state after polymerization, the relative external quantum efficiency (EQE) can be less than or equal to about 104% with respect to the initial EQE (100%).

[0154] The light of the predetermined wavelength can be green light or red light. The matrix can include a crosslinked polymer (including, for example, a polymerization product of the liquid monomer described above). The matrix can not include a linear polymer having a carboxylic acid group, a cardo binder resin, or a combination thereof.

[0155] The matrix can or can not include a linear polymer having a carboxylic acid group in a repeating unit (for example, a polymer having a relatively high acid value at an acid value of about 50 mg KOH / g to about 200 mg KOH / g), a cardo binder resin, or a combination thereof. The quantum dot composite can be prepared from the ink composition described above. Accordingly, the matrix can further include the dispersant described above. The quantum dot composite can further include the metal oxide fine particles described above.

[0156] The quantum dot composite can be in the form of a (patterned) film. The film can have a thickness greater than or equal to about 1 micrometer (pm), greater than or equal to about 5 pm, greater than or equal to about 6 pm, greater than or equal to about 7 pm, greater than or equal to about 8 pm, or greater than or equal to about 9 pm. The film can have a thickness less than or equal to about 20 pm, less than or equal to about 6 pm, less than or equal to about 10 pm, or less than or equal to about 8 pm.

[0157] The quantum dot composite can have an increased amount of inorganic material. In embodiments, the quantum dot composite can have an amount of inorganic material greater than or equal to about 50 wt%, greater than or equal to about 55 wt%, greater than or equal to about 57 wt%, greater than or equal to about 58 wt%, greater than or equal to about 59 wt%, greater than or equal to about 60 wt%, greater than or equal to about 61 wt%, greater than or equal to about 62 wt%, greater than or equal to about 63 wt%, greater than or equal to about 64 wt%, greater than or equal to about 65 wt%, greater than or equal to about 66 wt%, greater than or equal to about 67 wt%, greater than or equal to about 68 wt%, greater than or equal to about 69 wt%, or greater than or equal to about 70 wt%, based on the total weight of the quantum dot composite.

[0158] Details of the first and second quantum dots, the liquid monomer, the dispersant, and the metal oxide fine particles are the same as described above. The quantum dot composite (film or pattern) obtained from the ink composition of embodiments can be used in a color conversion device, which can be in the form of a color conversion panel and a display panel including the same. In embodiments, the color conversion panel includes a region configured (e.g., disposed on a substrate) in the form of a color conversion region that converts a color, the color conversion panel including the color conversion region and an optional partition wall that defines each region of the color conversion layer. The color conversion region includes a quantum dot (polymer) composite and a first region that emits a first light. Also, the color conversion region includes a first region configured to emit a first light (e.g., by irradiation of excitation light), and the first region includes a quantum dot composite. The color conversion region can further include a second region that emits a second light different from the first light and includes a quantum dot composite. Also, the color conversion region can further include a second region configured to emit a second light different from the first light (e.g., by irradiation of excitation light), and the second region can include a quantum dot composite.

[0159] The first light and the second light have different maximum emission peak wavelengths in an emission spectrum of light. In embodiments, the first light can be red light having a maximum emission peak wavelength present within about 600 nm to about 670 nm (e.g., about 620 nm to about 650 nm), and the second light can be green light having a maximum emission peak wavelength present within about 500 nm to about 580 nm (e.g., about 500 nm to about 550 nm).

[0160] In another embodiment, the display panel includes a light emitter, which can be in the form of a light emitting panel, a color conversion panel, a light-transmissive layer disposed between the light emitting panel and the color conversion panel. The display panel can further include an adhesive that adheres the light emitting panel and the color conversion panel. Hereinafter, the display panel and the color conversion panel will be described with reference to the accompanying drawings.

[0161] Figure 1 Perspective view of an embodiment of a display panel constructed in accordance with the principles of the present invention. Figure 2 Figure 1 Cross-sectional view of a display panel of

[0162] Referring to Figure 1 and Figure 2 , the display panel 1000 according to the embodiment includes a light emitting panel 100, a color conversion panel 200, a light-transmissive layer 300 disposed between the light emitting panel 100 and the color conversion panel 200, and an adhesive material 400 that adheres the light emitting panel 100 and the color conversion panel 200.

[0163] The light emitting panel 100 and the color conversion panel 200 face each other with the light-transmissive layer 300 left therebetween, and the color conversion panel 200 is disposed in a direction in which light is emitted from the light emitting panel 100. The adhesive material 400 is disposed along edges of the light emitting panel 100 and the color conversion panel 200, and can be, for example, a sealing material.

[0164] Figure 3 Plan view of an embodiment of a pixel arrangement of a display panel of Figure 1

[0165] Referring to Figure 3 , the display panel 1000 includes a display area 1000D that displays an image and a non-display area 1000P located in a peripheral area of the display area 1000D and provided with the adhesive material 400.

[0166] The display area 1000D includes a plurality of pixels PX arranged along rows (e.g., x-direction) and / or columns (e.g., y-direction), and each representative pixel PX includes a plurality of sub-pixels PX1, PX2, and PX3 that express different colors from each other. Herein, the embodiment is exemplified with a structure in which three sub-pixels PX1, PX2, and PX3 are configured to provide a pixel, but the embodiment is not limited thereto, and can further include additional sub-pixels such as a white sub-pixel, and can further include at least one sub-pixel that expresses the same color. The plurality of pixels PX can be, for example, arranged in a Bayer matrix, a matrix sold by Samsung Display Co., Ltd., Gyeonggi-do, Republic of Korea, under the trademark PenTile, and / or a diamond matrix, etc., but the embodiment is not limited thereto.

[0167] ​​Each of the sub-pixels PX1, PX2, and PX3 can represent the color of the three primary colors or a combination of the three primary colors, for example, it can represent the color of red, green, blue, or a combination thereof. For example, the first sub-pixel PX1 can represent red, the second sub-pixel PX2 can represent green, and the third sub-pixel PX3 can represent blue.

[0168] In the accompanying drawings, all subpixels are illustrated as having the same size, but the implementation is not limited to this, and at least one subpixel may be larger or smaller than the other subpixels. In the accompanying drawings, all subpixels are illustrated as having the same shape, but the implementation is not limited to this, and at least one subpixel may have a shape different from the other subpixels.

[0169] Figure 4 For along Figure 3 A cross-sectional view of the display panel taken from line IV-IV.

[0170] refer to Figure 4 The light-emitting panel 100 and the color conversion panel 200 will be described sequentially. The light-emitting panel 100 may include light-emitting elements that emit light in a predetermined wavelength range and circuit elements for switching and / or driving the light-emitting elements, and specifically, may include a lower substrate 110, a buffer layer 111, a thin film transistor (TFT), a light-emitting element 180, and an encapsulation layer 190.

[0171] The lower substrate 110 may be a glass substrate or a polymer substrate, and the polymer substrate may include, for example, polyimide, polyamide, polyamide-imide, polyethylene terephthalate, polyvinyl naphthalene, polymethyl methacrylate, polycarbonate, copolymers thereof, or any combination thereof, but the embodiments are not limited thereto.

[0172] The buffer layer 111 may comprise organic, inorganic, or organic-inorganic materials, and may include, for example, oxides, nitrides, or oxynitrides, such as silicon oxide, silicon nitride, silicon oxynitride, or any combination thereof, but the implementation is not limited thereto. The buffer layer 111 may be one or two or more layers, and may cover the entire surface of the lower substrate 110. The buffer layer 111 may be omitted.

[0173] The thin-film transistor (TFT) may be a three-terminal element (described below) for switching and / or driving the light-emitting element 180, and may include one, two, or more for each sub-pixel. The TFT includes a gate electrode 124, a semiconductor layer 154 overlapping the gate electrode 124, a gate insulating film 140 between the gate electrode 124 and the semiconductor layer 154, and a source electrode 173 and a drain electrode 175 electrically connected to the semiconductor layer 154. In the figures, a coplanar top-gate structure is shown as an example, but embodiments are not limited to this structure and various structures may be available.

[0174] The gate electrode 124 is electrically connected to a gate line, and can 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 any combination thereof, but is not limited thereto.

[0175] The semiconductor layer 154 can be an inorganic semiconductor such as amorphous silicon, polysilicon, or an oxide semiconductor; an organic semiconductor; an organic-inorganic semiconductor; or any combination thereof. For example, the semiconductor layer 154 can include an oxide semiconductor including at least one of indium (In), zinc (Zn), tin (Sn), and gallium (Ga), and the oxide semiconductor can include, for example, indium-gallium-zinc oxide, zinc-tin oxide, or a combination thereof, but is not limited thereto. The semiconductor layer 154 can include a channel region and a doped region disposed on both sides of the channel region and electrically connected to the source electrode 173 and the drain electrode 175, respectively.

[0176] The gate insulating film 140 can include an organic material, an inorganic material, or an organic-inorganic material, and can include, for example, an oxide, a nitride, or an oxynitride, such as silicon oxide, silicon nitride, silicon oxynitride, or any combination thereof, but is not limited thereto. As explained, an example in which the gate insulating film 140 is formed on the entire surface of the lower substrate 110 is shown, but the embodiment is not limited thereto, and can be selectively formed between the gate electrode 124 and the semiconductor layer 154. The gate insulating film 140 can be one or two or more layers.

[0177] The source electrode 173 and the drain electrode 175 can include a low-resistance metal such as aluminum (Al), molybdenum (Mo), copper (Cu), titanium (Ti), silver (Ag), gold (Au), an alloy thereof, or any combination thereof, but is not limited thereto. Each of the source electrode 173 and the drain electrode 175 can be electrically connected to the doped region of the semiconductor layer 154. The source electrode 173 is electrically connected to a data line, and the drain electrode 175 is electrically connected to a light emitter, which can be in the form of a light emitting element 180 to be described below.

[0178] The interlayer insulating film 145 is additionally formed between the gate electrode 124 and the source electrode 173 / drain electrode 175. The interlayer insulating film 145 can include an organic material, an inorganic material, or an organic-inorganic material, and can include, for example, an oxide, a nitride, or an oxynitride, such as silicon oxide, silicon nitride, silicon oxynitride, or any combination thereof, but is not limited thereto. The interlayer insulating film 145 can be one layer or two or more layers.

[0179] A protective film 160 is formed on the thin film transistor TFT. The protective film 160 can be, for example, a passivation film. The protective film 160 can include an organic material, an inorganic material, or an organic-inorganic material, and can include, for example, a polyacrylic compound, a polyimide, a polyamide, a polyamide-imide, or any combination thereof, but is not limited thereto. The protective film 160 can be one layer or two or more layers.

[0180] The light emitting element 180 can be dispersed in each sub-pixel PX1, PX2, PX3, and the light emitting element 180 disposed in each sub-pixel PX1, PX2, PX3 can be independently operated. The light emitting element 180 can be, for example, a light emitting diode, and can include a pair of electrodes and a light emitting layer located between the pair of electrodes. The light emitting layer can include a light emitter capable of emitting light in a predetermined wavelength region, for example, can include a light emitter that emits a first emission spectrum of light related to a visible light wavelength spectrum. The light emitter can include an organic light emitter, an inorganic light emitter, an organic / inorganic light emitter, or any combination thereof, and can be one type or at least two types.

[0181] The light emitting element 180 can be, for example, an organic light emitting diode, an inorganic light emitting diode, or a combination thereof. The inorganic light emitting diode can be, for example, a quantum dot light emitting diode, a perovskite light emitting diode, a micro light emitting diode, an inorganic nano light emitting diode, or any combination thereof, but is not limited thereto.

[0182] Figure 5 A cross-sectional view of an embodiment of a light emitting element configured according to the principles of the present application.

[0183] Reference Figure 5 The light emitting element 180 includes a first electrode 181 and a second electrode 182 facing each other; a light emitting layer 183 between the first electrode 181 and the second electrode 182; and an optional auxiliary layer 184 between the first electrode 181 and the light emitting layer 183 and an auxiliary layer 185 between the second electrode 182 and the light emitting layer 183.

[0184] The first electrode 181 and the second electrode 182 can be disposed to face each other along a thickness direction (e.g., a z direction), and either of the first electrode 181 and the second electrode 182 can be an anode and the other can be a cathode. The first electrode 181 can be a transmissive electrode, a semi-transmissive electrode, or a reflective electrode, and the second electrode 182 can be a transmissive electrode or a semi-transmissive electrode. The transmissive electrode or the semi-transmissive electrode can be made of, for example, a conductive oxide such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), tin oxide (SnO), aluminum tin oxide (AlTO), and fluorine-doped tin oxide (FTO), or a metal thin film including a thin single layer or multiple layers of silver (Ag), copper (Cu), aluminum (Al), magnesium (Mg), magnesium-silver (Mg-Ag), magnesium-aluminum (Mg-Al), or any combination thereof. The reflective electrode can include a metal, a metal nitride, or a combination thereof, for example, silver (Ag), copper (Cu), aluminum (Al), gold (Au), titanium (Ti), chromium (Cr), nickel (Ni), an alloy thereof, a nitride thereof (e.g., TiN), or any combination thereof, but is not limited thereto.

[0185] The light-emitting layer 183 can include a light emitter capable of emitting third light. An emission spectrum of the third light can belong to a relatively short wavelength region of a visible light wavelength spectrum, and can be, for example, a blue emission spectrum. A maximum light emission peak wavelength of the third light can belong to a wavelength range of greater than or equal to about 400 nm and less than about 500 nm, and a wavelength range of about 410 nm to about 490 nm or about 420 nm to about 480 nm within the above range. The light emitter can be one or two or more types.

[0186] For example, the light-emitting layer 183 can include a host material and a dopant material. For example, the light-emitting layer 183 can include a phosphorescent material, a fluorescent material, or a combination thereof. For example, the light emitter can include an organic light emitter, and the organic light emitter can be a low molecular weight compound, a polymer, or a combination thereof. When the light emitter includes an organic light emitter, the light-emitting element 180 can be an organic light-emitting diode.

[0187] For example, the light emitter can include an inorganic light emitter, and the inorganic light emitter can be an inorganic semiconductor, a quantum dot, a perovskite, or any combination thereof. When the light emitter includes an inorganic light emitter, the light-emitting element 180 can be a quantum dot light-emitting diode, a perovskite light-emitting diode, or a micro light-emitting diode.

[0188] The auxiliary layers 184 and 185 can be respectively disposed between the first electrode 181 and the light-emitting layer 183 and between the second electrode 182 and the light-emitting layer 183, and can be charge auxiliary layers that control injection and / or migration of charges. Each of the auxiliary layers 184 and 185 can be one or two or more layers, and can be, for example, a hole injection layer, a hole transport layer, an electron blocking layer, an electron injection layer, an electron transport layer, a hole blocking layer, or any combination thereof. At least one of the auxiliary layers 184 and 185 can be omitted.

[0189] The light-emitting elements 180 disposed in each of the sub-pixels PX1, PX2, and PX3 can be the same as or different from each other. The light-emitting elements 180 disposed in each of the sub-pixels PX1, PX2, and PX3 can emit light of the same emission spectrum as each other, for example, can each emit light of a blue emission spectrum, for example, can emit light of a blue emission spectrum having a maximum emission wavelength in a wavelength region of greater than or equal to about 400 nm and less than about 500 nm, about 410 nm to about 490 nm, or about 420 nm to about 480 nm. The light-emitting elements 180 disposed in each of the sub-pixels PX1, PX2, PX3 can be separated by a pixel-defining layer.

[0190] Referring back to Figures 1 to 4 The encapsulation layer 190 covers the light-emitting elements 180 and can include a glass plate, a metal thin film, an organic film, an inorganic film, an organic-inorganic film, or any combination thereof. The organic film can include, for example, an acrylic resin, a (meth)acrylic resin, a polyisoprene, a vinyl resin, an epoxy resin, a urethane resin, a cellulose resin, a perylene resin, or any combination thereof, but is not limited thereto. The inorganic film can include, for example, an oxide, a nitride, and / or an oxynitride, such as silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, zirconium oxide, zirconium nitride, zirconium oxynitride, titanium oxide, titanium nitride, titanium oxynitride, hafnium oxide, hafnium nitride, hafnium oxynitride, tantalum oxide, tantalum nitride, tantalum oxynitride, lithium fluoride, or any combination thereof, but is not limited thereto. The organic-inorganic film can include, for example, a polyorganosiloxane, but is not limited thereto. The encapsulation layer 190 can be one layer or two or more layers.

[0191] The color conversion panel 200 can convert light of a third emission spectrum (e.g., blue light) provided from the light-emitting panel 100 into light of a first or second emission spectrum (e.g., red or green light) different from the third emission spectrum, and emit the light to the viewer side, and specifically, can include an upper substrate 210, a light-blocking pattern 220, a color filter layer 230, a planarization layer 240, a separation wall 250, a color conversion layer 270, and an encapsulation layer 290.

[0192] The upper substrate 210 can be a glass substrate or a polymer substrate, and the polymer substrate can include, for example, polyimide, polyamide, polyamide-imide, polyethylene terephthalate, polyvinyl naphthalene, polymethyl methacrylate, polycarbonate, a copolymer thereof, or any combination thereof, but is not limited thereto.

[0193] The color conversion layer 270 faces the light emitting elements 180 of the light emitting panel 100. The color conversion layer 270 can include at least one color conversion region for converting an emission spectrum of light provided from the light emitting panel 100 into another emission spectrum, and the color conversion region can convert, for example, light of the emission spectrum provided from the light emitting panel 100 into light of a wavelength spectrum of a color displayed by each of the sub-pixels PX1, PX2, and PX3.

[0194] The color conversion region can convert and emit light of a wavelength spectrum of a color expressed in each of the sub-pixels PX1, PX2, and PX3, and thus the quantum dots included in each of the color conversion regions can be different from each other.

[0195] As shown in FIG. 1A, the color conversion layer 270 can include a first color conversion region 270a including first light emitting quantum dots 271a included in the first sub-pixel PX1, a second color conversion region 270b including second light emitting quantum dots 271b included in the second sub-pixel PX2, and a light transmission region 270c. Figure 4 The first light emitting quantum dots 271a included in the first color conversion region 270a can convert light of a third emission spectrum emitted from the light emitting panel 100 into light of a first emission spectrum identical to a wavelength spectrum of a color expressed in the first sub-pixel PX1. The first emission spectrum can be different from the third emission spectrum, and can be a longer wavelength spectrum than the third emission spectrum.

[0196] The second light emitting quantum dots 271b included in the second color conversion region 270b can convert light of the third emission spectrum emitted from the light emitting panel 100 into light of a second emission spectrum identical to a wavelength spectrum of a color expressed in the second sub-pixel PX2. The second emission spectrum can be different from each of the third and first emission spectra, and can be a longer wavelength spectrum than the third emission spectrum.

[0197] The second light emitting quantum dots 271b included in the second color conversion region 270b can convert light of the third emission spectrum emitted from the light emitting panel 100 into light of a second emission spectrum identical to a wavelength spectrum of a color expressed in the second sub-pixel PX2. The second emission spectrum can be different from each of the third and first emission spectra, and can be a longer wavelength spectrum than the third emission spectrum.

[0198] For example, when the light emitting elements 180 of the light emitting panel 100 emit light of a blue emission spectrum, and when the first, second, and third sub-pixels PX1, PX2, and PX3 express red, green, and blue, respectively, the first light emitting quantum dots 271a included in the first color conversion region 270a can convert the light of the blue emission spectrum into light of a red emission spectrum, and the second light emitting quantum dots 271b included in the second color conversion region 270b can convert the light of the blue emission spectrum into light of a green emission spectrum. In this case, since the first light emitting quantum dots 271a emit light of a longer wavelength spectrum than the second light emitting quantum dots 271b, the size of the first light emitting quantum dots 271a can be greater than the size of the second light emitting quantum dots 271b. The blue expressed in the third sub-pixel PX3 can be expressed by the light of the blue emission spectrum emitted from the light emitting elements 180 of the light emitting panel 100, and thus can be expressed by the light transmission region 270c having no additional color conversion body (quantum dot). However, the third sub-pixel PX3 can further include a color conversion body such as a quantum dot that emits light of a blue emission spectrum.

[0199] The first, second, and light transmission regions 270a, 270b, and 270c can each further include scattering particles 272a, 272b, and 272c. The scattering particles 272a, 272b, and 272c scatter and / or reflect light emitted from the quantum dots 271a, 271b, and / or the light emitting elements 180 of the light emitting panel 100, and introduce it into the color filter layer 230. The scattering particles 272a, 272b, and 272c can be nanoparticles having a low refractive index, for example, can be silicon oxide, titanium oxide, or a combination thereof, but are not limited thereto.

[0200] The first, second, and light transmission regions 270a, 270b, and 270c can each further include light transmission resins 273a, 273b, and 273c. The light transmission resins 273a, 273b, and 273c can be a dispersion medium in which the quantum dots 271a, 271b, and / or the scattering particles 272a, 272b, and 272c are dispersed, for example, can be an acrylic resin, a urethane resin, a silicone resin, an epoxy resin, a cardo-based resin, an imide resin, a derivative thereof, or any combination thereof, but are not limited thereto.

[0201] The separation wall 250 can define each of the color conversion layer 270, and can be located between adjacent regions. For example, the separation wall 250 can define each of the first color conversion region 270a, the second color conversion region 270b, and the light transmission region 270c described above, and can be located in each of between the adjacent first color conversion region 270a and the second color conversion region 270b, between the adjacent second color conversion region 270b and the light transmission region 270c, and between the adjacent first color conversion region 270a and the light transmission region 270c. In providing the first color conversion region 270a, the second color conversion region 270b, and the light transmission region 270c, the separation wall 250 can provide a space for applying a composition to the color conversion layer 270, and at the same time can prevent each component for the first color conversion region 270a, the second color conversion region 270b, and the light transmission region 270c from overflowing into the adjacent first color conversion region 270a, the second color conversion region 270b, and the light transmission region 270c.

[0202] The separation wall 250 can be in direct contact with the first color conversion region 270a, the second color conversion region 270b, and the light transmission region 270c, and in addition, no layer can be interposed between the separation wall 250 and the first color conversion region 270a, between the separation wall 250 and the second color conversion region 270b, and between the separation wall 250 and the light transmission region 270c. The substantially cylindrical separation wall 250 having the same width is exemplified in the drawings, but the embodiment is not limited thereto, and the separation wall 250 can have various sizes and shapes. For example, the separation wall 250 can have a substantially trapezoidal cross-sectional shape.

[0203] The color filter layer 230 is disposed in a direction in which light emitted through the color conversion layer 270 is emitted. The color filter layer 230 can include color filters 230a, 230b, and 230c that selectively transmit light of different wavelength spectra disposed in each of the sub-pixels PX1, PX2, and PX3. The color filters 230a, 230b, and 230c can selectively transmit light of the same wavelength spectrum as a color expressed in each of the sub-pixels PX1, PX2, and PX3, and selectively transmit light of an emission spectrum converted in each region of the color conversion layer 270.

[0204] For example, when the first, second, and third sub-pixels PX1, PX2, and PX3 express red, green, and blue colors, respectively, and when the first, second, and third color conversion regions 270a, 270b, and 270c emit each light in a red emission spectrum, a green emission spectrum, and a blue emission spectrum, respectively, the first color filter 230a overlapping the first color conversion region 270a can be a red filter, the second color filter 230b overlapping the second color conversion region 270b can be a green filter, and the third color filter 230c overlapping the light-transmissive region 270c can be a blue filter. The first, second, or third color filter 230a, 230b, or 230c can include a pigment or a dye that selectively transmits light of a red wavelength spectrum, a green wavelength spectrum, or a blue wavelength spectrum, respectively, and absorbs and / or reflects light of other wavelength spectrums.

[0205] The color filter layer 230 can enhance color purity of light emitted toward the upper substrate 210 by more specifically filtering light emitted from the color conversion layer 270. For example, the first color filter 230a overlapping the first color conversion region 270a can enhance color purity of light, for example, of a red emission spectrum, by blocking light that is not converted by the first luminescent quantum dot 271a of the first color conversion region 270a but passes as is. For example, the second color filter 230b overlapping the second color conversion region 270b can enhance color purity of light, for example, of a green emission spectrum, by blocking light that is not converted by the second luminescent quantum dot 271b of the second color conversion region 270b but passes as is. For example, the third color filter 230c disposed to overlap the light-transmissive region 270c can enhance color purity of light, for example, of a blue emission spectrum, by blocking light other than the light of the blue emission spectrum. For example, at least a portion of the first, second, and third color filters 230a, 230b, and 230c can be omitted, and for example, the third color filter 230c disposed to overlap the light-transmissive region 270c can be omitted.

[0206] The light-blocking pattern 220 can divide each of the sub-pixels PX1, PX2, and PX3, and can be located between adjacent sub-pixels PX1, PX2, and PX3. The light-blocking pattern 220 can be, for example, a black matrix. The light-blocking pattern 220 can overlap edges of the adjacent color filters 230a, 230b, and 230c.

[0207] The planarization layer 240 can be disposed between the color filter layer 230 and the color conversion layer 270, and can reduce or eliminate a step difference caused by the color filter layer 230. The planarization layer 240 can include an organic material, an inorganic material, an organic-inorganic material, or any combination thereof, for example, an oxide, a nitride, or an oxynitride, for example, silicon oxide, silicon nitride, silicon oxynitride, or any combination thereof, but is not limited thereto. The planarization layer 240 can be one or two or more layers, and can cover the entire surface of the upper substrate 210.

[0208] The encapsulation layer 290 covers the color conversion layer 270 and the separation wall 250, and can include a glass plate, a metal thin film, an organic film, an inorganic film, an organic-inorganic film, or any combination thereof. The organic film can include, for example, an acrylic resin, a (meth)acrylic resin, a polyisoprene, a vinyl resin, an epoxy resin, a urethane resin, a cellulose resin, a perylene resin, or any combination thereof, but is not limited thereto. The inorganic film can include, for example, an oxide, a nitride, and / or an oxynitride, such as silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, zirconium oxide, zirconium nitride, zirconium oxynitride, titanium oxide, titanium nitride, titanium oxynitride, hafnium oxide, hafnium nitride, hafnium oxynitride, tantalum oxide, tantalum nitride, tantalum oxynitride, lithium fluoride, or any combination thereof, but is not limited thereto. The organic-inorganic film can include, for example, a polyorganosiloxane, but is not limited thereto. The encapsulation layer 290 can be one layer or two or more layers.

[0209] The light-transmissive layer 300 can be disposed between the light-emitting panel 100 and the color conversion panel 200. The light-transmissive layer 300 can include, for example, a filler, and can include, for example, an organic material, an inorganic material, an organic-inorganic material, or any combination thereof, for example, an epoxy resin, a silicone compound, a polyorganosiloxane, or any combination thereof, but is not limited thereto.

[0210] The display panel 1000 described above can be applied to various electronic devices including a display device, for example, such as a television, a monitor, a computer, a tablet PC, or a mobile phone, or an illumination device such as a light source. In an embodiment, the electronic device (or display device) includes the color conversion panel or the display panel described herein.

[0211] Embodiments

[0212] Analysis method

[0213] [1] Measurement of external quantum efficiency (EQE) of quantum dot complex

[0214] The external quantum efficiency is measured using commercially available quantum efficiency measuring equipment (for example, a measuring device sold under the trademark QY manufactured by Hamamatsu Photonics K.K., Hamamatsu City, Japan) equipped with an integrating sphere, in accordance with the following equation. The excitation light at the time of measuring the quantum efficiency can be arbitrarily selected within 400 nm to 680 nm (for example, 450 nm) in consideration of the optical properties and the like of the quantum dots to be provided.

[0215] External quantum efficiency = [A / B] x 100 (%)

[0216] A: Number of photons emitted from the quantum dot complex

[0217] B: Number of photons of excitation light (supplied to the quantum dot complex)

[0218] Viscosity of the ink composition

[0219] The viscosity of the ink composition is measured at room temperature (for example, 25°C) using a viscometer or a rheometer.

[0220] Measurement of film residual rate

[0221] The film residual rate is measured at room temperature and in an air environment by the following equation.

[0222] Film residual rate = [(volume of the ink film) / (volume of the ink filled in pixel units)] x 100

[0223] Reference Example 1

[0224] Quantum dots were prepared according to a known method. In the presence of palmitic acid, indium acetate and tris(trimethylsilyl)phosphine were reacted in 1-octadecene to synthesize an indium phosphide (InP) core. The obtained core was dispersed in toluene. Zinc acetate, oleic acid and trioctylamine were vacuumed at an elevated temperature of about 120°C to provide a zinc precursor, and the toluene dispersion of the InP core and a predetermined amount of elemental sulfur (S) precursor were added to a reaction flask, and reacted at 280°C, and the reaction solution was rapidly cooled at room temperature to provide a reaction product including InP / zinc sulfide (ZnS) core-shell quantum dots.

[0225] An excess amount of ethanol was added to the reaction product and centrifuged. After centrifugation, the supernatant was discarded, and the precipitate was dried to provide quantum dots including oleic acid as an organic ligand on the surface thereof (hereinafter referred to as first quantum dots). It was confirmed that the first quantum dots emit red light.

[0226] Reference Example 2

[0227] The first quantum dots prepared in Reference Example 1 were subjected to a ligand exchange reaction under known conditions to provide second quantum dots including a second ligand represented by the following chemical formula:

[0228]

[0229] Comparative Example 1

[0230] (1) Preparation of an ink composition:

[0231] A second solution was prepared, which includes a liquid monomer (including hexamethylene diacrylate), and a second quantum dot and titanium oxide fine particles (average particle diameter: about 200 nm) dispersed in the liquid monomer. The total solid content of the second solution was 100 wt%.

[0232] In the second solution, the content of the second quantum dot was 43 wt% and the content of the titanium oxide was 10 wt% based on the total solid content.

[0233] Figure 6A An inkjet jet photograph of the ink composition of Comparative Example 1 having a viscosity of 43.2 cp at room temperature was depicted, in which jetting was performed at temperatures of 30°C, 40°C, and 50°C, respectively. Figure 6B An inkjet jet photograph of the ink composition of Example 1 prepared according to the principles of the present application and having a viscosity of 17.9 cp at room temperature was shown, in which jetting was performed at a temperature of 25°C.

[0234] (2) The ink composition prepared was jetted at a predetermined temperature by an inkjet device, and a photograph thereof is shown in Figure 6A It was confirmed that the jetting characteristics were not good even in a heated state. A film was obtained from the ink composition obtained by an inkjet method, and was left to stand at room temperature for 30 minutes in an air atmosphere to measure the film residual rate, and the results are shown in Figure 7

[0235] (3) The ink composition prepared was jetted by an inkjet device, and was exposed and cured to provide a solid quantum dot (polymer) composite. The quantum efficiency of the quantum dot composite obtained was measured at 60°C using a 450 nm excitation light, and Figure 8 is a graph showing the change in external quantum efficiency with time. From the results of Figure 8 it can be confirmed that the quantum dot composite obtained showed a significant and unexpected overshoot under the device driving conditions.

[0236] Example 1:

[0237] (1) Preparation of an ink composition:

[0238] A first solution was obtained, which includes a first quantum dot dispersed in an organic solvent (cyclohexyl acetate (CHA, 1.295 mmHg vapor pressure at 25°C)).

[0239] An ink composition was obtained according to the same procedure as in Comparative Example 1 (hereinafter, a second solution).​

[0240] The first and second solutions were mixed at a weight ratio of 20:80 to prepare the ink composition. It has been demonstrated that the obtained composition maintains a good (colloidal) dispersion without precipitation.

[0241] The prepared ink composition has a viscosity of 17.9 cP and a vapor pressure of less than or equal to 10 at 20°C. -3 The surface tension at 23°C is less than or equal to 35 mmHg. The prepared ink composition has an acid value and amine value of 30 to 50 mg KOH / g, respectively.

[0242] (2) An ink composition prepared by jetting using an inkjet printer, and a photograph of which is displayed. Figure 6B middle.

[0243] Figure 7 This is a graph showing the change in membrane residue over time of the membranes prepared from the quantum dot solution (first solution) of Reference Example 1, the ink composition of Comparative Example 1, and the ink composition of Example 1 prepared according to the principle of the present invention. Figure 8 This is a graph showing the change of external quantum efficiency over time for the quantum dot composite prepared from the ink composition of Comparative Example 1 and the quantum dot composite prepared from the ink composition of Example 1.

[0244] A first solution and ink composition were jetted using an inkjet printer to obtain a film. The obtained film was then allowed to stand in air at room temperature for 30 minutes to measure the film residue. The results were displayed as follows: Figure 7 middle. Figure 7 The results showed that the ink composition according to Example 1 had a film residue rate similar to that of the liquid monomer-based (non-solvent) composition according to Comparative Example 1. On the other hand, Figure 7 The results showed that the first solution exhibited a significant and unexpected reduction in membrane residue within a short period of time.

[0245] (3) The prepared ink composition was sprayed into an inkjet printer and exposed to light, then cured to provide a solid quantum dot (polymer) composite. The external quantum efficiency of the resulting quantum dot composite was measured, and the change in external quantum efficiency relative to the initial efficiency (100%) over time was shown in the figure. Figure 8 The curve in the graph. Figure 8 The results showed that the quantum dot composite prepared from the ink composition according to Example 1 significantly and unexpectedly reduced overshoot under device operating conditions.

[0246] Experimental Example 1:

[0247] Ink compositions (Ink Compositions 1 to 8) were prepared according to a similar procedure to Example 1, while adjusting the dispersant such that the first solution and the second solution were configured to meet the conditions described in the table below. The dispersion state of the prepared ink compositions were each visually monitored by the naked eye, and the results are summarized in Table 1.

[0248] Table 1

[0249]

[0250] 注释1) Amphoteric: cases where both acid value and amine value are present

[0251] While certain implementations and embodiments have been described herein, other implementations and embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. Therefore, the present implementations and embodiments are not intended to be limited to the implementations and embodiments described herein, but are to be accorded the full scope of the claims, and various modifications and equivalent arrangements can be used in the practice thereof, within the scope of the following claims.

Claims

1. An ink composition comprising a plurality of quantum dots, a liquid monomer, an initiator, and optionally an organic solvent, wherein the plurality of quantum dots comprises: a first quantum dot comprising a first ligand, and a second quantum dot comprising a second ligand different from the first ligand, and the ink composition is configured to emit a first light, wherein the ink composition has both an acid value and an amine value, and each of the acid value and the amine value is greater than or equal to 35 mg KOH / g, or the difference between the acid value and the amine value is less than or equal to 5 mg KOH / g.

2. The ink composition of claim 1, wherein the first light is green light, red light, or blue light, and a maximum emission peak of the first light has a full width at half maximum less than or equal to 45 nm.

3. The ink composition of claim 1, wherein RSH, R3PO, R3P, ROH, RCOOR', RPO(OH)2, RHPOOH, R2POOH, a polymeric organic ligand, or any combination thereof, wherein R and R' are each independently a substituted or unsubstituted C1to C 100 aliphatic hydrocarbon group, a substituted or unsubstituted C6to C 50 aromatic hydrocarbon group, or a combination thereof, and at least one methylene in the aliphatic hydrocarbon group is optionally replaced with a sulfonyl, carbonyl, ether linkage, sulfide linkage, sulfoxide linkage, ester linkage, amide group of the formula -C(=O)NR"-, or any combination thereof, wherein R" is hydrogen or C1to C 10 alkyl group, or wherein the first ligand comprises a monocarboxylic compound having a substituted or unsubstituted C 10 to C 40 hydrocarbon group, or wherein the second ligand comprises an organic compound having a functional group that is an amine group, a mercaptan group, a carboxylic acid group, a phosphine group, or any combination thereof, and a moiety connected to the functional group and having the formula: * - L - A wherein L is substituted or unsubstituted C1to C 30 alkylene, substituted or unsubstituted C2to C 30 alkenylene, substituted or unsubstituted C3to C 30 cycloalkylene, substituted or unsubstituted C3to C 30 heterocycloalkylene, substituted or unsubstituted C6to C 30 arylene, substituted or unsubstituted C3to C 30 heteroarylene, sulfonyl, carbonyl, ether, sulfido, sulfoxido, ester, amide of the formula -C(=0)NR"- or any combination thereof, A is hydrogen, -COOH, -NR"2, or any combination thereof, wherein R" is, independently of each other, hydrogen or Ci to C4alkyl, and 10 alkyl, and * is a site of attachment to the functional group.

4. The ink composition of claim 1, wherein the liquid monomer comprises a compound having a carbon-carbon double bond and a vapor pressure less than or equal to 10 -4 mmHg, or wherein the organic solvent comprises a substituted or unsubstituted C3 to C 40 aliphatic hydrocarbon solvent, a substituted or unsubstituted C6 to C 40 aromatic hydrocarbon solvent, a substituted or unsubstituted C3 to C 40 alicyclic hydrocarbon solvent, an alkylene glycol alkyl ether acetate solvent, an alkyl acetamide solvent, or any combination thereof, or wherein the liquid monomer comprises a monoacrylate compound, a diacrylate compound, a triacrylate compound, a tetraacrylate compound, a pentaacrylate compound, a hexaacrylate compound, or any combination thereof, or the organic solvent comprises propylene glycol monomethyl ether acetate, dimethylacetamide, cyclohexyl acetate, or any combination thereof.

5. The ink composition of claim 1, wherein the ink composition has a viscosity of less than or equal to 40 cP and a vapor pressure of less than or equal to 10 mmHg, or -3 less than or equal to 5 mmHg. wherein the ink composition is configured to exhibit a film retention greater than or equal to 90% after 30 minutes after it forms a film, or wherein in a solid state after the ink composition is polymerized, the ink composition is configured to show a relative external quantum efficiency less than or equal to 104% relative to an initial value of 100% external quantum efficiency during a period of 100 hours of irradiation at a temperature of 60 °C with an excitation light having a wavelength of 450 nm.

6. A method of preparing the ink composition of any one of claims 1 to 5, comprising preparing a first solution comprising the first quantum dot and the organic solvent, a second solution is prepared comprising said second quantum dots and said liquid monomer; and mixing the first solution and the second solution to maintain a colloidal dispersion state, wherein the first solution and the second solution satisfy one of the following conditions: at least one of the first solution and the second solution does not exhibit both an acid value and an amine value; when the first solution exhibits an acid value or an amine value, then the second solution exhibits one of an acid value or an amine value; when the first solution is amphoteric exhibiting both an acid value and an amine value, then the second solution is also amphoteric; or when one of the first solution and the second solution is amphoteric and the other exhibits an acid value or an amine value, then in the solution that is amphoteric, the difference between the acid value and the amine value is less than 5 mg KOH / g, or all of the acid value and the amine value are greater than or equal to 35 mg KOH / g.

7. An ink composition comprising a liquid carrier comprising an organic solvent and a liquid monomer; and a plurality of quantum dots and optionally metal oxide particles dispersed in the liquid carrier, In the ink composition, an amount of the organic solvent is less than or equal to 20 wt% based on a total weight of the ink composition, and in a solid state after the ink composition is polymerized, the ink composition is configured to show a relative external quantum efficiency of less than or equal to 104% relative to an initial external quantum efficiency of 100% during a period in which the ink composition is irradiated with excitation light having a wavelength of 450 nm at a temperature of 60 °C for 100 hours, wherein the ink composition has both an acid value and an amine value, and each of the acid value and the amine value is greater than or equal to 35 mg KOH / g, or a difference between the acid value and the amine value is less than or equal to 5 mg KOH / g.

8. A quantum dot composite comprising a matrix and a plurality of quantum dots dispersed in the matrix, wherein the plurality of quantum dots includes first quantum dots including a first ligand and second quantum dots including a second ligand different from the first ligand, the quantum dot composite emits light of a predetermined wavelength, and in a solid state of the quantum dot composite, the quantum dot composite is configured to show a relative external quantum efficiency of less than or equal to 104% relative to an initial external quantum efficiency of 100% during a period in which the quantum dot composite is irradiated with excitation light having a wavelength of 450 nm at a temperature of 60 °C for 100 hours, wherein the ink composition has both an acid value and an amine value, and each of the acid value and the amine value is greater than or equal to 35 mg KOH / g, or a difference between the acid value and the amine value is less than or equal to 5 mg KOH / g.

9. A color conversion apparatus comprising a layer including a region for converting a color, and the region includes a first region for emitting first light, the first region including the quantum dot composite of claim 8; and an isolation wall defining each region in the layer.

10. The color conversion apparatus of claim 9, wherein the first region includes a plurality of the quantum dot composite.

Images