A ink composition containing metal oxide with core-shell structure

Abstract

The present invention relates to an ink composition for an electron transport layer comprising a core-shell structured metal oxide surface-treated with a ligand compound, and more specifically, to an ink composition for an electron transport layer comprising a core-shell structured metal oxide surface-treated with a ligand compound; and a solvent. The present invention can provide an ink composition for an electron transport layer that has excellent dispersion stability and processability in solvents through surface modification of core-shell structured metal oxide nanoparticles, and can improve quantum efficiency, brightness, optical properties, device performance, etc. by reducing surface defects of the nanoparticles.

Description

Technology Field

[0001] The present invention relates to an ink composition for an electron transport layer comprising a core-shell structured metal oxide surface-treated with a ligand compound, and more specifically, to an ink composition for an electron transport layer comprising a core-shell structured metal oxide surface-treated with a ligand compound; and a solvent. Background Technology

[0003] Nanoparticles exhibit significantly different optical, electrical, and surface properties compared to bulk materials, and based on these changes in physical properties, they have the potential for application in various fields such as information, energy, medicine, and processing.

[0004] In particular, luminescent nanoparticles are attracting attention as key materials in the field of optoelectronic devices, such as solar cells, light-emitting diodes, and lasers.

[0005] Meanwhile, synthesized nanoparticles must have excellent dispersibility in organic solvents for device fabrication; however, nanoparticles aggregate over time, leading to a decrease in dispersion stability and consequently making solution processing difficult.

[0006] In addition, device performance may degrade due to surface defects in the nanoparticles used as the electron transport layer.

[0007] Therefore, various studies are being conducted to improve dispersibility and processability by modifying the surface properties of nanoparticles.

[0008] In this regard, Korean Published Patent No. 10-2022-0003406 discloses a nanoparticle composed of magnesium hydroxide [Mg(OH)2] and alloyed magnesium (Mg) doped zinc oxide (ZnO) nanoparticles, and further comprising an ethanolamine capping layer on the surface of the nanoparticle.

[0009] However, the technology disclosed in the aforementioned literature cannot be reliably used as an electron transport layer for electroluminescent devices due to poor dispersibility, processability, quantum efficiency, brightness, and optical properties.

[0010] Therefore, there is a need to develop technology that offers excellent dispersion stability and processability in solvents, and can improve quantum efficiency, brightness, optical properties, and device performance by reducing surface defects of nanoparticles. Prior art literature

[0012] Korean Patent Publication No. 10-2022-0003406 The problem to be solved

[0013] The present invention aims to solve the problems of the prior art described above by providing an ink composition for an electron transport layer that has excellent dispersion stability and processability in solvents through surface modification of core-shell structured metal oxide nanoparticles, and can improve quantum efficiency, brightness, optical properties, and device performance by reducing surface defects of the nanoparticles. means of solving the problem

[0015] To achieve the above objectives, the present invention provides an ink composition for an electron transport layer comprising: a core-shell structured metal oxide surface-treated with a ligand compound; and a solvent.

[0016] In one embodiment of the present invention, the core of the metal oxide is used from one or more of ZnO, ZnMgO, ZnAlO, ZnCoO, ZnNiO, ZnGaO, TiO2, and SnO2, and

[0017] The shell of the metal oxide above is characterized by using one or more of ZnS, ZnSe, ZnTe, ZnSeS, ZnTeS, GaAs, GaP, GaN, GaO, and GaSb.

[0018] In one embodiment of the present invention, the ligand compound is characterized by comprising one or more functional groups selected from the group comprising an ethoxy group, a methoxy group, an adamantane group, and a carboxyl group.

[0019] In one embodiment of the present invention, the metal oxide surface-treated with the ligand compound is characterized by being surface-treated using 3 to 30 parts by weight of the ligand compound per 100 parts by weight of the metal oxide.

[0020] In addition, the present invention provides an electron transport layer comprising the ink composition for the electron transport layer.

[0021] In addition, the present invention provides an electroluminescent device comprising the electron transport layer. Effects of the invention

[0023] The present invention can provide an ink composition for an electron transport layer that has excellent dispersion stability and processability in solvents through surface modification of core-shell structured metal oxide nanoparticles, and can improve quantum efficiency, brightness, optical properties, device performance, etc. by reducing surface defects of the nanoparticles. Brief explanation of the drawing

[0025] Figure 1 shows a core-shell structured metal oxide surface-treated with a ligand compound of the present invention. Figure 2 shows the degree of reduction in surface defects of ZnO / ZnS nanoparticles surface-treated with ethoxyacetic acid. Figure 3 shows the brightness when surface-treated ZnO / ZnS nanoparticles are used. Figure 4 shows the external quantum efficiency when using surface-treated ZnO / ZnS nanoparticles. Specific details for implementing the invention

[0026] The present invention will be described in detail below based on the following examples. The terms, examples, etc. used in the present invention are merely illustrative to explain the invention more specifically and to aid the understanding of those skilled in the art, and the scope of the rights, etc., of the present invention should not be interpreted as being limited thereto.

[0027] Unless otherwise defined, technical and scientific terms used in this invention represent the meanings commonly understood by those skilled in the art to which this invention pertains.

[0029] The present invention relates to an ink composition for an electron transport layer comprising: a core-shell structured metal oxide surface-treated with a ligand compound; and a solvent.

[0030] The above ink composition may include 1 to 20 parts by weight of a surface-treated core-shell structured metal oxide per 100 parts by weight of solvent.

[0032] The core of the metal oxide may be one or more of ZnO, ZnMgO, ZnAlO, ZnCoO, ZnNiO, ZnGaO, TiO2, and SnO2, and the shell of the metal oxide may be one or more of ZnS, ZnSe, ZnTe, ZnSeS, ZnTeS, GaAs, GaP, GaN, GaO, and GaSb.

[0034] The metal oxide nanoparticles with the above-mentioned core-shell structure must have excellent dispersibility in organic solvents for device fabrication; however, as the nanoparticles aggregate over time, their dispersion stability deteriorates, which can consequently make solution processing difficult.

[0035] In addition, device performance may be degraded due to surface defects in the nanoparticles used as the electron transport layer.

[0037] The present invention can improve the performance of a manufactured device by surface treating the surface of a metal oxide with a core-shell structure with a ligand compound, thereby reducing surface defects of nanoparticles and improving dispersibility and processability in a solvent (Fig. 1).

[0039] The above ligand compound may include one or more functional groups selected from the group comprising ethoxy groups, methoxy groups, adamanthine groups, and carboxyl groups.

[0040] In addition, the above ligand compound may have the structure of Chemical Formula 1 below.

[0041] [Chemical Formula 1]

[0042] R1-CH2-(OR2) n OR3

[0043] In the above chemical formula 1, R1 is one of a carboxyl group, a thiol, an amine, a hydroxyl group, and a salt thereof; R2 represents a C1-C4 alkyl group; n is an integer from 0 to 10; and R3 represents hydrogen or a C1-C4 alkyl group.

[0044] As an example, the ligand compound is ethoxyacetic acid, 2-hydroxyethoxyacetic acid, ethoxymethanol, 1-ethoxy-1-propanol, 1-ethoxy-2-propanol, 2-ethoxyethanol, ethoxydiglycol, 2-ethoxybutanoic acid, 4-ethoxybutanoic acid, methoxyacetic acid, 1-methoxy-2-propanol, 2-methoxy-1-propanol, 2-methoxyethanol, 3-methoxy-1-butanol, 2-methoxybutanoic acid, 4-methoxybutanoic acid, 1-adamanthene carboxylic acid, 1-adamanthene methylamine, One or more selected from 1-adamanthene amine, 1-adamanthene ethanol, acetic acid, formic acid, butyric acid, pentacarbonic acid, adipic acid, succinic acid, malonic acid, etc. may be used.

[0046] A core-shell structured metal oxide surface-treated with the above-mentioned ligand compound can be surface-treated using 3 to 30 parts by weight of the ligand compound per 100 parts by weight of the metal oxide.

[0047] When the content satisfies the above numerical range, dispersion stability, processability, quantum efficiency, brightness, optical properties, device performance, etc., can be maximized.

[0049] In addition, the present invention can surface treat the core-shell structured metal oxide with ethoxyacetic acid and 2-hydroxyethoxyacetic acid.

[0050] At this time, it is preferable that the weight ratio of ethoxyacetic acid and 2-hydroxyethoxyacetic acid be 60~80:20~40, and when the weight ratio satisfies the above numerical range, dispersion stability, processability, quantum efficiency, brightness, optical properties, device performance, etc. can be maximized.

[0052] In addition, the present invention can surface treat the metal oxide with ethoxyacetic acid, 2-hydroxyethoxyacetic acid, and methoxyacetic acid.

[0053] At this time, the weight ratio of ethoxyacetic acid, 2-hydroxyethoxyacetic acid, and methoxyacetic acid is preferably 100:20 to 50:5 to 20, and when the weight ratio satisfies the above numerical range, dispersion stability, processability, quantum efficiency, brightness, optical properties, device performance, etc. can be maximized.

[0055] In addition, the present invention can surface treat the metal oxide with ethoxyacetic acid, 2-hydroxyethoxyacetic acid, methoxyacetic acid, and acetic acid.

[0056] At this time, it is preferable that the weight ratio of ethoxyacetic acid, 2-hydroxyethoxyacetic acid, methoxyacetic acid, and acetic acid be 100:20 to 50:5 to 20:2 to 10, and when the weight ratio satisfies the above numerical range, dispersion stability, processability, quantum efficiency, brightness, optical properties, device performance, etc. can be maximized.

[0058] The present invention improves dispersion stability and processability in solvents by surface-treating metal oxide nanoparticles with a ligand compound, and can improve quantum efficiency, brightness, optical properties, device performance, etc. by reducing surface defects of the nanoparticles.

[0060] In addition, the metal oxide nanoparticles can be further surface-treated with a beta-diketone compound.

[0061] The above beta-diketone compounds are 2,4-pentanedione, 3-(1-hydroxyethylidene)-2,4-pentanedione, 2,6-dimethyl-3,5-heptanedione, 2,4-hexanedione, 5-methyl-3,5-hexanedione, 2,2-dimethyl-3,5-hexanedione, 3,5-heptanedione, and 2-methyl-3,5-heptanedione. One or more selected from the group comprising 2,2-dimethyl-3,5-heptanedione, 2,2,6-trimethyl-3,5-heptanedione, 2,2,6,6-tetramethyl-3,5-heptanedione, and 2,2,6,6-tetramethyl-3,5-octanedione may be used.

[0062] At this time, the weight ratio of the surface-treated ligand compound and the beta-diketone compound is preferably 60 to 80:20 to 40, and when the weight ratio satisfies the above numerical range, dispersion stability, processability, quantum efficiency, brightness, optical properties, device performance, etc. can be maximized.

[0063] In addition, the present invention may use a mixture of 3-(1-hydroxyethylidene)-2,4-pentanedione and 2,4-pentanedione as the beta-diketone compound.

[0064] At this time, it is preferable that the weight ratio of 3-(1-hydroxyethylidene)-2,4-pentanedione and 2,4-pentanedione be 60~80:20~40, and when the weight ratio satisfies the above numerical range, dispersion stability, processability, quantum efficiency, brightness, optical properties, device performance, etc. can be maximized.

[0066] In addition, the metal oxide nanoparticles may be further surface-treated with hydroxy ketone compounds such as 4-hydroxy-2-butanone, 1-hydroxy-2-butanone, and 5-hydroxy-2-pentanone.

[0067] At this time, the weight ratio of the surface-treated ligand compound and hydroxy ketone compound is preferably 60 to 80:20 to 40, and when the weight ratio satisfies the above numerical range, dispersion stability, processability, quantum efficiency, brightness, optical properties, device performance, etc. can be maximized.

[0068] In addition, the present invention may use a mixture of 4-hydroxy-2-butanone and 1-hydroxy-2-butanone as the hydroxy ketone compound.

[0069] At this time, the weight ratio of 4-hydroxy-2-butanone and 1-hydroxy-2-butanone is preferably 60~80:20~40, and when the weight ratio satisfies the above numerical range, dispersion stability, processability, quantum efficiency, brightness, optical properties, device performance, etc. can be maximized.

[0071] In addition, the metal oxide nanoparticles may be further surface-treated with a copolymer of an acrylate group-containing silane coupling agent, 2-hydroxyethyl acrylate (HEA), and 2-hydroxypropyl acrylate (HPA).

[0072] The above acrylate group-containing silane coupling agents include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, methacryloxymethyltriethoxysilane, and methacryloxymethyltrimethoxysilane.

[0073] The weight ratio of the above acrylate group-containing silane coupling agent, 2-hydroxyethyl acrylate (HEA), and 2-hydroxypropyl acrylate (HPA) is preferably 100:20 to 50:5 to 20.

[0074] At this time, the weight ratio of the surface-treated ligand compound and the copolymer is preferably 60 to 80:20 to 40, and when the weight ratio satisfies the above numerical range, dispersion stability, processability, quantum efficiency, brightness, optical properties, device performance, etc. can be maximized.

[0076] The above solvent may be one or more selected from the group comprising ethanol, n-butanol, acetone, diethyl ether, ethyl acetate, distilled water, chloroform, dichloromethane, n-propanol, methanol, hexane, cyclohexylbenzene, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, icosane, anisole, dimethyl anisole, xylene, toluene, mesitylene, methyl benzoate, dioxane, tetrahydrofuran, methyl tetrahydrofuran, tetrahydropyran, tetratraline, veratrol, chlorobenzene, N-methylpyrrolidone, N,N-dimethylformamide, and dimethyl sulfoxide.

[0077] In addition, the above solvent may be used alone or in combination with a compound having a boiling point of 60 to 250°C.

[0079] In addition, the present invention relates to an electron transport layer comprising the ink composition for the electron transport layer.

[0080] In addition, the present invention relates to an electroluminescent device comprising the electron transport layer described above.

[0082] The ink composition for an electron transport layer of the present invention has excellent dispersion stability and processability in solvents through surface modification of core-shell structured metal oxide nanoparticles, and since surface defects of the nanoparticles are reduced, it exhibits excellent quantum efficiency, brightness, optical properties, and device performance, and can be used as an electron transport layer for an electroluminescent device.

[0084] The present invention will be described in detail below through examples and comparative examples. The following examples are merely illustrative for the implementation of the present invention, and the scope of the present invention is not limited by the following examples.

[0086] (Example 1)

[0087] Surface-treated ZnO / ZnS nanoparticles were prepared by surface-treating core-shell structured ZnO / ZnS nanoparticles with ethoxyacetic acid.

[0088] At this time, 10 parts by weight of ethoxyacetic acid were used for every 100 parts by weight of nanoparticles.

[0089] An ink composition was prepared by mixing 10 parts by weight of the surface-treated nanoparticles and 100 parts by weight of ethanol.

[0091] Figure 2 shows the degree of reduction in surface defects of ZnO / ZnS nanoparticles surface-treated with ethoxyacetic acid.

[0092] It can be seen that in the case of nanoparticles surface-treated with 10 parts by weight of ethoxyacetic acid, surface defects are reduced compared to nanoparticles that are not surface-treated.

[0094] Figure 3 shows the brightness when surface-treated ZnO / ZnS nanoparticles are used.

[0095] It can be seen that nanoparticles surface-treated with ethoxyacetic acid have increased brightness compared to nanoparticles that are not surface-treated.

[0097] Figure 4 shows the external quantum efficiency when using surface-treated ZnO / ZnS nanoparticles.

[0098] It can be seen that in the case of nanoparticles surface-treated with ethoxyacetic acid, the external quantum efficiency increases compared to nanoparticles that are not surface-treated.

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Claims

Claim 1 Core-shell structured metal oxide surface-treated with a ligand compound; An electron transport layer ink composition for reducing surface defects of metal oxide nanoparticles, comprising: and a solvent; wherein the core of the metal oxide is used from one or more of ZnO, ZnMgO, ZnAlO, ZnCoO, ZnNiO, ZnGaO, TiO2, and SnO2, and the shell of the metal oxide is used from one or more of ZnS, ZnSe, ZnTe, ZnSeS, ZnTeS, GaAs, GaP, GaN, GaO, and GaSb; the ligand compound comprises one or more functional groups selected from the group comprising ethoxy groups, methoxy groups, and adamantane groups; and the ligand compound is ethoxyacetic acid, 2-hydroxyethoxyacetic acid, ethoxymethanol, 1-ethoxy-1-propanol, 1-ethoxy-2-propanol, 2-ethoxyethanol, ethoxydiglycol, 2-ethoxy One or more selected from butoxybutanoic acid (2-ethoxybutanoic acid), 4-ethoxybutanoic acid, methoxyacetic acid, 1-methoxy-2-propanol, 2-methoxy-1-propanol, 2-methoxyethanol, 3-methoxy-1-butanol, 2-methoxybutanoic acid (2-methoxybutanoic acid), 4-methoxybutanoic acid (4-methoxybutanoic acid), 1-adamantane carboxylic acid, 1-adamantane methylamine, 1-adamantane amine, and 1-adamantane ethanol are used, and the metal oxide surface-treated with the ligand compound is surface-treated using 3 to 30 parts by weight of the ligand compound per 100 parts by weight of the metal oxide, and the ink composition comprises 1 to 20 parts by weight of the surface-treated core-shell structured metal oxide per 100 parts by weight of the solvent An electron transport layer ink composition for reducing surface defects of metal oxide nanoparticles, characterized by including and surface treating the surface of the core-shell structured metal oxide with a ligand compound to reduce surface defects of the metal oxide nanoparticles and improve dispersibility in a solvent, thereby improving the quantum efficiency and brightness of the manufactured electroluminescent device. Claim 2 delete Claim 3 The electron transport layer ink composition for reducing surface defects of metal oxide nanoparticles according to claim 1, characterized in that the solvent is a compound having a boiling point of 60 to 250°C, used alone or in combination. Claim 4 delete Claim 5 delete Claim 6 An electron transport layer comprising an electron transport layer ink composition for reducing surface defects of metal oxide nanoparticles according to claim 1. Claim 7 An electroluminescent device comprising the electron transport layer of claim 6.

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