Metal oxide to which thiocarboxylic acid ligand is bound, and ink composition comprising same

Abstract

The present invention relates to a metal oxide to which a thiocarboxylic acid ligand is bound, and an ink composition comprising same, and, more specifically, to a metal oxide to which a thiocarboxylic acid ligand is bound, and an ink composition comprising same, the surface of a particle of the metal oxide having, bound thereto, a ligand compound with a thiocarboxylic acid group so that surface defects of a metal oxide are minimized and dispersion stability in an organic solvent is improved, the performance of a device can be increased.

Description

Metal oxide bonded with thiocarboxylic acid ligand and ink composition containing the same

[0001] The present invention relates to a metal oxide having a thiocarboxylic acid ligand bonded thereto and an ink composition comprising the same, and more particularly, to a metal oxide having a thiocarboxylic acid ligand bonded thereto, which can increase the characteristics of a device by minimizing surface defects of the metal oxide and improving dispersion stability in an organic solvent by bonding a ligand compound having a thiocarboxylic acid group to the surface of metal oxide particles.

[0002]

[0003] Metal oxide nanoparticles exhibit significantly different optical, electrical, and surface properties compared to bulk materials, and based on these property changes, they have potential applications 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, metal oxide nanoparticles must have excellent dispersibility in organic solvents for device fabrication. However, nanoparticles may aggregate over time, reducing dispersion stability, and thus making solution processing difficult.

[0006] Additionally, device performance may be degraded due to surface defects in metal oxide nanoparticles used as electron transport layers.

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

[0008] Conventional carboxylic acid ligands have a slow bonding speed and reduced stability when bonded to metal oxides, and cannot reduce surface defects of the metal oxide, which may deteriorate the characteristics of the device.

[0009] In addition, Korean Patent Publication No. 10-2022-0003406 discloses a nanoparticle comprising 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 nanoparticles.

[0010] However, the technology disclosed in the above document cannot be stably used as an electron transport layer of an electroluminescent device due to poor dispersibility, processability, quantum efficiency, brightness, optical properties, etc.

[0011] Therefore, it is necessary to develop a technology that can minimize surface defects of metal oxides by bonding to the surface of metal oxides, has excellent dispersion stability and processability in solvents, and improves quantum efficiency, brightness, optical properties, and device performance of the device.

[0012]

[0013] (Patent Document 1) Korean Patent Publication No. 10-2022-0003406

[0014] (Related assignment) Assignment ID: 1415185804, 1345370812

[0015]

[0016] The present invention is intended to solve the problems of the above-mentioned prior art, and aims to provide a ligand compound for surface modification of metal oxide particles, which can be bonded to the surface of metal oxide particles to minimize surface defects of the metal oxide, has excellent dispersion stability and processability for solvents, and can improve quantum efficiency, brightness, optical properties, device performance, etc. of the device.

[0017] In addition, the present invention aims to provide surface-modified metal oxide particles and an ink composition including the same, which can be used as an electron transport layer of a display device or an electroluminescent device due to their excellent dispersibility, quantum efficiency, brightness, optical properties, and device performance.

[0018]

[0019] In order to achieve the above purpose, the present invention provides a ligand compound for surface modification of a metal oxide, which contains a thiocarboxylic acid group.

[0020] In one embodiment of the present invention, the ligand compound is characterized in that it further includes at least one functional group selected from the group including an alkyl group, a benzene group, an alkoxy group, a hydroxy group, an amine group, a halogen group, an ester group, and an ether group.

[0021] 본 발명의 일실시예에 있어서, 상기 리간드 화합물은 2,4,6,8,10-pentaoxadodecane-12-thioic S-acid, 2,4,6,8-tetraoxadecane-10-thioic S-acid, 2,5,8,11-tetraoxatridecane-13-thioic S-acid, 2-((methoxymethoxy)methoxy)ethanethioic S-acid, 2-(2-(2-ethoxyethoxy)ethoxy)ethanethioic S-acid, 2-(2-(2-methoxyethoxy)ethoxy)ethanethioic S-acid, 2-(2-ethoxyethoxy)ethanethioic S-acid, 2-(2-methoxyethoxy)ethanethioic S-acid, 2-(methoxymethoxy)ethanethioic S-acid, 2-ethoxyethanethioic S-acid, 2-methoxyethanethioic S-acid, 3,6,9,12-tetraoxatetradecane-1-thioic S-acid, O-(((methoxymethoxy)methoxy)methyl) S-hydrogen carbonothioate, O-((methoxymethoxy)methyl) S-hydrogen carbonothioate, O-(methoxymethyl) S-hydrogen carbonothioate, O-2,4,6,8-tetraoxanonyl S-hydrogen carbonothioate, O-methyl S-hydrogen carbonothioate, butanethioic S-acid compound with decanethioic S-acid, dodecanethioic S-acid, ethanethioic S-acid, heptanethioic S-acid, hexanethioic S-acid, methanethioic S-acid, nonanethioic S-acid, octanethioic S-acid,It is characterized by at least one selected from the group including pentanethioic S-acid, propanethioic S-acid, tridecanethioic S-acid, undecanethioic S-acid, 3-chloropropanethioic S-acid, 3-aminopropanethioic S-acid, 2-(2-aminoethoxy)ethanethioic S-acid, 2-(2-chloroethoxy)ethanethioic S-acid and benzothioic S-acid.

[0022] The present invention also provides a metal oxide surface-modified with the ligand compound.

[0023] In one embodiment of the present invention, the metal oxide is characterized in that at least one of ZnO, ZnMgO, ZnMgLiO, ZnAlO, ZnCoO, ZnNiO, ZnGaO, TiO2, and SnO2 is used.

[0024] The present invention also provides an ink composition comprising the surface-modified metal oxide and a solvent.

[0025]

[0026] The present invention provides a ligand compound for surface modification of metal oxide particles, which can be bonded to the surface of metal oxide particles to minimize surface defects of the metal oxide, has excellent dispersion stability and processability for a solvent, and can improve quantum efficiency, brightness, optical properties, device performance, etc. of the device.

[0027] In addition, the present invention can provide surface-modified metal oxide particles and an ink composition including the same, which can be used as an electron transport layer of a display device or an electroluminescent device due to their excellent dispersibility, quantum efficiency, brightness, optical properties, device performance, etc.

[0028]

[0029] Figure 1 shows the dispersion stability of ZnO nanoparticles surface-treated with 2-ethoxyethanethioic S-acid (EETA) or 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA).

[0030] Figure 2 shows the degree of reduction in surface defects of ZnO nanoparticles surface-treated with 2-ethoxyethanethioic S-acid (EETA) or 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA).

[0031] Figure 3 shows the degree of reduction in surface defects of ZnMgO nanoparticles surface-treated with 2-ethoxyethanethioic S-acid (EETA) or 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA).

[0032] Figure 4 shows the external quantum efficiency of ZnMgO nanoparticles surface-treated with 2-ethoxyethanethioic S-acid (EETA) or 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA).

[0033]

[0034] The present invention will be described in detail below based on examples. Terms, examples, and the like used herein are merely illustrative examples to more specifically explain the invention and aid understanding by those skilled in the art. The scope of the invention should not be construed as being limited thereto.

[0035] Technical and scientific terms used in the present invention, unless otherwise defined, have the meaning commonly understood by a person of ordinary skill in the art to which this invention belongs.

[0036]

[0037] The present invention relates to a ligand compound for surface modification of a metal oxide, comprising a thiocarboxylic acid group.

[0038]

[0039] The present invention can improve the performance of a manufactured device by reducing surface defects of metal oxide nanoparticles and improving dispersibility and processability in a solvent by surface-treating the surface of metal oxide particles with the ligand compound.

[0040]

[0041] The above ligand compound may additionally include one or more functional groups selected from the group including an alkyl group, a benzene group, an alkoxy group, a hydroxy group, an amine group, a halogen group, an ester group, and an ether group.

[0042]

[0043] 또한 상기 리간드 화합물은 2,4,6,8,10-pentaoxadodecane-12-thioic S-acid, 2,4,6,8-tetraoxadecane-10-thioic S-acid, 2,5,8,11-tetraoxatridecane-13-thioic S-acid, 2-((methoxymethoxy)methoxy)ethanethioic S-acid, 2-(2-(2-ethoxyethoxy)ethoxy)ethanethioic S-acid, 2-(2-(2-methoxyethoxy)ethoxy)ethanethioic S-acid, 2-(2-ethoxyethoxy)ethanethioic S-acid, 2-(2-methoxyethoxy)ethanethioic S-acid, 2-(methoxymethoxy)ethanethioic S-acid, 2-ethoxyethanethioic S-acid, 2-methoxyethanethioic S-acid, 3,6,9,12-tetraoxatetradecane-1-thioic S-acid, O-(((methoxymethoxy)methoxy)methyl) S-hydrogen carbonothioate, O-((methoxymethoxy)methyl) S-hydrogen carbonothioate, O-(methoxymethyl) S-hydrogen carbonothioate, O-2,4,6,8-tetraoxanonyl S-hydrogen carbonothioate, O-methyl S-hydrogen carbonothioate, butanethioic S-acid compound with decanethioic S-acid, dodecanethioic S-acid, ethanethioic S-acid, heptanethioic S-acid, hexanethioic S-acid, methanethioic S-acid, nonanethioic S-acid, octanethioic S-acid, pentanethioic S-acid,At least one selected from the group consisting of propanethioic S-acid, tridecanethioic S-acid, undecanethioic S-acid, 3-chloropropanethioic S-acid, 3-aminopropanethioic S-acid, 2-(2-aminoethoxy)ethanethioic S-acid, 2-(2-chloroethoxy)ethanethioic S-acid and benzothioic S-acid may be used.

[0044]

[0045] The present invention also relates to a metal oxide surface-modified with the above ligand compound.

[0046]

[0047] The above metal oxide may be one or more selected from ZnO, ZnMgO, ZnMgLiO, ZnAlO, ZnCoO, ZnNiO, ZnGaO, TiO2, and SnO2.

[0048]

[0049] The metal oxide surface-treated with the above ligand compound can be surface-treated using 1 to 30 parts by weight of the ligand compound per 100 parts by weight of the metal oxide.

[0050] When the content satisfies the above numerical range, dispersion stability, processability, quantum efficiency, brightness, optical properties, and device performance can be maximized.

[0051]

[0052] The present invention can surface-treat the metal oxide with 2-ethoxyethanethioic S-acid (EETA) and 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA).

[0053] At this time, the weight ratio of 2-ethoxyethanethioic S-acid (EETA) and 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA) 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 characteristics, device performance, etc. can be maximized.

[0054]

[0055] In addition, the present invention can surface-treat the metal oxide with 2-ethoxyethanethioic S-acid (EETA), 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA), and 2-(methoxymethoxy)ethanethioic S-acid.

[0056] At this time, the weight ratio of 2-ethoxyethanethioic S-acid (EETA), 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA) and 2-(methoxymethoxy)ethanethioic S-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 characteristics, device performance, etc. can be maximized.

[0057]

[0058] In addition, the present invention can surface-treat the metal oxide with 2-ethoxyethanethioic S-acid (EETA), 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA), 2-(methoxymethoxy)ethanethioic S-acid, and 2-methoxyethanethioic S-acid.

[0059] At this time, the weight ratio of 2-ethoxyethanethioic S-acid (EETA), 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA), 2-(methoxymethoxy)ethanethioic S-acid and 2-methoxyethanethioic S-acid is preferably 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 characteristics, device performance, etc. can be maximized.

[0060]

[0061] Additionally, the metal oxide nanoparticles can be further surface-treated with an acrylate group-containing silane coupling agent, a copolymer of 2-hydroxyethyl acrylate (HEA) and 2-hydroxypropyl acrylate (HPA).

[0062] The above acrylate group-containing silane coupling agent includes 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, methacryloxymethyltriethoxysilane, methacryloxymethyltrimethoxysilane, etc.

[0063] It is preferable that the weight ratio of the above acrylate group-containing silane coupling agent, 2-hydroxyethyl acrylate (HEA) and 2-hydroxypropyl acrylate (HPA) is 100:20 to 50:5 to 20.

[0064] At this time, the weight ratio of the ligand compound to be surface-treated 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 characteristics, device performance, etc. can be maximized.

[0065]

[0066] The present invention also relates to an ink composition comprising the surface-modified metal oxide and a solvent.

[0067] The solvent may be at least one selected from the group consisting of 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, tetralin, veratrol, chlorobenzene, N-methyl pyrrolidone, N,N-dimethylformamide, and dimethyl sulfoxide.

[0068]

[0069] The ligand compound of the present invention can be bound to the surface of metal oxide particles to minimize surface defects of the metal oxide and improve dispersion stability and processability in a solvent.

[0070] In addition, the ink composition of the present invention has excellent dispersibility, quantum efficiency, brightness, optical properties, device performance, etc., and can be used as an electron transport layer of a display device or an electroluminescent device.

[0071]

[0072] The present invention is described in detail through the following 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 to the following examples.

[0073]

[0074] (Synthesis of 2-ethoxyethanethioic S-acid (EETA))

[0075]

[0076]

[0077] Add 1:0.55 (eq) of ethoxyacetic acid and Laweeson's reagent to a microwave vessel along with 20 ml of acetonitrile and operate at 100°C for 15 minutes.

[0078] After the reaction was complete, all of the solvent, Acetonitrile, was evaporated using a rotary evaporator, NaOH was added, and the mixture was stirred in an ice bath for 30 minutes. The stirring speed was kept very fast to ensure sufficient precipitation of the solid.

[0079] After stirring, the precipitated solid was filtered, and the remaining solution was acidified to pH 2 with HCl. At this time, the HCl was added dropwise rather than all at once. Impurities generated during acidification were filtered out with cotton, and the purified solution was extracted with MC and distilled water. The extraction was repeated at least three times to increase purity, and MC and sulfate were used to remove moisture.

[0080] Finally, all organic solvents were removed in a vacuum oven to obtain a brown, clear liquid.

[0081]

[0082] (Synthesis of 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA))

[0083] Add (2-methoxyethoxy)acetic acid and Laweeson's reagent in an equivalent ratio of 1:0.55 (eq) together with 20 ml of Acetonitrile to a microwave vessel and operate at 100°C for 15 minutes.

[0084] After the reaction was complete, all of the solvent, Acetonitrile, was evaporated using a rotary evaporator, NaOH was added, and the mixture was stirred in an ice bath for 30 minutes. The stirring speed was kept very fast to ensure sufficient precipitation of the solid.

[0085] After stirring, the precipitated solid was filtered, and the remaining solution was acidified to pH 2 with HCl. At this time, the HCl was added dropwise rather than all at once. Impurities generated during acidification were filtered out with cotton, and the purified solution was extracted with MC and distilled water. The extraction was repeated at least three times to increase purity, and MC and sulfate were used to remove moisture.

[0086] Finally, all organic solvents were removed in a vacuum oven to obtain a clear liquid.

[0087]

[0088] (Example 1)

[0089] Surface-treated nanoparticles were manufactured by surface-treating ZnO nanoparticles with 2-ethoxyethanethioic S-acid (EETA). At this time, 5 parts by weight of 2-ethoxyethanethioic S-acid (EETA) was used per 100 parts by weight of nanoparticles.

[0090] An ink composition was prepared by mixing 10 parts by weight of the surface-treated nanoparticles and 100 parts by weight of ethanol.

[0091]

[0092] (Example 2)

[0093] An ink composition was prepared in the same manner as in Example 1, except that 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA) was used instead of 2-ethoxyethanethioic S-acid (EETA).

[0094]

[0095] Figure 1 shows the dispersion stability of ZnO nanoparticles surface-treated with 2-ethoxyethanethioic S-acid (EETA) or 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA).

[0096] It was found that the dispersion stability of nanoparticles surface-treated with 2-ethoxyethanethioic S-acid (EETA) or 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA) was improved compared to untreated nanoparticles.

[0097] Untreated nanoparticles aggregate after 30 days, whereas surface-modified nanoparticles do not aggregate even after 30 days.

[0098]

[0099] Figure 2 shows the degree of reduction in surface defects of ZnO nanoparticles surface-treated with 2-ethoxyethanethioic S-acid (EETA) or 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA).

[0100] In the case of nanoparticles surface-treated with 2-ethoxyethanethioic S-acid (EETA) or 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA), it was found that surface defects were reduced by 64-67% compared to untreated nanoparticles.

[0101]

[0102] (Example 3)

[0103] An ink composition was prepared in the same manner as in Example 1, except that ZnMgO was used instead of ZnO.

[0104]

[0105] (Example 4)

[0106] An ink composition was prepared in the same manner as in Example 2, except that ZnMgO was used instead of ZnO.

[0107]

[0108] Figure 3 shows the degree of reduction in surface defects of ZnMgO nanoparticles surface-treated with 2-ethoxyethanethioic S-acid (EETA) or 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA).

[0109] For nanoparticles surface-treated with 2-ethoxyacetic acid (EAA) or 2-(2-methoxyethoxy)acetic acid (MEAA), surface defects were found to be reduced by 31-40% compared to untreated nanoparticles.

[0110] Additionally, it was found that in the case of nanoparticles surface-treated with 2-ethoxyethanethioic S-acid (EETA) or 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA), surface defects were reduced by 91 to 92% compared to untreated nanoparticles.

[0111]

[0112] Figure 4 shows the external quantum efficiency of ZnMgO nanoparticles surface-treated with 2-ethoxyethanethioic S-acid (EETA) or 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA).

[0113] It was found that the external quantum efficiency of nanoparticles surface-treated with 2-ethoxyethanethioic S-acid (EETA) or 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA) increased compared to untreated nanoparticles and 2-(2-methoxyethoxy)acetic acid (MEAA).

[0114]

[0115] (Example 5)

[0116] An ink composition was prepared in the same manner as in Example 3, except that 3.5 parts by weight of 2-ethoxyethanethioic S-acid (EETA) and 1.5 parts by weight of 2-(2-methoxyethoxy)ethanethioic S-acid (MEETA) were used instead of 5 parts by weight of 2-ethoxyethanethioic S-acid (EETA).

[0117]

[0118] (Comparative Example 1)

[0119] An ink composition was prepared in the same manner as in Example 3, except that non-surface-treated ZnMgO nanoparticles were used.

[0120]

[0121] (Comparative Example 2)

[0122] An ink composition was prepared in the same manner as in Example 3, except that 2-ethoxyacetic acid (EAA) was used instead of 2-ethoxyethanethioic S-acid (EETA).

[0123]

[0124] (Comparative Example 3)

[0125] An ink composition was prepared in the same manner as in Example 3, except that 2-(2-methoxyethoxy)acetic acid (MEAA) was used instead of 2-ethoxyethanethioic S-acid (EETA).

[0126]

[0127] The characteristics of the ink compositions manufactured from the above examples and comparative examples were measured, and the results are shown in the table below.

[0128]

[0129] (dispersive)

[0130] After the ink compositions prepared from the above examples and comparative examples were left at room temperature for 8 days, the increase rate of particle size was calculated by comparing the size of the initial nanoparticles with the size of the nanoparticles after 8 days of leaving.

[0131]

[0132] (Surface defect reduction rate)

[0133] After measuring the degree of surface defects of the ink compositions manufactured from the above examples and comparative examples, the degree of reduction in surface defects compared to untreated nanoparticles was calculated.

[0134]

[0135] Increase rate of particle size (%), decrease in surface defects (%), Example 33.592, Example 42.791, Example 51.695, Comparative Example 110.4, Comparative Example 26.840, Comparative Example 37.331

[0136]

[0137] From the results in Table 1 above, it can be seen that Examples 3 to 5 have excellent dispersibility and surface defect reduction, and in particular, Example 5 has the best of these characteristics.

[0138] On the other hand, it can be seen that Comparative Examples 1 to 3 have inferior characteristics compared to the Examples.

[0139]

[0140] The present invention provides a ligand compound for surface modification of metal oxide particles, which can be bonded to the surface of metal oxide particles to minimize surface defects of the metal oxide, has excellent dispersion stability and processability for a solvent, and can improve quantum efficiency, brightness, optical properties, device performance, etc. of the device.

[0141] In addition, the present invention can provide surface-modified metal oxide particles and an ink composition including the same, which can be used as an electron transport layer of a display device or an electroluminescent device due to their excellent dispersibility, quantum efficiency, brightness, optical properties, device performance, etc.

Claims

1. A ligand compound for surface modification of a metal oxide, containing a thiocarboxylic acid group.

2. In paragraph 1, A ligand compound for surface modification of a metal oxide, characterized in that the ligand compound further comprises at least one functional group selected from the group comprising an alkyl group, a benzene group, an alkoxy group, a hydroxy group, an amine group, a halogen group, an ester group, and an ether group.

3. In paragraph 2, 상기 리간드 화합물은 2,4,6,8,10-pentaoxadodecane-12-thioic S-acid, 2,4,6,8-tetraoxadecane-10-thioic S-acid, 2,5,8,11-tetraoxatridecane-13-thioic S-acid, 2-((methoxymethoxy)methoxy)ethanethioic S-acid, 2-(2-(2-ethoxyethoxy)ethoxy)ethanethioic S-acid, 2-(2-(2-methoxyethoxy)ethoxy)ethanethioic S-acid, 2-(2-ethoxyethoxy)ethanethioic S-acid, 2-(2-methoxyethoxy)ethanethioic S-acid, 2-(methoxymethoxy)ethanethioic S-acid, 2-ethoxyethanethioic S-acid, 2-methoxyethanethioic S-acid, 3,6,9,12-tetraoxatetradecane-1-thioic S-acid, O-(((methoxymethoxy)methoxy)methyl) S-hydrogen carbonothioate, O-((methoxymethoxy)methyl) S-hydrogen carbonothioate, O-(methoxymethyl) S-hydrogen carbonothioate, O-2,4,6,8-tetraoxanonyl S-hydrogen carbonothioate, O-methyl S-hydrogen carbonothioate, butanethioic S-acid compound with decanethioic S-acid, dodecanethioic S-acid, ethanethioic S-acid, heptanethioic S-acid, hexanethioic S-acid, methanethioic S-acid, nonanethioic S-acid, octanethioic S-acid, pentanethioic S-acid,A ligand compound for surface modification of a metal oxide, characterized in that it is at least one selected from the group consisting of propanethioic S-acid, tridecanethioic S-acid, undecanethioic S-acid, 3-chloropropanethioic S-acid, 3-aminopropanethioic S-acid, 2-(2-aminoethoxy)ethanethioic S-acid, 2-(2-chloroethoxy)ethanethioic S-acid and benzothioic S-acid.

4. A metal oxide surface-modified with a ligand compound according to any one of claims 1 to 3.

5. In paragraph 4, A surface-modified metal oxide characterized in that the metal oxide is at least one selected from ZnO, ZnMgO, ZnMgLiO, ZnAlO, ZnCoO, ZnNiO, ZnGaO, TiO2, and SnO2.

6. An ink composition comprising the surface-modified metal oxide of paragraph 4 and a solvent.

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