KR20200048819A - ink composition for inkjet printing and method for forming fine pattern using the same - Google Patents

Abstract

The present invention relates to a light-emitting material ink composition for inkjet, capable of improving a thermal transfer process and thin film uniformity. The ink composition for inkjet printing comprises a light emitting material, a polymer organic compound, and a solvent. A technology is for improving the thermal transfer process and the thin film uniformity. The fine-pattern produced by the ink composition of the present invention can improve the surface roughness, improve the flatness and thickness uniformity of a thin film pattern, and transfer the fine pattern through a subsequent photothermal transfer process.

Description

Ink composition for inkjet printing and method for forming fine pattern using the same}

The present invention relates to a light-emitting material ink composition for inkjet printing and a pattern forming method using the same, and more particularly, to a technique for improving the film quality of a fine pattern formed during an inkjet printing process and enabling photothermal transfer in a subsequent process. .

Inkjet printing technology is a technology that sprays a small amount of droplets of a few picoliters (pL) through a fine nozzle to form a droplet pattern of several tens to several tens of micros. . In the case of the deposition process using the existing FMM (Fine Metal Mask), the production of fine pixels for ultra-high resolution displays due to limitations such as the dead space problem caused by the shadow area caused by the mask thickness and the decrease in pattern precision due to the sagging of the mask. On the other hand, inkjet printing technology has the advantage of being able to form finer patterns than conventional deposition processes. Inkjet printing technology is divided into continuous type and drop-on-demand type. Piezoelectric actuating type is mainly used for printing for electronic materials. Piezoelectric Actuating is a method in which a piezoelectric element is placed on the back of a nozzle to send a signal through a current, causing the plate to bend and vibrate to push ink through the vibration. The continuous method has the advantage of high speed, but the head structure is complicated and has been applied only for special business due to limited inkjet characteristics.

The subsequent process, the IPL photothermal transfer process, transfers a sublimation-type luminescent material printed on a substrate from heat generated through strong light irradiation for a short time to a photothermal conversion substrate layer, and emits light that forms a fine pattern through it. By transferring the material to the target substrate, it is possible to fabricate fine pixels and produce ultra-high resolution displays.

The light emitting material can be divided into a fluorescent material, a phosphorescent material, and a delayed fluorescent method TADF. Alq3, a green phosphorescence emitting material, was announced by Kodak in 1987, and its maximum efficiency is more than 15 cd / m2. Among these derivatives, Alq3 (4-MAlq3) substituted with methyl at the 4-position is known to have the highest luminous efficiency. have. The red fluorescent light emitting material has disadvantages such as inherently low luminous efficiency, light emission attenuation due to intermolecular interaction through an extended pylon at high concentrations, and deterioration of color purity due to a wide luminescence band, but development of a new material with a rigid structure Or it can be improved by applying a host / dopant system. The most widely known fluorescent material is the Kodak DCJTB dopant, and it is known that the use of the yellow light emitting material Rubrene and the blue light emitting material NPD as a co-dopant with DCJTB has improved light emission efficiency. As a blue fluorescent light emitting material, it is known that it exhibits the highest efficiency is a distrile compound of idemitsu-gosan. A known structure includes DPVBi, and Modified-DPVBi-based compounds have better luminescence properties. Fluorene derivatives, pyrene derivatives, anthracene derivatives and spirobifluorene derivatives with high PL efficiency are also used. The study of blue fluorescent light emitting materials aims to improve color purity and light emission efficiency by suppressing exciton formation caused by intermolecular interaction.

Ir (PPy) 3 is known as a green phosphorescence emitting material, and quinoline, isoquinoline, etc. of a red phosphorescence emitting material are known. However, quinoline, isoquinoline, etc. have a high molecular weight, so the sublimation efficiency of the material is low, and an auxiliary ligand may be introduced. The performance of the blue phosphorescence emitting material is still in commercialization, and representatively, there is FIrpic developed jointly by the Thomson Group and UDC.

In the case of the existing monomolecular light-emitting material ink, in the inkjet printing process, the surface of the printed fine pattern has a higher surface roughness than other processes such as vapor deposition or spin coating, and crystallization and coffee ring effects due to the characteristics of the solution process of the single molecule ( Coffee-ring effect) makes it difficult to produce a uniform thickness pattern. Therefore, there is a need to improve the problem of non-uniformity of the thin film surface that occurs when manufacturing a fine pattern using an existing single ink.

In the prior art, an ink composition comprising an organic electronic material and an ink composition containing the organic electronic material is an organic electron having at least one polymerizable substituent and having a polymer or oligomer having a number average molecular weight of 3000 or more. However, it is only necessary to provide a luminous ink composition capable of inkjet printing, and thus it is required to improve the print quality or improve the quality of the photothermal transferred film.

Korean Patent Publication No. 10-2012-0020178

The technical problem to be achieved by the present invention is to provide a light-emitting material ink composition for inkjet that can improve the film quality of a fine pattern formed by inkjet printing.

In addition, another technical problem to be achieved by the present invention is to provide a light-emitting material ink composition for inkjet capable of IPL photothermal transfer in a subsequent process of inkjet printing.

In addition, another technical problem to be achieved by the present invention is to provide a pattern forming method by inkjet printing using the ink composition.

The technical problem to be achieved by the present invention is not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary knowledge in the technical field to which the present invention belongs from the following description. There will be.

In order to achieve the above technical problem, an embodiment of the present invention provides an ink composition for inkjet printing, comprising a luminescent material, a non-sublimable polymer organic compound, and a solvent.

In an embodiment of the present invention, the luminescent material may include a host material and a dopant material, and the non-sublimable polymer organic compound may be 0.1 to 20% by weight based on 100% by weight of the ink solids. The non-sublimable polymer organic compound may be an acrylate-based polymer and may be selected from the group consisting of polymethyl methacrylate, polyacrylic acid, and polymethyl acrylate.

Further, the solvent is one or two or more selected from the group consisting of ammonium hydroxide, isopropyl alcohol, chlorobenzene, dichlorobenzene, toluene, chloroform, hexane, N-methyl pyrrolidone, ethanol amine, ethanol and methanol. It can be a mixture.

Another embodiment of the present invention comprises the steps of compounding the ink composition, inkjet printing the blended ink composition on a substrate surface, and photothermal transfer of the ink composition printed on the substrate surface to a target substrate. It provides a pattern forming method by. The inkjet printing may be selected from the group consisting of continuous ink-jet printing and drop-on-demand inkjet printing.

In the photothermal transfer step, the photothermal transfer step presses the inkjet printed substrate against the target substrate and irradiates a light source to the photothermal conversion layer from the printed substrate toward the target substrate to target the printed ink composition to the target. It may include the step of transferring to the substrate.

In addition, the light source may be selected from the group consisting of laser, IPL (Intense Pulse Light) and combinations thereof.

The ink composition for inkjet printing of the present invention and the pattern production method by inkjet printing using the ink composition prevent crystallization and coffee ring phenomenon of the ink composition, thereby improving the surface roughness of the fine pattern, the flatness of the thin film pattern and the uniformity of the thickness Do.

In addition, the ink composition for inkjet printing of the present invention can be subjected to a subsequent photothermal transfer process, so that a fine pattern can be transferred to the target substrate.

It should be understood that the effects of the present invention are not limited to the above-described effects, and include all effects that can be deduced from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a view schematically showing a pattern forming method by inkjet printing using the ink composition of the present invention.
2 is a light emitting image of a fine pattern embedded in the partition wall by an inkjet printing process.
FIG. 3 is a scanned image analyzed by AFM of the surface of the printed micropattern and height measurement data of the coated film surface.
4 is an image in which the light emitting material is thermally transferred after spin coating the ink composition of the comparative example.
5 is an image in which the light emitting material is thermally transferred after spin coating the ink composition of the embodiment.

Hereinafter, the present invention will be described with reference to the accompanying drawings. However, the present invention may be implemented in various different forms, and thus is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and like reference numerals are assigned to similar parts throughout the specification.

Throughout the specification, when a part is "connected (connected, contacted, coupled)" with another part, it is not only "directly connected" but also "indirectly connected" with another member in between. "It also includes the case where it is. Also, when a part “includes” a certain component, this means that other components may be further provided instead of excluding other components, unless otherwise stated.

The terms used herein are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “include” or “have” are intended to indicate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, and that one or more other features are present. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

According to the ink composition for inkjet printing of the present invention, the ink composition includes a luminescent material, a non-sublimable polymer organic compound, and a solvent. Since the ink composition for an organic light-emitting device of the present invention contains a light-emitting material, it can be used for forming a light-emitting layer of an organic light-emitting device.

The light emitting material has a function of directly or indirectly contributing to light emission using holes and electrons in the light emitting layer. In addition, in this specification, "luminescence" shall include light emission by fluorescence, light emission by phosphorescence, and light emission by delayed fluorescence method.

There are single and triplet states of excitation of electrons in a compound. The probability of a singlet state is 1/4 and the probability of a triplet state is 3/4. Falling from the singlet state to the ground state is fluorescence, and falling from the triplet state to the ground state is called phosphorescence.

The fluorescent material is derived from the singlet excitation state, the phosphorescent material is derived from the triplet exciton, and the delayed fluorescence method has recently been studied around the Adachi group and allows fluorescence to occur through the triplet. Depending on the emission color, it can be divided into blue, green, and red emission materials and yellow and orange emission materials necessary for better natural color realization. These colors are determined by the band gap of the luminescent material. In general, luminescent materials can express all the desired colors with only the three primary colors of light, red, green, and blue, but yellow and orange are also used for perfect color.

The emission color of the light-emitting material of the present invention may be blue, green, and red, for example, and may be yellow and orange for better color realization. The emission color and purity of the light emitting material are determined by the band gap of the light emitting material. For example, the band gap generally refers to a material having a band gap of 2.0 eV to 4.0 eV. At this time, around 2.75 eV corresponds to 450 nm as the wavelength of light, blue refers to blue, 2.4 eV refers to green at 510 nm, and 2.0 eV refers to red at 620 nm.

The green fluorescent light emitting material of the present invention may specifically be Alq3, which is a green light emitting material, and C-545T (10- (2-benzothiazolyl) -1,1,7,7-tetramethyl- using Alq3 as a host. 2,3,6,7-tetrahydro-1H, 5H, 11H- [l] benzo-pyrano [6,7,8-ij] quinolizine-11-one) and its derivatives and quinacridone derivatives It can be. The red light emitting material of the present invention may be specifically DCJTB of Kodak Corporation, 3- (dicyanomethylene) -5,5-dimethyl-1-[(4-dimethylamino) styryl] cyclohexene (DCDDC) , 6-methyl-3- {3- (1,1,6,6-tetramethyl-10-oxo-2,3,5,6-tetrahydro-1H, 4H, 10H-11-oxa-3a-aza Benzo [di] -9-anthracenyl) acryloyl} pyran-2,4-dione (AAAP). The blue light emitting material of the present invention may be 4,4-bis (2,2-diphenylethene-1-yl) biphenyl (DPVBi), Modified-DPVBi, fluorene derivative, pyrene derivative, anthracene derivative, spirobifluorene derivative, etc. have.

The limit of internal quantum efficiency of luminescent materials using fluorescence is about 25%, and the limit of internal quantum efficiency of luminescent devices using phosphorescence is about 75%. Therefore, the phosphorescent material has been spotlighted as a light-emitting material with improved luminous efficiency. Since the energy transfer must occur well from a singlet or triplet excited state to a triplet excited state, an organic compound having a transition metal as a central atom is preferable to exhibit such properties. Materials known to date include iridium (Ir), platinum (Pt), europium (Eu), and terbium (Tb) -based compounds, but most of the Ir-based compounds are used because PT, Eu, and Tb do not have high luminous efficiency. Ir-based compounds are compounds composed of phenyl pyridine ligands, and the color can be controlled by changing the length of the conjugate, introducing electron donors, or electron withdrawing groups. In general, when the length of the conjugate is elongated, it may appear red, and when an electron donor is introduced into pyridine or an electron withdrawing group may be introduced into phenyl, blue may be exhibited. The color can also be changed by adjusting the auxiliary ligand, but it has a disadvantage that stability is lower than that of the homologous ligand compound.

In one embodiment, the luminescent material includes a host material and a dopant material. When using only one material as a luminescent material, there is a problem of poor color purity and luminous efficiency. Therefore, using a host / dopant system that matches the absorption spectrum of the host and the dopant of the host, color purity and luminous efficiency can be improved compared to when used alone. It is preferred because it can. The host / dopant system is intended to increase the luminous efficiency through energy transfer from the host to the dopant and to reduce energy loss such as quenching by minimizing the interaction between the dopant and the light emitting material distributed in the host. Looking at the working process, first, holes and electrons excite the host, and the dopant absorbs the energy emitted therefrom and then emits light again. In an ideal host / dopant system, the emission spectrum of the host and the absorption spectrum of the dopant must coincide, so that energy transfer from the host to the dopant can occur well. However, in general, it is known that even if there is an overlap of about 1/3 or more, energy transfer can occur sufficiently. Phosphorescent materials have the disadvantage that efficiency is reduced by the triplet-triplet extinction phenomenon, but can be improved by doping the host material. The energy level of the singlet and triplet of the host material must be higher than that of the dopant material to prevent the reverse charge transfer to the host where the exciton in the triplet is transferred back to the host. In addition, high thermal stability and charge mobility within the device must be maintained at a constant level. Currently, many types of host materials have been developed, but the host materials of carbazole derivatives show the best performance as a blue phosphorescent host.

The host material usually has a function of transporting holes and electrons injected into the light emitting layer. Host materials are classified into high molecular weight host materials and low molecular weight host materials. In addition, in this specification, "low molecular weight" means that the weight average molecular weight (Mw) is 5,000 or less. In addition, in this specification, "polymer" means that the weight average molecular weight (Mw) exceeds 5,000. In one embodiment, the polymer host material is poly (9-vinylcarbazole) (PVK), poly (p-phenylene vinylene) (PPV), poly (fluorene) (PF), and an airborne monomer unit thereof. Can be coalescence. Low molecular host materials include 4,4'di (N-carbazolyl) -1,1'-biphenyl (CBP), 1,3-bis (N-carbazolyl) benzene (mCP), 1,3,5 -Tris (9-carbazolyl) benzene (TCP), 1,3,5-tris [4- (N-carbazolyl) phenyl] benzene (TCPB) and 9- [4- (10-phenyl-9- Anthryl) phenyl] -9H-carbazole (CzPA) and the like. The above-described host materials can be used alone or in combination of two or more. Specifically, it is more preferable to use 4,4 'di (N-carbazolyl) -1,1'-biphenyl (CBP).

The dopant material has a function of emitting light using energy obtained by recombining transported holes and electrons. As a polymer dopant material, polyfluorene (PFO), polyphenylenevinylene (PPV), cyanopolyphenylenevinylene (CN-PPV), poly (4-vinylpyridine), poly (fluorenyleneethynylene) (PFE) and copolymers containing these monomer units. Fluorescent light emitting materials, phosphorescent light emitting materials, etc. are mentioned as a low molecular dopant material. As the fluorescent material, naphthalene, perylene, pyrene, chrysene, anthracene, coumarin, benzopyran, rhodamine, benzothioxanthene, azabenzothioxanthene, and derivatives thereof may be used. Examples of the phosphorescent material include organometallic compounds having ruthenium, palladium, osmium, rhenium, iridium, platinum, and the like as a central atom, and the transition between singlet or triplet excited state to triplet excited state or energy transfer is good. It is desirable because it can happen. Specifically, tris [2- (p-tolyl) pyridine] ruthenium, tris (2-phenylpyridine) ruthenium, tris (2-phenylpyridine) palladium, tris [2- (p-tolyl) pyridine] palladium, tris (2 -Phenylpyridine) osmium, tris [2- (p-tolyl) pyridine] osmium, tris [2- (p-tolyl) pyridine] rhenium, tris (2-phenylpyridine) rhenium, tris (2-phenylpyridine) iridium ( Ir (ppy) 3), tris [2- (p-tolyl) pyridine] iridium (Ir (mppy) 3), bis (2-phenylpyridine) platinum, tris [2- (p-tolyl) pyridine] platinum, etc. Can be lifted. Among the above-mentioned dopant materials, the dopant material is preferably a low-molecular dopant material and more preferably a phosphorescent material. For example, tris (2-phenylpyridine) iridium (Ir (ppy) 3) may be included as the green phosphorescent material, and red phosphorescent material quinoline, isoquinoline, or the like. The blue phosphorescent material may include FIrpic jointly developed by the Thomson Group and UDC. More specifically, the light emitting material is more preferably tris (2-phenylpyridine) iridium (Ir (ppy) 3). The above-mentioned dopant material can be used individually or in combination of 2 or more types.

The non-sublimable polymer organic compound serves to prevent crystallization and coffee ring phenomena occurring in the ink composition composed of only a single molecule material. Non-sublimable polymer organic compounds are preferred because they do not sublime during the process and can maintain the concentration and viscosity of the ink composition uniformly. In addition, it is preferable because only the light-emitting material can be selectively transferred in a subsequent photothermal transfer process.

The content of the non-sublimable polymer organic compound is preferably 0.1 to 20% by weight, and more preferably 0.1 to 10% by weight with respect to 100% by weight of the ink solid content. The ink solid content means a mixture of a luminescent material and a non-sublimable polymer organic compound. If the content of the non-sublimable polymer organic compound is less than 0.1% by weight, crystallization and coffee ring phenomenon of the ink composition cannot be prevented. On the other hand, if the content of the non-sublimable polymer is more than 20% by weight, the viscosity of the ink composition is greatly increased, and process convenience is lowered.

The non-sublimable polymer organic compound may be a vinyl polymer, preferably an acrylic polymer organic compound. The above-mentioned non-sublimable polymers include polymethyl methacrylate (PMMA), polymethyl acrylate (PMA), polybutyl methacrylate (PBuMA), polytertbutyl methacrylate (PtBM), and polytertbutyl acrylate (PtBA). , Polyhydroxyethyl methacrylate (PHEMA) and copolymers containing these monomer units. A specific example of the non-sublimable polymer organic compound may be polymethyl methacrylate (PMMA).

The weight-average molecular weight (Mw) of the non-sublimable polymer organic compound is preferably 5,000 to 5,000,000 or less, more preferably 5,000 to 1,000,000 or less.

As the solvent, a known one can be used, and an aromatic solvent, an alkane solvent, an ether solvent, an alcohol solvent, an ester solvent, an amide solvent, and other solvents can be used. Specifically, one or two or more mixtures selected from the group consisting of ammonium hydroxide, isopropyl alcohol, chlorobenzene, dichlorobenzene, toluene, chloroform, hexane, N-methyl pyrrolidone, ethanol amine, ethanol and methanol Can be.

In the ink composition of the present invention, the solvent may be included in a range of 80 to 99.9 wt%, preferably 95 to 99 wt%, based on 100 wt% of the total ink composition. If the content of the solvent is less than 80% by weight, the viscosity of the ink composition may be high, resulting in poor processability, and if it exceeds 99.9% by weight, viscosity may be low, resulting in poor processability and separation of ink solids.

The viscosity of the ink composition is preferably 1 to 50 mPas, and more preferably 1 to 20 mPa · s. When the viscosity of the ink composition is 1 mPa · s or more, it is preferable since it is possible to suitably prevent the occurrence of a wave when drying the coating film. In addition, when the viscosity of the ink composition for an organic light emitting device is 20 mPa · s or less, it is easy to apply and is preferable because it has process suitability.

In this specification, the value of "viscosity" is assumed to be a value measured by a rotary viscometer.

In the inkjet composition of the present invention, various surfactants may be added as needed in addition to the light emitting material, the non-sublimable polymer, and the solvent. The surfactant may be, for example, an anionic surfactant, a cationic surfactant, or a nonionic surfactant. In addition, a low molecular weight or high molecular weight fluorine-based or silicone-based surfactant can be used. The composition according to the invention is additionally, surface active compounds, lubricants, wetting agents, dispersing agents, hydrophobicizing agents, adhesives, flow enhancers, antifoaming agents, diluents, degassing agents, auxiliary agents, coloring agents, dyes, sensitizers, stable It may include one or more additional ingredients, such as a topic.

The method of forming a pattern by inkjet printing of the present invention comprises the steps of blending the ink composition described above (S100), inkjet printing the blended ink composition on the substrate surface (S200), and the ink composition printed on the substrate surface. It may include the step (S300) of photo-thermal transfer to the target substrate.

The step (S100) of blending the ink composition is a method of preparing a solution or dispersion containing a solvent, adding a luminescent material to the solution or dispersion, and then adding a non-sublimable polymer organic compound, a luminescent material and a solvent. Method for preparing a solution or dispersion comprising a solution, and then adding a non-sublimable polymer organic compound to the solution or dispersion, a solution or dispersion containing a solvent and a solution or dispersion containing a luminescent material and a solvent and a non-sublimable polymer organic compound It may include a method of preparing a solution or dispersion containing each, and mixing these solutions or dispersion. In addition, the use of high-purity products that do not contain impurities or ionic components, such as luminescent materials, non-sublimable polymer organic compounds, and solvents, which are raw materials used for mixing the ink composition, can prevent nozzle clogging and are required by each material. It is preferable because it can perform a sufficient function. The ink composition obtained by the above-described method can be used in a conventional inkjet recording type printer such as continuous inkjet printing and drop-on-demand.

The step (S200) of inkjet printing the blended ink composition onto the substrate surface may be performed by continuous inkjet printing and drop-on-demand inkjet printing. For a specific example, a piezo method, a thermo bubble method, and a bubble jet injection method may be used. Only the drop-on-demand method is used for printing electronic materials, and the drop-on-demand method has the advantage of being able to print the same area with less material. The thermo-bubble method is the vapor pressure generated by heating the spray nozzle. The ink jet is ejected and a resistor, which is a heat conductor, is combined with the spray nozzle, and when the current rises the temperature of the resistor according to the input signal, the ink boils up instantaneously and the ink droplets splash out. Therefore, when pushing out the ink in the nozzle, air bubbles are used.

A drop-on-demand printing head is preferably used as the inkjet printer used in the step of inkjet printing the blended ink composition on the substrate surface, for example, Canon, Hewlett-Packard (Hewlett) -In general inkjet printers sold by Packard, etc., industrial inkjet printers such as Dimatix can be used.

In the step S300 of photothermal transfer of the ink composition printed on the substrate surface to the target substrate, the inkjet printed substrate and the target substrate are pressed against each other, and the light substrate is irradiated from the printed substrate to the target substrate to illuminate the photothermal conversion layer for printing. It may include the step of transferring the ink composition to the target substrate. The photothermal conversion layer functions to absorb light of a specific wavelength and convert at least a portion of incident light into heat. The light source may be selected from the group consisting of laser, IPL (Intense Pulse Light) and combinations thereof.

[Production Example 1]

An example of manufacturing an ink composition for an inkjet printer comprising a luminescent material and a solvent.

In a reaction vessel equipped with a stirrer, Chlorobenzene ((d) of Chemical Formula 1) used as a solvent was prepared at 99wt% based on 100wt% of the total ink composition, and used as a phosphorescent host CBP [4,4'-N, N'-dicarbazole- biphenyl] ((a) of formula 1) and Ir (ppy) 3 [tris (2-phenylpyridine) -iridium] ((b) of formula 1) as a dopant. The ink solids content is CBP + Irmppy3 = 10mg, CBP is 90wt% and Ir (ppy) 3 is 10wt% based on the ink solids content according to Table 1.

[Production Example 2]

An example of manufacturing an ink composition for an inkjet printer comprising a luminescent material, a non-sublimable polymer organic compound and a solvent.

In a reaction vessel equipped with a stirrer, Chlorobenzene ((d) of Chemical Formula 1) used as a solvent was prepared at 99 wt% based on 100 wt% of the total ink composition, and used as a phosphorescent host CBP [4,4'-N, N'-dicarbazole- biphenyl] ((a) of formula 1) and Ir (ppy) 3 [tris (2-phenylpyridine) -iridium] ((b) of formula 1) as a dopant. To this, PMMA (Poly (methyl methacrylate)) (Formula 1 (c)) is added as a non-sublimable polymer organic compound. The solid content of the ink is CBP + Irmppy3 + PMMA = 10mg, CBP is 81wt%, Ir (ppy) 3 is 9wt%, and PMMA is 10wt% based on the ink solids content according to Table 1.

CBP (wt%) Ir (mppy) ₃ (wt%) PMMA (wt%) Preparation Example 1 90 10 0 Preparation Example 2 81 9 10

[Formula 1]

[Experimental Example 1]

Fluorescence image of the inkjet printed fine pattern using the ink composition of Preparation Example 1 and Preparation Example 2.

The ink composition of Preparation Example 1 is sprayed in the form of droplets between the partition walls through a printing nozzle to form a fine pattern. After the light was irradiated to the formed fine pattern, a light luminescence image was taken.

Figure 2 is a fluorescence image of the fine pattern embedded in the inkjet printing process inside the partition wall, the left is a fluorescence image of the fine pattern inkjet printed using the ink composition of Preparation Example 1, the right is inkjet printing using the ink composition of Preparation Example 2 It is a fluorescent image of a fine pattern.

The coffee-ring phenomenon is a phenomenon in which a drop of coffee is formed into a ring while having a clear line on the outside of a droplet when it dries on the desk and dries. . During the coating process, as the coating liquid evaporates, fine particles mixed with the coating liquid are concentrated only toward the outer side, and a coffee ring phenomenon in which there are no particles in the center appears, deteriorating the coating quality.

In Experimental Example 1 of the present invention, referring to FIG. 2, in the case of the micropattern, a micropattern was formed with a uniform thickness compared to the comparative example, and it can be confirmed from the image that the coffee ring phenomenon in which particles are driven into the partition wall is also small. In addition, while the fine pattern printing result of the comparative example overflowed to the outside of the barrier layer, in the case of the example, it can be confirmed that only the inside of the desired barrier rib layer contained ink.

[Experimental Example 2]

AFM measurement data of the inkjet printed fine pattern using the ink composition of Preparation Example 1 and Preparation Example 2.

The ink composition of Preparation Example 1 is sprayed in the form of droplets between the partition walls through a printing nozzle to form a fine pattern. The formed fine pattern was obtained by using AFM [Atomic Force Microscope] to obtain surface scan images and roughness data.

A fine pattern is formed by spraying the ink composition of Preparation Example 2 in the form of droplets between partition walls through a printing nozzle. The formed fine pattern was obtained by using AFM [Atomic Force Microscope] to obtain surface scan images and roughness data.

3 is a scan result of analyzing the surface of the printed micropattern by AFM and the height measurement result of the surface of the coating film, the left is the scanned image and data of the inkjet printed micropattern using the ink composition of Preparation Example 1, and the right is Production Example 2 This is a scanned image and data of an inkjet printed micropattern using an ink composition of.

In Experimental Example 2 of the present invention, referring to Figure 3, AFM analysis shows a surface roughness value of 18 nm in the case of a comparative example containing only a single molecule luminescent material, whereas in the example containing a polymer additive, a roughness value of 1.9 nm As a result, it can be seen that a substantially improved uniform thin film surface is formed compared to the comparative example.

 [Experimental Example 3]

Thermal transfer of inkjet printed micropatterns using the ink compositions of Preparation Example 1 and Preparation Example 2.

The ink composition of Preparation Example 1 was spin coated on a glass substrate and then transferred to a target substrate by thermal transfer treatment at a temperature of 300 ° C./15 minutes.

The ink composition of Preparation Example 2 was spin coated on a glass substrate and then transferred to a target substrate by thermal transfer treatment at a temperature of 300 ° C./15 minutes.

4 is an image in which the light emitting material is thermally transferred to a target substrate after spin coating the ink composition of Preparation Example 1.

5 is an image in which the light emitting material is thermally transferred to a target substrate after spin coating the ink composition of Preparation Example 1.

Referring to FIGS. 4 and 5 of Experimental Example 3, the results of the subsequent thermal transfer process test, both the comparative example and the light emitting material of the example can be transferred to the target substrate through the thermal transfer process, thereby producing a fine pixel pattern through the thermal transfer process and It can be confirmed that it is possible to manufacture an ultra-high resolution display.

Therefore, the present invention can improve the thin film homogeneity of the inkjet printed fine pattern by introducing a non-sublimation type polymer into the ink composition for inkjet printing, and it is possible to produce micro-pixels and ultra-high resolution displays through this because photothermal transfer is possible in a subsequent process. It is possible.

The above description of the present invention is for illustration only, and those skilled in the art to which the present invention pertains can understand that the present invention can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted to be included in the scope of the present invention.

Claims (10)

An ink composition for inkjet printing, comprising a luminescent material, a non-sublimable polymer organic compound, and a solvent. According to claim 1,
The luminescent material is an ink composition for inkjet printing, characterized in that it comprises a host material and a dopant material. According to claim 1,
The non-sublimable polymer organic compound is an ink composition for inkjet printing, characterized in that 0.1 to 20% by weight based on 100% by weight of the ink solids. According to claim 1,
The non-sublimable polymer organic compound is an acrylate-based polymer inkjet printing ink composition, characterized in that. According to claim 1,
The non-sublimable polymer organic compound is an ink composition for inkjet printing, characterized in that it is selected from the group consisting of polymethyl methacrylate, polyacrylic acid, and polymethyl acrylate. According to claim 1,
The solvent is one or a mixture of two or more selected from the group consisting of ammonium hydroxide, isopropyl alcohol, chlorobenzene, dichlorobenzene, toluene, chloroform, hexane, N-methyl pyrrolidone, ethanol amine, ethanol and methanol. Characterized in that the ink composition for inkjet printing. Compounding the ink composition according to claim 1;
Inkjet printing the blended ink composition onto a substrate surface;
Photothermal transfer of the ink composition printed on the substrate surface to a target substrate;
Pattern formation method by inkjet printing comprising a. The method of claim 7,
The inkjet printing may include continuous inkjet printing; And
Drop-on-demand (drop-on-demand) inkjet printing; pattern formation method by inkjet printing, characterized in that selected from the group consisting of. The method of claim 7,
The photothermal transfer,
Pressing the inkjet printed substrate against the target substrate; And
Transferring the printed ink composition to the target substrate by irradiating a light source to the photothermal conversion layer in the direction of the target substrate from the printed substrate;
The method of forming a pattern by inkjet printing, characterized in that it comprises. The method of claim 9,
The light source is a laser, IPL (Intense Pulse Light) and a pattern formation method by inkjet printing, characterized in that selected from the group consisting of a combination thereof.

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