KR20240057680A - Ink composition, organic light emitting device using same and method of manufacturing same - Google Patents

Abstract

This specification provides a functional layer forming material; aromatic solvent; and a cyclic ketone-based solvent, wherein the cyclic ketone-based solvent is contained in an amount of 0.1% by weight to 10% by weight based on the total ink composition.

Description

Ink composition, organic light emitting device using the same, and manufacturing method thereof {INK COMPOSITION, ORGANIC LIGHT EMITTING DEVICE USING SAME AND METHOD OF MANUFACTURING SAME}

The present invention relates to an ink composition, an organic light-emitting device using the same, and a method for manufacturing the same.

Conventionally, a deposition process has been mainly used to manufacture organic light-emitting devices. However, when manufacturing an organic light-emitting device using a deposition process, there is a problem that a lot of material loss occurs and it is difficult to manufacture a large-area device.

To solve this problem, devices manufactured through a solution process are being developed, and the development of ink with excellent spreadability is required to ensure the flatness of a film formed through a solution process.

Korean Patent Publication No. 10-2012-0037409

Since organic light-emitting devices have a multi-layer structure, if the ink film formed through a solution process is not flat, the manufactured device not only exhibits unstable light-emitting characteristics, but also reduces lifespan and efficiency.

Therefore, the present invention provides an ink composition capable of forming a flat functional layer film after drying by adding a cyclic ketone-based solvent to improve the spreadability of the ink, and an organic light-emitting device manufactured using the same.

The present invention relates to a functional layer forming material; aromatic solvent; and a cyclic ketone-based solvent, wherein the cyclic ketone-based solvent is contained in an amount of 0.1% by weight to 10% by weight based on 100 weight of the total ink composition.

In addition, the present invention includes a first electrode; It includes a second electrode and one or more organic layers provided between the first electrode and the second electrode, and one or more of the one or more organic layers is a functional layer containing the above-described ink composition or a cured product thereof. An organic light emitting device is provided.

Finally, the present invention includes preparing a first electrode; Forming one or more organic layers on the first electrode; And forming a second electrode on the one or more organic material layers, wherein the step of forming the one or more organic material layers includes forming a functional layer using the above-described ink composition. Provides a manufacturing method.

The ink composition according to the present invention includes a cyclic ketone-based compound as a solvent, thereby improving the spreadability of the ink and enabling the formation of a flat film after drying.

Figure 1 shows an example of an organic light-emitting device according to an exemplary embodiment of the present specification.
Figure 2 is a diagram showing the results of the ink spreadability test of Example 1.
Figure 3 is a diagram showing the results of the ink spreadability test of Comparative Example 1.
Figure 4 is a graph measuring the flatness (thickness uniformity) of a thin film formed using the ink of Example 1.
Figure 5 is a graph measuring the flatness (thickness uniformity) of a thin film formed using the ink of Comparative Example 1.
Figure 6 is a diagram showing the x-axis and y-axis in the line bank.
Figure 7 shows a substrate on which a line bank is formed on which an ink composition according to an exemplary embodiment of the present specification is applied.
Figure 8 shows an ink composition according to an exemplary embodiment of the present specification being applied on a substrate on which a line bank is formed.
Figure 9 shows a substrate on which a line bank is formed on which an ink composition according to an exemplary embodiment of the present specification is applied, dried, and heat treated.

Hereinafter, the present invention will be described in detail. The following content is intended to aid understanding of the present invention, and does not determine or limit the scope of the invention.

In this specification, when a member (layer) is said to be located “on” another member (layer), this means not only when a member (layer) is in contact with another member (layer), but also when there is another member (layer) between the two members (layers). Also includes cases where (layer) exists.

In this specification, when a part “includes” a certain component, this means that it does not exclude other components but may further include other components, unless specifically stated to the contrary.

The ink composition according to the present invention includes a functional layer forming material; aromatic solvent; and a cyclic ketone-based solvent, wherein the cyclic ketone-based solvent is included in an amount of 0.1% to 10% by weight based on 100 weight of the total ink composition.

The functional layer forming material according to the present invention refers to an organic semiconductor compound that can exhibit semiconductor properties, that is, the energy gap between the conduction band and the valence band is within the range of 0.1 to 4 eV, and the organic semiconductor compound includes tri. Examples include phenylamine derivatives, carbazole derivatives, aminophenylcyclohexane derivatives, and polyparaphenylvinylene derivatives (PPV), and other water-soluble conjugated small molecules or water-soluble conjugated polymers can also be used as functional layer forming materials.

The content of the functional layer forming material is 0.1% to 10% by weight, preferably 0.5% to 7% by weight, and more preferably 1% to 5% by weight, based on 100 weight of the total ink composition. If the content of the functional layer forming material is less than 0.1% by weight based on 100 weight of the total ink composition, the thickness of the functional layer manufactured by the solution process method may become relatively thin and there is a risk that the functional layer forming material may not play its role. If it is included in an amount exceeding 10% by weight based on 100 weight of the total ink composition, there is a possibility that a functional layer of more than an appropriate thickness may be formed due to the high concentration of the functional layer forming material.

According to one embodiment according to the present invention, the functional layer includes a hole injection layer (HIL), a hole transfer layer (HTL), and an electron transfer layer (ETL) that constitute an organic light emitting device. ), electron injection layer (EIL), and emission layer (EML), and the functional layer forming material may vary depending on the type of functional layer to be formed.

For example, when the purpose is to manufacture a hole injection layer or a hole transport layer, polythiophene derivative, PEDOT:PSS (Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)), a mixture of polythiophene and polystyrenesulfonic acid, Alternatively, it may be a phenylamine derivative containing a curable functional group such as styrene, benzocyclobutene, trifluorovinylether, ethynyl (C≡C), etc. If the purpose is to manufacture a light-emitting layer, It may be a mixture of a dopant-based material such as a phenylpyridine derivative, an iridium-based complex compound coordinated with a ligand, and a host-based material such as a polyvinylcarbazole derivative, a phosphine oxide-based carbazole derivative, and an electron transport layer and an electron injection layer. If the purpose is to manufacture, benzene derivatives with phenylbenzimidazolyl or phenoxy substituents introduced, or water-soluble conjugated low molecules or polymers, can be used as materials for the OLED functional layer. The usual things can be applied mutatis mutandis.

Next, the aromatic solvent is a benzene-based solvent that can be divided into low boiling point, middle boiling point, or high boiling point, and is a component that allows the functional layer forming material to dissolve well. The boiling point of the aromatic solvent may be 150 ℃ to 350 ℃, specifically, the boiling point of the low boiling point aromatic solvent is 150 ℃ to 250 ℃, the boiling point of the medium boiling point aromatic solvent is 200 ℃ to 300 ℃, and the high boiling point aromatic solvent The boiling point may be 250°C to 350°C.

According to one embodiment of the present invention, the aromatic solvent may be one type or a mixture of two or more types. Specifically, the aromatic solvents include terphenyl, methylbiphenyl, ethylbiphenyl, butylbiphenyl, isopropylbiphenyl, diisopropylbiphenyl, triisopropylbiphenyl, tetraisopropylbiphenyl, methylnaphthalene, and ethyl. Naphthalene, isopropylnaphthalene, dimethylnaphthalene, propylnaphthalene, butylnaphthalene, cyclohexylbenzene, cyclohexylmethylbenzene, dimethylanisole, diphenyl ether, dibenzyl ether, tetrarone, tetralin, 3-phenoxy toluene and these It may be selected from the group consisting of mixtures containing two or more of the above, but a typical benzene-based solvent may be used without limitation.

In addition, the content of the aromatic solvent or benzene-based solvent is 80% by weight to 99.8% by weight, preferably 85% by weight to 99.8% by weight, more preferably 90% by weight to 99.8% by weight, based on 100% by weight of the total ink composition. , if the content of the benzene-based solvent is less than 80% by weight based on 100% by weight of the total ink composition, there is a risk that the solubility of the functional layer forming material may decrease or the nozzle of the print head may be clogged during the inkjet process. When the benzene-based solvent is included in an amount exceeding 99.8% by weight based on 100 weight of the total ink composition, the amount of the following cyclic ketone-based solvent added becomes too small, and the effect that can be obtained by adding the cyclic ketone-based solvent may be minimal. You can.

According to one embodiment of the present invention, the aromatic solvent has a water solubility of 0.01 g/L or less.

According to another exemplary embodiment, the water solubility of the aromatic solvent is 0.00001 g/L to 0.01 g/L.

The water solubility is a calculated result predicted at room temperature (25°C) using ACD (Advanced Chemistry Development, Inc) Percepta.

The cyclic ketone-based solvent of the present invention has excellent spreadability of ink applied within the substrate pixel, and thus the film flatness of the functional layer formed after vacuum drying is excellent.

The cyclic ketone-based solvent includes a ketone-based unit (-C=O-) and a cyclic unit in the molecule. At this time, the cyclic unit may be an aliphatic ring or a ring in which an aliphatic ring and an aromatic ring are condensed, but is not limited thereto, and the cyclic unit may be substituted with a substituent.

In one embodiment of the present invention, the cyclic ketone-based solvent is represented by the following formula (1).

[Formula 1]

In Formula 1,

A1 is a substituted or unsubstituted hydrocarbon ring.

According to one embodiment of the present invention, A1 is a substituted or unsubstituted hydrocarbon ring having 3 to 60 carbon atoms.

According to another embodiment, A1 is a substituted or unsubstituted hydrocarbon ring having 3 to 30 carbon atoms.

According to another exemplary embodiment, A1 is a hydrocarbon ring having 3 to 60 carbon atoms that is unsubstituted or substituted with one or more selected from the group consisting of a cycloalkyl group and a cycloalkenyl group.

According to another embodiment, A1 is a hydrocarbon ring having 3 to 30 carbon atoms that is unsubstituted or substituted with one or more selected from the group consisting of a cycloalkyl group and a cycloalkenyl group.

According to another exemplary embodiment, A1 is substituted or unsubstituted cyclopentane; Substituted or unsubstituted cyclohexane; Or substituted or unsubstituted tetrahydronaphthalene ( )am.

According to another exemplary embodiment, A1 is pentane substituted or unsubstituted with one or more selected from the group consisting of an alkyl group, a cycloalkyl group, and a cycloalkenyl group; Cyclohexane substituted or unsubstituted with one or more selected from the group consisting of alkyl group, cycloalkyl group and cycloalkenyl group; or tetrahydronaphthalene substituted or unsubstituted with one or more selected from the group consisting of an alkyl group, a cycloalkyl group, and a cycloalkenyl group. The alkyl group may have 1 to 20 carbon atoms, and the cycloalkyl group and the cycloalkenyl group may each have 3 to 30 carbon atoms.

According to another exemplary embodiment, A1 is pentane substituted or unsubstituted with a pentyl group, hexyl group, or cyclohexenyl group; Hexane substituted or unsubstituted with a pentyl group, hexyl group, or cyclohexenyl group; Or it is tetrahydronaphthalene substituted or unsubstituted with a pentyl group, hexyl group, or cyclohexenyl group.

In one embodiment of the present invention, the cyclic ketone-based solvent is represented by the following formula 1-1 or 1-2.

[Formula 1-1]

[Formula 1-2]

In Formulas 1-1 and 1-2,

B1 to B10 and C1 to C8 are the same or different from each other, and are each independently hydrogen; heavy hydrogen; hydroxyl group; Substituted or unsubstituted alkyl group; Substituted or unsubstituted cycloalkyl group; Substituted or unsubstituted cycloalkenyl group; Substituted or unsubstituted alkoxy group; Or, it is a substituted or unsubstituted aryl group, or combines with adjacent substituents to form a substituted or unsubstituted ring.

According to an exemplary embodiment of the present invention, B1 to B10 and C1 to C8 are the same or different from each other, and are each independently hydrogen; heavy hydrogen; hydroxyl group; A substituted or unsubstituted alkyl group having 1 to 20 carbon atoms; A substituted or unsubstituted cycloalkyl group having 3 to 30 carbon atoms; A substituted or unsubstituted cycloalkenyl group having 3 to 30 carbon atoms; A substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms; Alternatively, it is a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or is bonded with adjacent substituents to form a substituted or unsubstituted aromatic ring having 6 to 30 carbon atoms.

According to another exemplary embodiment, B1 to B10 and C1 to C8 are the same or different from each other, and each independently represents hydrogen; an alkyl group having 1 to 20 carbon atoms; Cycloalkyl group having 3 to 30 carbon atoms; Alternatively, it is a cycloalkenyl group having 3 to 30 carbon atoms, or is bonded to an adjacent substituent to form an aromatic ring having 6 to 30 carbon atoms.

According to another exemplary embodiment, B1 to B10 and C1 to C8 are the same or different from each other, and each independently represents hydrogen; Substituted or unsubstituted pentyl group; Substituted or unsubstituted hexyl group; Or, it is a substituted or unsubstituted cyclohexenyl group, or it combines with adjacent substituents to form a benzene ring.

According to another exemplary embodiment, B1 to B10 and C1 to C8 are the same or different from each other, and each independently represents hydrogen; pentyl group; hexyl group; Or, it is a cyclohexenyl group, or combines with adjacent substituents to form a benzene ring.

According to an exemplary embodiment of the present invention, the cyclic ketone-based solvent may have any one of the following structures.

The boiling point of the cyclic ketone-based solvent according to the present invention may be 150 ℃ to 300 ℃, and if the boiling point is excessively low, the ink is quickly volatilized while jetting during the inkjet process, causing ink stains to remain in the nozzle, making the jetting performance unstable. .

In one embodiment of the present invention, the content of the cyclic ketone-based solvent is 0.1 to 10% by weight, preferably 0.1 to 5% by weight, based on 100 weight of the total ink composition. If the content of the cyclic ketone-based solvent is less than 0.1% by weight based on 100 weight of the total ink composition, the effect obtained by adding the cyclic ketone-based solvent may be minimal, and the cyclic ketone-based solvent may be absorbed by the entire ink. If it is included in an amount exceeding 10% by weight based on 100 weight of the composition, the viscosity of the ink composition may increase, which may cause problems in the inkjet process, and the amount that can dissolve the solute (functional layer forming material) decreases, causing ink to precipitate. may occur.

According to one embodiment of the present invention, the cyclic ketone-based solvent has a water solubility of 0.4 g/L or more.

According to another exemplary embodiment, the cyclic ketone-based solvent has a water solubility of 0.4 g/L to 1.5 g/L.

Meanwhile, the present invention provides a solidified functional layer formed by applying the above-described ink composition to a substrate for an organic light-emitting device by an inkjet method and drying it. That is, the ink composition is applied to an area where pixels dividing pixels are patterned to a certain size, and the pixel area is surrounded by a hydrophobic bank with liquid repellency, The functional layer can be manufactured through a printing process in which an ink fluid in which the functional layer material is dissolved is applied to the pixel area, and a drying process in which the solvent of the applied ink composition is evaporated. In addition, there are no particular restrictions on the specific application and drying method, such as using a normal inkjet method.

An organic light emitting device according to an exemplary embodiment of the present invention includes a first electrode; It includes a second electrode and one or more organic layers provided between the first electrode and the second electrode, and one or more of the one or more organic layers is a functional layer containing the above-described ink composition or a cured product thereof.

According to one embodiment of the present invention, the functional layer includes a substrate on which line-shaped banks are formed. The line-shaped bank refers to a line in which a plurality of pixels are arranged in a row. Additionally, the functional layer may include a plurality of line-shaped banks, and FIG. 7 shows a substrate including a plurality of line-shaped banks.

The line-shaped bank may define a line-shaped pixel area and/or a sub-pixel area. In a typical case, the light-emitting layer of the organic material layer consists of a red light-emitting layer, a green light-emitting layer, and a blue light-emitting layer located in each of the red subpixel, green subpixel, and blue subpixel. At this time, the pixel may correspond to the pixel or subpixel. As a preferred example, the pixel corresponds to the subpixel.

The line-shaped bank, as shown in FIG. 6, is formed with two layers along the x-axis and with one layer along the y-axis. In the x-axis, the lower layer of the two layers is formed of a weakly hydrophobic material, and the upper layer is formed of a strongly hydrophobic material. At this time, the height of the x-axis is 1 to 2 ㎛, and the height of the y-axis is 0.5 to 1 ㎛. The y-axis is formed of the same weakly hydrophobic material as the lower layer of the x-axis.

The above-mentioned ink composition has excellent compatibility with the weakly hydrophobic material forming the y-axis of the line-shaped bank, so that when the ink composition is applied to a substrate on which the line-shaped bank is formed, the ink in the y-axis of the ink composition The spreadability is very excellent, so a flat thin film can be obtained.

According to an exemplary embodiment of the present specification, the strongly hydrophobic material and the weakly hydrophobic material may be polyimide resin, polyacrylic resin, etc., but are not limited thereto.

According to an exemplary embodiment of the present specification, the above-described ink composition is applied on a substrate provided with line-shaped banks, and dried and heat-treated to form a thin film.

The functional layer may be a hole injection layer, a hole transport layer, a light emitting layer, an electron injection layer, or an electron transport layer.

Among the one or more organic material layers provided between the first electrode and the second electrode, the organic material layers excluding the functional layer include a hole injection layer, a hole transport layer, a hole injection and transport layer, an electron blocking layer, a light emitting layer, an electron injection layer, an electron transport layer, and an electron It may be one or two or more layers selected from the group consisting of an injection and transport layer, and a hole blocking layer.

The structure of an organic light-emitting device according to an exemplary embodiment of the present specification is illustrated in FIG. 1.

1 shows an anode 201, a hole injection layer 301, a hole transport layer 401, a light emitting layer 501, an electron transport layer 601, an electron injection layer 701, and a cathode 801 on a substrate 101. The structure of this sequentially stacked organic light emitting device is illustrated. One or more of the hole injection layer, hole transport layer, light emitting layer, electron transport layer, and electron injection layer may be the above-mentioned functional layer, but is not limited thereto.

When the organic light emitting device includes a plurality of organic material layers, the organic material layers may be formed of the same material or different materials.

The anode material is generally preferably a material with a large work function to facilitate hole injection into the organic layer. Specific examples of anode materials that can be used in the present invention include metals such as vanadium, chromium, copper, zinc, and gold, or alloys thereof; metal oxides such as zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); ZnO:Al or SnO ₂ : Combination of metal and oxide such as Sb; Conductive polymers such as poly(3-methylthiophene), poly[3,4-(ethylene-1,2-dioxy)thiophene] (PEDOT), polypyrrole, and polyaniline are included, but are not limited to these.

The cathode material is generally preferably a material with a small work function to facilitate electron injection into the organic layer. Specific examples of cathode materials include metals such as barium, magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin and lead, or alloys thereof, LiF/Al or LiO ₂ /Al There are multi-layer structure materials such as, but it is not limited to these.

The hole injection layer is a layer that injects holes from an electrode. The hole injection material has the ability to transport holes and has an excellent hole injection effect at the anode, a light-emitting layer or a light-emitting material, and has an excellent hole injection effect on the light-emitting layer or light-emitting material. A compound that prevents movement of excitons to the electron injection layer or electron injection material and has excellent thin film forming ability is preferred. It is preferable that the highest occupied molecular orbital (HOMO) of the hole injection material is between the work function of the anode material and the HOMO of the surrounding organic material layer. Specific examples of hole injection materials include metal porphyrin, oligothiophene, arylamine-based organic materials, hexanitrilehexaazatriphenylene-based organic materials, quinacridone-based organic materials, and perylene. These include, but are not limited to, organic materials such as anthraquinone, polyaniline, and polythiophene series of conductive polymers.

The hole transport layer is a layer that receives holes from the hole injection layer and transports holes to the light-emitting layer. The hole transport material is a material that can receive holes from the anode or hole injection layer and transfer them to the light-emitting layer, and has high mobility for holes. The material is suitable. Specific examples include arylamine-based organic materials, conductive polymers, and block copolymers with both conjugated and non-conjugated portions, but are not limited to these.

The hole injection and transport layer may include the above-described hole transport layer and/or hole injection layer material.

The light-emitting material is a material that can emit light in the visible range by receiving and combining holes and electrons from the hole transport layer and the electron transport layer, respectively, and is preferably a material with good quantum efficiency for fluorescence or phosphorescence. Specific examples include 8-hydroxy-quinoline aluminum complex (Alq ₃ ); Carbazole-based compounds; dimerized styryl compounds; BAlq; 10-hydroxybenzoquinoline-metal compound; Compounds of the benzoxazole, benzthiazole and benzimidazole series; Poly(p-phenylenevinylene) (PPV) series polymer; Spiro compounds; Polyfluorene, rubrene, etc., but are not limited to these.

The light emitting layer may include a host material and a dopant material. Host materials include condensed aromatic ring derivatives or heterocyclic ring-containing compounds. Specifically, condensed aromatic ring derivatives include anthracene derivatives, pyrene derivatives, naphthalene derivatives, pentacene derivatives, phenanthrene compounds, and fluoranthene compounds, and heterocycle-containing compounds include carbazole derivatives, dibenzofuran derivatives, and ladder-type compounds. These include, but are not limited to, furan compounds and pyrimidine derivatives.

Dopant materials include aromatic amine derivatives, strylamine compounds, boron complexes, fluoranthene compounds, and metal complexes. Specifically, aromatic amine derivatives include condensed aromatic ring derivatives having a substituted or unsubstituted arylamino group, such as pyrene, anthracene, chrysene, and periplanthene, and styrylamine compounds include substituted or unsubstituted arylamino groups. It is a compound in which at least one arylvinyl group is substituted on the arylamine, and is substituted or unsubstituted with one or two or more substituents selected from the group consisting of aryl group, silyl group, alkyl group, cycloalkyl group, and arylamino group. Specifically, styrylamine, styryldiamine, styryltriamine, styryltetraamine, etc. are included, but are not limited thereto. Additionally, metal complexes include, but are not limited to, iridium complexes and platinum complexes.

The electron transport layer is a layer that receives electrons from the electron injection layer and transports electrons to the light-emitting layer. The electron transport material is a material that can easily inject electrons from the cathode and transfer them to the light-emitting layer, and a material with high electron mobility is suitable. do. Specific examples include Al complex of 8-hydroxyquinoline; Complex containing Alq ₃ ; organic radical compounds; Hydroxyflavone-metal complexes, etc., but are not limited to these. The electron transport layer can be used with any desired cathode material as used according to the prior art. In particular, examples of suitable cathode materials are conventional materials with a low work function followed by an aluminum layer or a silver layer. Specifically, cesium, barium, calcium, ytterbium and samarium, in each case followed by an aluminum layer or a silver layer.

The electron injection layer is a layer that injects electrons from an electrode. The electron injection material has the ability to transport electrons, has an excellent electron injection effect from the cathode, a light emitting layer or a light emitting material, and is generated in the light emitting layer. A compound that prevents movement of excitons to the hole injection layer and has excellent thin film forming ability is preferred. Specifically, fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxazole, oxadiazole, triazole, imidazole, perylenetetracarboxylic acid, preorenylidene methane, anthrone, etc. and their derivatives, metals. These include, but are not limited to, complex compounds and nitrogen-containing five-membered ring derivatives.

The electron injection and transport layer may include the materials of the electron transport layer and/or electron injection layer described above.

Examples of the metal complex compounds include 8-hydroxyquinolinato lithium, bis(8-hydroxyquinolinato)zinc, bis(8-hydroxyquinolinato)copper, bis(8-hydroxyquinolinato)manganese, Tris(8-hydroxyquinolinato)aluminum, Tris(2-methyl-8-hydroxyquinolinato)aluminum, Tris(8-hydroxyquinolinato)gallium, bis(10-hydroxybenzo[h] Quinolinato)beryllium, bis(10-hydroxybenzo[h]quinolinato)zinc, bis(2-methyl-8-quinolinato)chlorogallium, bis(2-methyl-8-quinolinato)( o-cresolato) gallium, bis(2-methyl-8-quinolinato)(1-naphtolato) aluminum, bis(2-methyl-8-quinolinato)(2-naphtolato) gallium, etc. It is not limited to this.

The hole blocking layer is a layer that blocks holes from reaching the cathode, and can generally be formed under the same conditions as the hole injection layer. Specifically, it includes oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, BCP, aluminum complex, etc., but is not limited thereto.

The electron blocking layer is a layer that blocks electrons from reaching the anode, and materials known in the art can be used.

The organic light emitting device according to the present specification may be a front emitting type, a back emitting type, or a double-sided emitting type depending on the material used.

According to an exemplary embodiment of the present specification, in order to manufacture the organic light emitting device, preparing a first electrode; Forming one or more organic layers on the first electrode; It includes forming a second electrode on the one or more organic material layers, and the step of forming the one or more organic material layers includes forming a functional layer using the above-described ink composition.

In one embodiment of the present specification, forming the functional layer includes applying the ink composition on a substrate on which line-shaped banks are formed.

For example, the above-described ink composition may be applied to a substrate on which line-shaped banks are formed (FIG. 7) (FIG. 8), and then the ink composition may be dried and heat-treated to form a thin film (FIG. 9).

The organic light emitting device of the present specification can be manufactured by methods such as solution process and deposition process using materials known in the art.

Examples of the deposition process include, but are not limited to, a PVD (physical vapor deposition) method such as sputtering or e-beam evaporation.

Examples of the solution process include spin coating method and printing method, but are not limited thereto.

In the context of the present specification, the printing method includes, for example, inkjet printing, nozzle printing, offset printing, transfer printing, or screen printing, but is not limited thereto. When forming a layer using a solution process as described above, it is economical in terms of time and cost when manufacturing a device.

In an exemplary embodiment of the present specification, when forming an organic layer using the solution process, coating an ink composition containing an organic layer material and a solvent; and heat-treating or light-treating the coated coating composition.

In one embodiment of the present specification, the heat treatment step may be performed through heat treatment, and the heat treatment temperature in the heat treatment step may be 60 ℃ to 250 ℃, and according to one embodiment, it may be 100 ℃ to 250 ℃, In another embodiment, the temperature may be 150°C to 250°C.

In another embodiment, the heat treatment time in the heat treatment step is 1 minute to 2 hours, according to one embodiment, it may be 1 minute to 1 hour, and in another embodiment, it is 30 minutes to 1 hour. It could be 1 hour.

In another embodiment, the viscosity of the ink composition is 1 cP to 20 cP at room temperature. If the above viscosity is satisfied, it is easy to manufacture a device.

When the step of forming an organic material layer using the solution process includes the heat treatment or light treatment step, a plurality of the compounds included in the coating composition can form crosslinks to provide an organic material layer including a thin film structure.

Therefore, when the organic material layer formed using the solution process includes a heat treatment or light treatment step, the resistance to solvent increases, so that a multilayer can be formed by repeatedly performing the solution deposition and crosslinking methods, and the stability increases, thereby improving the device's stability. Lifespan characteristics can be increased.

Hereinafter, in order to explain the present specification in detail, examples will be given in detail. However, the embodiments according to the present specification may be modified in various other forms, and the scope of the present specification is not to be construed as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain the present specification to those with average knowledge in the art.

< Experiment example 1. Preparation of ink composition>

Example 1 to 8.

2% by weight of the functional layer forming material below was mixed with 98% by weight of a mixed solvent including an aromatic solvent and a cyclic ketone solvent shown in Table 1 below, mixed at 80°C for 24 hours, and mixed at room temperature for an additional 2 hours. Afterwards, ink was manufactured through a 0.45μm PTFE (polytetrafluoroethylene) filter process. At this time, the types and contents of the aromatic solvent and cyclic ketone solvent used are shown in Table 1 below.

[Functional layer forming material]

Comparative example 1 to 3.

Mix 2% by weight of the functional layer forming material and 98% by weight of a mixed solvent consisting of the aromatic solvent listed in Table 1 below, mix at 80°C for 24 hours, mix at room temperature for an additional 2 hours, and then perform a 0.45μm PTFE filter process. Ink was manufactured through this process. At this time, the type and content of the aromatic solvent used are shown in Table 1 below.

Experiment example Primary aromatic solvent
(Content based on weight of 100 ink) secondary aromatic solvent
(Content based on weight of 100 ink) Tertiary aromatic solvent (content per 100% weight of ink) Cyclic ketone solvent
(Content based on weight of 100 ink) Example 1 6-ethyltetralin (68% by weight) 4-butylbiphenyl
(25% by weight) - 2-(1-cyclohexenyl)cyclohexanone
(5% by weight) Example 2 6-ethyltetralin (68% by weight) Therminol 62
(25% by weight) - 2-(1-cyclohexenyl)cyclohexanone
(5% by weight) Example 3 6-ethyltetralin (68% by weight) 4-butylbiphenyl
(15% by weight) Therminol 62
(10% by weight, Eastman) 2-(1-cyclohexenyl)cyclohexanone
(5% by weight) Example 4 6-ethyltetralin (68% by weight) 4-butylbiphenyl
(25% by weight) - 1-tetralone
(5% by weight) Example 5 6-ethyltetralin (68% by weight) Therminol 62
(25% by weight) - 1-tetralone
(5% by weight) Example 6 6-ethyltetralin (68% by weight) 4-butylbiphenyl
(15% by weight) Therminol 62
(10% by weight) 1-tetralone
(5% by weight) Example 7 6-ethyltetralin (68% by weight) Therminol 62
(20~30% by weight) - 2-cyclopentylcyclopnetanone
(5% by weight) Example 8 6-ethyltetralin (68% by weight) Therminol 62
(25% by weight) - 2-cyclohexylcyclohexanone
(5% by weight) Primary aromatic solvent (content per 100% weight of ink) secondary aromatic solvent
(Content based on weight of 100 ink) Tertiary aromatic solvent (content per 100% weight of ink) Cyclic ketone solvent Comparative Example 1 6-ethyltetralin (68% by weight) 4-butylbiphenyl
(30% by weight) - - Comparative Example 2 6-ethyltetralin (68% by weight) Therminol 62
(30% by weight) - - Comparative Example 3 6-ethyltetralin (68% by weight) 4-butylbiphenyl
(20% by weight) Therminol 62
(10% by weight) -

** 6-ethyltetralin: boiling point 246 ℃, water solubility 0.004415 g/L

** 4-butylbiphenyl: boiling point 318 ℃, water solubility 9.93 x 10 ^-5 g/L

** Therminol 62: boiling point 333 ℃, water solubility 2 x 10 ^-5 g/L

** 2-(1-cyclohexenyl)cyclohexanone: boiling point 282 ℃, water solubility 0.44934 g/L

** 2-cyclohexylcyclohexanone: Boiling point 264℃

** 2-cyclopentylcyclopnetanone: boiling point 232.5 ℃, water solubility 1.3047 g/L

** 1-tetralone: boiling point 255 ℃, water solubility 0.99688 g/L

< Experiment example 2. Measurement of spreadability and flatness of the prepared ink composition>

The ink spreadability and flatness of thin films formed using the ink compositions prepared in Examples 1 to 8 and Comparative Examples 1 to 3 were measured as follows.

(1) Ink spreadability

Droplets of 9 pL per drop were printed on the red, green, and blue pixels in the line bank on the substrate using an inkjet printer. As the number of droplets printed for each pixel was increased, the discharge amount at the moment when the half tone of the pixel's y-axis was connected to ink was confirmed, and is shown in Table 2 below. Additionally, the ink spreadability test results of Example 1 and Comparative Example 1 are shown in Figures 2 and 3, respectively. From Figures 2 and 3, it can be seen that in Example 1, the ink spreads uniformly within the pixel at a discharge amount of 36 pL, but in Comparative Example 1, the ink does not spread even at 108 pL.

At this time, in the order of Red, Green, and Blue pixels, the x-axis length of the pixel is long, so the pixel area is wide (the y-axis length is the same).

Experiment example Red pixel half tone connection discharge amount Green pixel half tone connection discharge amount Blue pixel half tone connection discharge amount Example 1 36pL 36pL 36pL Example 2 36pL 36pL 36pL Example 3 36pL 36pL 36pL Example 4 54pL 90pL 126pL Example 5 54pL 72pL 108pL Example 6 54pL 72pL 108pL Example 7 54pL 72pL 72pL Example 8 54pL 72pL 72pL Comparative Example 1 108pL 252pL 306pL Comparative Example 2 126pL 252pL 306pL Comparative Example 3 126pL 252pL 306pL

In Examples 1 to 8 using the ink composition of the present application, the half tone of the pixel y-axis is connected to ink even with a small discharge amount, but in Comparative Examples 1 to 3 without adding a cyclic ketone solvent, the half tone of the pixel y-axis is connected to ink. It was confirmed that a larger discharge amount than Examples 1 to 8 was required to lead to . From this, it was confirmed that the ink composition of the present invention containing a cyclic ketone solvent had superior ink spreadability than the ink compositions of Comparative Examples 1 to 3.

(2-1) Flatness

The solvent in the ink was removed through a drying process of the substrate that had completed the ink spreadability test in (1) above. The drying process was carried out through vacuum drying. Specifically, drying was carried out at 10 ^-2 torr using a rotary pump, and then dried at 10 ^-4 to 10 ^-5 torr using a turbo molecular pump. The formed thin film was checked through an optical microscope (Bruker), and if the central thickness and edge thickness of the thin film within each pixel satisfied Equation 1 below, it was judged to be flat (OK). If Equation 1 below was not satisfied, it was judged to be flat. It was determined that it was not done (NG) and is shown in Table 3 below.

[Equation 1]

Pixel center thickness - pixel edge thickness ≤ 15 nm

The 'pixel center thickness' refers to the thickness of the midpoint of two y-axis partitions (meaning partitions perpendicular to the y-axis) in one pixel, and the 'pixel edge thickness' refers to the thickness of the pixel from the y-axis partition of the pixel. It refers to the thickness at a point of 10 ㎛ toward the center. There were two points corresponding to 10 ㎛ from the y-axis partition toward the center of the pixel, and when the thin film thicknesses of the two locations and the thin film thickness of the center of the pixel were both 15 nm or less, it was judged to be flat.

Experiment example flatness Example 1 OK Example 2 OK Example 3 OK Example 4 OK Example 5 OK Example 6 OK Example 7 OK Example 8 OK Comparative Example 1 NG Comparative Example 2 NG Comparative Example 3 NG

(2-2) Measurement of thin film flatness (thickness uniformity)

Using an inkjet printer, 126 pL, 162 pL, and 216 pL of ink were ejected from Example 1 or Comparative Example 1 to the Red, Green, and Blue pixels in the line bank on the substrate, respectively, and then subjected to a vacuum drying process. A thin film was formed, and the formed thin film was vacuum deposited on 100 nm aluminum. The interference phenomenon was analyzed using an optical profiler (Bruker, counter GT model), and the flatness (thickness uniformity) of the thin film was measured and analyzed. The flatness (thickness uniformity) measurement results of the thin film formed using the ink of Example 1 are shown in Figure 4, and the flatness (thickness uniformity) measurement results of the thin film formed using the ink of Comparative Example 1 are shown in Figure 5. shown in 4 and 5, the horizontal axis represents one side of the substrate on which the line bank is formed.

It refers to the location of the partition or the gap between pixels (㎛), and the vertical axis refers to the thickness of the thin film (nm).

101: substrate
201: anode
301: Hole injection layer
401: Hole transport layer
501: light emitting layer
601: Electron transport layer
701: Electron injection layer
801: cathode

Claims (15)

functional layer forming material; aromatic solvent; An ink composition comprising a cyclic ketone-based solvent,
An ink composition in which the cyclic ketone-based solvent is contained in an amount of 0.1% to 10% by weight based on 100 weight of the total ink composition. In claim 1,
An ink composition in which the cyclic ketone-based solvent is contained in an amount of 0.1% to 5% by weight based on 100 weight of the total ink composition. In claim 1,
The ink composition wherein the cyclic ketone-based solvent includes a ketone-based unit (-C=O-) and a cyclic unit in the molecule. In claim 1,
An ink composition wherein the cyclic ketone-based solvent is represented by the following formula (1):
[Formula 1]

In Formula 1,
A1 is a substituted or unsubstituted hydrocarbon ring. In claim 1,
An ink composition wherein the cyclic ketone solvent is represented by the following formula 1-1 or 1-2:
[Formula 1-1]

[Formula 1-2]

In Formulas 1-1 and 1-2,
B1 to B10 and C1 to C8 are the same or different from each other, and are each independently hydrogen; heavy hydrogen; hydroxyl group; Substituted or unsubstituted alkyl group; Substituted or unsubstituted cycloalkyl group; Substituted or unsubstituted cycloalkenyl group; Substituted or unsubstituted alkoxy group; Or, it is a substituted or unsubstituted aryl group, or combines with adjacent substituents to form a substituted or unsubstituted ring. In claim 1,
The ink composition wherein the cyclic ketone solvent has a boiling point of 150°C to 300°C. In claim 1,
The ink composition wherein the cyclic ketone-based solvent has a water solubility of 0.4 g/L or more. In claim 1,
The ink composition wherein the aromatic solvent has a boiling point of 150°C to 350°C. In claim 1,
The ink composition wherein the aromatic solvent is one type or a mixture of two or more types. In claim 1,
The ink composition wherein the content of the functional layer forming material is 0.1% by weight to 10% by weight based on 100 weight of the total ink composition. In claim 1,
An ink composition in which the content of the aromatic solvent is 80% by weight to 99.8% by weight based on 100 weight of the total ink composition. first electrode; It includes a second electrode and one or more organic layers provided between the first electrode and the second electrode,
An organic light-emitting device wherein at least one layer among the one or more organic layers is a functional layer containing the ink composition or a cured product thereof according to any one of claims 1 to 11. In claim 12,
An organic light emitting device wherein the functional layer includes a substrate on which line-shaped banks are formed. Preparing a first electrode;
Forming one or more organic layers on the first electrode; and
Comprising the step of forming a second electrode on the one or more organic layers,
The step of forming one or more organic layers includes forming a functional layer using the ink composition of any one of claims 1 to 11. In claim 14,
The method of forming the functional layer includes applying the ink composition on a substrate on which line-shaped banks are formed.