Conductive ink comprising diacetylene diol monomer and conductive polymer and method for manufacturing fine pattern using the same
阅读说明：本技术 包含二乙炔二醇单体和导电聚合物的导电油墨和使用其制造微细图案的方法 (Conductive ink comprising diacetylene diol monomer and conductive polymer and method for manufacturing fine pattern using the same ) 是由 李粲雨 金钟满 朴帅敏 于 2018-09-20 设计创作，主要内容包括：提供了一种含有二乙炔二醇单体和导电聚合物的导电油墨和一种使用其制造微细图案的方法。所述导电油墨包含导电聚合物和由以下化学式1表示的二乙炔二醇单体：[化学式1]HO-(R<Sub>1</Sub>)<Sub>n</Sub>-C≡C-C≡C-(R<Sub>2</Sub>)<Sub>m</Sub>-OH。在化学式1中,n和m彼此独立地为1至10,R<Sub>1</Sub>和R<Sub>2</Sub>彼此独立地为CR<Sub>a</Sub>R<Sub>b</Sub>或(CR<Sub>a</Sub>R<Sub>b</Sub>)<Sub>x</Sub>O,R<Sub>a</Sub>和R<Sub>b</Sub>各自独立地为氢或卤素,并且x为1至3的整数。在化学式1中,R<Sub>1</Sub>和R<Sub>2</Sub>可以都是CH<Sub>2</Sub>,并且n和m可以是彼此独立地为1至4的整数。(A conductive ink containing a diacetylene glycol monomer and a conductive polymer and a method for manufacturing a fine pattern using the same are provided. The conductive ink includes a conductive polymer and a diacetylene glycol monomer represented by the following chemical formula 1: [ chemical formula 1]HO‑(R 1 ) n ‑C≡C‑C≡C‑(R 2 ) m -OH. In chemical formula 1, n and m are each independently 1 to 10, R 1 And R 2 Independently of one another are CR a R b Or (CR) a R b ) x O，R a And R b Each independently hydrogen or halogen, and x is an integer from 1 to 3. In chemical formula 1, R 1 And R 2 May all be CH 2 And n and m may be integers of 1 to 4 independently of each other.)
1. A conductive ink comprising a conductive polymer and a diacetylene glycol monomer represented by the following chemical formula 1:
[ chemical formula 1]
HO-(R1)n-C≡C-C≡C-(R2)m-OH
In the chemical formula 1, the first and second,
n and m are independently of each other 1 to 10,
R1and R2Independently of one another are CRaRbOr (CR)aRb)xO，
RaAnd RbEach independently hydrogen or halogen, and x is an integer from 1 to 3.
2. The conductive ink according to claim 1, wherein, in chemical formula 1, R1And R2Are all CH2And n and m are each independently an integer of 1 to 4.
3. The conductive ink according to claim 1, wherein the conductive polymer has a monomer represented by the following chemical formula 2:
[ chemical formula 2]
In the chemical formula 2, the first and second organic solvents,
x is S or Se, and the compound is,
R1and R2Independently of one another, hydrogen, halogen, hydroxy, C1-C10 alkyl, C1-C10 alkoxy, or R1And R2Linked together to form a 3 to 5 membered alkylene, alkenylene or alkylenedioxy group.
4. The conductive ink of claim 3, wherein the conductive polymer is PEDOT (poly (3, 4-ethylenedioxythiophene)).
5. The conductive ink of claim 1, further comprising a polymer anion that is a polymeric carboxylic acid or a polymeric sulfonic acid.
6. The conductive ink of claim 1, further comprising water, alcohol, or a mixture thereof as a solvent.
7. The conductive ink according to claim 1, wherein the diacetylene glycol monomer is present in an amount of 1 to 600 parts by weight based on 100 parts by weight of the conductive polymer.
8. The conductive ink according to claim 7, wherein the diacetylene glycol monomer is present in an amount of 100 to 400 parts by weight.
9. The conductive ink according to claim 8, wherein the diacetylene glycol monomer is present in an amount of 100 to 250 parts by weight.
10. A method for producing a fine pattern, comprising:
forming a conductive film by coating a conductive ink including a conductive polymer and a diacetylene glycol monomer represented by the following chemical formula 1 on a substrate;
disposing a photomask on the conductive film and irradiating ultraviolet rays on the photomask to provide a first region having the conductive polymer and polydiacetylene formed by crosslinking the diacetylene glycol monomer, and a second region in which the diacetylene glycol monomer remains in the conductive film; and
selectively removing the second region to form a conductive polymer micro pattern:
[ chemical formula 1]
HO-(R1)n-C≡C-C≡C-(R2)m-OH
In the chemical formula 1, the first and second,
n and m are independently of each other 1 to 10,
R1and R2Independently of one another are CRaRbOr (CR)aRb)xO，
RaAnd RbEach independently hydrogen or halogen, and x is an integer from 1 to 3.
11. The method of claim 10, wherein the substrate is a silicon wafer, a glass substrate, a plastic substrate, paper, or a metal substrate.
12. The method of claim 10, wherein the conductive ink contains 0.1 to 300 parts by weight of diacetylene glycol based on 100 parts by weight of conductive polymer.
13. The method of claim 10, wherein the selective removal of the second region is performed using water, alcohol, or a mixture thereof.
14. The method of claim 10, further comprising doping the conductive polymer micropattern with one or more dopants selected from the group consisting of perfluorinated acids, sulfuric acid, sulfonic acids, formic acid, hydrochloric acid, perchloric acid, nitric acid, acetic acid, DMF (dimethylformamide), DMSO (dimethyl sulfoxide), hydroquinone, catechol, and ethylene glycol.
15. The method of claim 14, wherein the dopant is a perfluorinated acid represented by the following chemical formula 3:
[ chemical formula 3]
CF3-(CF2)n-A
In the chemical formula 3, the first and second,
n is an integer from 3 to 20, and A may be SO3H、OPO3H or CO2H。
16. The method of claim 15, wherein n is an integer from 6 to 8, and a may be SO3H。
17. The method of claim 15, wherein the conductive polymer micropattern is an electrode of an organic electronic device.
18. A film or pattern comprising a conductive polymer and polydiacetylene represented by the following chemical formula 1A:
[ chemical formula 1A ]
In the chemical formula 1A, the metal oxide,
R1and R2Independently of one another are CRaRbOr (CR)aRb)xO，
RaAnd RbIndependently of one another, hydrogen or halogen radicals,
x is an integer of 1 to 3, and
n and m are each independently an integer of 1 to 10.
19. The film or pattern of claim 18, further comprising a perfluorinated acid represented by the following chemical formula 3:
[ chemical formula 3]
CF3-(CF2)n-A
In the chemical formula 3, the first and second,
n is an integer of 3 to 20, and A is SO3H、OPO3H or CO2H。
20. The film or pattern of claim 18, further comprising a polymeric anion that is a polymeric carboxylic acid or a polymeric sulfonic acid.
Technical Field
The present invention relates to a conductive ink and a method of manufacturing a pattern using the same, and more particularly, to a conductive ink containing a conductive polymer and a method of manufacturing a pattern using the same.
Background
In general, a pixel electrode applied to a display should be a transparent electrode and should satisfy electrical and optical properties, such as 10 as electrical properties3A sheet resistance of omega/sq or less and 10-3A resistivity of Ω cm or less, and a transmittance in a visible light region of 80% or more as an optical property.
The transparent electrode is applied to various fields such as Organic Light Emitting Diodes (OLEDs), solar cells, touch screens, and keypads for mobile phones according to conductivity. Research is actively being conducted to replace ITO electrodes, which are conventional inorganic transparent electrode materials, and research and development of new electrode materials using a metal thin film, an inorganic composite material including conductive powder, or a conductive polymer as an organic material are being conducted.
There are two types of conductive polymers: composite materials made by incorporating conductive fillers such as metals and carbon into a common plastic matrix that is nonconductive, and Inherently Conductive Polymers (ICP) where the polymer matrix itself is inherently conductive.
Among them, as the ICP, many different types of conductive polymers such as polyparaphenylene, polypyrrole, polythiophene, polyaniline, and the like have been developed. However, conductive polymers such as polypyrrole, polyaniline have not yet exhibited appropriate conductivity for transparent electrode applications, and have poor processability due to insolubility in general-purpose solvents. In particular, in implementing a flexible display considered as a next-generation display device, a conductive polymer patterning technology capable of achieving a micrometer wiring line width has been studied in a large amount academically and industrially to form a thin film transistor or a wiring electrode inside the display device. The conductive polymer patterning technology is difficult to apply to the transparent electrode because conductivity is inevitably reduced when a soluble functional group is introduced into the polymer to improve its solubility in an organic solvent.
PEDOT: PSS (poly (3, 4-ethylenedioxythiophene): poly (styrenesulfonate)) is one of the most widely used conductive polymer materials because it has good transmittance in the visible region, it is soluble in water, making it useful for an environmentally friendly solution process, and it is excellent in stability. However, it has a very low conductivity of 1S/cm when used as a transparent electrode. In addition, in order to improve light transmittance, a thin film should be coated. In this case, the surface resistance increases, which makes it difficult to use it as a transparent electrode.
Disclosure of Invention
Technical problem
Accordingly, an object of the present invention is to provide a conductive ink composition containing a conductive polymer, which can be easily patterned using a photolithography process while greatly improving conductivity, and a method of forming a conductive pattern using the same.
The object of the present invention is not limited to the above object, and other objects not mentioned will be clearly understood by those skilled in the art from the following description.
Technical scheme
One aspect of the present invention provides a conductive ink. The conductive ink includes a conductive polymer and a diacetylene glycol monomer represented by the following
[ chemical formula 1]
HO-(R1)n-C≡C-C≡C-(R2)m-OH
In
The conductive polymer may have a monomer represented by the following
[ chemical formula 2]
In
The conductive ink can further include a polymeric anion that is a polymeric carboxylic acid or a polymeric sulfonic acid. The conductive ink may further contain water, alcohol or a mixture thereof as a solvent.
The content of the diacetylene glycol monomer can be 1 to 600 parts by weight, for example 100 to 400 parts by weight, specifically 100 to 250 parts by weight, based on 100 parts by weight of the conductive polymer.
Another aspect of the present invention provides a method of preparing a fine pattern. The method includes forming a conductive film by coating a conductive ink including a conductive polymer and a diacetylene glycol monomer represented by
The substrate may be a silicon wafer, a glass substrate, a plastic substrate, paper or a metal substrate. The conductive ink may contain 0.1 to 300 parts by weight of diacetylene glycol based on 100 parts by weight of the conductive polymer. Selective removal of the second region may be performed using water, alcohol or a mixture thereof.
The conductive polymer fine pattern may be doped with one or more dopants selected from the group consisting of perfluorinated acid, sulfuric acid, sulfonic acid, formic acid, hydrochloric acid, perchloric acid, nitric acid, acetic acid, DMF (dimethylformamide), DMSO (dimethyl sulfoxide), hydroquinone, catechol, and ethylene glycol. The dopant may be a perfluorinated acid represented by the following chemical formula 3.
[ chemical formula 3]
CF3-(CF2)n-A
In chemical formula 3, n is an integer of 3 to 20, and A is SO3H、OPO3H or CO2H. N in chemical formula 3 may be an integer of 6 to 8, and A is SO3H。
The conductive polymer fine pattern may be an electrode of an organic electronic device.
[ advantageous effects ]
According to the present invention as described above, there can be provided a conductive ink composition containing a conductive polymer, which can be easily patterned using a photolithography process while greatly improving conductivity, and a method of forming a conductive pattern using the same.
However, the effects of the present invention are not limited to the above-described effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.
Drawings
Fig. 1a to 1c are schematic views illustrating a method of manufacturing a fine pattern according to an embodiment of the present invention.
Fig. 2 is a graph showing the conductivity of the conductive film as a function of the weight percent of diacetylene glycol.
Fig. 3 is an optical photograph of fine patterns manufactured by using the conductive ink compositions according to the conductive ink preparation examples 6 and 10 to 12.
Fig. 4 is a photograph taken during the processes of fine pattern preparation example 1 and fine pattern doping example 1 using the conductive ink composition according to conductive ink preparation example 6.
Fig. 5 shows the difference in thickness before and after development (a) and the thickness and width of the pattern formed during the execution of the fine pattern preparation example 1 (B).
Fig. 6 is a photograph of fine patterns obtained by the fine pattern preparation examples 1 to 3 using the conductive ink composition according to the conductive ink preparation example 6.
Fig. 7 shows an ultraviolet-visible spectrum (a), an FT-IR spectrum (b), a raman spectrum (c, d), an XRD (X-ray diffraction) pattern (e), and a pattern (f) of a change in conductivity of a product obtained during the fine pattern preparation example 1 using the conductive ink composition according to conductive ink preparation example 6.
Fig. 8a and 8b are graphs showing UV-vis absorption spectrum and transmission spectrum of the conductive pattern obtained by performing fine pattern preparation example 1 using the conductive ink composition according to conductive ink preparation example 6 and the doped conductive pattern obtained by doping example 1 with a fine pattern using the conductive pattern, respectively.
Fig. 9 shows infrared spectra of the conductive film obtained during fine pattern preparation example 1 using the conductive ink composition according to conductive ink preparation example 6 and the doped conductive film obtained by fine pattern doping example 1 on the conductive film.
FIG. 10 is a graph showing the electrical conductivities of a PEDOT: PSS film, a fine pattern obtained according to fine pattern preparation example 1 using the conductive ink composition of preparation example 1, a sulfuric acid-doped fine pattern, and a PFOSA-doped fine pattern.
Fig. 11 is a graph showing the relative change in conductivity with time after doping a fine pattern with sulfuric acid or PFOSA.
Detailed Description
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings to describe the present invention in more detail. However, the present invention is not limited to the embodiments described herein, but may be embodied in other forms. In the drawings, when a layer is referred to as being "on" another layer or substrate, it can be directly formed on the other layer or substrate, or a third layer can be interposed therebetween. In the present embodiment, "first", "second" or "third" is not intended to impose any limitation on elements, but should be understood as a term for distinguishing the elements.
As used herein, unless otherwise defined, "alkyl" refers to an aliphatic hydrocarbon group, and may be a "saturated alkyl" group that does not include a double or triple bond. The saturated alkyl groups may be linear.
As used herein, unless otherwise defined, "alkylene" refers to a divalent group that is an alkane group of a saturated hydrocarbon group, and may be a linear alkylene group.
In the present specification, when "carbon number X to carbon number Y" is described, it should be construed that a case having carbon numbers corresponding to all integers between the carbon number X and the carbon number Y is also described.
As used herein, "halogen" or "halo" is an element belonging to group 17, which may be, in particular, a fluoro, chloro, bromo or iodo group.
In the present specification, when "X to Y" are described, numerals corresponding to all integers between X and Y should be construed as being described together.
Conductive inks with diacetylene glycol
The conductive ink according to an embodiment of the present invention may contain 100 parts by weight of a conductive polymer, 1 to 600 parts by weight of a diacetylene glycol monomer, and the remainder of a solvent. The solvent may be a polar protic solvent, such as an alcohol, water or a mixture thereof. For example, the solvent may be water. The alcohol may be methanol, ethanol, propanol or a mixture thereof, but is specifically ethanol.
The diacetylene diol monomer may be a substance having diacetylene and a diol in a molecule, and may be represented by the following
[ chemical formula 1]
HO-(R1)n-C≡C-C≡C-(R2)m-OH
In
In one embodiment, R1And R2All can be CH2Wherein n and m may be, independently of each other, an integer of 1 to 4. In this case, the diacetylene glycol monomer can be well dissolved in water.
The conductive polymer may have a monomer represented by the following
[ chemical formula 2]
In the
x may be S or Se, or a salt thereof,
R1and R2May be, independently of one another, hydrogen, halogen, hydroxy, C1-C10 alkyl, C1-C10 alkoxy, or R1And R2May be linked together to form a 3 to 5 membered alkylene group, alkenylene group, alkylenedioxy group. The alkylenedioxy group may be a methylenedioxy group, an ethylenedioxy group, or a propylenedioxy group. Specifically, the conductive polymer may be PEDOT (poly (3, 4-ethylenedioxythiophene)).
The conductive polymer may be a water-soluble polymer. For example, some of the aromatic rings forming the backbone of the conductive polymer, i.e., thiophene or selenophene, may exhibit a positive charge. The conductive ink may further include a polymer anion for stabilizing the conductive polymer having a positive charge on the main chain. The polymer anion can be a polymeric carboxylic acid or a polymeric sulfonic acid. The polymeric carboxylic acid may be polyacrylic acid, polymethacrylic acid or polymaleic acid, and the polymeric sulfonic acid may be polystyrene sulfonic acid or polyvinyl sulfonic acid. The polymer anion may be included in the conductive ink in an amount of 10 to 200 parts by weight, for example, 100 to 150 parts by weight.
The conductive ink is obtained by dissolving a diacetylene glycol monomer in an aqueous conductive polymer solution in which a conductive polymer and a polymer anion are dissolved. The conductive ink can exhibit a solution state without aggregation. For this reason, after mixing the aqueous conductive polymer solution with the diacetylene glycol monomer, a homogeneous solution can be obtained by further ultrasonic treatment.
Method for manufacturing fine pattern using conductive ink
Fig. 1a to 1c are schematic views illustrating a method of manufacturing a fine pattern according to an embodiment of the present invention.
Referring to fig. 1a, the above-described conductive ink may be coated on a
The coating may be a wet coating such as spin coating or doctor blade, but is not limited thereto. For example, the coating may be spin coating, and a conductive film having an appropriate thickness can be obtained with a minimum number of coatings.
The
The diacetylene glycol monomer 23 is an amphiphilic substance having both a hydrophilic functional group and a hydrophobic functional group in the molecule. Thus, in the
A photomask PM having a light-transmitting region may be disposed on the
Referring to fig. 1b, diacetylene glycol can crosslink in the ultraviolet irradiated regions 20 'in the
[ chemical formula 1A ]
In chemical formula 1A, R1And R2May be CR independently of one anotheraRbOr (CR)aRb)xO，RaAnd RbMay be independently of each other hydrogen or halogen groups, and x may be an integer from 1 to 3. Further, each of n and m may be, independently of the other, an integer of 1 to 10, specifically 1 to 4. The halogen group may be F, Cl, Br or I, but may be F as an example. In one embodiment, R1And R2All can be CH2Wherein n and m may be, independently of each other, an integer of 1 to 4.
The polydiacetylene formed by crosslinking the diacetylene diol monomers has a pi-conjugated backbone due to the overlap of the pi-orbitals, and thus the ultraviolet radiation region 20' can have a yellow color.
Referring to fig. 1c, the
During the development, since the water-soluble diacetylene glycol monomer remains, the regions not irradiated with ultraviolet rays can be selectively washed away by the developer, and since polydiacetylene is insoluble in water, the ultraviolet-irradiated regions 20 'can remain as the fine pattern 20' containing polydiacetylene and the electroconductive polymer. Since the fine pattern is formed to correspond to the light transmitting region of the photomask, it may be referred to as a negative pattern. In addition, the fine pattern may have a line width of a nano size or a micro size.
In order to form such a fine pattern with high resolution, the content of diacetylene glycol in the conductive ink can be controlled. As an example, the diacetylene glycol can be present in an amount of 0.1 to 300 parts by weight, specifically 10 to 300 parts by weight, more specifically 10 to 250 parts by weight, based on 100 parts by weight of the conductive polymer. In addition, the content of diacetylene glycol may be 100 to 250 parts by weight, about 110 to 250 parts by weight, or about 130 to 250 parts by weight, in view of the conductivity of the fine pattern. However, even when the content of diacetylene glycol is low and thus the conductivity of the fine pattern is low, the conductivity of the fine pattern can be further improved by a doping process described later.
The conductivity can be improved by adding a dopant to the fine pattern 20' to further dope the conductive polymer in the fine pattern. The dopant may be at least one selected from the group consisting of perfluorinated acids, sulfuric acid, sulfonic acids, formic acid, hydrochloric acid, perchloric acid, nitric acid, acetic acid, DMF (dimethylformamide), DMSO (dimethyl sulfoxide), hydroquinone, catechol, and ethylene glycol. The sulfonic acid may be selected from the group consisting of methanesulfonic acid, trifluoromethanesulfonic acid, perchloric acid, benzenesulfonic acid, and p-toluenesulfonic acid, but is not limited thereto.
The perfluorinated acid may be represented by the following chemical formula 3.
[ chemical formula 3]
CF3-(CF2)n-A
In the above-mentioned formula, the compound of formula,
n may be 3 to 20, and A may be SO3H、OPO3H or CO2H。
As an example, n in chemical formula 3 may be in the range of 4 to 9, specifically, 6 to 8, and a may be SO3H。
The perfluorinated acid represented by chemical formula 3 has superhydrophobicity and chemical resistance properties due to substitution of hydrogen by fluorine atoms in the carbon main chain, and has high hydrophilicity due to sulfonic acid groups, phosphoric acid groups, or carboxylic acid groups at the ends of the carbon main chain. Therefore, it has an amphiphilic molecular structure having both hydrophilicity and hydrophobicity in the molecule. Generally, amphiphilic materials exhibit a layered structure in which molecules are spontaneously oriented, as in a cell membrane. The perfluorinated acid exhibits amphiphilic properties due to having a superhydrophobic alkyl chain and a hydrophilic functional group (sulfonic acid, etc.), and may have a layered structure spontaneously oriented on the conductive polymer, resulting in an extended structure of the conductive polymer. In addition, the hydrophilic functional group (sulfonic acid or the like) can improve the conductivity of the conductive polymer by cation-doping the conductive polymer. Thus, the perfluorinated acid may help electrons to flow more easily in the main chain of the conductive polymer, i.e., the conjugated polymer.
Generally, the conductive polymer is oxidized by moisture and various contaminants in the air, and thus has very poor long-term stability in terms of conductivity. Perfluoroalkyl chains not only induce a spontaneously oriented layer structure, but also induce superhydrophobicity, and can be effectively used for blocking water or air pollutants in the air. As a result, the perfluorinated acid can be used to straighten the conductive polymer chain to have a molecular structure through which charges can flow well, and at the same time, can be used to improve the long-term stability of the conductivity of a fine pattern.
In formula 3, n may be 3 to 20, and most preferably n may be 4 to 9. If the value of n is less than 3, it is difficult to maintain the conductivity of the conductive polymer for a long period of time. If the value of n is greater than 20, the size of the molecule is large, making it difficult to penetrate between polymer chains, and thus it is difficult to dope the polymer, thereby decreasing conductivity.
In the doping step, the fine pattern may be treated with a solution containing a dopant, specifically, an aqueous solution containing a dopant. The aqueous dopant solution can contain about 10 to 60 weight percent, specifically about 30 to 50 weight percent, more specifically 35 to 45 weight percent dopant. Then, the dopant that has not penetrated into the fine pattern is washed with a solvent such as ethanol, and the washed pattern is dried. At this time, the drying may be performed at 60 to 160 ℃. Treating the fine pattern with the dopant-containing solution may include spraying, coating, or adding the dopant-containing solution on the fine pattern, or dipping the substrate on which the fine pattern is formed in the dopant-containing solution. As an example, a dipping method may be used.
The prepared fine pattern 20' may include a conductive polymer and polydiacetylene represented by chemical formula 1A. Polydiacetylenes can self-assemble onto conducting polymers through interactions such as hydrogen bonding; thus, the conductive polymer may be transformed from a benzene-type structure to a quinone-type structure to have a linear or extended coil form. Therefore, the conjugation length of the conductive polymer can be increased, and the conductivity can be improved. In addition, the fine pattern 20' may further include a perfluorinated acid represented by chemical formula 3 as an example of a dopant. Also, the fine pattern 20' may further include a polymer anion, which is a polymerized carboxylic acid or a polymerized sulfonic acid.
Meanwhile, the fine pattern may be used as an electrode in a display device or an electrochemical device, particularly, an organic electronic device. The display device may be an organic light emitting diode, and the electrochemical device may be an organic solar cell or a dye-sensitized solar cell. The organic electronic device may be an organic thin film transistor. Other electrochemical devices may be capacitors.
Method for manufacturing conductive film using conductive ink
The conductive film using the conductive ink according to the present embodiment can be manufactured by omitting the patterning step including the exposure and development steps of the above-described fine pattern manufacturing method. Specifically, after the conductive ink is coated on a substrate and dried to form a conductive film, the above dopant may be applied to the conductive film. In this case, the content of the diacetylene glycol in the conductive ink can be about 100 to 400 parts by weight, about 110 to 350 parts by weight, or about 130 to 260 parts by weight, based on 100 parts by weight of the conductive polymer.
As such, although patterning is omitted, a doping step may be performed. Alternatively, after the conductive film is formed, another photoresist may be used to pattern the conductive film, or another patterning method such as a stamping method may be used to pattern the conductive film, and then a doping step may be performed.
The prepared conductive film may further include a conductive polymer and polydiacetylene represented by chemical formula 1A. Polydiacetylenes can self-assemble onto conducting polymers through interactions such as hydrogen bonding; and thus, the conductive polymer can be transformed from a benzene-type structure to a quinone-type structure to form a linear or extended coil form; therefore, the conjugate length can be increased, and the conductivity can be improved. In addition, the conductive film may further include a perfluorinated acid represented by chemical formula 3 as an example of a dopant. Also, the conductive film may further include a polymeric anion, which is a polymeric carboxylic acid or a polymeric sulfonic acid.
Hereinafter, preferred embodiments are provided to aid understanding of the present invention. However, the following experimental examples are only to help understanding of the present invention, and the present invention is not limited by the following experimental examples.
Examples of preparation of conductive ink composition for optical microfabrication
< conductive ink composition preparation examples 1 to 9>
2, 4-hexadiyne-1, 6-diol (HDO) was added to 1g of an aqueous PEDOT: PSS solution (Sigma-Aldrich) containing 0.5 wt% of PEDOT and 0.8 wt% of PSS as shown in Table 1, and sufficiently dissolved by sonication for 10 minutes to obtain a mixed solution. The mixed solution was filtered using a 0.45mm filter to remove impurities, to obtain conductive ink compositions for optical micro-processing according to preparation examples 1 to 9.
TABLE 1
< conductive ink composition preparation examples 10 to 12>
A composition was prepared in the same manner as in preparation example 6 except that 6.5mg of 3, 5-octadiyne-1, 8-diol (composition preparation example 10), 6.5mg of 4, 6-decanediyne-1, 10-diol (composition preparation example 11) or 6.5mg of 5, 7-dodecadiyne-1, 12-diol (composition preparation example 12) was used in place of 6.5mg of 2, 4-hexadiyne-1, 6-diol (HDO).
Fine pattern production example
< fine Pattern production example 1>
One of the prepared conductive ink compositions was spin-coated on a glass substrate to obtain a uniform conductive film, and then dried to measure the conductivity of the conductive film. A photomask having a light-transmitting pattern was provided on the conductive film, and the photomask was used as a mask to irradiate a light having a wavelength of 254nm (12.5 mWcm)-2) Ultraviolet light of (1) for 10 seconds. After the ultraviolet exposure, the substrate having the conductive film was immersed in water to remove portions not irradiated with UV, and then washed with ethanol to form a conductive pattern. Then, the conductive pattern is dried, and the conductivity of the dried conductive pattern is measured.
< fine Pattern production examples 2 and 3>
A fine pattern was prepared in the same manner as in the fine pattern preparation example 1, except that the silicon wafer (fine pattern preparation example 2) or the PET substrate (fine pattern preparation example 3) was used instead of the glass substrate.
Fine pattern doping example
< fine Pattern doping example 1>
The substrate on which the fine pattern was prepared was immersed in a 40 wt% aqueous solution of perfluorooctane sulfonic acid (PFOSA) for 10 minutes, and then taken out, and washed with water and ethanol in order, thereby doping the fine pattern.
< fine Pattern doping example 2>
The fine pattern was doped using the same method as in fine pattern doping example 1, except that an 18M sulfuric acid solution was used instead of the PFOSA solution.
Table 2 summarizes the conductivity of the conductive film obtained in the fine pattern preparation example and the state of the formed conductive pattern.
TABLE 2
Fig. 2 is a graph showing the conductivity of the conductive film as a function of the weight percent of diacetylene glycol.
Referring to fig. 2 and table 2, the conductivity (47S/cm) of the PEDOT: PSS conductive film was hardly increased until the weight part of HDO, which is diacetylene glycol, was about 65 weight parts based on 100 weight parts of PEDOT. From 100 parts by weight (preparation example 4) showed a large increase, such as an electrical conductivity exceeding 1000S/cm. Thereafter, when about 260 parts by weight was added, the conductivity exceeded 4000S/cm, and when more was added, the conductivity decreased again. As can be seen from these results, about 100 to 400 parts by weight of diacetylene glycol can be added based on 100 parts by weight of PEDOT to obtain the conductivity of the conductive film of more than 1000S/cm. Also, it can be seen that about 110 to 350 parts by weight of diacetylene glycol can be added based on 100 parts by weight of PEDOT to obtain the conductivity of the conductive film of more than 2000S/cm. Also, it can be seen that about 130 to 260 parts by weight of diacetylene glycol can be added based on 100 parts by weight of PEDOT to obtain the conductivity of the conductive film of more than 3000S/cm.
Meanwhile, in the case of generating a pattern by ultraviolet exposure and development of a conductive film, it can be seen that no pattern is formed when the content of diacetylene glycol exceeds 300 parts by weight (ink composition preparation example 8). In addition, it can be seen that, in order to obtain a good pattern, the content of diacetylene glycol may be 250 parts by weight or less (ink composition preparation examples 1 to 6).
Therefore, when the conductive film according to an embodiment of the present invention is used without patterning the conductive film, or when patterning is performed by using another photo-resist layer other than a method of exposing and developing the conductive film by irradiation, or when other patterning such as a stamping method is performed, the content of the diacetylene glycol in the conductive ink may be about 100 to 400 parts by weight, about 110 to 350 parts by weight, or about 130 to 260 parts by weight based on 100 parts by weight of the conductive polymer in terms of the conductivity of the conductive film.
However, when the conductive film is to be subjected to radiation exposure and development to form a conductive pattern, a good pattern should be first considered so that the diacetylene glycol in the conductive ink is about 10 to 300 parts by weight, about 10 to 250 parts by weight, and further the conductivity of the pattern is considered about 100 to 250 parts by weight, about 110 to 250 parts by weight, or about 130 to 250 parts by weight, based on 100 parts by weight of the conductive polymer. Meanwhile, when the conductivity of the pattern is not satisfactory, the pattern may be additionally doped.
Fig. 3 is an optical photograph of fine patterns manufactured by using the conductive ink compositions according to the conductive ink preparation examples 6 and 10 to 12.
Referring to fig. 3, in the case of hexadiynediol and octadiynediol, high resolution patterns were obtained, but in the case of decadiynediol and dodecadiynediol, slightly lower resolution patterns were obtained. This means that the shorter the hydrocarbon chain length of the diacetylene diol compound, the more hydrophilic, the more soluble in water, so that a homogeneous composition can be obtained during the preparation of the ink composition and can be washed clean during development.
Fig. 4 is a photograph taken during the processes of fine pattern preparation example 1 and fine pattern doping example 1 using the conductive ink composition according to conductive ink preparation example 6.
Referring to fig. 4, after spin coating the conductive ink composition onto the glass substrate and after irradiation exposure, the pattern was not confirmed, but after development, the pattern was confirmed and maintained even after doping with PFOSA.
Fig. 5 shows the difference in thickness before and after development (a) and the thickness and width of the pattern formed during the execution of the fine pattern preparation example 1 (B).
Referring to fig. 5A, it can be seen that the thickness of the film after spin coating before development was about 120nm, and the thickness of the film developed with DI water was reduced to 95 nm. The reduction in thickness is presumably due to the washing away of unpolymerized HDO monomer and non-conductive PSS.
Referring to fig. 5B, it can be seen that the resulting pattern after development is a clear pattern having sub-patterns each having a width of about 70 μm and a thickness of 95 nm.
Fig. 6 is a photograph of fine patterns obtained by the fine pattern preparation examples 1 to 3 using the conductive ink composition according to the conductive ink preparation example 6.
Referring to fig. 6, a micro pattern of a micrometer size, specifically, having a line width of about 10 to 200 μm is clearly formed such that the end of the pattern has a clear shape not only on a glass substrate (a) but also on a silicon wafer substrate (b and c) and on a flexible and transparent PET substrate (d).
Fig. 7 shows an ultraviolet-visible spectrum (a), an FT-IR spectrum (b), a raman spectrum (c, d), an XRD (X-ray diffraction) pattern (e), and a pattern (f) of a change in conductivity of a product obtained during the fine pattern preparation example 1 using the conductive ink composition according to conductive ink preparation example 6.
Referring to fig. 7a, the film formed by spin coating the conductive ink composition containing HDO and PEDOT: PSS is referred to as "pristine". After the formed film is irradiated with ultraviolet rays, the irradiated film is developed (referred to as "irradiation") and washed. The washed membrane is referred to as "washed". The original film (original), the irradiated film (irradiated) and the washed film (washed) exhibited an absorption peak at about 225nm in the uv-visible spectrum due to the peak of PSS. However, this PSS peak at 225nm was reduced by water washing during development. From this, it can be estimated that unpolymerized HDO monomer and excessively added PSS were removed in the development step. Meanwhile, after the film was irradiated with ultraviolet radiation of 254nm, a new peak appeared in the vicinity of 450nm due to color change (red line) caused by polymerization of HDO.
Referring to FIG. 7b, the FT-IR spectrum (black line) of the conductive ink composition containing HDO and PEDOT: PSS, the FT-IR spectrum (red line) of HDO, and the FT-IR spectrum (blue line) of PEDOT: PSS are shown. FT-IR spectroscopy of a conductive ink composition containing HDO and PEDOT PSS showed HDO at 1348cm-1、1030cm-1And 913cm-1All characteristic peaks at (a), and broad PEDOT: PSS peaks; thus, it can be seen that HDO and PEDOT: PSS are well mixed in the conductive ink composition containing HDO and PEDOT: PSS.
Referring to FIG. 7c, it can be seen from the Raman spectrum (black line) of the conductive ink composition containing HDO and PEDOT: PSS and the Raman spectrum (red line) of the film after spin coating and then irradiating with ultraviolet rays at 1500cm after the ultraviolet irradiation-1(C ═ C) and 2070cm-1A new peak indicative of conjugated ene-yne appears at (C ≡ C). These peaks generally appear upon formation of the polydiacetylene, indicating successful formation of the polydiacetylene from the HDO in the film by uv irradiation.
Referring to fig. 7d, from the raman spectrum (red line) of the conductive ink composition containing HDO and PEDOT: PSS and the raman spectrum (black line) of the PEDOT: PSS itself, it can be seen that by adding HDO, the peak of the symmetrical C α ═ C β stretch band (about 1440 cm) of PEDOT-1) Has moved. This indicates that the addition of HDO changes the structure of PEDOT from a benzene-type structure to a quinone-type structure. The benzene-type structure means that the conductive PEDOT has the shape of a coil surrounded by the non-conductive PSS, whereas the quinoid structure conversely has the form of a linear or extended coil in which the conductive PEDOT has a longer conjugate length. Thus, the conductivity can be improved since the form of PEDOT is linearly extended by the addition of HDO.
Referring to fig. 7e, from the X-ray diffraction (XRD) of the conductive ink composition containing HDO and PEDOT: PSS (red line) and the XRD of PEDOT: PSS itself (black line), the structural change as shown in fig. 7d can be observed. Initially the peak of PEDOT to PSS is broad but the peak intensity of the mixture of PEDOT to PSS and HDO increases. The increase in peak intensity is due to the increase in crystallinity resulting from HDO self-assembly. In addition, the peak representing the pi-pi stacking distance between PEDOT chains (about 25 degrees) moves to a greater degree. This means that Bragg's law is usedDistance between PEDOT chains in the calculationReduced to
With reference to FIG. 7f, the conductivity of HDO-containing PEDOT: PSS films was 3007S/cm due to structural changes, but after UV irradiation at 254nm, the conductivity dropped to 1667S/m, presumably due to photo-oxidation of PEDOT. After the development process with DI water, the conductivity increased again, presumably due to the non-conductive PSS being washed away.
Fig. 8a and 8b are graphs showing UV-vis absorption spectrum and transmission spectrum of the conductive pattern obtained by performing fine pattern preparation example 1 using the conductive ink composition according to conductive ink preparation example 6 and the doped conductive pattern obtained by doping example 1 with a fine pattern using the conductive pattern, respectively.
Referring to FIG. 8a, the absorption band occurring in the 230nm region of the conductive pattern (PEDOT: PSS + HDO) before doping is attributed to PSS, and the intensity of this absorption band is reduced in the conductive pattern doped with PFOSA (PFOSA treatment). This means that PSS in the PEDOT: PSS film is partially removed during washing after doping with PFOSA, and in addition, PSS of PEDOT: PSS can be replaced by perfluorinated acid by doping with perfluorinated acid.
Referring to fig. 8b, it was confirmed that the conductive pattern before doping (PEDOT: PSS + HDO) and the conductive pattern after doping (PFOSA treatment) both showed excellent transmittance in the visible light region, and thus, it was possible to replace the transparent electrode material such as ITO.
Fig. 9 shows infrared spectra of the conductive film obtained during fine pattern preparation example 1 using the conductive ink composition according to conductive ink preparation example 6 and the doped conductive film obtained by fine pattern doping example 1 on the conductive film.
Referring to fig. 9, PE doped with perfluorosulfonic acid (PFOSA treatment) is compared to the conductive film (virgin)DOT/PSS film at 1280cm-1A typical perfluorosulfonic acid peak is shown. This means that perfluorinated acids are doped in PEDOT: PSS films.
FIG. 10 is a graph showing the electrical conductivities of a PEDOT: PSS film, a fine pattern obtained according to fine pattern preparation example 1 using the conductive ink composition of preparation example 1, a sulfuric acid-doped fine pattern, and a PFOSA-doped fine pattern.
Referring to fig. 10, the conductivity of the fine pattern obtained according to fine pattern preparation example 1 using the conductive ink composition according to conductive ink preparation example 1 (containing 13 parts by weight of HDO) was increased by about two times as compared to a PEDOT: PSS film obtained by spin-coating a PEDOT: PSS aqueous solution. In the case of the sulfuric acid doping according to the fine pattern doping example 2, the conductivity of the doped fine pattern was greatly increased to about 1418S/cm. However, when the fine pattern was PFOSA doping according to the fine pattern doping example 1 instead of sulfuric acid, it can be seen that the conductivity of the doped fine pattern was significantly increased to about 4179S/cm. Therefore, when the content of HDO in the conductive ink composition is relatively low and the conductivity after forming a fine pattern is not high, the conductivity can be greatly improved by doping PFOSA or the like.
Fig. 11 is a graph showing the relative change in conductivity with time after doping a fine pattern with sulfuric acid or PFOSA.
Referring to fig. 11, in the case of doping with sulfuric acid, the conductivity after doping greatly decreases with time, whereas in the case of doping with PFOSA, the decrease with time of the conductivity after doping is not as large as that in the case of doping with sulfuric acid. This is presumably due to the decomposition and oxidation of polydiacetylene by strongly acidic sulfuric acid, thereby reducing the doping effect. In addition, the fine pattern treated with the perfluorinated acid (PFOSA) shows stability to humidity and organic solvent vapor.
The present invention has been described in detail with reference to the preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications and changes can be made by those skilled in the art within the spirit and scope of the present invention.