WO2015182954A1 - Conductive polymer ink composition - Google Patents

Abstract

The present invention relates to a conductive polymer ink composition and a transparent electrode manufactured using the same, wherein the composition comprises 1) an aqueous PEDOT:PSS dispersion, 2) dimethyl sulfoxide, 3) a solvent, 4) a surfactant, and 5) a phosphate compound represented by chemical formula 1. The use of the ink composition according to the present invention makes it possible to form a conductive polymer thin film that is excellent in jetting characteristics, coatability or processability, such as spreadability on the substrate, transmittance, and electrical conductivity.

Description

Conductive Polymer Ink Composition

The present invention relates to a conductive polymer ink composition, and more particularly, to a conductive polymer ink composition excellent in coatability (processability) and conductivity.

PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate)) has high electrical conductivity and transparency, and thus is actively applied to the optoelectronic organic device field. In particular, PEDOT: PSS film can be applied to touch screens, organic light emitting diodes, and electronic papers. For this application, attempts have been made to increase conductivity by using dimethyl sulfoxide, sorbitol, ionic liquids and surfactants.

Meanwhile, various coating methods may be used to form a uniform PEDOT: PSS film. For example, spin coating, bar coating, slot die coating, gravure printing, There are methods such as inkjet printing, spray, and off-set printing. Among these, in order to apply to a printing process, an organic solvent should be added to the PEDOT: PSS ink composition to ensure coating property. That is, in order to make a PEDOT: PSS ink composition capable of a printing process, a solvent having a high boiling point (bp 100 ° C. or more) must be added to the ink, which causes a problem of poor conductivity of the coating film. In particular, in the case of inkjet printing, when a high boiling point solvent is added, the jetting property is improved, the spreadability of the ink is improved, but the conductivity is reduced.

Therefore, there is a need for an ink composition that satisfies both conductivity and coating property (processability).

In order to solve the problems of the prior art, an object of the present invention is to provide an ink composition excellent in coatability (processability) and conductivity.

In order to solve the above problems, the present invention 1) PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate)) aqueous dispersion; 2) dimethyl sulfoxide (DMSO); 3) solvents; It provides a conductive polymer ink composition comprising 4) a surfactant and 5) a phosphate compound represented by the following formula (1).

<Formula 1>

In Chemical Formula 1,

R _1, R ₂ and R ₃ are each independently linear or branched alkyl having 1 to 20 carbon atoms; Linear or branched alkenyl having 1 to 20 carbon atoms; Cycloalkyl having 5 to 60 carbon atoms; Cycloalkenyl having 5 to 60 carbon atoms; And it is selected from the group consisting of carbonyl having 1 to 20 carbon atoms,

When R _1, R _2, and R ₃ are substituted by other substituents, these substituents include an alkyl group having 1 to 30 carbon atoms; Vinyl groups having 2 to 40 carbon atoms; Aryl groups having 6 to 40 carbon atoms; Halogen group; OH (hydroxy) group; Carbonyl group: an alkoxy group having 1 to 30 carbon atoms; Alkoxycarbonyl groups having 1 to 30 carbon atoms; Epoxy groups; And heterocycloalkyl groups having 3 to 40 carbon atoms.

In addition, the present invention provides a transparent electrode including a transparent conductive polymer thin film prepared using the ink composition.

By using the ink composition according to the present invention, it is possible to form a conductive polymer thin film having excellent coating properties such as jetting properties, spreadability on a substrate, and excellent processability and conductivity.

The transparent conductive polymer thin film prepared by using the ink composition according to the present invention has excellent conductivity, and can be used as a transparent electrode to replace ITO, and can be used as an electrode layer or a buffer layer (hole transport layer) of an organic solar cell.

1 is a jetting image of the ink composition of Example 1, a photograph of a drop of the ink drops from the nozzle portion of the top.

2 is a jetting image of the ink composition of Comparative Example 1, and FIG. 3 is a jetting image of the ink composition of Comparative Example 2. FIG.

Hereinafter, the present invention will be described in detail.

The conductive polymer ink composition of the present invention comprises 1) PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate)) aqueous dispersion, 2) dimethyl sulfoxide, 3) solvent, 4) surfactant, and 5) The phosphate compound represented by 1 is included.

<Formula 1>

In Chemical Formula 1,

R _1, R ₂ and R ₃ are each independently linear or branched alkyl having 1 to 20 carbon atoms; Linear or branched alkenyl having 1 to 20 carbon atoms; Cycloalkyl having 5 to 60 carbon atoms; Cycloalkenyl having 5 to 60 carbon atoms; And it is selected from the group consisting of carbonyl having 1 to 20 carbon atoms,

When R _1, R _2, and R ₃ are substituted by other substituents, these substituents include an alkyl group having 1 to 30 carbon atoms; Vinyl groups having 2 to 40 carbon atoms; Aryl groups having 6 to 40 carbon atoms; Halogen group; OH (hydroxy) group; Carbonyl group: an alkoxy group having 1 to 30 carbon atoms; Alkoxycarbonyl groups having 1 to 30 carbon atoms; Epoxy groups; And heterocycloalkyl groups having 3 to 40 carbon atoms.

1) PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate)) The aqueous dispersion means an aqueous dispersion solution containing a PEDOT: PSS polymer or copolymer.

The content of the PEDOT: PSS aqueous dispersion is preferably 10 to 60% by weight, more preferably 20 to 40% by weight based on the total weight of the ink composition. If it is less than 10% by weight, the content of PEDOT: PSS is too low to secure sufficient conductivity, and if it is more than 60% by weight, the spreadability is not good, it is difficult to form a uniform thin film, and the jetting property is poor at ink jetting.

In a preferred embodiment of the present invention, Heraeus PH-1000 was used as the PEDOT: PSS aqueous dispersion.

2) Dimethyl sulfoxide (DMSO) is added to improve the conductivity of the ink composition, the content is preferably 0.5 to 3.0% by weight relative to the total weight of the ink composition. If it is less than 0.5% by weight, the conductivity improvement effect does not appear, and when it exceeds 3.0% by weight, the conductivity of the ink appears to be low and the stability is low.

3) As the solvent, a) DI water and b) polyalcohols can be used.

The a) deionized water serves to disperse the PEDOT: PSS aqueous dispersion, the content of which is preferably 10 to 60% by weight based on the total weight of the ink composition. If the amount of deionized water exceeds 60% by weight based on the total weight of the ink composition, the surface tension of the ink is high, so that the jetting is difficult to spread on the substrate. There is a problem.

The b) polyhydric alcohols may be diethylene glycol, ethylene glycol, propylene glycol, glycerol, sorbitol, and the like, but is not limited thereto. Preferably propylene glycol or glycerol.

The polyhydric alcohols are included in the solvent to improve the dispersibility and conductivity of the ink composition. The content is preferably 5 to 45% by weight with respect to the total weight of the ink composition, when the content exceeds 45% by weight, the conductivity is rather reduced, when less than 5% by weight does not show the effect of improving the conductivity.

As another embodiment of the present invention, the ink composition may further include other solvents to improve the conductivity of the ink composition.

The other solvent may be methanol, ethanol, propanol, and the like, but is not limited thereto.

The content of the other solvents is preferably 1.0 to 10% by weight relative to the total weight of the ink composition, and when the content exceeds 10% by weight, the conductivity decreases, and when the content is less than 1.0% by weight, the conductivity improvement effect does not appear.

 4) The surfactant is included to improve the spreadability of the ink composition, the content is preferably 0.01 to 3.0% by weight relative to the total weight of the ink composition. If it is less than 0.01% by weight, a desired level of spreadability may not be obtained, and if it exceeds 3.0% by weight, the conductivity of the ink may appear.

The surfactant is preferably a nonionic surfactant, but a fluorine-based surfactant is not limited thereto.

The 5) phosphate compound is included to improve processability, such as jetting characteristics of the ink composition, spreadability on a substrate, and may be represented by the following Chemical Formula 1.

<Formula 1>

In Chemical Formula 1,

R _1, R ₂ and R ₃ are each independently linear or branched alkyl having 1 to 20 carbon atoms; Linear or branched alkenyl having 1 to 20 carbon atoms; Cycloalkyl having 5 to 60 carbon atoms; Cycloalkenyl having 5 to 60 carbon atoms; And it is selected from the group consisting of carbonyl having 1 to 20 carbon atoms,

When R _1, R _2, and R ₃ are substituted by other substituents, these substituents include an alkyl group having 1 to 30 carbon atoms; Vinyl groups having 2 to 40 carbon atoms; Aryl groups having 6 to 40 carbon atoms; Halogen group; OH (hydroxy) group; Carbonyl group: an alkoxy group having 1 to 30 carbon atoms; Alkoxycarbonyl groups having 1 to 30 carbon atoms; Epoxy groups; And heterocycloalkyl groups having 3 to 40 carbon atoms.

The R _1, R ₂ and R ₃ may each be a group represented by one of the following structural formula, but is not limited thereto.

The content of the phosphate compound is preferably 0.5 to 20% by weight, more preferably 5 to 15% by weight based on the total weight of the ink composition. If it is less than 0.5% by weight, desired levels of process characteristics and spreadability on the substrate may not be obtained. If it is more than 20% by weight, the conductivity of the ink may appear.

Preferred examples of the phosphate compound include, but are not limited to, triethyl phosphate, tris (2-ethylhexyl) phosphate, trimethyl phosphate, and the like. .

As a method of forming a PEDOT: PSS thin film on a substrate using the ink composition of the present invention, bar coating, spin coating, inkjet printing, spray coating, and the like can be generally used. have. Among them, ink jet printing is preferable because of the advantage of using a small amount of material to directly pattern the desired portion.

The ink composition of the present invention is excellent in jetting properties and spreadability on a substrate by including a phosphate compound, and can be suitably used for inkjet printing.

In addition, the transparent conductive polymer thin film prepared using the ink composition of the present invention greatly improves not only the transmittance but also the conductivity of the PEDOT: PSS thin film.

Another aspect of the invention provides a transparent electrode comprising a transparent conductive polymer thin film prepared using the ink composition.

In addition, another aspect of the present invention provides an organic solar cell including the transparent conductive polymer thin film as a buffer layer or an electrode layer.

Hereinafter, the present invention will be described in more detail with reference to Examples.

<Example 1>

PEDOT: PSS aqueous dispersion solution PH-1000 (Heraeus) 32.9% by weight, DMSO 1.6% by weight, deionized water 32.7% by weight, propylene glycol (Propylene glycol) 19.6% by weight was mixed.

Then, 0.1 wt% of surfactant F-555 (DIC) and 13.1 wt% of triethyl phosphate were added, followed by stirring for 2 hours to prepare an ink composition.

<Example 2>

An ink composition was prepared in the same manner as in Example 1, except that tris (2-ethylhexyl) phosphate (Tris (2-ethylhexyl) phosphate) was used instead of triethyl phosphate.

<Example 3>

An ink composition was prepared in the same manner as in Example 1 except that trimethyl phosphate was used instead of triethyl phosphate.

Comparative Example 1

32.8% by weight of PH-1000, 1.6% by weight of DMSO, 31.1% by weight of deionized water, 12.4% by weight of butyl cellosolve, 18.7% by weight of propylene glycol, 3.3% by weight of glycerol .

Then 0.1-% by weight of F-555 was added, followed by stirring for 2 hours to prepare an ink composition.

Comparative Example 2

32.8 wt% PH-1000, 1.6 wt% DMSO, 37.30 wt% deionized water, 24.9 wt% propylene glycol, 3.3 wt% glycerol were mixed.

Then 0.1-% by weight of F-555 was added, followed by stirring for 2 hours to prepare an ink composition.

<Manufacture example 1>

PEDOT: PSS thin film by spin coating (500 rpm, 9 seconds) using the ink compositions of Example 1 and Comparative Examples 1 to 2, drying on a hot plate at 120 ° C./30 minutes Formed.

<Evaluation of characteristics of the ink composition>

Jetting, Contact Angle and Drop Size Evaluation

Jetting evaluation was performed about the ink compositions of Example 1 and Comparative Examples 1 to 2. Unijet inkjet equipment (UJ200) and SL-128 / 80 Head were used for this purpose (Nozzle number: 128, Drop volume: 80 pL). Evaluate the case of consistently good jetting with Ο, and initially evaluate the case where jetting is good but not discharged over time with △, and evaluate the case of poor jetting with X at the beginning. It is shown in Table 1 below.

In addition, after dropping one drop of the ink composition of Example 1 and Comparative Examples 1 to 2 on the PET film, the drop size was measured, and the results are shown in Table 1 below.

In addition, the contact angle was measured by dropping 0.3 μl of ink on a glass substrate, and the results are shown in Table 1 below. Smaller contact angle means better spreading on the substrate.

<Thin Film Characterization>

The sheet resistance of the PEDOT: PSS thin film prepared in Preparation Example 1 was measured using 4-point-probe, and the results are shown in Table 1 below.

In addition, the thin film properties were evaluated by measuring the transmittance.

Table 1

division	Permeability (%)	Sheet resistance (Ω / □)	Contact angle	Jetting	Drop size (㎛)
Example 1	89.22	269	6.4	Ο	143
Example 2	91.05	483	10.4	Ο	128
Example 3	90.28	409.2	8.2	Ο	135
Comparative Example 1	89.22	508	6.4	Ο	119
Comparative Example 2	89.37	263	17.4	x	x

As shown in Table 1, the ink composition of Comparative Example 2 was poor in jetting property, so that no drop was formed and it did not spread well on the substrate.

In addition, it was found that the thin film prepared by using the ink composition of Comparative Example 1 had a high sheet resistance and low conductivity.

On the other hand, the ink composition of Example 1 according to the present invention was excellent in jetting property and spread well on the substrate, the thin film prepared by using the low sheet resistance and high transmittance.

In particular, the ink compositions of Examples 2 and 3 exhibited sheet resistance of 400 to 500 kPa / square level at the transmittance of 90 to 91%.

1 is a jetting image of the ink composition of Example 1, and FIG. 2 is a jetting image of the ink composition of Comparative Example 1. FIG. Using the ink compositions of Example 1 and Comparative Example 1 with reference to Figures 1, 2 it can be confirmed that the ink droplets are formed well off the nozzle.

3 is a jetting image of the ink composition of Comparative Example 2. FIG. When using the ink composition of Comparative Example 2 with reference to Figure 3 it can be seen that the ink droplets are not well formed during jetting, the nozzle is clogged as shown in the right picture is not discharged when jetting is continued.

From the above evaluation, it was confirmed that according to the present invention, an ink composition having excellent processability in the inkjet process can be prepared, and a transparent transparent polymer thin film having excellent transmittance and conductivity can be prepared using the same.

Claims (14)

1) PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (styrenesulf onate)) aqueous dispersion, 2) dimethyl sulfoxide, 3) solvent, 4) surfactant and 5) phosphate compound represented by the following formula (1) Conductive polymer ink composition comprising:

<Formula 1>

In Chemical Formula 1,

R _1, R ₂ and R ₃ are each independently linear or branched alkyl having 1 to 20 carbon atoms; Linear or branched alkenyl having 1 to 20 carbon atoms; Cycloalkyl having 5 to 60 carbon atoms; Cycloalkenyl having 5 to 60 carbon atoms; And it is selected from the group consisting of carbonyl having 1 to 20 carbon atoms,

When R _1, R _2, and R ₃ are substituted by other substituents, these substituents include an alkyl group having 1 to 30 carbon atoms; A vinyl group having 2 to 40 carbon atoms: an aryl group having 6 to 40 carbon atoms; Halogen group; OH (hydroxy) group; Carbonyl group: an alkoxy group having 1 to 30 carbon atoms; Alkoxycarbonyl groups having 1 to 30 carbon atoms; Epoxy groups; And heterocycloalkyl groups having 3 to 40 carbon atoms.

The conductive polymer according to claim 1, wherein the content of 1) PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate)) aqueous dispersion is 10 to 60% by weight based on the total weight of the ink composition. Ink composition.

The conductive polymer ink composition of claim 1, wherein the content of 2) dimethyl sulfoxide (DMSO) is 0.5 to 3.0% by weight based on the total weight of the ink composition.

The conductive polymer ink composition of claim 1, wherein the solvent 3) is a) deionized water and b) polyhydric alcohols.

The conductive polymer ink composition of claim 4, wherein the content of a) deionized water is 10 to 60% by weight based on the total weight of the ink composition.

The conductive polymer ink composition of claim 4, wherein the b) polyhydric alcohols are 5 to 45 wt% based on the total weight of the ink composition.

The conductive polymer ink composition of claim 4, wherein the solvent further comprises methanol, ethanol or propanol as other solvents.

The conductive polymer ink composition of claim 7, wherein the content of the other solvent is 1.0 to 10% by weight based on the total weight of the ink composition.

The conductive polymer ink composition of claim 1, wherein the content of the surfactant is 0.01 to 3.0% by weight based on the total weight of the ink composition.

The conductive polymer ink composition of claim 1, wherein the content of the 5) phosphate compound is 0.5 to 20% by weight based on the total weight of the ink composition.

The conductive polymer ink composition of claim 1, wherein R _1, R _2, and R ₃ are each a group represented by one of the following structural formulas:

The conductive polymer ink composition of claim 1, wherein the conductive polymer ink composition forms a transparent conductive polymer thin film by inkjet printing.

Transparent electrode comprising a transparent conductive polymer thin film prepared using the ink composition of claim 1.

An organic solar cell comprising a transparent conductive polymer thin film prepared using the ink composition of claim 1 as a buffer layer or an electrode layer.

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