WO2015190727A1

WO2015190727A1 - Conductive polymeric ink composition

Info

Publication number: WO2015190727A1
Application number: PCT/KR2015/005395
Authority: WO
Inventors: 김미경
Original assignee: 주식회사 엘지화학
Priority date: 2014-06-13
Filing date: 2015-05-29
Publication date: 2015-12-17

Abstract

The present invention relates to a conductive polymeric ink composition and, more specifically, to a pH-adjusted conductive polymeric ink composition, characterized in that the pH of the ink composition is adjustable to a desired range by increasing the pH of the ink composition to neutral while maintaining the dispersibility of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), which is a main component of the ink composition, thereby solving problems, such as shortening the lifespan of devices due to strong acid, and a transparent conductive polymer thin film manufactured using the ink composition has a lower haze value than thin films manufactured by existing methods, and retains excellent electrical conductivity due to low sheet resistance.

Description

Conductive Polymer Ink Composition

The present invention is to increase the pH of the ink composition to neutral while maintaining the dispersibility of the conductive polymer ink composition, more specifically, PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate)) which is the main component of the ink composition By adjusting the pH to a desired range, it is possible to solve problems such as shortening the life of the device due to strong acidity, and the transparent conductive polymer thin film manufactured by using the ink composition is a thin film prepared by the conventional method. It relates to a pH-adjusted conductive polymer ink composition, characterized in that the haze (Haze) value can be lowered and the sheet resistance is low compared to the excellent conductivity.

PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate)) is highly applied to the optoelectronic organic device field because of its high electrical conductivity and transparency. 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.

In addition, PEDOT: PSS is intended to be used as a hole transport layer for transparent electrodes, organic photovoltaics (OPV), organic light emitting diode (OLED), etc. In this case, PEDOT: PSS has a strong acidity (pH 1 ~ 2). There is a problem that the life of the device is shortened, and the disadvantages such as corrosion of the equipment may appear. In order to solve this problem, there have been attempts to adjust the pH of PEDOT: PSS to neutrality by adding a strong basic solution such as ammonia water or sodium hydroxide (NaOH), but in this case, the dispersion of PEDOT: PSS is broken, causing rapid There was a problem that could cause a drop in conductivity. Therefore, there is a need for a study on how to increase the pH to neutral without breaking the dispersion of PEDOT: PSS.

In order to solve the problems of the prior art, an object of the present invention is to provide an ink composition excellent in conductivity that can increase the pH of the ink composition to neutral while maintaining the dispersibility of PEDOT: PSS, the main component of the ink composition. .

In order to solve the above problems, the present invention

a) neutralizing a PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate)) aqueous solution by mixing an amine compound and an organic solvent phase-separated from water;

b) phase-separating the mixed solution of step a) into an aqueous layer of a lower layer comprising a neutralized PEDOT: PSS aqueous dispersion and an organic layer of an upper layer comprising an amine compound and an organic solvent;

c) removing the upper organic layer; And

It provides a method for producing a neutralized PEDOT: PSS aqueous dispersion comprising a; d) washing with the addition of an organic solvent to the water layer from which the organic layer has been removed, and removing the organic layer to obtain a neutralized PEDOT: PSS aqueous dispersion.

In addition, the present invention provides a neutralized PEDOT: PSS aqueous dispersion, characterized in that prepared by the above production method.

In addition, the present invention provides a conductive polymer ink composition comprising 1) PEDOT: PSS aqueous dispersion neutralized by the preparation method, 2) dimethyl sulfoxide, 3) solvent and 4) surfactant.

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

In addition, the present invention provides an organic light emitting diode comprising a transparent conductive polymer thin film prepared using the ink composition as a buffer layer, an electrode layer or a hole transport layer.

The present invention also provides an organic solar cell including the transparent conductive polymer thin film manufactured using the ink composition as a buffer layer, an electrode layer or a hole transport layer.

By using the ink composition containing the neutralized PEDOT: PSS aqueous dispersion according to the present invention, it is possible to increase the pH of the ink composition to neutral while maintaining the dispersibility of PEDOT: PSS, thereby controlling the pH to a desired level. Therefore, it is possible to solve problems such as shortening the life of the device or corrosion of equipment due to strong acidity. In addition, because of the scattering characteristics of light on the substrate, haze (Haze) value can be lowered and the sheet resistance value is also lowered, thereby forming a conductive polymer thin film having excellent conductivity.

Therefore, 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, a buffer layer, or a hole transport layer of an organic solar cell.

1 is a view showing the step of separating the organic layer and the water layer in the method for producing a neutralized PEDOT: PSS aqueous dispersion of the present invention.

Hereinafter, the present invention will be described in detail.

The present invention relates to a method for providing an ink composition having excellent conductivity capable of increasing the pH of an ink composition to neutrality while maintaining the dispersibility of PEDOT: PSS, which is a main component of the ink composition, and specifically, a neutralized PEDOT: PSS aqueous dispersion. The manufacturing method of

c) removing the upper organic layer; And

and d) washing the organic layer by adding an organic solvent to the water layer from which the organic layer has been removed, and removing the organic layer to obtain a neutralized PEDOT: PSS aqueous dispersion.

The PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate)) aqueous dispersion is a polymer mixture composed of PEDOT and an ionomer called PSS, which is a charged macromolecular salt, that is, a conductive polymer material. When the hole transport layer is manufactured in the organic solar cell using the conductive polymer material, when the energy barrier occurs at the metal (electrode) -semiconductor contact, the hole transport layer serves as a buffer layer between the barriers and facilitates the movement of holes. do. In addition, the lower electrode layer and the active layer serves to make the inorganic and organic contact more smoothly. However, in the PEDOT: PSS aqueous dispersion, PSS is an acidic material, and there is a problem in that the lower electrode layer (eg, ITO) component of the organic solar cell is corroded (or etched), thereby shortening the life of the organic solar cell. There is a problem. Therefore, when the acidic hole transport layer composition is adjusted to neutral pH using a basic material, it is possible to prevent damage to the lower electrode layer, resulting in an effect of extending the life of the organic solar cell. However, if the pH of the PEDOT: PSS is adjusted to neutral by adding a basic solution, there may be a problem in that the dispersion of PEDOT: PSS is broken and a sharp drop in conductivity may appear. Therefore, the present inventors conducted a study on a method for increasing the pH to neutral without breaking the dispersion of PEDOT: PSS, and completed the present invention.

Specifically, in the method for preparing the neutralized PEDOT: PSS aqueous dispersion of the present invention, to adjust the pH of the PEDOT: PSS aqueous dispersion to neutral, a strong basic substance such as ammonia water or sodium hydroxide (NaOH) may be directly added. In the method of addition, the amine compound which is a kind of basic substance can be added indirectly. The addition method is to add the amine compound together with the organic solvent which is phase separated from water, so as not to directly affect the PEDOT: PSS layer. The added amine compound may be at least one selected from the group consisting of a primary amine compound, a secondary amine compound, a tertiary amine compound and a pyridine compound, and specifically, the amine compound may be triethylamine. , 3,5-lutidine and 3,5-lutidine and 2,4,6-trimethylpyridine may be one or more selected from the group consisting of.

In addition, the organic solvent phase-separated from water added to phase-separate into the water layer of the lower layer containing the PEDOT: PSS aqueous dispersion and the organic layer of the upper layer containing the amine compound and the organic solvent, the specific gravity of the water is different and can be separated from water. An organic solvent can be used. The organic solvent may also be a single solvent or a mixed solvent. As an example of the organic solvent, diethyl ether may be used. The organic solvent serves to physically separate the two layers.As a result, the amine compound is more soluble in the organic solvent than water, so that a large amount of the added amine compound stays in the organic layer, and the amine compound is present only at the interface between the organic layer and the water layer. Meet with the water layer (PEDOT: PSS). The amine compound may be dissolved in a small amount in water. The content of the organic solvent of step a) may be 50 to 500 parts by weight based on 100 parts by weight of the PEDOT: PSS aqueous dispersion, and when the content of the organic solvent is in the above range, the concentration of the amine compound may be maintained at an appropriate level. In addition, PEDOT: neutralizes under conditions that do not impair the dispersibility of PPS. If the content of the organic solvent is less than the above-described range, the amine compound may directly affect the PEDOT: PSS layer to break up the dispersion, thereby causing a problem of low conductivity.

In addition, the concentration of the organic layer of the amine compound of step a) is preferably included to be 0.1 to 50% by weight. When the content of the amine compound is in the above range, it is possible to adjust the pH without affecting the dispersibility of PEDOT: PSS.

In addition, in the method for preparing the neutralized PEDOT: PSS aqueous dispersion, the mixing time of step a) is preferably 5 minutes to 24 hours, more preferably 30 minutes to 4 hours. The mixing time can vary depending on the concentration.

The method of mixing the phase-separated water layer and the organic layer may be a method of physically mixing, a specific example may be mixed in a shaker, or by adding a magnetic bar, stirring using a vortex, etc. It is not limited to this.

Thereafter, the organic layer, which is the upper layer, is removed, and the organic solvent is removed by adding an organic solvent to the water layer from which the organic layer is removed. A dispersion can be obtained.

A part of the water layer may be lost in the process of removing the organic layer, and thus the content of the finally obtained PEDOT: PSS aqueous dispersion may be 70 to 90 parts by weight based on 100 parts by weight of the initially introduced PEDOT: PSS aqueous dispersion. .

Thereafter, a method of further removing the remaining organic solvent and the amine compound may be further included.

In addition, the present invention provides a neutralized PEDOT: PSS aqueous dispersion, characterized in that produced by the above production method. The neutralized PEDOT: PSS may be included in an amount of 0.001 to 3.0% by weight, and more preferably 0.01 to 1.0% by weight, based on the total weight of the aqueous dispersion.

The neutralized PEDOT: PSS aqueous dispersion prepared by the method of one embodiment of the present invention has a small amount of the amine compound in the PEDOT: PSS aqueous dispersion after neutralization, compared to the case where the amine compound is directly added to the ink composition, so that PEDOT: PSS Dispersibility can be maintained, and thus pH can be increased to neutral when prepared with the ink composition, so that the pH can be adjusted to a desired level. In addition, when the neutralized PEDOT: PSS aqueous dispersion according to the present invention is used as the ink composition, the haze value that appears hazy due to the light scattering characteristics of the substrate can be lowered. It is low and can exhibit an excellent effect of conductivity.

In addition, the present invention relates to a pH controlled conductive polymer ink composition, wherein the conductive polymer ink composition is 1) neutralized PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly ( styrenesulfonate)) aqueous dispersion, 2) dimethyl sulfoxide (DMSO), 3) solvent and 4) surfactant.

1) The neutralized PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate)) aqueous dispersion means an aqueous dispersion solution containing a PEDOT: PSS polymer or copolymer, and is used in the present invention. The PSS aqueous dispersion is characterized by using PEDOT: PSS aqueous dispersion which has undergone the above neutralization step.

The content of the PEDOT: PSS aqueous dispersion is preferably 10 to 60% 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. If it is more than 60% by weight, the spreadability is not good, and 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 0.3 to 5.0% by weight relative to the total weight of the ink composition. When the amount is less than 0.3 wt%, the conductivity improvement effect is not observed. When the amount is more than 5.0 wt%, the conductivity of the ink is decreased 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 relative to 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 and difficult to jet, and when the content is less than 10% by weight, it is not suitable as an inkjet ink. 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 1 to 45% by weight based on the total weight of the ink composition, when the content exceeds 45% by weight, the conductivity is rather reduced, and when the content is less than 1% by weight, the conductivity improvement effect does not appear.

In another embodiment of the present invention, the ink composition may further include other solvents to improve the process characteristics (jetting characteristics) and conductivity of the ink composition.

The other solvent may be an organic solvent butyl carbitol or triethyl phosphate, but is not limited thereto.

The content of the other solvent butyl carbitol or triethyl phosphate is preferably 1.0 to 40% by weight based on the total weight of the ink composition, when the content exceeds 40% by weight rather the fairness is reduced, less than 1.0% by weight fairness There is no improvement.

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. If it exceeds 3.0% by weight, the conductivity of the ink may appear.

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

The pH of the conductive polymer ink composition is preferably 4.0 to 10.0, more preferably 5.0 to 8.0. When the pH is in the above range, the pH of the ink composition can be adjusted to a desired range while maintaining the dispersibility of the ink composition, so that the lower electrode layer is damaged by strong acidity, which shortens the life of the device or corrodes the equipment. You can solve the problem. When the ink composition pH is less than 4.0, the acidity may cause high damage to the lower electrode layer, and when the pH exceeds 10.0, the hole transport layer may be impeded from transporting holes, thereby reducing energy conversion efficiency when used in an organic solar cell. .

As a method of forming a PEDOT: PSS thin film on a substrate using the ink composition of the present invention, slot die coating, bar coating, spin coating, inkjet printing are commonly used. printing), spray coating and the like can be used. Inkjet printing is preferred because of the advantage of being able to pattern directly where desired, using a small amount of material.

In addition, the transparent conductive polymer thin film by inkjet printing prepared using the ink composition of the present invention is excellent in the transmittance as well as 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 light emitting diode (OLED) including the transparent conductive polymer thin film as a buffer layer, an electrode layer or a hole transport layer.

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

Hereinafter, preferred examples are provided to help the understanding of the present invention, but the following examples are merely for exemplifying the present invention, and various changes and modifications within the scope and spirit of the present invention are apparent to those skilled in the art. It goes without saying that changes and modifications belong to the appended claims.

To 4.5 g of PEDOT: PSS aqueous solution PH-1000 (Heraeus), 4.5 g of diethyl ether and 0.055 g of triethylamine were added. The organic layer was removed after mixing for 2 hours to mix the water layer and the organic layer. 4.5g of diethyl ether was added to wash the water layer and the organic layer was poured out. After repeating the process of washing the water layer 2 to 3 times was able to obtain a neutralized PEDOT: PSS aqueous dispersion. The triamine, which is an amine compound, in 4.2 g of the neutralized PEDOT: PSS aqueous solution thus obtained was measured to contain 0.017 g. To 4.2 g of the neutralized PEDOT: PSS aqueous dispersion solution, 0.21 g of DMSO, 4.2 g of DI water, 2.52 g of propylene glycol, 1.68 g of butyl carbitol and 0.008 g of surfactant F-555 (DIC) were added, followed by stirring. PSS ink compositions were prepared.

A PEDOT: PSS ink composition was prepared in the same manner as in Example 1, except that 2,4,6-trimethylpyridine was added instead of triethylamine as an amine compound, of which neutralized PEDOT: PSS aqueous solution was 4.2g 2,4,6-trimethylpyridine was determined to contain 0.016g.

Comparative Example 1

To 4 g of PEDOT: PSS aqueous solution PH-1000 (Heraeus), 0.2 g of ammonia water was added and stirred for 2 hours. Then 0.2 g DMSO, 4 g DI water, 2.4 g propylene glycol, 1.6 g butyl carbitol and surfactant F-555 (DIC)

After adding 0.006 g, the mixture was stirred to prepare a PEDOT: PSS ink composition.

Comparative Example 2

PEDOT: 4 g of PH-1000 (Heraeus), an aqueous solution of PDS, 0.2 g of DMSO, 4 g of DI water, 2.4 g of propylene glycol, 1.6 g of butyl carbitol and surfactant F-555 (DIC)

Comparative Example 3

After adding 0.006 g, it was stirred for 2 hours. Thereafter, 0.3 g of 3,5-diethylpyridine was further added and stirred to prepare a PEDOT: PSS ink composition.

Table 1 shows the amounts of amine compounds contained in the PEDOT: PSS aqueous dispersion neutralized in Examples 1 and 2 and Comparative Example 3, respectively. The neutralized PEDOT: PSS aqueous dispersions of Examples 1 and 2 prepared by the method of the present invention as described below were compared to Comparative Example 3 in which the amine compound was added directly to the ink composition, and then neutralized in the PEDOT: PSS aqueous dispersion after neutralization. By remaining of the trace amount, the dispersibility of PEDOT: PSS can be maintained, and thus the pH can be increased to neutral when prepared with the ink composition, so that the pH can be adjusted to a desired level. In addition, when the neutralized PEDOT: PSS aqueous dispersion according to the present invention is used as the ink composition, the haze value that appears hazy due to the light scattering characteristics of the substrate can be lowered. It is low and can exhibit an excellent effect of conductivity.

Table 1

	Type of amine compound	Amine Compound / Neutralized PEDOT: PSS Aqueous Dispersion Content (g)
Example 1	Triethylamine	0.017 / 4.2
Example 2	2,4,6-trimethylpyridine	0.016 / 4.2
Example 3	3,5-diethylpyridine	0.3 / 4.3

Spin coating (500 rpm, 9 seconds) using the ink compositions of Examples 1 to 2 and Comparative Examples 1 to 3, followed by drying on a hot plate at 120 ° C./30 minutes to form a PEDOT: PSS thin film. Formed.

pH measurement evaluation

The ink compositions of Examples 1 to 2 and Comparative Examples 1 to 3 were subjected to pH measurement evaluation using a Jenway Model 430 portable pH / conductivity meter.

For each PEDOT: PSS thin film prepared in the preparation example, the sheet resistance was measured using 4-point-probe, and the results are shown in Table 2 below.

In addition, the thin film properties were evaluated through the transmittance and Haze measurement.

TABLE 2

As shown in Table 2, the ink compositions of Examples 1 and 2 according to the present invention were able to make the ink neutral without breaking the dispersion of PEDOT: PSS, and the thin film prepared using the same had low sheet resistance and high permeability, Because of the scattering properties of the light on the substrate, haze values that look hazy can be lowered.

On the other hand, in the ink composition of Comparative Example 1 using ammonia water as the basic substance, the dispersion of PEDOT: PSS was broken and a polymer mass was observed. In the ink composition of Comparative Example 2, in which the amine compound was not added, the pH was measured to be acidic.

In addition, the ink composition of Comparative Example 3 in which the amine compound was added directly to the ink composition showed an effect of increasing pH, and no agglomerate was observed, but the thin film prepared using the same showed a large decrease in conductivity due to large sheet resistance. .

From the above evaluation, the ink composition according to the present invention can adjust the pH of the ink composition to a desired level while maintaining the dispersibility of PEDOT: PSS, it is possible to produce an ink composition excellent in processability during the inkjet process, and transmittance and conductivity It was confirmed from the above results that an excellent and uniform transparent conductive polymer thin film can be prepared.

Claims

a) neutralizing a PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate)) aqueous solution by mixing an amine compound and an organic solvent phase-separated from water;

b) phase-separating the mixed solution of step a) into an aqueous layer of a lower layer comprising a neutralized PEDOT: PSS aqueous dispersion and an organic layer of an upper layer comprising an amine compound and an organic solvent;

c) removing the upper organic layer; And

d) a method of preparing a neutralized PEDOT: PSS aqueous dispersion, comprising the steps of: washing an organic solvent by adding an organic solvent to the water layer from which the organic layer has been removed, and removing the organic layer to obtain a neutralized PEDOT: PSS aqueous dispersion.
The neutralized PEDOT: PSS aqueous dispersion according to claim 1, wherein the amine compound is at least one selected from the group consisting of a primary amine compound, a secondary amine compound, a tertiary amine compound, and a pyridine compound. Method of preparation.
The method of claim 2, wherein the amine compound is a group consisting of triethylamine, 3,5-lutidine and 2,4,6-trimethylpyridine. Method for producing a neutralized PEDOT: PSS aqueous dispersion, characterized in that at least one selected from.
The method according to claim 1, wherein the organic solvent is diethyl ether, characterized in that the method for producing a neutralized PEDOT: PSS aqueous dispersion.
The method according to claim 1, wherein the content of the organic solvent of step a) is 50 to 500 parts by weight based on 100 parts by weight of PEDOT: PSS aqueous dispersion, the method of producing a neutralized PEDOT: PSS aqueous dispersion.
The method according to claim 1, wherein the concentration of the organic layer of the amine compound of step a) is characterized in that it comprises 0.1 to 50% by weight, the method of producing a neutralized PEDOT: PSS aqueous dispersion.
A neutralized PEDOT: PSS aqueous dispersion, which is prepared by the process of claim 1.
The neutralized PEDOT: PSS aqueous dispersion according to claim 7, wherein the neutralized PEDOT: PSS aqueous dispersion comprises 0.001 to 3.0 wt% of the amine compound based on the total weight of the neutralized PEDOT: PSS aqueous dispersion.
1) A conductive polymer ink composition comprising the neutralized PEDOT: PSS aqueous dispersion of claim 7, 2) dimethyl sulfoxide (DMSO), 3) solvent and 4) surfactant.
The conductive polymer ink composition of claim 9, wherein the content of 1) the neutralized PEDOT: PSS aqueous dispersion is 10 to 60% by weight based on the total weight of the ink composition.
The conductive polymer ink composition of claim 9, wherein the content of 2) dimethyl sulfoxide is 0.3 to 5.0 wt% based on the total weight of the ink composition.
The conductive polymer ink composition of claim 9, wherein the 3) solvent comprises a) deionized water and b) polyhydric alcohols.
The conductive polymer ink composition of claim 12, wherein the b) polyhydric alcohols are 1 to 45 wt% based on the total weight of the ink composition.
The conductive polymer ink composition according to claim 9, wherein the content of the surfactant 4) is 0.01 to 3.0% by weight based on the total weight of the ink composition.
The conductive polymer ink composition of claim 9, wherein the pH of the conductive polymer ink composition is 4.0 to 10.0.
Transparent electrode comprising a transparent conductive polymer thin film manufactured using the ink composition of claim 9.
An organic light emitting diode comprising a transparent conductive polymer thin film prepared using the ink composition of claim 9 as a buffer layer, an electrode layer or a hole transport layer.
An organic solar cell comprising a transparent conductive polymer thin film prepared using the ink composition of claim 9 as a buffer layer, an electrode layer or a hole transport layer.