KR20090112894A - Organic Electrode Composition - Google Patents

Abstract

The present invention relates to a composition for an organic electrode, 100 parts by weight of an aqueous dispersion of polyethylenedioxythiophene having a polystyrene sulfonate doped in a 1 to 3 molar ratio and having a solids content of 1 to 3% by weight, an amide solvent, a furan solvent, and a sulfoxide. The composition for organic electrodes which consists of 1-50 weight part of system solvents or these mixed solvents, and 0.001-1 weight part of surfactants is provided.

The present invention, the composition for an organic electrode can significantly improve the economics and productivity of the manufacturing process compared to the metal oxide electrode using a conventional vacuum process. In addition to the transparent electrode for display, the electrode manufactured by this electrode is an organic transistor electrode, wiring material, smart card. It is useful because it can be widely applied to various fields such as electrodes of antennas, cells and fuel cells, capacitors or inductors for PCBs, electromagnetic shielding, sensors, touch screens, and flexible displays.

Description

Composition for organic electrodes

The present invention relates to a composition for organic electrodes, particularly a composition for organic electrodes that can be used in a transparent conductive film or pattern.

As a method of manufacturing transparent electrodes widely used in electronic devices including flat panel displays, chemical vapor deposition using spontaneous metal oxides such as indium, tin, zinc, titanium, and cesium, especially indium tin oxide, sputtering, and reactive evaporation It is used.

Since materials such as ITO are rare metals, they are expensive, and in order to coat a substrate, process conditions such as vacuum conditions are difficult and expensive equipment is required, and a high heat treatment temperature of 200 ° C. or more is required. Expensive process costs must be invested. In addition, in order to form a desired pattern, a subtractive method (ie, a resist film such as photolithography, a complex, expensive and waste-prone process such as exposure and etching, etc.) may be used. You have to go through.

In the plastic substrate of the flexible display which can be folded and rolled like newspapers or thin magazines, which are needed in recent years, and are portable and easy to carry, the inorganic materials for transparent electrode in the form of metal oxides are It is difficult to apply because of low flexibility, complicated process and high cost.

As a method for manufacturing a transparent electrode that does not require high cost, a method of using a conductive polymer has also emerged to apply the transparent electrode to a flexible display. In the case of an electrode manufactured by using a conductive polymer, various existing polymer coating methods can be used, thereby greatly reducing the process cost. In addition, the organic-based transparent electrode may be manufactured by an inkjet method, which is one of an additive method, which is an environmentally friendly process of reducing process cost and reducing waste by reducing process shortening and material loss during pattern formation. Therefore, research and development of organic-based electrode compositions using conductive polymers such as polyacetylene, polypyrrole, polythiophene, polyphenylenevinylene, polyphenylene, polysilane, polyfluorene, and polyaniline have been made.

However, in spite of these attempts, the conductive polymer generally absorbs light in the visible light region, and there is a problem that the conductivity of the organic electrode made of the conductive polymer is low. When the conductive film is thinly coated to increase the transmittance, the sheet resistance increases, which makes it difficult to apply to applications of transparent electrodes such as touch panels and flexible displays.

In view of this point, the present invention is to provide a composition for an organic electrode that the coating film has a transmittance of 80% or more and a sheet resistance of several hundred kPa / square or less and can be applied to an actual electronic device.

In addition, the present invention is to provide a composition capable of producing an organic transparent electrode by ink jet printing.

According to the present invention, 100 parts by weight of an aqueous dispersion of polyethylenedioxythiophene doped with polystyrenesulfonate at a molar ratio of 1 to 3 and a solids content of 1 to 3% by weight, an amide solvent, a furan solvent, a sulfoxide solvent and their The composition for organic electrodes which consists of 1-50 weight part of solvents chosen from the group which consists of mixtures, and 0.001-1 weight part of surfactants is provided. When the polyethyleneoxythiophene-based conductive polymer aqueous dispersion and a surfactant doped with polystyrene sulfonate are mixed with a amide solvent, a sulfoxide solvent, or a mixed solvent thereof, the conductive polymer particles in the conductive polymer aqueous dispersion are nanoscaled. By fine phase separation, highly conductive and highly transparent organic electrodes can be prepared. When the composition is spin-coated and dip-coated (roll-to-roll) or slot die wet coating (roll-to-roll) on a transparent substrate, the visible light region transmittance of the organic conductive film may be 80% or more and a sheet resistance of 250 to 900 kW / square.

The composition for an organic electrode of the present invention is mixed with the composition components and then treated several times at a rotational speed of 10,000 to 20,000 rpm for about 10 minutes with a homogenizer, and then in a few minutes with an ultrasonic generator having a power of 60 to 200 W near a frequency of 40,000 Hz. Prepare by dispersing for several hours. The composition for organic electrodes is coated on a transparent substrate, dried, and coated to a thickness of 0.2 to 2 µm. The material of the transparent substrate is, for example, glass, polyester, polyamide, polycarbonate, polystyrene, polypropylene, polyethylene, polyvinylchloride or polyacrylate, preferably polyester terephthalate (PET).

The polyethylene dioxythiophene (PEDOT) -based conductive polymer aqueous dispersion is a form in which an ethylene dioxythiophene oligomer having a repeating unit of about 5 is dispersed in a polystyrene sulfonate (PSS) gel of several tens of nanometers in size, and polyethylene in the aqueous dispersion The concentration of dioxythiophene and polystyrenesulfonate solids is preferably in an amount of 0.3 to 0.8% by weight of polyethylenedioxythiophene and 0.8 to 2.2% by weight of polystyrenesulfonate based on the total weight of the aqueous dispersion. In the method for preparing a conductive polymer aqueous dispersion according to the present invention, water and polystyrene sulfonate (PSS) are first introduced into a reaction vessel. At this time, the concentration of polyethylenedioxythiophene and polystyrenesulfonate solids is 1 to 3% by weight based on the total weight of the aqueous dispersion, and the polyethylenedioxythiophene and polystyrenesulfonate molar ratio is 1: 1 to 1: 3, and polystyrene sulfo Nate is 0.5 to 2.0% by weight. In order to prevent side reactions caused by oxygen present in the raw materials while stirring at several hundred rpm at room temperature, a nitrogen treatment is carried out for several minutes, preferably at least 30 minutes, and then an oxidizing agent such as Na ₂ S ₂ O ₈ is 0.8 to 0.9. The amount of the weight percent is added, followed by several minutes, preferably at least 30 minutes of nitrogen treatment, and then about 0.3 to 0.5% by weight of ethylenedioxythiophene and about 0.005 to 0.01% by weight of Fe ₂ (SO ₄ ) ₃ for a fixed time. It is possible to make the color lighter and make the particles smaller while keeping constant by injecting and reacting for 12 hours. Nitrogen is continuously added during the reaction time.

On the other hand, the solvent used in the present invention is excellent in affinity with the polystyrene sulfonate which is a dopant constituting the conductive polymer nanoparticle gel to easily swell the gel. As the amide solvent, N, N-dimethylformamide, N-methylpyrrolidone, or the like may be used. Dimethyl sulfoxide and the like are used as the sulfoxide solvent. Such solvent is used based on 100 parts by weight of the polyethylene dioxythiophene aqueous dispersion, 1 to 50 parts by weight of an amide solvent, a furan solvent, a sulfoxide solvent or a mixed solvent thereof. If such a solvent is added in an amount of less than 1 part by weight, the effect of the added solvent may be insignificant to obtain a desirable result in permeability and surface resistance. If it is more than 50 parts by weight, the concentration of the conductive polymer is low, which is desirable in transparency and surface resistance. No results are obtained.

In the present invention, the surfactant serves to stabilize the conductive polymer particles of the present invention by fine phase separation at a nanoscale. The surfactant can be both nonionic, anionic and cationic. The surfactant also serves to improve the wetting properties when the composition for organic electrodes of the present invention is coated on a transparent substrate. As the non-ionic surfactant, for example, polyoxyalkylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyalkylene alkylphenyl ethers including polyoxy ethylene nonylphenyl ether and the like, sorbitan triol Polyoxyalkylene fatty acid esters including sorbitan fatty acid esters including ate and the like, polyoxyalkylene sorbitan fatty acid esters including polyoxyethylene sorbitan monolaurate and the like, polyoxyethylene monostearate and the like Glycerin fatty acid esters including stearic acid monoglycerides, polyoxyethylene-polypropylene block copolymers, and the like, and anionic surfactants include fatty acid salts including sodium laurate, sodium dodecylbenzene, and the like. Alkyl aryl sulfonates, sodium lauryl sulfide, including sulfonate, etc. Alkylsulfosuccinic ester salts including sodium sulfate, sodium monooctylsulfosuccinate, sodium dioctylsulfosuccinate, sodium polyoxyethylene laurylsulfosuccinate, and the like, sodium polyoxyethylene Polyoxyalkylene alkyl ether sulfuric acid ester salts including uryl ether sulfate and the like, polyoxyalkylene alkylaryl ether sulfuric acid ester salts including sodium polyoxyethylene nonylphenyl ether sulfate and the like can be used. As cationic surfactants and amphoteric surfactants, alkylamine salts including laurylamine acetate and the like, quaternary ammonium salts including lauryltrimethylammonium chloride, alkylbenzyldimethylammonium chloride and the like, polyoxyethylenealkyl-amines, etc. may be used. Can be.

The surfactant of the present invention is preferably a fluorine-based surfactant. Fluorine-based surfactants are those in which some hydrogen atoms of a hydrocarbon straight chain are substituted with fluorine, and thus cationic, anionic and nonionic compounds are possible depending on functional groups. Fluorine-based surfactants include R _f CH ₂ CH ₂ SCH ₂ CH ₂ CO ₂ Li, (R _f CH ₂ CH ₂ O) P (O) (ONH ₄ ) ₂ , (R _f CH ₂ CH ₂ O) ₂ P ( O) (ONH ₄ ), R _f CH ₂ CH ₂ O (CH ₂ CH ₂ O) _y H, R _f CH ₂ CH ₂ SO ₃ X, R _f CH ₂ CH ₂ NHSO ₃ X or mixtures thereof Wherein _y is an integer from 8 to 15, X is H or NH ₄ , R _f is F (CF ₂ CF ₂ ) _z , where _z is an integer from 3 to 8).

In the present invention, the surfactant is used in 0.001 to 1 parts by weight based on 100 parts by weight of the polyethylene dioxythiophene aqueous dispersion. When added in an amount of less than 0.001 parts by weight, there may be a problem in the uniformity of the composition for the organic electrode, the wettability is poor, the film formation is not uniform. In addition, since the surface tension is high, tailing may occur during jetting using the inkjet, and the contact angle is large, and thus the pattern tends to be narrowed upon firing. When added in an amount of more than 1 part by weight, the surfactant and the conductive polymer nanoparticles may be phase-separated to form an opaque film. The surface tension may be low, causing floating during jetting, and the contact angle is small, making pattern formation difficult. .

The composition for an organic electrode of the present invention is capable of batch spin coating or ink jet printing capable of forming a pattern, and in particular, a dip coating (roll-to-roll) capable of continuously producing can be used for a large-area flexible material having excellent conductivity and permeability. A transparent organic electrode can be manufactured. Compared to the metal oxide electrode using the conventional vacuum process, the economics and productivity of the manufacturing process can be significantly improved. In addition to the transparent electrode for display, the electrode manufactured by this electrode is an organic transistor electrode, wiring material, smart card. It is useful because it can be widely applied to various fields such as electrodes of antennas, cells and fuel cells, capacitors or inductors for PCBs, electromagnetic shielding, sensors, touch screens, and flexible displays.

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

Production Example

Conductive Polymer Aqueous Dispersion

Ethylenedioxythiophene (EDOT, Aldrich) is polymerized in the presence of polystyrenesulfonate (PSS, 18%, Aldrich) in a 1: 2 molar ratio. At this time, water and polystyrene sulfonate (PSS) were first added and stirred at 350 rpm, followed by nitrogen treatment for at least 30 minutes to prevent side reactions caused by oxygen present in the raw materials, and then the initiator (oxidizing agent) was Na ₂ S ₂ O. ₈ (Aldrich) and nitrogen treatment for more than 30 minutes, EDOT and the catalyst (Fe ₂ (SO ₄ ) ₃ , Aldrich) diluted with water and reacted with a constant input for a certain time to make the color lighter The particles can be made smaller while being constant. Nitrogen is continuously added during the reaction time. The reacted conductive polymer is treated with a cation exchange resin (Bi Chemical) to remove the catalyst in the aqueous dispersion, and the cation exchange resin is removed by filtering using a mesh network.

Examples 1-7

Dimethylformamide (Aldrich), N-methylpyrrolidone (Aldrich) or sulfone-based dimethyl sulfoxide (Dimethlysulfoxide; Aldrich) as a solvent in 100 parts by weight of the conductive polymer aqueous dispersion synthesized above ), Zonyl FSO-100 (Dupont), NP1026 (East Synthetic Synthesis), and DBA-MEA (Laboratory Preparation, Monoethanolamine dodecylbenzensulfonate) as surfactants were added according to the composition shown in Table 1, and stirred at 350rpm for 24 hours and then homogenizer (ULTRA- TURRAX IKA T25 digital, IKA Co., Ltd.) and an ultrasonic machine (JAC Ultrasonic 201, Advanced Technology Co., Ltd.) were sequentially processed to prepare a composition for an organic electrode. The organic electrode composition was spin-coated on a polyester film for 20 seconds at a first 150 rpm and 30 seconds at a second 500 rpm, and dried at 60 ° C. under vacuum for 6 hours to prepare a conductive organic electrode. Surface resistance and transmittance of the prepared organic electrode were measured and shown in Table 1 below. Here, sheet resistance was evaluated using a sheet resistor (Loresta-GP, Mitsubishi Corporation), and transmittance was evaluated at 550 nm using an ultraviolet spectrometer (S-310, Shinkosa). As can be seen from Table 1, the sheet resistance belonged to 250 to 900 kW / square in all the transparent electrodes, and the visible light region transmittance was 80% or more.

Comparative Example 1

Example 1 was carried out as described above but no solvent was added. The visible light transmittance was 88.6%, but the sheet resistance was 3280Ω / □.

Table 1.

Example (unit: parts by weight) One 2 3 4 5 6 7 Comparative Example 1 Conductive Polymer Dispersion (1.5%) synthetic 100 100 100 100 100 100 100 100 Amide Solvent DMF 25 NMP 25 Furan solvent THF 25 Sulfoxide solvents DMSO 25 2 33 50 Surfactants FSO-100 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 NP1026 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 DBA-MEA 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 Sheet resistance Ω / □ 650 900 846 533 692 802 995 3280 Transmittance % 84.8 82.4 85.5 90.01 93.0 85.1 85.5 88.6

DMF: Dimethylformamide, NMP: N-methlypyrrolidone,

THF: Tetrahydrofuran, DMSO: Dimethlysulfoxide,

FSO-100: Fluorine-based surfactant, NP1026: Polyethylene glycol nonyl phenyl ether,

DBA-MEA: Monoethanol amine dodecyl benzene sulfate

Claims (4)

Solvent selected from the group consisting of 100 parts by weight of an aqueous dispersion of polyethylenedioxythiophene doped with polystyrenesulfonate at a molar ratio of 1 to 3 and a solids content of 1 to 3% by weight, an amide system, a furan system, a sulfoxide system and a mixture thereof. An organic electrode composition comprising from 50 parts by weight to 0.001 part by weight of surfactant. The composition for organic electrodes of claim 1, wherein the organic light emitting layer has a visible light transmittance of 80% or more and a surface resistance of 250 to 900 Ω / □ when the transparent substrate is coated with the composition for organic electrodes. The method of claim 1, wherein the material of the transparent substrate is selected from the group consisting of glass, polyester, polyamide, polycarbonate, polystyrene, polypropylene, polyethylene, polyvinyl chloride and polyacrylate, the amide solvent is N, N-dimethylformamide or N-methylpyrrolidone, the furan solvent is tetrahydrofuran, the sulfoxide solvent is dimethyl sulfoxide, and the surfactant is a nonionic surfactant, anionic surfactant or cationic interface. The composition for organic electrodes which is an active agent. The method of claim 3, wherein the surfactant is R _f CH ₂ CH ₂ SCH ₂ CH ₂ CO ₂ Li, (R _f CH ₂ CH ₂ O) P (O) (ONH ₄ ) ₂ , (R _f CH ₂ CH ₂ O) ₂ P (O) (ONH ₄ ), R _f CH ₂ CH ₂ O (CH ₂ CH ₂ O) _y H, R _f CH ₂ CH ₂ SO ₃ X, R _f CH ₂ CH ₂ NHSO ₃ X and these The composition for organic electrodes chosen from the fluorine-type surfactant which consists of a mixture of these. (Wherein _y is an integer from 8 to 15, X is H or NH ₄ , R _f is F (CF ₂ CF ₂ ) _z , where _z is an integer from 3 to 8.