KR101843268B1 - Method for manufacturing silver nanowire film using 1,8-diazabicycloundec-7-ene and silver nanowire film made by the same - Google Patents

Abstract

The present invention improves the conductivity without inhibiting the permeability by a simple method using DBU (1,8-diazabicyclo deck-7-ene), so that a flexible substrate susceptible to heat in a simple process without additional processing through high- To a method of manufacturing a silver nanowire film usable as a wire film, and to a silver nanowire film produced thereby.

Description

A method for producing a silver nanowire film using a 1,8-diazabicyclooldec-7-ene solution and a silver nanowire film prepared thereby, which method comprises using a silver nanowire film using 1,8-diazabicycloundec-7-ene silver nanowire film made by the same}

The present invention relates to a method for producing a silver nanowire film using a DBU (1,8-diazabicyclooldec-7-ene) solution and a silver nanowire film produced by the method. In a simple method using a DBU solution, A silver nanowire film which can be used as a silver nanowire film by using a flexible substrate susceptible to heat in a simple process without any process through high temperature heat treatment by improving the conductivity without inhibiting the silver nanowire film and a silver nanowire film produced thereby .

Currently, information and communication devices are becoming increasingly smaller and lighter as science and technology are rapidly developed, and devices with various functions and flexibility are required. To fabricate flexible electronic devices such as flexible displays, touch panels, solar cells, and transistors, transparent and flexible electrodes must be used. These electrodes must form a thin film on a flexible substrate such as polyethylene terephthalate (PET), polyethersulfone (PES), etc., and exhibit high conductivity and good transmittance in the visible region.

Indium tin oxide (ITO) thin films are the most commonly used transparent electrodes, but ITO thin films are not flexible and have resource limitations. Therefore, they are used as flexible materials in future electronic devices. It is difficult to become a reality. Therefore, in order to overcome the limitation of ITO thin film, development of alternative materials using various materials is actively studied. The alternative materials include transparent conducting oxide (TCO), metallic nanowire, carbon nanotube (CNT), graphene, and conducting polymer, They are the next generation materials that can be used as flexible transparent electrodes, and research is under way along with the growth of the future display industry.

In order to simplify the manufacturing process, the electrode thin film is formed by applying a roll-to-roll process under normal temperature and normal pressure conditions such as inkjet printing, spraying, gravure, slot die coating, Research is also under way.

In the case of metal nanowires that can form a random network in the production of a material, electrode films can be manufactured at low cost and thin films can be manufactured through a roll-to-roll process using a solution. In recent years, Is a next-generation material under active research. In particular, silver nanowires (Ag NWs) are attracting attention as materials with high potential for use as transparent conductors because of their excellent optical properties, flexibility and high conductivity. Silver nanowires are not as good in surface roughness and haze as other materials, but they can be applied to various sheet resistances by controlling the density of silver nanowires. However, the lower the sheet resistance, the disadvantage is that the density of the nanowires increases and the transmittance is lowered. Therefore, the post treatment process is required to improve the conductivity without inhibiting the permeability. However, since heat treatment requires the use of a substrate that can withstand high temperatures (150 ° C), there is a limitation in that a flexible polymer substrate that is weak to heat can not be used.

Therefore, in order to secure high transparency and high conductivity of transparent electrode using silver nanowire, it is necessary to study a treatment process that can replace high temperature heat treatment process.

Korean Patent Registration No. 10-1470752 Korean Patent Registration No. 10-1324281

The present invention provides a silver nanowire film manufacturing method capable of improving the conductivity of a silver nanowire film without inhibiting the permeability by a simple method of treating the silver nanowire with a DBU solution and a silver nanowire film produced thereby .

According to an aspect of the present invention, there is provided a method of manufacturing a silver nanowire film, including: coating a silver nanowire on a substrate; And a DBU processing step of treating the coated silver nanowire with DBU.

The silver nanowire may have a diameter of 10 to 100 nm and a length of 2 to 100 탆.

The substrate may be at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene (PE), polyether sulfone (PES), polycarbonate (PC), polyarylate (PAR), and polyimide One can be included.

The coating step may be performed by any one of bar coating, spin coating, spray coating, casting, and dip coating.

The DBU treatment step may be carried out using DBU solution containing 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) alone or a mixture of DBU and at least one organic solvent.

The DBU processing step may be performed for 1 minute to 1 hour.

The present invention can provide a silver nanowire film produced according to the above-described manufacturing method. The silver nanowire film may have a sheet resistance value of 65 to 90? / Sq.

In addition, the present invention can provide a transparent electrode including the silver nanowire film.

The silver nanowire film manufacturing method according to the present invention can replace the heat treatment process at a high temperature by a simple method of DBU treatment of silver nanowires, so that the conductivity of the silver nanowire film can be improved without inhibiting the permeability through a simple process There is an advantage.

In addition, since silver nanowire films can be produced without heat treatment at a high temperature, the manufacturing process can be simplified and the process cost can be saved.

In addition, since the silver nanowire film of the present invention can be applied to a flexible substrate, there is an advantage that it can be used for manufacturing a transparent transparent electrode.

FIG. 1 is a schematic diagram showing the reaction between a silver nanowire and a DBU. FIG.
2 is a graph showing sheet resistance (a) and transmittance (b) of a silver nanowire film by DBU treatment according to an embodiment of the present invention.
FIG. 3 is a SEM photograph showing the microstructure of a silver nanowire film treated with a DBU according to an embodiment of the present invention.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described in detail below. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. In addition, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

The present invention relates to a method of manufacturing a silver nanowire film by DBU treatment and a silver nanowire film produced thereby, by treating silver nanowires coated on a substrate with DBU alone or DBU solution to improve conductivity without inhibiting permeability The silver nanowire film can be substituted for a high temperature heat treatment, which is a subsequent process for improving the conductivity of the nanowire film, and a silver nanowire film produced thereby.

First, a method of manufacturing a silver nanowire film includes: a coating step of coating a silver nanowire on a substrate; And a DBU processing step of treating the coated silver nanowire with DBU.

Wherein the coating step comprises coating the silver nanowire on the substrate such that at least one point of the silver nanowire is joined or crossed with the other silver nanowire to form a network like a net, .

Silver is the most conductive material among metals and has a self-resistance value of 80 to 120 Ω, which is lower than that of ITO having a thickness of 200 to 400 Ω, which is advantageous for enlarging and can be used for a flexible display .

The diameter of the silver nanowire may be 10 to 100 nm, preferably 15 to 70 nm. When the diameter of the nanowire is less than 10 nm, the mechanical stability is deteriorated. When the diameter is more than 100 nm, the light transmittance is deteriorated.

Further, the length of the silver nanowire may be 2 to 100 mu m, preferably 5 to 50 mu m. When the length of the nanowire is less than 2 탆, the length of the nanowire is too short, so that the other silver is difficult to be joined or crossed with the nanowire. Thus, the electrical characteristics of the nanowire are deteriorated. When the length exceeds 100 탆, And the light transmittance is lowered.

The silver nanowire may be coated on a substrate by forming a dispersion solution. The dispersion solution may further include a solvent and a dispersant, which are formed from water, alcohol, volatile organic solvents, etc. in addition to silver nanowires.

In the silver nanowire dispersion solution, the content of the silver nanowires is preferably 0.5 to 1 wt% based on the total weight of the dispersion solution. If the silver nanowire is less than 0.5 wt%, the conductivity may be too low, %, The transmittance may become too low, which is undesirable.

The substrate to be used in the present invention can be any flexible substrate that can be coated with silver nanowires without any particular limitation. Preferably, the substrate is a flexible polymer substrate such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene (PE) (PET), polyether sulfone (PES), polycarbonate (PC), polyarylate (PAR), and polyimide (PI), and more preferably polyethylene terephthalate (PET).

The method of coating the silver nanowire on the substrate may be any method as long as it is a coating method capable of coating a solution, but it is preferably one of a bar coating, a spin coating, a spray coating, a casting and a dip coating, It may be a bar coating. The bar coating is advantageous in that it can be uniformly coated with a simple process without additional equipment.

Next, the DBU processing step is a step of reacting the silver nanowire with DBU by treating the silver nanowire coated on the substrate with DBU alone or DBU solution, and the reaction formula of the silver nanowire and DBU is as follows.

[Reaction Scheme 1]

Specifically, there is an oxide film (Ag ₂ O) on the surface of the silver nanowire, which interferes with the contact between the silver nanowires, thereby lowering the conductivity of the silver nanowire film. This reaction is used in the present invention to treat silver nanowires with DBU by removing the oxide film to form silver (Ag) Increasing contact between the nanowires improves conductivity, which can replace the conventional high temperature heat treatment process to improve conductivity without inhibiting permeability.

In the DBU processing step used in the present invention, the silver nanowire reacts with the DBU to remove the oxide film on the silver nanowire surface. In the DBU processing step, a DBU solution may be used, or a DBU solution in which DBU and at least one organic solvent are mixed.

The organic solvent is not particularly limited and includes, for example, acetone.

When the DBU solution is used, the concentration of DBU in the solution is preferably 85 wt% or more, and when the DBU solution is used at a lower concentration, the sheet resistance is increased.

The DBU can be treated within a time when silver nanowires are not damaged, and can be treated for preferably 1 minute to 1 hour, more preferably 1 minute to 30 minutes. If the thickness is out of the above range, the surface resistance is increased and silver nanowires are damaged.

By treating the silver nanowires coated on the substrate with DBU, the sheet resistance (Ω / sq) before DBU treatment is reduced from about 1,000 to less than 90 after the treatment, thereby improving the electrical conductivity of the silver nanowire film.

Therefore, when the DBU according to the present invention is processed, the conductivity of the silver nanowire film coated on the flexible substrate susceptible to heat can be improved by a simple method without high temperature heat treatment.

That is, the method of manufacturing the silver nanowire film of the present invention is economical and can simplify the manufacturing process and enhance safety by replacing the conventional high temperature heat treatment process by treating the DBU.

The present invention can provide a silver nanowire film produced by the above manufacturing method. The silver nanowire film may have a sheet resistance value of 65 to 90? / Sq, preferably 70 to 85? / Sq, and more preferably 70 to 80? / Sq.

In addition, the present invention can provide a transparent electrode including the silver nanowire film. The transparent electrode can be applied as a transparent electrode of a flexible electronic device such as a display, a solar cell, a touch panel, or a transistor.

Hereinafter, the present invention will be described in detail with reference to the following examples, which should not be construed as limiting the scope of protection defined by the appended claims.

< Example  1>

A dispersion solution in which 0.2 wt% of silver nanowires (10 m in length and 40 nm in diameter) was dispersed in isopropyl alcohol was bar-coated on the PET substrate at a rate of 10 mm / sec. The bar coater used for the bar coating was 400 mm in length, 6.35 mm in thickness, and 13.7 μm in wound wire thickness. The nanowire-coated substrate was reacted with DBU for 1 minute, and washed sequentially with dichloromethane, acetone, and distilled water to prepare a silver nanowire film.

< Example  2>

Was carried out in the same manner as in Example 1, except that the nanowire-coated substrate was reacted in a 90 wt% DBU acetone solution for a maximum of 1 hour.

< Comparative Example  1>

In the same manner as in Example 1, the silver nanowires were coated on the PET substrate, and then the substrate coated with the silver nanowires was reacted with DBU for 30 seconds and then washed with dichloromethane, acetone and distilled water in order, .

< Comparative Example  2>

In the same manner as in Example 1, the silver nanowires were coated on the PET substrate, and then the silver nanowire-coated substrate was reacted in an 80 wt% DBU acetone solution for 2 hours. Then, dichloromethane, acetone and distilled water To prepare a silver nanowire film.

< Comparative Example  3>

Silver nanowires were coated on the PET substrate in the same manner as in Example 1, and then the substrate coated with the silver nanowires was reacted in an aqueous ammonia solution of 30 wt% for 150 seconds, and then washed with dichloromethane, acetone and distilled water A silver nanowire film was prepared.

The minimum sheet resistance (Ω / sq) of the silver nanowire films prepared according to Examples 1 and 2 and Comparative Examples 1 to 3 is shown in Table 1 below, and the silver nanowire film manufacturing methods of Examples 1 and 2 The sheet resistance (Ω / sq), the transmittance, and the microstructure of the silver nanowires according to the DBU treatment time are shown in FIG. 2 and FIG. 3, respectively.

Treatment type Reaction time Sheet resistance (Ω / sq) High temperature heat treatment - 300 seconds 71 Example 1 DBU 1 minute 70 Example 2 90% by weight of DBU acetone solution 1 hours 79 Comparative Example 1 DBU 30 seconds 300 Comparative Example 2 80% by weight of DBU acetone solution 2 hours 95 Comparative Example 3 30% by weight aqueous ammonia solution 150 seconds 500

The high-temperature heat-treated silver nanowire film was obtained by heat-treating the nanowire-coated PET substrate at 170 ° C in the same manner as in Example 1. The sheet resistance before the heat treatment was 1000 Ω / sq and the minimum sheet resistance value was 71 Ω / sq.

For embodiments, it has been observed that the initial sheet resistance 1000 OMEGA / sq varies with processing time. Particularly, when the DBU was treated for 1 minute to 1 hour, it was observed that the sheet resistance reached the lowest (Fig. 2A). The microstructure was analyzed by SEM and the results are shown in FIG. Therefore, when the DBU was treated for 1 minute to 1 hour, only the oxide film on the silver nanowire surface was removed, and the sheet resistance was decreased. Also, it was confirmed that the transmittance did not decrease as shown in FIG. 2 (b).

On the other hand, in the case of Comparative Example 1 in which the DBU was treated for 30 seconds, in Comparative Example 2 in which the lowest sheet resistance values were much higher than those in Examples 1 and 2, and the low DBU acetone solution was treated for 2 hours, 2, and the time required for reaching the minimum sheet resistance was longer. In the case of Comparative Example 3 treated with 30 wt% aqueous ammonia solution, even though the reaction was performed for 150 seconds in a very short time, the sheet resistance (500 Ω / sq), which indicates that the treatment with ammonia aqueous solution removes the oxide film in seconds and damages the silver nanowire.

Therefore, the DBU treatment of Examples 1 and 2 can replace the high-temperature heat treatment in an effective aspect, and the time required to reach the minimum sheet resistance is also shorter than that in the high-temperature heat treatment, which is economical in cost.

Although the configuration of the present invention has been proven by the above embodiments, the present invention is not necessarily limited to the above configuration, and various permutations, modifications, and variations are possible without departing from the technical idea of the present invention. Therefore, the above description does not limit the scope of the present invention, which is defined by the limitations of the following claims.

Claims (8)

A coating step of coating the nanowire on the substrate; And
Treating the coated silver nanowire with 90 to 100 wt% 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) for 1 minute to 1 hour. A method of manufacturing a nanowire film.
The method according to claim 1,
Wherein the silver nanowire has a diameter of 10 to 100 nm and a length of 2 to 100 탆.
The method according to claim 1,
The substrate is at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene (PE), polyethersulfone (PES), polycarbonate (PC), polyarylate (PAR), and polyimide Gt; a &lt; / RTI &gt; nanowire film.
The method according to claim 1,
Wherein the coating step is performed by any one of bar coating, spin coating, spray coating, casting, and dip coating.
delete delete 5. A silver nanowire film produced by the method according to any one of claims 1 to 4 and having a sheet resistance value of from 65 to 90? / Sq.
A transparent electrode comprising a silver nanowire film according to claim 7.

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