KR102247511B1 - Structure including conductive composite layer, production methods thereof, and electronic devices including the same - Google Patents

Abstract

A deformable substrate; And a conductive composite layer disposed on at least a portion of the surface of the deformable substrate, wherein the conductive composite layer includes a polymer matrix and a plurality of conductive particles embedded in the polymer matrix, and the conductive composite layer, It is arranged to be bent or elongated together with the deformable substrate, and at least a part of the surface of the conductive composite layer is treated with a solvent capable of dissolving the polymer matrix to expose part or all of the conductive particles. A structure and an electronic device including the same are provided.

Description

A structure including a conductive composite layer, a method for manufacturing the same, and an electronic device including the same TECHNICAL FIELD OF THE INVENTION

It relates to a structure including a conductive composite layer, a method of manufacturing the same, and an electronic device including the same.

Composites including conductive fine particles and a polymer matrix have been studied for their application in electronic devices such as actuators. In stretchable electronic devices that have recently attracted attention, the use of such a composite has been proposed for fabricating a stretchable interconnector. In an electronic device, the flexible interconnect is in contact with an electrode so that a voltage is applied thereto. In the case of using a composite of the prior art as an interconnector, the contact resistance is high and the electrical conductivity is lowered. In order to solve this problem, attempts have been made to include a large amount of conductive fine particles. However, as the content of the conductive fine particles increases in such a composite, the elasticity that can be exhibited is significantly lowered, and mechanical properties may be greatly reduced.

Accordingly, there is an urgent need to develop a composite structure capable of exhibiting low contact resistance and improved conductivity while maintaining excellent mechanical properties such as elasticity.

One embodiment relates to a structure including a conductive composite capable of exhibiting excellent electrical properties so that it can be used in a stretchable electronic circuit or the like.

Another embodiment relates to a method of manufacturing such a structure.

Another embodiment relates to an electronic device comprising such a structure.

One embodiment, a deformable substrate (deformable substrate); And

A structure comprising a conductive composite layer disposed on at least a portion of the surface of the deformable substrate,

The conductive composite layer includes a polymer matrix and a plurality of conductive particles embedded in the polymer matrix,

The conductive composite layer is disposed to be bent or stretched together with the deformable substrate,

At least a portion of the surface of the conductive composite layer is treated with a solvent capable of dissolving the polymer matrix to provide a structure in which some or all of the conductive particles are exposed.

The conductive composite layer may include a step formed by the surface treatment with a solvent, and all or part of the conductive particles may be exposed on a lower surface of the conductive composite layer.

The step may have a height of 30 μm or less.

The deformable substrate may include a stainless steel foil having a planarizing and insulating oxide deposited thereon, a polyimide, an elastomer, or a combination thereof. The conductive composite layer may be a patterned layer.

The polymer matrix may be an elastomer.

The elastomer may include silicone rubber, natural rubber, vinylidene fluoride-hexafluoropropylene copolymer, or a combination thereof.

The conductive particles may include carbon-based particles (eg, carbon nanotubes, graphene, carbon black, etc.), conductive metal nanoparticles, conductive metal nanowires, or a combination thereof.

The surface of the conductive composite layer treated with the solvent may exhibit an increased surface roughness of 500% or less compared to the untreated surface.

The surface of the conductive composite layer treated with the solvent may exhibit a lower surface roughness than the untreated surface.

The conductive composite layer may contain the conductive particles in an amount of 0.001% to 50% by weight.

In another embodiment, a deformable substrate; And a conductive composite layer disposed on at least a portion of the surface of the deformable substrate, wherein the conductive composite layer comprises a polymer matrix and conductive particles embedded in the polymer matrix, and the conductive composite layer comprises the deformable Obtaining a structure arranged to be bent or stretchable with the substrate; And

It provides a structure manufacturing method comprising the step of exposing a portion of the conductive particles to the surface of the composite layer by contacting at least a portion of the surface of the conductive composite layer with a reactive solvent for the polymer matrix for a predetermined period of time.

The reactive solvent may be a solvent that is non-reactive to the conductive particles and capable of dissolving the polymer matrix.

The polymer matrix is a polymer having elastomeric properties, and includes silicone rubber, natural rubber, a polymer including a structure having a double bond between carbon atoms, or a combination thereof, and the conductive particles are carbon nanotubes, carbon black, carbon nanoparticles. Fibers, graphite particles, graphene, reduced graphene oxide, graphite nanoplatelets, fullerene, silver nanowires, silver nanoparticles, gold nanowires, gold nanoparticles, copper nanowires, copper nanoparticles, nickel nanowires, Nickel nanoparticles, or electroconductive particles in which metal nanoparticles or oxide nanoparticles are attached or uniformly coated on these electroconductive particles, or a combination thereof. The conductive particles may have a wire shape, a disk shape, a spherical shape, etc., but are not limited thereto. In this case, the reactive solvent may include trifluoroacetic acid.

The contacting may be performed for a period of time such that the rate of increase in illuminance is 500% or less.

In another embodiment, a deformable substrate; And a structure including a conductive composite layer disposed on at least a portion of the surface of the deformable substrate,

The conductive composite layer includes a polymer matrix and conductive particles embedded in the polymer matrix, and the conductive composite layer is disposed to be bent together with the deformable substrate, and at least a part of the surface of the conductive composite layer is , By treating with a solvent capable of dissolving the polymer matrix, part or all of the conductive particles are exposed.

The electronic device may have a bent portion or may be a device that can be stretched and contracted.

The electronic device may be a stretchable organic light emitting diode display, a stretchable human motion sensor, a stretchable artificial muscle, a stretchable actuator, or a stretchable semiconductor.

The conductive composite included in the structure according to the embodiment may maintain a low content of conductive particles to exhibit excellent electrical properties without deteriorating mechanical properties. Therefore, it can be used as an elastic conductor or an interconnector in an electronic device or an electronic component of a complex shape, which can be stretched, deformed, or folded.

1 is a diagram schematically showing a cross section of a structure according to an embodiment of the present invention.
FIG. 2 shows a scanning electron microscope image of the surface of a conductive composite surface treated with a structure prepared in Comparative Example 1. FIG.
3 shows a scanning electron microscope image of the surface of a conductive composite surface treated with a structure prepared in Example 1. FIG.
4 shows a scanning electron microscope image of the surface of a conductive composite surface-treated structure manufactured in Example 2. FIG.
5 is a graph showing electrical conductivity and surface roughness measurement results for structures of Comparative Examples 1, 1, and 2;
6 is a graph showing electrical conductivity and surface roughness measurement results for structures of Comparative Examples 2, 3, and 4;
7 is a graph showing electrical conductivity and etching depth measurement results for structures of Comparative Examples 2, 3, 4, 5, and Reference Examples 1 and 2. FIG.
8 shows the results of measuring contact resistance with respect to the structure of Example 1 according to the TLM method.
9 shows the results of measuring contact resistance with respect to the structure of Example 3 according to the TLM method.
10 is a diagram for explaining the principle of the TLM method.

Advantages and features of the present invention, and a method of achieving them will become apparent with reference to implementation examples described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms different from each other, and only these embodiments make the disclosure of the present invention complete, and common knowledge in the technical field to which the present invention pertains. It is provided to completely inform the scope of the invention to the possessor, and the invention is only defined by the scope of the claims. Thus, in some implementations, well-known techniques have not been described in detail in order to avoid obscuring interpretation of the present invention. Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used with meanings that can be commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in a commonly used dictionary are not interpreted ideally or excessively unless explicitly defined specifically. When a part of the specification "includes" a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

In addition, the singular form includes the plural form unless specifically stated in the text.

In the present specification, the term "deformable substrate" includes a substrate capable of elastic or plastic deformation, and the deformation is flexural deformation, elongational deformation, warping deformation, shear deformation, or Includes a combination of these.

In the present specification, "non-reactive" means not triggering an adverse chemical reaction in forming a conductive network structure including conductive particles. For example, a solvent that is non-reactive to the conductive particles may not cause a chemical reaction to the conductive particles contained in the polymer matrix. Alternatively, a solvent that is non-reactive to the conductive particles may cause a chemical reaction on the surface of the conductive particles, but this reaction does not affect the electrical network structure including the conductive particles, or forms an electrical network structure. Can help.

In one embodiment, the structure is a deformable substrate; And a conductive composite layer disposed on the surface of at least a portion of the deformable substrate. The conductive composite layer includes a polymer matrix and a plurality of conductive particles embedded in the polymer matrix, and the conductive composite layer is disposed to be bent or stretched together with the deformable substrate, and the surface of the conductive composite layer At least a portion of the polymer matrix is treated with a solvent capable of dissolving the polymer matrix to expose part or all of the conductive particles.

The deformable substrate may include a stainless steel foil, polyimide, elastomer, or a combination thereof on which a planarized insulating oxide layer is deposited. Herein, "elastomer" is a polymer having viscoelasticity, and has a low Youngs modulus of usually 1.0 GPa or less, such as 500 MPa or less, 100 MPa or less, such as 50 MPa or less, or 10 MPa or less It refers to a material with high failure strain. The elastomer is present as an amorphous polymer above its glass transition temperature, which is usually below room temperature, and thus segment motion is possible. The elastomer may be thermosetting or thermoplastic. The elastomer can be a crosslinked polymer. The type of polymer constituting the elastomer is not particularly limited. The elastomer is, but not limited to, an alkyl acrylate copolymer such as an ethyl acrylate-chloroethyl vinyl ether copolymer, a butyl rubber containing a small amount of bromine, a polybutadiene or a copolymer thereof, a polyisoprene or a copolymer thereof, a chlorinated polyethylene, Butyl rubber with a small amount of chlorine added, chlorosulfonyl polyethylene, epichlorohydrin polymer, poly(ethylene-co-propylene), poly(ethylene-propylene-diene) copolymer, vinylidene fluoride-hexafluoropropylene co Fluorinated or perfluorinated olefin polymers such as polymers, hydrogenated polynitrile rubbers, silicone rubbers such as polydimethylsiloxane, natural rubbers, butadiene-acrylonitrile copolymers, polyurethanes, and the like, but are not limited thereto.

The thickness of the deformable substrate is not particularly limited and may be appropriately selected depending on the material. For example, the stainless steel foil substrate may be 3 to 200 μm, but is not limited thereto. The polyimide substrate or the elastomer substrate may be 3 to 1,000 μm, for example, 5 to 600 μm, but is not limited thereto. Such substrates can be prepared by known methods or are commercially available.

The deformable substrate may be modified with a known surface modifier to have a hydrophilic or hydrophobic surface to facilitate formation of a conductive composite layer described later. For example, the deformable substrate may be surface modified by oxygen plasma.

The polymer matrix of the conductive composite layer may be an elastomer. The type of elastomer is as described above with respect to the deformable substrate. In one embodiment, the elastomer may include silicone rubber, natural rubber, vinylidene fluoride-hexafluoropropylene copolymer, or a combination thereof. The conductive particles may include carbon nanotubes such as single-walled nanotubes and multi-walled nanotubes, graphene, carbon black, conductive metal nanoparticles, conductive metal nanowires, or a combination thereof. These conductive particles can be produced by a known method or are commercially available. The conductive composite layer is obtained by mixing a solution in which the elastomer is dissolved in a predetermined solvent or a liquid precursor of the elastomer (eg, a prepolymer) and the conductive particles to obtain a mixture, and the obtained mixture is inkjetted on a deformable substrate. , Spin coating, dipping, screen printing, or the like, or applied using a doctor blade, followed by heating and/or drying. The solvent can dissolve the polymer matrix and may be appropriately selected (eg, non-reactive) that does not affect the conductive particles. For example, when the conductive particles are carbon nanotubes and the polymer matrix is a fluorinated olefin copolymer (eg, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene), the solvent is 4-methyl-2-pentanone Etc. may be ketones. When the conductive particles are carbon nanotubes, and the polymer matrix is a fluorinated olefin copolymer (eg, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene), an ionic liquid (eg, 1-butyl-3-methyl Further imidazolium bis(trifluoromethanesulfonyl)imide) can be added.

The conductive composite layer is disposed to be bent and/or stretchable together with the deformable substrate. For example, the conductive composite layer has an affinity/adhesion to the substrate sufficient to be able to bend and/or stretch with the substrate. If necessary, in order to improve the adhesion/affinity of the conductive composite layer to the deformable substrate, an adhesion promoter or crosslinking agent such as a known silane coupling agent may be added to the elastomer-conductive particle mixture.

The thickness of the conductive composite layer is not particularly limited, and may be appropriately selected as necessary. The thickness of the conductive composite layer can have a thickness ranging from nanometers to several millimeters. For example, the thickness of the conductive composite layer may be 1 mm or less, 1 to 500 µm, or 5 to 300 µm, but is not limited thereto. The conductive composite layer may contain the conductive particles in an amount of 0.1 wt% to 50 wt%, for example, 0.5 wt% to 30 wt%, 1 wt% to 25 wt%, or 1 wt% to 21 wt% have. As described below, the structure according to the exemplary embodiment may exhibit a high level of conductivity even when a reduced content of conductive particles is included. In addition, it may be very advantageous in maintaining a desired level of mechanical properties such as elongation, including a reduced content of conductive particles.

The conductive composite layer may be a patterned layer. The method of patterning the conductive composite layer is not particularly limited and can be appropriately selected. For example, the conductive composite layer may be patterned by a direct printing method of an elastomer/conductive particle mixture (inkjet printing, screen printing, etc.). Alternatively, the conductive composite layer may be patterned using photolithography using a photoresist or direct etching using a laser or the like. The conductive composite layer formed on the deformable substrate by the above-described method may be bent or stretched together with the deformable substrate.

In the conductive composite layer, a part or all of the surface is treated with a solvent capable of dissolving the polymer matrix (hereinafter, referred to as a reactive solvent), so that some or all of the plurality of conductive particles are exposed on the surface. The reactive solvent may be non-reactive with respect to the conductive particles included in the conductive composite layer. In other words, as the reactive solvent, any solvent that does not affect the conductive particles while dissolving the polymer matrix of the conductive composite can be selected. For example, the conductive particles are carbon-based particles such as carbon nanotubes, grapheme, and carbon black, or metal particles such as silver nanofibers and nickel nanoparticles, and the polymer matrix is silicone rubber, natural rubber, or a combination thereof. In the case of, trifluoroacetic acid, sulfuric acid, dipropylamine, or a combination thereof may be used. The combination of the polymer matrix and the solvent may be determined in consideration of the reactivity between the polymer and the solvent, whether or not swelling, or a swelling ratio, among solvents capable of dissolving the polymer. When a part of the surface of the conductive composite layer is treated with a reactive solvent, the conductive composite layer may include a step formed by the surface treatment with the solvent, and in this case, the lower surface of the conductive composite layer All or part of the said electroconductive particle is exposed. The height of the step may be 30 µm or less, for example, 25 µm or less, 20 µm or less, 15 µm or less, 10 µm or less, or 5 µm or less. Without limitation, referring to FIG. 1, a portion of the surface of the composite layer in contact with the electrode is subjected to surface treatment by being brought into contact with a reactive solvent for a predetermined period of time, as described later. On the thus-treated surface, conductive particles (eg, carbon nanotubes) that have been buried are exposed to the composite surface while a part of the polymer matrix is removed. This surface-treated portion may exhibit lower contact resistance and higher electrical conductivity than before treatment.

Stretchable electronics are attracting a lot of attention due to their potential applications in various fields, such as bio-integrated devices, from sensory skin and wearable communication devices of robots. Such electronic components may include elastic interconnectors such as elastic electrical wiring and elastic conductors on a deformable (e.g., stretchable) substrate, such as conductive particles and elastomers. A structure including a composite of (hereinafter referred to as a conductive composite) has been proposed. The conductive composite for the stretchable interconnect is required to have a low contact resistance, but the currently proposed conductive composite does not provide sufficiently low contact resistance.

However, the structure according to the above-described embodiment may have a conductive composite surface exhibiting a remarkably reduced contact resistance by treatment with a reactive solvent. Such low contact resistance is advantageous in maintaining high conductivity while maintaining a low level of the amount of conductive particles added, ensuring high stretchability, and increasing power efficiency. In general, when the amount of the conductive particles added increases, the conductivity of the conductive composite can be improved, but mechanical properties such as elongation are significantly deteriorated. However, in the case of the structure according to the above-described embodiment, an improved level of electrical conductivity may be exhibited while ensuring excellent mechanical properties (especially, high extensibility) by maintaining a low level of the added amount of conductive particles. In addition, when the contact resistance is reduced, power consumption can also be reduced.

In one embodiment, the contact resistance of the conductive composite layer having a surface treated with a reactive solvent may be 70% or less, for example, 60% or less, 50% or less, or 40% or less of the contact resistance of the composite layer before treatment. In one embodiment, the electrical conductivity of the conductive composite layer having a surface treated with a reactive solvent is 1.5 times or more, such as 1.6 times or more, 1.7 times or more, 1.8 times or more, 1.9 times or more, or It can be more than 2.0 times.

Surface treatment may be performed on the entire surface of the conductive composite or may be selectively performed on a part of the surface. The treatment on the entire surface may be performed by applying a reactive solvent to the entire surface and after a predetermined period of time, washing/removing with a cleaning solvent (eg, water, etc.). The selective treatment of some surfaces may be performed by dispense of a reactive solvent at a desired location and spraying a cleaning solvent after a predetermined period of time. Alternatively, selective treatment of some surfaces is performed by forming a photoresist pattern on the entire surface of the composite before treatment, allowing the reactive solvent to contact the exposed part, and then washing/removing the reactive solvent after a predetermined period of time. Can be done.

The surface of the conductive composite layer treated by the solvent may have a surface roughness that is 500% or less, for example, 1% to 500%, 5% to 200%, or 10% to 150%, compared to the untreated surface. have. Alternatively, the surface of the conductive composite layer treated with the solvent may exhibit a further reduced surface roughness compared to the untreated surface. Such surface roughness can be measured using an optical microscope device (for example, an optical microscope device manufactured by Olympus, product name OLS3000).

In another embodiment, a method of manufacturing a structure includes a deformable substrate; And a conductive composite layer disposed on at least a portion of the surface of the deformable substrate, wherein the conductive composite layer comprises a polymer matrix and conductive particles embedded in the polymer matrix, and the conductive composite layer comprises the deformable Obtaining a structure arranged to be bent or stretchable with the substrate; And

And exposing a portion of the conductive particles to the surface of the composite layer by contacting at least a portion of the surface of the conductive composite layer with a reactive solvent for the polymer matrix for a predetermined period of time.

Details of the deformable substrate, the polymer matrix, the conductive particles, the reactive solvent, and the conductive composite layer are as described above.

The contact time with the reactive solvent can be appropriately selected in consideration of the type of the polymer matrix, the thickness of the conductive composite layer, and/or the degree of reactivity or swelling of the polymer between the solvent and the polymer. In one embodiment, the contact time may be less than 180 seconds, such as less than 120 seconds, less than 100 seconds, less than 90 seconds, less than 80 seconds, or less than 70 seconds. The contacting may be performed for a period of time such that an increase rate of the surface roughness of the composite layer contacted with the reactive solvent is 500% or less, for example, 400% or less, 300% or less, or 200% or less. After the contact, it may further include the step of removing the reactive solvent by washing the structure with water or an organic solvent (eg, acetone, ethanol, etc.).

In another embodiment, a deformable substrate; And a structure including a conductive composite layer disposed on at least a portion of the surface of the deformable substrate. In the electronic device, the conductive composite layer comprises a polymer matrix and conductive particles embedded in the polymer matrix. Including, wherein the conductive composite layer is disposed so as to be bent together with the deformable substrate, and at least a part of the surface of the conductive composite layer is treated with a solvent capable of dissolving the polymer matrix to provide the conductive material. Part or all of the particles are exposed.

In one embodiment, the electronic device may be a stretchable electronic device. For example, the electronic device may be a stretchable organic light emitting diode display, a stretchable human motion sensor, a stretchable artificial muscle, a stretchable actuator, or a stretchable semiconductor.

Hereinafter, specific embodiments of the present invention are presented. However, the examples described below are only for illustrating or explaining the present invention in detail, and the present invention is not limited thereto.

[ Example ]

Comparative Example 1 :

Polydimethylsiloxane prepolymer composition (manufacturer: Dow Corning, trade name: Sylgard 184, two-component) 8.06 grams of carbon nanotubes (average diameter: 3 nm or less Average length: several um or less Manufacturer: Carbon nanotechnologies SP-SWNT) 1.94 grams are mixed to obtain a mixture having a carbon nanotube content of 19.4% by weight.

The obtained mixture was applied to a polyimide substrate, flattened with a doctor blade, and then heat-treated at 100°C for 60 minutes to obtain a structure in which a conductive composite layer having a thickness of 1 mm was formed on the polyimide substrate.

Comparative Example 2 :

Polydimethylsiloxane prepolymer composition (manufacturer: Dow Corning, trade name: Sylgard 184, two-component) 9.9 grams of carbon nanotubes (average diameter: 3 nm or less Average length: several um or less Manufacturer: Carbon nanotechnologies In the same manner as in Comparative Example 1, except that 0.1 g grams of SP-SWNT) was mixed to obtain a mixture having a carbon nanotube content of 1.0% by weight, a structure in which a conductive composite layer having a thickness of 1 mm was formed on a polyimide substrate was obtained.

Example 1 :

The structure obtained in the same manner as in Comparative Example 1 was immersed in trifluoroacetic acid (TFA, manufacturer: Sigma aldrich, 10 ml), or applied to a predetermined portion of the surface of the conductive composite layer of the structure obtained in the same manner as in Comparative Example 1. Then, trifluoroacetic acid is brought into contact with the surface. After 10 seconds, the structure is washed with acetone, alcohol, and distilled water in order to remove trifluoroacetic acid on the surface of the conductive composite layer, thereby obtaining a structure in which a part or all of the surface of the conductive composite layer is treated with TFA.

Example 2 :

The conductive composite layer was prepared in the same manner as in Example 1, except that the TFA was brought into contact with the surface, and the structure was washed with distilled water after 30 seconds to remove the trifluoroacetic acid adhering to the surface of the conductive composite layer. A structure in which part or all of the surface is treated with TFA is obtained.

Example 3 :

In the same manner as in Example 1, except that the structure of Comparative Example 2 was used, a structure in which a part or all of the surface of the conductive composite layer was treated with TFA was obtained.

Example 4 :

Example 2 except that the structure of Comparative Example 2 was used, and the TFA was brought into contact with the surface, and after 30 seconds the structure was washed with distilled water and washed to remove the trifluoroacetic acid adhering to the surface of the conductive composite layer. In the same manner as in 1, a structure in which a part or all of the surface of the conductive composite layer is treated with TFA is obtained.

Example 5 :

Example 2 except that the structure of Comparative Example 2 was used and the TFA was brought into contact with the surface, and after 60 seconds, the structure was washed with distilled water and washed to remove the trifluoroacetic acid adhering to the surface of the conductive composite layer. In the same manner as in 1, a structure in which a part or all of the surface of the conductive composite layer is treated with TFA is obtained.

Reference Example 1 :

Example 2 except that the structure of Comparative Example 2 was used and the TFA was brought into contact with the surface, and after 120 seconds, the structure was washed with distilled water and washed to remove the trifluoroacetic acid adhering to the surface of the conductive composite layer. In the same manner as in 1, a structure in which a part or all of the surface of the conductive composite layer is treated with TFA is obtained.

Reference Example 2 :

Example 2 except that the structure of Comparative Example 2 was used and the TFA was brought into contact with the surface, and after 180 seconds, the structure was washed with distilled water and washed to remove the trifluoroacetic acid adhering to the surface of the conductive composite layer. In the same manner as in 1, a structure in which a part or all of the surface of the conductive composite layer is treated with TFA is obtained.

Experimental Example 1 : Scanning electron microscopy analysis of the conductive composite structure

The surfaces of the conductive composite layer of the structures of Comparative Example 1, Example 1, and Example 2 were observed with a scanning electron microscope (manufacturer: Hitachi, model name: S-4500), and the results are shown in FIGS. 2, 3, and 4 Each is shown in.

The surface of the conductive composite layer of the structure of Comparative Example 1 and the surface of the conductive composite layer of the structures of Examples 1 and 2 treated with TFA are morphologically different, and the surface of the conductive composite layer of the structures of Examples 1 and 2 It is confirmed that the particles are present.

Experimental Example 2 : Measurement of surface roughness and electrical conductivity of a conductive composite structure I

[1] With respect to the surfaces of the conductive composites of the structures of Comparative Examples 1, 1, and 2, the surface roughness was measured using an optical microscope of Olympus, OLS3000, for an area of 50 um X 50 um.

The results are summarized in Table 1 and Fig. 5 below.

[2] For the surfaces of the conductive composites of the structures of Comparative Examples 1, 1, and 2, electrical conductivity was measured in the following manner. Electrical conductivity is measured at room temperature using a 2-point method using Keithley's digital multimeter AIX200, and the electrical conductivity is calculated using the following equation.

Where R is the measured volume resistance (Ω), σ Is the electrical conductivity (S/m), L is the length of the sample (m), A is the cross-sectional area perpendicular to the sample length direction (m ² ), w is the width of the sample (m), and t is the thickness of the sample (m). Say.

The electrode on the conductive composite was formed by uniformly applying silver paste (Dotite D-500, Fujikura Kasei) to the surface-treated position, and then curing at 100°C for 1 hour.

The results are summarized in Table 1 and Fig. 5 below.

division Surface roughness (㎛) Electrical conductivity (S/m) Comparative Example 1 (19.4% SWNT) 1.437 43.0 Example 1 (19.4% SWNT + 10 seconds) 1.353 69.3 Example 2 (19.4% SWNT + 30 seconds) 2.11 86.7

From the results of Table 1 and FIG. 5, the conductive composite in the structure of Example 1 showed slightly reduced surface roughness and 61% higher electrical conductivity than before the surface treatment, and the conductive composite in the structure of Example 2 was compared before the surface treatment. It is confirmed that it has a higher surface roughness and 102% higher electrical conductivity. These results suggest that the conductive composite according to the embodiment can exhibit remarkably high electrical conductivity while maintaining the conductive particle content at a low level.

Experimental Example 3 : Measurement of Surface Roughness and Electrical Conductivity of Conductive Composite Structure II

[1] For the conductive composite surfaces of the structures of Comparative Example 2, Example 3, and Example 4, the surface roughness was measured in the same manner as in Experimental Example 2, and the results are summarized in Tables 2 and 6 below.

[2] For the conductive composite surfaces of the structures of Comparative Examples 2, 3, 4, 5, 1, and 2, electrical conductivity was measured in the same manner as in Experimental Example 2, and The results are summarized in Table 2 and Fig. 6 below.

[3] For the conductive composite surfaces of the structures of Comparative Examples 2, 3, 4, 5, Reference Example 1, and Reference Example 2, an optical microscope manufactured by Olympus, OLS3000 for an area of 50 um X 50 um was used. Then, the etching depth was measured, and the results are summarized in Table 2 and FIG. 7 below.

division Surface roughness (㎛) Electrical conductivity (S/m) Etch depth (mm) Comparative Example 2 (1.0% SWNT) 0.244 0.58 0 Example 3 (1.0% SWNT + 10 seconds) 0.287 1.27 4.282 Example 4 (1.0% SWNT + 30 seconds) 0.382 1.69 10.392 Example 5 (1.0% SWNT + 60 seconds) 0.453 2.25 16.183 Reference Example 1 (1.0% SWNT + 120 sec) 0.521 1.01 25.320 Reference Example 2 (1.0% SWNT + 180 sec) 0.952 0.8 26.047

From the results of Table 2 and FIG. 6, the conductive composite in the structure of Example 3 showed slightly increased surface roughness and 120% higher electrical conductivity than before the surface treatment, and the conductive composite in the structure of Example 4 was compared before the surface treatment. It is confirmed that it has a higher surface roughness and a 191% higher electrical conductivity. These results suggest that the conductive composite according to the embodiment can exhibit remarkably high electrical conductivity while maintaining the conductive particle content at a low level. On the other hand, when the surface treatment time exceeds a predetermined time, it is confirmed that the conductivity improvement rate is greatly reduced.

Experimental Example 4: Measurement of the contact resistance of the conductive composite structure

For the conductive composites of Comparative Example 1, Comparative Example 2, Example 1, and Example 3, the contact resistance was measured using the same method as when obtaining electrical conductivity based on a transfer length method (TLM). The results are summarized in Table 3 below and in FIGS. 8 and 9. See FIG. 10 for the transfer length method. The specimen having the pattern shown in FIG. 10 was prepared in the same manner as described above.

Contact resistance Rc [Ω] Non-contact resistance ρc [Ωcm ² ] Comparative Example 1 4.13 0.28 Comparative Example 2 154.5 8.54 Example 1 2.15 0.12 Example 3 73.1 3.74

From the results of Table 3 and FIGS. 8 and 9, it is confirmed that the conductive composites surface-treated in the structures of Examples 1 and 3 may exhibit significantly lower non-contact resistance compared to the conductive composites of Comparative Examples without surface treatment. .

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention defined in the following claims are also present. It is within the scope of the invention.

Claims (16)

A deformable substrate; And
A structure comprising a conductive composite layer disposed on at least a portion of the surface of the deformable substrate,
The conductive composite layer includes a polymer matrix and a plurality of conductive particles embedded in the polymer matrix,
The conductive composite layer contains the conductive particles in an amount of 0.001% to 50% by weight,
The conductive composite layer is disposed to be bent or stretched together with the deformable substrate,
A structure in which at least a part of the surface of the conductive composite layer is treated with a solvent capable of dissolving the polymer matrix to expose part or all of the conductive particles. The method of claim 1,
The conductive composite layer includes a step formed by the surface treatment with the solvent, and a structure in which all or part of the conductive particles are exposed on a lower surface of the conductive composite layer. The method of claim 1,
The deformable substrate is a structure comprising a metal foil, polyimide, elastomer, or a combination thereof on which a planarized insulating oxide layer is deposited. The method of claim 1,
The conductive composite layer is a patterned layer. The method of claim 1,
The polymer matrix is an elastomer structure. The method of claim 5,
The elastomer is a structure comprising a silicone rubber, a natural rubber, a vinylidene fluoride-hexafluoropropylene copolymer, or a combination thereof. The method of claim 1,
The conductive particle is a structure including a carbon-based material, a conductive metal nanoparticle, a conductive metal nanowire, or a combination thereof. The method of claim 1,
A structure in which the surface of the conductive composite layer treated with the solvent has an increased surface roughness of 500% or less compared to the untreated surface. delete A deformable substrate; And a conductive composite layer disposed on at least a portion of the surface of the deformable substrate, wherein the conductive composite layer includes a polymer matrix and conductive particles embedded in the polymer matrix, and the conductive composite layer comprises the conductive particles And obtaining a structure in which the conductive composite layer is arranged to be bent or stretchable together with the deformable substrate in an amount of 0.001 wt% to 50 wt%; And
And exposing a portion of the conductive particles to the surface of the composite layer by contacting at least a portion of the surface of the conductive composite layer with a reactive solvent for the polymer matrix for a predetermined period of time. The method of claim 10,
The reactive solvent is non-reactive to the conductive particles and is a solvent capable of dissolving the polymer matrix. The method of claim 10,
The polymer matrix includes silicone rubber, natural rubber, or a combination thereof, and the conductive particles are carbon nanotubes, graphene, carbon black, silver nanowires, silver nanoparticles, gold nanowires, gold nanoparticles, copper Nanowires, copper nanoparticles, nickel nanowires, nickel nanoparticles, or a combination thereof, and the reactive solvent is trifluoroacetic acid, sulfuric acid, dipropylamine, or a combination thereof. The method of claim 10,
The contacting is performed for a period of time such that the increase rate of the roughness of the surface of the composite layer contacted with the reactive solvent is 500% or less. A deformable substrate; And a structure including a conductive composite layer disposed on at least a portion of the surface of the deformable substrate,
The conductive composite layer includes a polymer matrix and conductive particles embedded in the polymer matrix, the conductive composite layer includes the conductive particles in an amount of 0.001 wt% to 50 wt%, and the conductive composite layer comprises the An electronic device having conductive particles that are disposed to be bent together with a deformable substrate, and at least a part of the surface of the conductive composite layer is exposed by being treated with a solvent capable of dissolving the polymer matrix. The method of claim 14,
The device is a stretchable electronic device. The method of claim 14,
The device is a stretchable organic light emitting diode display, a stretchable human motion sensor, a stretchable artificial muscle, a stretchable actuator, or a stretchable semiconductor.

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