KR102242028B1 - Forming Methods of Graphene Nano Patterns, Apparatus Used Therein, And Ink Therefor - Google Patents

Abstract

A method of printing graphene nanopatterns is disclosed. The present invention comprises the steps of providing an ink in which graphene oxide sheets are dispersed in a solvent to a nozzle; Positioning the nozzle at a predetermined point on the substrate; And printing the graphene oxide nano pattern corresponding to the movement path of the nozzle by moving the nozzle along a predetermined path on the substrate while discharging the ink from the nozzle, and printing the graphene oxide nano pattern. In, the nano-patterns are printed as graphene oxide sheets stacked by evaporation of a solvent in a meniscus formed by the ink discharged from the nozzle between the nozzle and the substrate, and printed graphene oxide nano-patterns It provides a printing method of graphene oxide nanopatterns, characterized in that the size of is controlled by controlling the pulling speed of the nozzle, and includes thermal and chemical reduction treatment of the printed graphene oxide pattern. According to the present invention, a graphene oxide pattern or a graphene pattern having a nano size of less than 1 micron can be printed without a matrix for maintaining the shape of graphene.

Description

Graphene Nano Patterns, Apparatus Used Therein, And Ink Therefor. {Forming Methods of Graphene Nano Patterns, Apparatus Used Therein, And Ink Therefor}

The present invention relates to a method of printing graphene nanopatterns.

Graphene is one of the carbon allotropes made of carbon atoms. In general, graphene refers to a ^{two-dimensional single sheet composed of a sp 2} hybrid of carbon, has a large surface area, has excellent mechanical, thermal, optical and electrical properties, and has flexibility and transparency. As a result, it has been in the spotlight as a candidate material for realizing next-generation flexible electric devices.

In order to implement a next-generation graphene-based flexible device, there is a need for a 3D patterning technology capable of fabricating a nanometer-sized graphene 3D structure at a desired location in a large area.

Printed electronics technology uses a direct printing process of various functional ink materials, as well as digital home appliances such as smartphones, digital cameras, DVD (Digital Versatile Disc), and LCD (Liquid Crystal Display), as well as electronic paper and flexible physical and chemical sensors. It is a technology capable of manufacturing various next-generation flexible electronic devices such as, etc. Manufacturing electronic devices through a printing process can have several advantages over existing processes. First of all, a variety of processes are possible without an expensive manufacturing process, so the process cost can be drastically lowered, and the process speed can also be increased through a continuous process. In addition, it is environmentally friendly by reducing the consumption of various energy such as electricity used to maintain the process, and since it is possible to selectively manufacture electronic devices only in the desired part, it is possible to minimize the discharge of unnecessary chemical waste. In addition, printed electronics technology has very high process suitability with flexible electronic device technology that implements electronic devices on flexible plastic substrates because many ink materials can be processed at low temperatures.

In the printed electronics technology, in addition to the method of manufacturing electronic devices in the form of scanning, copying, and outputting a flat two-dimensional object, there is a three-dimensional printing method capable of producing a three-dimensional pattern. 3D printing technology is an additive manufacturing method based on 3D design data based on materials such as insulators such as rubber, nylon and plastic, stainless steel, and metal such as titanium. Can shape. These 2D and 3D printing technologies have been applied to some areas such as circuits of printed circuit boards, photomasks of semiconductors, and color filters of displays. It plays a role as a catalyst to grow into a new area while developing and converging. In particular, it is believed that 3D printing technology can present a revolutionary direction in the manufacture of new types of electronic devices and parts.

However, using the existing 3D printing technology, materials such as carbon nanotubes and graphene can be filled as fillers in a matrix such as plastic to produce a structure having a size of at least tens of micrometers. It is not possible to create a three-dimensional nanostructure composed entirely of graphene.

K. Y. Shin et. al, Advanced Materials, 23, 2113 (2011)

In order to solve the problems of the prior art, the present invention aims to provide a graphene oxide pattern having a nano size of less than 1 micron and a printing method of the graphene pattern.

In addition, an object of the present invention is to provide a method of printing a graphene nanopattern without a matrix for pattern printing.

In addition, an object of the present invention is to provide a printing method of graphene nanopatterns capable of maintaining the structure of the pattern by the bonding force between graphene sheets.

In addition, an object of the present invention is to provide a printing method of a flexible graphene electronic device.

In addition, an object of the present invention is to provide a graphene nano-pattern printing apparatus suitable for carrying out the above-described method.

In addition, an object of the present invention is to provide a graphene oxide ink suitable for use in the above-described graphene nanopattern printing method.

In order to achieve the above technical problem, the present invention includes the steps of supplying an ink in which graphene oxide sheets are dispersed in a solvent to a nozzle; Positioning the nozzle at a predetermined point on the substrate; And printing the graphene oxide nano pattern corresponding to the movement path of the nozzle by moving the nozzle along a predetermined path on the substrate while discharging the ink from the nozzle, and printing the graphene oxide nano pattern. In, the nano-patterns are printed as graphene oxide sheets stacked by evaporation of a solvent in a meniscus formed by the ink discharged from the nozzle between the nozzle and the substrate. Provides a method for printing patterns.

In this case, the concentration of the graphene oxide sheet is preferably from 1g/L to 10g/L.

In addition, it is preferable that the moving speed of the nozzle is 0.1 μm/sec to 200 μm/sec, and the diameter of the nozzle is 0.1 μm to 50 μm.

In addition, in the present invention, the solvent is preferably at least one selected from a polar solvent group consisting of water, alcohol, acetone and dichloromethane.

In addition, according to another aspect of the present invention for achieving the above technical problem, the present invention comprises the steps of supplying an ink in which a graphene oxide sheet is dispersed in a solvent to a nozzle; Contacting the nozzle with the substrate; Separating the nozzle from the substrate by a predetermined distance so that a meniscus is formed between the substrate and the nozzle; And depositing graphene oxide sheets by evaporation of the solvent in the meniscus, and printing the graphene oxide nano pattern by moving the nozzle to the substrate to induce the continuous graphene oxide deposition. It provides a printing method of graphene oxide nano-patterns.

In the present invention, the evaporation of the solvent may be performed below the boiling point of the solvent, and in particular, may be performed at room temperature.

In addition, in the present invention, the stacked graphene oxide sheets are bonded by van der Waals force.

In addition, in the present invention, the size of the stacked graphene oxide nanopatterns is controlled by inducing a change in the size of the meniscus through a change in the pulling speed of the nozzle.

In addition, in order to achieve the above other technical problem, the present invention provides a graphene oxide nanopattern prepared by the above-described method; And reducing the graphene oxide nanopatterns to print the graphene nanopatterns. In the present invention, the reduction process may be performed by heat treatment in a vacuum or non-oxidizing atmosphere, or may be performed by hydrazine treatment.

In addition, according to another aspect of the present invention, the present invention is graphene oxide sheets; It provides a graphene oxide pattern printing ink, characterized in that it contains a solvent in which the graphene sheets are dispersed and does not contain a binder for forming the graphene oxide sheets. In this case, it is preferable that the solvent has a boiling point of 100°C or less.

According to the present invention, it is possible to print without a matrix for maintaining the shape of the graphene oxide pattern or the shape of the graphene pattern having a nano size of less than 1 micron. In addition, in the present invention, the graphene oxide sheets are firmly bonded by their van der Waals force to maintain the shape of the pattern. Accordingly, the present invention provides a method for producing a nano-pattern made of only graphene without undergoing a complicated treatment. This can be used as a printing technology to implement flexible and transparent next-generation graphene-based electronic devices.

1 is a diagram schematically illustrating a printing technique according to an embodiment of the present invention.
2 is a conceptual diagram showing in more detail an operation process of the printing pen 110 for printing a graphene oxide pattern according to an embodiment of the present invention.
3 is a diagram illustrating an example of a pattern printing method according to an embodiment of the present invention.
4 is a view schematically showing a graphene nano pattern printing apparatus according to an embodiment of the present invention.
5 is a graph plotting the size change of the graphene oxide (GO) wire according to the nozzle pulling speed of the graphene nanowire manufactured according to the present embodiment.
6 is a photograph showing a change in the nozzle pulling speed, graphene oxide size, and diameter of the nanowire of the graphene nanowire prepared according to an embodiment of the present invention.
7 is a photograph showing the electrical and mechanical properties of the graphene wire prepared in an embodiment of the present invention.
8 is a diagram showing an application example of a graphene nano-patterned elastic interconnect and a gas sensing transducer according to an embodiment of the present invention.
9 is a photograph showing various types of application patterns manufactured according to the present invention.

Although preferred embodiments of the present invention have been described above, the above-described embodiments illustrate the present invention and do not limit the present invention.

Terms used in the specification of the present invention are used in the usual meaning of the term. However, terms specially defined in this specification are used as defined. For example,'nano' means a size of less than 1 micrometer, that is, several to several hundreds of nanometers in a conventional sense, and'nano pattern' means a pattern in which the line width of the pattern is nano-sized. In the present invention, the pattern is a structure that functions as an electrical device, and includes not only two-dimensional but also three-dimensional structures, for example, including all wire-shaped structures that are stacked in a direction parallel to the substrate surface or extend in a direction perpendicular to the substrate. .

1 is a diagram schematically illustrating the printing technology of the present invention. Referring to FIG. 1, the graphene oxide ink in which the graphene oxide sheet is dispersed in a predetermined concentration is maintained in the printing pen 110. As the printing pen 110 contacts the substrate 10 and the pen 110 moves from the contact point in a specific direction, for example, in a vertical direction, at a predetermined speed (v), ink is discharged to the nozzle at the tip of the pen at a predetermined flow rate (W). do.

The ink discharged near the nozzle of the tip of the pen forms a meniscus (B) by surface tension. Instantaneous evaporation of the ink solvent from the meniscus surface leaves a pure graphene oxide sheet stack (A) on the substrate. As the printing pen 110 moves upward, the surface tension caused by the meniscus (B) formed at the tip of the nozzle causes the solution to be discharged out of the nozzle without interruption. In this way, the solution in the nozzle is continuously discharged according to the movement of the nozzle, and a laminated structure (A) of graphene oxide sheet is printed on the evaporation area close to the substrate, while a meniscus (B) is formed on the nozzle side. A continuous process occurs.

As a result, a predetermined graphene oxide lamination pattern corresponding to the movement trajectory of the nozzle may be printed on the substrate.

2A to 2C are conceptual diagrams showing in more detail an operation process of the printing pen 110 for printing a graphene oxide pattern according to an embodiment of the present invention.

2A shows an initial state in which the nozzle of the pen 110 contacts the substrate 10 and the nozzle. An ink composed of a graphene oxide sheet 22 and a dispersion medium 24 for dispersing the graphene oxide sheet is stored in the pen 110.

When the pen 110 moves upward at a predetermined interval from the state (a) of FIG. 2, a meniscus (B) of ink is formed in the gap between the nozzle and the substrate.

In this state, when the pen 110 moves upward at a predetermined speed, ink is discharged from the nozzle. In the manner described with reference to FIG. 1, a meniscus (B) is formed on the nozzle side to which surface tension is applied by ink in a solution state, and graphene oxide 22 is deposited on the substrate side by evaporation of the solvent 24. Form the structure (A). In the present invention, the solvent of the meniscus (B) has a high specific surface area and thus spontaneously evaporates even at room temperature. Of course, in some cases, the present invention does not exclude that an appropriate heating means is added to the operation process of the pen. In the present invention, formation of the meniscus and evaporation of the solvent occur almost simultaneously, leaving a graphene oxide pattern composed of a pure graphene oxide sheet in a very short time.

The graphene oxide pattern printed in the present invention is composed of a plurality of graphene oxide sheets. The lamination pattern is supported by a bonding force resulting from the graphene oxide sheet itself such as Van der Waals force, and does not require a separate binder or bonding matrix for bonding between sheets.

In the present invention, the width of the meniscus is kept within an appropriate range to provide a high specific surface area for evaporation of the solvent. In the present invention, the width of the meniscus depends on the aperture of the nozzle and the moving speed of the nozzle. In addition, since the graphene oxide sheet flows in the meniscus pipe, the line width of the resulting graphene oxide stacked pattern has a value equal to or smaller than the width d of the meniscus.

Referring back to FIG. 1, the meniscus has a width d of a predetermined size at a predetermined moving speed v. However, as the movement speed increases, the width of the meniscus has a smaller value. This relationship can be expressed by the following formula, the so-called material balance law.

r = [W(v)/(πv)] ^1/2

(Where, r is the radius of the meniscus, v is the moving speed of the nozzle, and W is the flow speed of the ink)

Meanwhile, the graphene oxide nanopattern printed by the method of the present invention may be reduced to a graphene nanopattern in an appropriate manner. As an example of the reduction method, a heat treatment process may be performed in a vacuum or non-oxidizing atmosphere. The heat treatment temperature and time can be appropriately designed in consideration of the heat resistance of devices printed on the substrate and nearby devices. In addition, when a low temperature is required, the reduction process may be performed by chemical treatment such as hydrazine. Of course, in the present invention, the reduction process may be performed by performing heat treatment and chemical treatment in parallel.

On the other hand, the graphene oxide nano pattern printing method of the present invention can be applied to various types of patterns.

3 is a diagram illustrating an example of a pattern printing method according to the present invention.

Referring to FIG. 3A, the print pen 110 may move in a direction parallel to the substrate. Even in this case, the formation of a local meniscus, evaporation of the solution, and preparation of the graphene oxide nanopatterns can be carried out by the same mechanism as described above. In addition, such a pattern may be applied to printing a pattern of a two-dimensional surface shape.

In addition, FIG. 3B shows that the print pen 110 moves in a direction perpendicular to the substrate, so that a freestanding wire pattern can be manufactured in a direction perpendicular to the substrate.

In addition, it will be appreciated by those skilled in the art of the present invention that wire bonding in a three-dimensional space may be possible by appropriately combining movements in two directions.

4 is a view schematically showing a graphene nano-pattern printing apparatus according to an embodiment of the present invention.

Referring to FIG. 4, the graphene nano pattern printing apparatus 100 of the present invention may include a printing pen 110, a substrate stage 120, and a position control unit 140.

The printing pen 110 has a loading space for storing the graphene oxide ink 20 therein, and discharges the graphene oxide ink 20 through a nozzle provided at the tip. In the present invention, the cross section of the nozzle of the printing pen 110 may have various shapes such as a circular shape, a sand shape, and a hexagonal shape.

In the present invention, the nozzle has a predetermined diameter. As described above, the line width of the pattern printed by the movement of the nozzle depends on the movement speed of the nozzle. Therefore, in order to obtain a nano-sized pattern, the nano-sized aperture is not required. Preferably, in the present invention, the diameter of the nozzle is preferably 0.1 μm to 50 μm. When the diameter of the nozzle is 50 μm or more, the specific surface area of the meniscus to be formed is small, making it difficult to print the laminated structure. In addition, when the nozzle diameter is less than 0.1 μm, clogging of the nozzle may occur.

An ink supply tank (not shown) and an ink supply valve (not shown) may be connected to the printing pen 110. The ink supply valve may regulate the flow of ink flowing into the printing pen 110. In addition, the printing pen 110 may be attached to a transfer mechanism for three-axis transfer, such as a transfer arm, and the transfer arm transfers the printing pen 110 in the X, Y, and Z axis directions.

The substrate stage 110 may include an integral means for holding a substrate to be printed. The substrate stage 120 may include a transfer mechanism (not shown) movable in a three-axis direction.

In addition, the position control unit 140 controls the position of at least one of the printing pen 110 and the substrate stage 120. To this end, a three-dimensional relative position of the printing pen 110 and the substrate stage 120 may be controlled by driving a transfer mechanism of the printing pen 110 and the substrate stage 120.

In addition, the position control unit 140 controls the relative movement speed of the printing pen 110 with respect to the substrate. In the present invention, the moving speed of the nozzle for pattern printing is designed in consideration of the evaporation rate of the solution in the meniscus and the surface tension of the solution. When water, ethanol or acetone is used as a solvent, the moving speed of the nozzle is preferably in the range of 0.1 µm/sec to 200 µm/sec. At a moving speed of less than 0.1 µm/sec, fast evaporation causes clogging of the nozzle. Occurs, and at a moving speed of 200 µm/sec or more, the pattern breaks.

Of course, in the present invention, the position control unit 120 may control the position of the printing pen 110 and/or the substrate holder 120 by referring to the shape of the unit structure obtained through the CCD camera 142. In this case, the position control unit 140 may control the shape of the meniscus 113 formed between the printing pen 110 and the substrate 120 to adjust the growth direction of the structure.

In the present invention, the ink supplied as a raw material for the graphene nano pattern printing apparatus 100 preferably has the following characteristics.

The ink is composed of a solvent (or dispersion medium) and a graphene oxide sheet dispersed in the solvent.

In the present invention, it is preferable that the solvent does not generate a residue after evaporation. In the present invention, as the solvent, a polar inorganic solvent or an organic solvent may be used. Preferably, water may be used as the inorganic solvent, and alcohol, dichloromethane, and acetone may be used as the organic solvent. In addition, in the present invention, evaporation of the solvent and printing of the pattern must occur substantially in-situ. Therefore, in the present invention, the boiling point temperature of the solvent is preferably equal to or lower than that of water, and is preferably 100° C. or less.

In the present invention, the graphene oxide sheet is dispersed in the solvent. In the present invention, the concentration of the graphene oxide sheet in the ink is preferably in the range of 1g/L to 10g/L. At a lower concentration than this, the concentration of the graphene oxide sheet is low, so that a structure is not produced during printing. At a concentration exceeding this, the graphene oxide sheet may block the opening of the nozzle due to evaporation of the solvent.

In the present invention, the average size of the graphene oxide sheet may have a value larger than the aperture of the nozzle. The graphene oxide sheet has high flexibility, and even if a graphene oxide sheet larger than the nozzle diameter is used, the graphene oxide sheet can pass through the nozzle in a bent or curled state while passing through the nozzle. However, a graphene oxide sheet having an average size that is 10 times or more larger than the nozzle diameter may close the nozzle diameter, and thus is not preferable.

Hereinafter, exemplary embodiments of the present invention will be described.

<Preparation example of graphene oxide ink>

Graphene oxide sheets having an average size (width) of 1, 3, and 5 μm, respectively, were prepared. The graphene oxide sheet was prepared from a natural graphite, Alfa Aesar (purity 99.999%, 200 mesh or less) by a modified Hummer method. Specifically, 20 g of graphite and 460 mL of H ₂ SO ₄ were mixed in a flask, and _{60 g of KMnO 4} was slowly added in a cold water bath for 1 hour or more. Subsequently, the mixed solution was vigorously stirred at room temperature for 3 days, then 920 mL of deionized water was added, followed by stirring for 10 minutes. Then, _{50 mL of H 2} O ₂ (30 wt% aqueous solution) was added, and the mixture was stirred at room temperature for about 2 hours. The final mixed solution was centrifuged at 10000 rpm to prepare graphite oxide powder. The graphite oxide was peeled off by ultrasonic waves to prepare a graphene oxide sheet.

The prepared graphene oxide sheet was dispersed in water at a concentration of 1 g/L to prepare an aqueous solution sample. In this case, a separate aqueous solution sample was prepared using graphene oxide sheets having an average size of 1, 3, and 5 μm, respectively.

<Example 1: Preparation of graphene nanowire>

Using the prepared graphene oxide aqueous solution sample, a graphene nanowire was prepared. A glass micro-pippet was used as a nozzle, and two nozzle diameters of 1.3 μm and 2.6 μm were used.

A free standing graphene oxide wire was printed on a gold-coated silicon substrate. The graphene oxide ink was supplied through the rear end of the pipette (pen) and discharged from the tip without any pressure other than capillary force. In the manufacturing process of the nanowire, the position and pulling speed of the micropipette were precisely controlled with a position precision of 250 nm with a three-axis stepping motor.

The prepared graphene oxide nanowire (GO) was heat-treated in a vacuum atmosphere at 400° C. for 1 hour to prepare a reduced graphene nanowire (rGO).

5 is a graph plotting the size change of the graphene oxide (GO) wire according to the pulling speed of the graphene nanowire prepared according to the present embodiment.

At this time, the nozzle diameter used was 1.3 μm, and ink in which graphene oxide sheets having sizes of 1, 3, and 5 μm were dispersed, respectively, was used. As the pulling speed of the nozzle increased from 1.2 µm/s to 140.4 µm/s, the radius of the wire decreased from 625 nm to 150 nm. Plotting according to the material balance law described above, it can be seen that ^{this wire follows the condition of r ~ v -2.5.} On the other hand, the lower drawing of FIG. 5 shows a photograph of the shape of the graphene wire at each speed.

Meanwhile, referring to FIG. 5, it can be seen that the graphene wire prepared in the present invention exhibits various surface structures according to the pulling speed. For example, as shown in (c) to (d) of Figure 5, it can be seen that the individual graphene nanosheets constituting the graphene nanowires at a low pulling speed (c) are curled or crumpled and severely deformed. Many wrinkles are formed on the surface of the graphene nanopatterns due to wrinkles or entanglement of the graphene nanosheets. However, as the pulling speed increases, the wrinkles on the surface of the graphene nanopatterns gradually decrease. In other words, as the pulling speed increases, the arrangement of the graphene oxide sheets is arranged so that the faces of the graphene sheets are aligned in the direction of pulling the nozzle from the random arrangement (that is, the normal vector of the graphene sheets is aligned so that it is substantially perpendicular to the pulling direction of the nozzle) Indicates a trend. Since the former exhibits a low resistance when moving along the surface of the graphene, when the surfaces of the graphene sheets are aligned in the nozzle direction, paths with low resistance increase, thereby improving the conductivity of the graphene structure.

6 is a photograph showing the change in the nozzle pulling speed, the size of the graphene oxide, and the line width of the nanowire of the graphene nanowire prepared according to the present embodiment.

Referring to FIG. 6, it can be seen that, regardless of the size of the graphene (rGO) wire sheet, as the nozzle pulling speed increases, a wire having a thin line width is obtained.

<Example 2: Electrical and mechanical properties of graphene wire>

Using the same apparatus as in Example 1, a graphene oxide nanowire was printed on a gold electrode having a gap of 10 μm to prepare an interconnect connecting the two electrodes. Reduction from graphene oxide to graphene was heat-treated in vacuum (at 400° C. for 1 hour).

7 is a photograph showing the characteristics of the interconnect manufactured in this embodiment.

Figure 7 (a) is a graph plotting the current-voltage characteristics of the prepared graphene nano interconnect.

Current-voltage characteristics were measured by a two-probe method using a Keithley 2612A instrument at room temperature. It can be seen from (a) of FIG. 7 that a linear current characteristic is shown in the measured voltage section.

7B is a photograph showing the mechanical properties of the prepared graphene nano interconnect. 7B shows that the wire deformed under pressure by the stress is restored by removing the stress.

<Example 3: Fabrication of a telescopic interconnect and a gas sensing transducer>

FIG. 8A shows an application example of a stretchable wiring electrode. To this end, an interconnect connecting the two electrodes was prepared by printing graphene oxide nanowires on a gold electrode having a gap of 30 μm on a deformable PDMS. In order to prevent damage to PDMS during the reduction process, reduction of graphene oxide to graphene was performed by hydrazine treatment (12 hours at 120°C). It can be seen that the interconnect has no change in resistance even with 340% deformation, and shows stable characteristics without change in resistance even after 120 repeated deformations between 25% and 150%.

Figure 8 (b) shows an application example of a gas sensing transducer. Printing 5 graphene nanowires connecting platinum patterns with 10 μm intervals in parallel were prepared to print a gas sensor transducer. It shows that the nanowire transducer reacts linearly to the change in the concentration of carbon dioxide injected at room temperature from 0.25% to 5%.

.

<Various embodiments of graphene nanowires>

9 is a photograph showing various types of wire patterns printed according to an example of the present invention.

Figure 9 (a) is an arrangement of free standing wires, Figure 9 (b) is a zigzag-shaped nano-arch, Figure 9 (c) is a chain structure wire, Figure 9 (d) is the letter'KERI', Figure 9 (e) shows a weaving structure.

10 substrate
20 Graphene oxide nano pattern printing ink
22 Graphene oxide nanosheets
24 solvent
100 graphene oxide nano pattern printing device
110 nozzle
120 substrate stage
140 position control
142 camera

Claims (15)

delete delete delete delete delete Supplying ink in which the graphene oxide sheet is dispersed in a solvent to the nozzle;
Contacting the nozzle with the substrate;
A three-dimensional graphene oxide nano, in which graphene oxide sheets are stacked by moving the nozzle relative to the substrate to form a meniscus by the ink between the nozzle and the substrate, and evaporation of a solvent in the meniscus. Printing a pattern; And
Including the step of reducing the graphene oxide nano-pattern,
The nano-pattern printing method, characterized in that in the 3D nano-pattern printing step, the nano-patterns are bonded by Van der Waals force between graphene oxide sheets.
The method of claim 6,
The evaporation of the solvent is a graphene nanopattern printing method, characterized in that carried out below the boiling point of the solvent.
delete delete delete delete delete The method of claim 6,
The printing method of the graphene nano pattern, characterized in that the ink does not contain a binder for forming the graphene oxide sheet.
The method of claim 13,
Graphene nano-pattern printing method, characterized in that the concentration of the graphene oxide sheet in the ink is 1g / L ~ 10g / L. The method of claim 13,
The method of printing a graphene nanopattern, characterized in that the solvent has a boiling point of 100° C. or less.

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