KR20180036262A - Method for doping and manufacturing graphene, graphene manufactured by the method - Google Patents

Abstract

The purpose of the present invention is to provide a graphene doping method and a graphene preparation method which are capable of greatly improving surface resistance of graphene through doping of graphene, and the graphene prepared thereby. The graphene doping method according to the present invention comprises the steps of: (a) forming a graphene on a metal catalyst layer; (b) mixing an etchant with 4-hydroxybenzenesulfonic acid to prepare a mixed etchant; and (c) dipping the graphene-formed metal catalyst layer in the mixed etchant to etch the metal catalyst layer and dope the graphene with 4-hydroxybenzenesulfonic acid at the same time. The graphene preparation method according to the present invention can efficiently prepare graphene having improved surface resistance properties by doping the graphene with 4-hydroxybenzenesulfonic acid having electrical characteristics.

Description

TECHNICAL FIELD The present invention relates to a graphene doping method, a graphene doping method, a graphene doping method, and a graphene graphene graphene graphene graphene graphene graphene graphening method.

More particularly, the present invention relates to a method of doping graphene to reduce sheet resistance, a method of manufacturing graphene using such graphene doping method, and a graphene produced thereby.

As is well known, graphene is a conductive material having a thickness of one layer of atoms, with the carbon atoms forming a honeycomb arrangement in a two-dimensional fashion. It has become an important model for studying various low-dimensional nano phenomena as graphite when accumulated in three dimensions, carbon nanotubes when dried one-dimensionally, and fullerene as a zero-dimensional structure when it is in a ball shape.

Graphene is not only very stable both structurally and chemically, but it is also known to be a very good conductor that can transport electrons 100 times faster than silicon and about 100 times more current than copper. The characteristics of graphene were experimentally confirmed in 2004, when the method of separating graphene from graphite was found.

Graphene is made of only carbon, which is a relatively light element, which makes it very easy to fabricate 1D or 2D nanopatterns, which can control the semiconductor-conductor properties. In addition, by using the variety of chemical bonds of carbon, it is possible to manufacture a wide variety of functional devices such as sensors and memories.

Graphene has the advantage of being able to be synthesized and patterned in a relatively simple manner while having excellent stretchability, flexibility and transparency. In OLEDs and organic solar cells, which are currently under widespread use, the use of conventional inorganic-based electrodes degrades electrode characteristics due to differences in work function of the contact sites. When graphene is used, the work function difference This problem can be solved easily because it is not large. Graphene transparent electrodes are expected to revolutionize the entire next-generation flexible electronic industry technology as well as import substitution effects through the establishment of mass production technology in the future.

Graphene is largely manufactured using mechanical stripping, chemical vapor deposition, epitaxial synthesis, or chemical stripping. Among them, the chemical vapor deposition method can control the number of graphene layers by controlling the type and thickness of the catalyst, the reaction time, the cooling rate, and the concentration of the reaction gas, and has a surface resistance and a transparency Graphene can be produced.

In a simple chemical vapor deposition method, copper or the like to be used as a catalyst layer is deposited on a substrate, and reacted with methane and hydrogen mixed gas at a high temperature of about 1000 degrees Celsius so that an appropriate amount of carbon is dissolved or adsorbed in the catalyst layer. After cooling, the carbon atoms contained in the catalyst layer are crystallized on the surface to form a graphene crystal structure. The graphene thus synthesized can be separated from the substrate by etching the catalyst layer and then used for a desired application.

In order to use graphene as an electric and electronic material such as a display, it is necessary to reduce sheet resistance. There is no sheet resistance standard for graphene required in the current market, but the lower the sheet resistance, the higher the value of graphene. For use as a touch panel or an OLED electrode element, a sheet resistance of about 200? /? Is required. However, the sheet resistance of the graphene is about 230? /?

Patent Registration No. 1590709 (Feb.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a graphene doping method and a graphene doping method capable of greatly improving the sheet resistance of graphene through doping of graphene, .

According to another aspect of the present invention, there is provided a method of doping graphene, comprising: (a) preparing a mixed etching solution by mixing 4-hydroxybenzenesulfonic acid with an etchant; And (b) etching the metal catalyst layer by immersing the metal catalyst layer having the graphene in the mixed etching solution, and doping the graphene with 4-hydroxybenzenesulfonic acid.

In the step (a), the etchant may include H2SO4, H2O2, and a surfactant.

The mixed nicking solution may be prepared by mixing 8-12 v / v% of H2SO4, 8-12 v / v% of H2O2, 0.1-0.6 v / v% of the surfactant, 4-hydroxybenzenesulfonic acid acid in an amount of 0.1 to 0.3 v / v%.

The step (b) may be performed at a temperature of 25 to 40 ° C.

According to another aspect of the present invention, there is provided a doping method of graphene comprising the steps of: (a) forming graphene on a metal catalyst layer; (b) preparing a mixed etchant by mixing 4-hydroxybenzenesulfonic acid in the etchant; And (c) etching the metal catalyst layer by immersing the metal catalyst layer having the graphene in the mixed etching solution, and doping the graphene with 4-hydroxybenzenesulfonic acid do.

The method of doping graphene according to the present invention comprises the steps of: (d) attaching the graphene to a film before the step (c); And (e) after the step (c), peeling the graphene from the film.

The graphene manufacturing method according to the present invention can efficiently produce graphene having improved sheet resistance characteristics by doping 4-hydroxybenzenesulfonic acid having electrical properties into graphene.

Also, the graphene production method according to the present invention can be performed by mixing 4-hydroxybenzenesulfonic acid in an etchant and doping it into graphene, and performing an etching process and a doping process simultaneously without a separate doping process . Therefore, the manufacturing process is efficient, and manufacturing time and manufacturing cost can be reduced.

FIG. 1 is a step-by-step view illustrating a method of manufacturing a graphene according to an embodiment of the present invention.
FIG. 2 shows the molecular structure of 4-hydroxybenzenesulfonic acid used as a dopant in the method of preparing graphene according to an embodiment of the present invention.
FIG. 3 is a view for explaining a process of measuring the sheet resistance of graphene produced through an experiment to which the present invention is applied.

Hereinafter, the graphene doping method and the manufacturing method according to the present invention and the graphene produced thereby will be described in detail with reference to the drawings.

FIG. 1 is a step-by-step view illustrating a method of manufacturing a graphene according to an embodiment of the present invention.

1, a method of manufacturing a graphene according to an embodiment of the present invention includes the steps of forming a graphene 10 on a metal catalyst layer 20 and attaching a film 30 to the formed graphene 10 ; And etching the metal catalyst layer (20) and doping the graphene (10). The graphene 10 thus manufactured is peeled off from the film 30 and transferred to another substrate or the like, so that it can be used as an element of various electric and electronic elements such as a touch panel and an OLED electrode element.

In the step of forming the graphenes 10, various graphene forming methods may be used. In this embodiment, graphene synthesis using chemical vapor deposition (CVD) is taken as an example.

In the graphene synthesis step using the chemical vapor deposition method, first, a metal catalyst layer 20 is prepared as shown in Fig. 1 (a). The metal catalyst layer 20 may be formed of a metal such as Ni, Co, Fe, Pt, Au, Al, Cr, Cu, Mg, Mn, Mo, Rh, Si, Ta, Ti, W, U, V, Zr, Ge, ), Bronze, white copper, stainless steel, and combinations thereof. Next, the graphene 10 is formed on the metal catalyst layer 20. Since various methods are known for forming the graphene 10 on the metal catalyst layer 20, detailed description thereof will be omitted.

After the formation of the graphene 10, the film 30 is attached to the graphen 10 as shown in Fig. 1 (c). It is possible to attach the thin film 10 to the film 30 by attaching the film 30 to one surface of the metal catalyst layer 20 on which the graphene 10 is formed. As the film 30, a variety of materials which are not corroded or damaged in a subsequent etching process can be used while supporting the graphen 10 formed by a thermal release film or the like without bruising.

Next, as shown in FIG. 1 (d), a step of etching the metal catalyst layer 20 and doping the graphene 10 is performed. This step can be proceeded by preparing the mixed etching solution S and immersing the metal catalyst layer 20 on which the graphene 10 is formed in the prepared mixed etching solution S. [

The mixed etching solution S may be prepared by mixing a dopant for doping the graphene 10 into an etching solution capable of etching the metal catalyst layer 20. As the etching solution, H2SO4, H2O2, a surfactant, and deionized water may be used. Various surfactants such as benzimidazole and benzotroazole may be used as the surfactant. As the dopant, 4-hydroxybenzenesulfonic acid is used.

4-hydroxybenzenesulfonic acid is a structure in which double bonding is performed through the resonance structure of S and benzene, as shown in the molecular structural formula shown in FIG. 2, which is a structure in which electricity can communicate with each other. That is, 4-hydroxybenzenesulfonic acid has electrical characteristics. In addition, 4-hydroxybenzenesulfonic acid is a structure in which oxygen having single bonding can stably receive hydrogen, and hydrogen generated by the reaction of H2SO4, H2O2 and the metal catalyst layer (20) It can contribute to the stabilization of the etching liquid, and can exhibit a synergistic effect with the etching liquid.

It is preferable that the content of the main constituent constituting the mixed etching solution (S) is limited to a certain range, respectively.

First, the contents of H2SO4 and H2O2, which are etching materials used for etching the metal catalyst layer 20, are preferably limited to the range of 8-12 v / v%. When the contents of H2SO4 and H2O2 are less than 8 v / v%, the metal catalyst layer 20 is not smoothly etched. If the content of H2SO4 and H2O2 exceeds 12 v / v%, safety problems may occur during the etching operation It is not preferable.

Next, the content of the surfactant is preferably limited to 0.1 to 0.6 v / v%. When the content of the surfactant is less than 0.1 v / v%, the function of the surfactant itself, that is, the barrier function against the etchant is not exhibited. When the content of the surfactant exceeds 0.6 v / ) Can not be smoothly etched.

The content of 4-hydroxybenzenesulfonic acid in the total mixed etching solution (S) is preferably in the range of 0.1 to 0.3 v / v%. When the amount of 4-hydroxybenzenesulfonic acid is less than 0.1 v / v%, the effect of improving the sheet resistance of graphene 10 is insignificant. On the other hand, when the content of 4-hydroxybenzenesulfonic acid exceeds 0.3 v / v%, the etching efficiency of the etching solution is lowered.

As shown in FIG. 1 (d), the mixed etching solution S is filled in the process tank 40 and the metal catalyst layer 20 on which the graphene 10 is formed is dipped in the etching solution and the doping solution can do. When the metal catalyst layer 20 on which the graphene 10 is formed is immersed in the mixed etching solution S, the metal catalyst layer 20 is etched and removed, and the graphene 10 is formed of 4-hydroxybenzenesulfonic acid, Lt; / RTI >

As shown in FIG. 1 (e), after the etching and the doping process, the graphene 10 may be discharged from the mixed etching solution S while being attached to the film 30. During the etching process, the graphene 10 may be contaminated by substances (such as catalyst metal ions (e.g., Cu ions), etchant ions, or organic materials such as resin of the film 30) formed during the etching process, The foreign matter can be removed through the process.

Thereafter, a process of peeling the graphene 10 from the film 30 can be performed. Various methods can be used as the method of peeling the graphene 10 from the film 30. For example, when a heat peelable film is used as the film 30, the graphene 10 may be peeled off from the film 30 by applying heat to the film 30. That is, the film 30 on which the graphene 10 is attached is laminated on the substrate so that the graphene 10 is in contact with one side of the substrate, heat is applied to the film 30, The graphene 10 can be separated from the film 30 and transferred to the substrate.

Various functional elements can be manufactured by separating the graphene 10 from the film 30 and transferring it to another substrate or the like. The graphene 10 according to the present invention is uniformly doped with 4-hydroxybenzenesulfonic acid having electrical properties and thus has excellent sheet resistance properties and is applied to various electric and electronic devices such as a touch panel or an OLED electrode device, Performance can be achieved.

Table 1 below shows the results of measuring the sheet resistance of the graphene prepared by the experiment using the graphene manufacturing method of the present invention, and FIG. 3 illustrates the process of measuring the sheet resistance of the graphene according to the experimental example .

<Table 1>

In this experimental example, Cu was used as the metal catalyst layer 20. The metal catalyst layer 20 having the graphene 10 formed on the CU metal catalyst layer 20 and the graphene 10 formed on the mixed etchant S mixed with the etchant and the dopant was simultaneously etched and doped. The mixed etching solution (S) was prepared by mixing 4-hydroxybenzenesulfonic acid in an etching solution containing H2SO4, H2O2, a surfactant, and deionized water. The content of the main component constituting the mixed etching solution (S) is within the range described above, and the reaction temperature is room temperature less than 40 캜. The processing time is approximately one hour.

Through this process, rectangular graphene 10 of approximately A3 size area was obtained and sheet resistance was measured at several points (P) of graphene 10 to obtain the results shown in Table 1 above.

3, the left side of the produced graphen 10 is taken as the Y axis, the lower side of the graphen 10 is defined as the X axis, and the vertexes of the graphenes 10, (0, 0), and the sheet resistance at various coordinates of the graphene 10 was measured.

 The numerical values shown in the uppermost row in Table 1 indicate the horizontal direction of the graphene 10 (hereinafter, referred to as X axis) and the numerals in the vertical column of the left end indicate the vertical direction of the graphene 10 , &Quot; Y axis &quot;). The numerical values in the bottom row indicate the average sheet resistance in the selected seven X axis coordinates of the X axis coordinates of the graphene 10 and the numerical values in the right end column indicate the Y axis coordinates of the graphen 10 And the average sheet resistance in the 13 Y-axis coordinates. And the values in the middle rows and columns are the sheet resistance at each of the selected measurement points (P).

For example, the sheet resistance of the graphene 10 at the measurement point P of the X-Y coordinates 145 and 225 of the graphene 10 is 188? / ?. Here, the coordinates in the X and Y axes mean the distance (mm) away from the origin in the axial direction.

These results indicate that the average sheet resistance of the graphene 10 doped with 4-hydroxybenzenesulfonic acid is less than about 200? /? Sufficient to be used as a touch panel or OLED electrode device .

As described above, according to the graphene production method of the present invention, 4-hydroxybenzenesulfonic acid having electrical properties is applied to the graphene 10 to be used as a touch panel or an OLED electrode element The graphene 10 having improved sheet resistance can be produced.

In the method of manufacturing graphene according to the present invention, 4-hydroxybenzenesulfonic acid (4-hydroxybenzenesulfonic acid) is mixed with an etchant and doped into the graphene 10 to perform an etching process and a doping process without a separate doping process Can be performed simultaneously. Therefore, the manufacturing process is efficient, and manufacturing time and manufacturing cost can be reduced.

Although the preferred embodiments of the present invention have been described above, the scope of the present invention is not limited to those described and illustrated above.

For example, the etchant used for etching the metal catalyst layer 20 is not limited to that described above, and may be variously changed. In addition to the above-mentioned H2SO4 and H2O2, KOH (Potassium Hydroxide), TMAH (Tetra Methyl Ammonium Hydroxide), EDP (Ethylene Diamine Pyrocatechol), BOE (Burrered Oxide Etch), FeCl3, Fe (NO3) Various compositions including various etchants such as HPO4, HCl, NaF, KF, NH4F, AlF3, NaHF2, KHF2, NH4HF2, HBF4 and NH4BF4 can be used.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Those skilled in the art will appreciate that numerous modifications and variations can be made in the present invention without departing from the spirit and scope of the appended claims.

10: graphene 20: metal catalyst layer
30: Film 40: Process tank
S: mixed etching solution

Claims (8)

(a) preparing a mixed etchant by mixing 4-hydroxybenzenesulfonic acid in an etchant; And
(b) immersing the metal catalyst layer in which the graphene is formed in the mixed etching solution to etch the metal catalyst layer and doping the graphene with 4-hydroxybenzenesulfonic acid. Doped graphene. The method according to claim 1,
Wherein the etching solution includes H2SO4, H2O2, and a surfactant in the step (a). 3. The method of claim 2,
The mixed nicking solution may be prepared by mixing 8-12 v / v% of H2SO4, 8-12 v / v% H2O2, 0.1-0.6 v / v% of the surfactant, 4-hydroxybenzenesulfonic acid acid in an amount of 0.1 to 0.3 v / v%. The method according to claim 1,
Wherein the step (b) is performed at a temperature of 25 to 40 ° C. Graphene doped by a doping method according to any one of claims 1 to 4. (a) forming graphene on the metal catalyst layer;
(b) preparing a mixed etchant by mixing 4-hydroxybenzenesulfonic acid in the etchant; And
(c) etching the metal catalyst layer by immersing the metal catalyst layer having the graphene in the mixed etching solution, and doping the graphene with 4-hydroxybenzenesulfonic acid &Lt; / RTI &gt; The method according to claim 6,
Wherein the etchant includes H2SO4, H2O2, and a surfactant in the step (b). The method according to claim 6,
(d) attaching the graphene to the film before the step (c); And
(e) peeling the graphene from the film after the step (c).

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