CN104528698B - A kind of stable doping method of Graphene - Google Patents

Abstract

The invention relates to a stable doping method of graphene, comprising the steps of wrapping dopant reagent molecules between graphene and graphene and/or wrapping dopant reagent molecules between substrate and graphene, and A temporary substrate is used in the step where dopant reagent molecules are wrapped between the substrate and the graphene. The present invention achieves a stable doping effect by covering the dopant molecules between the graphene layer and the base layer, avoiding direct contact between the air and the dopant molecules, and maintaining the original shape of the dopant molecules on the graphene surface for a long time. Doping state, so that the long-term stability of the doping effect can be maintained.

Description

A kind of stable doping method of graphene

technical field

The invention relates to a stable doping method of graphene, in particular to a method for stably improving the electrical properties of a graphene film, and belongs to the field of graphene film processing methods.

Background technique

Graphene is a two-dimensional material in which sp ² hybridized carbon atoms are arranged in a hexagonal lattice. The unique two-dimensional crystal structure endows graphene with unique properties. The thickness of single-layer graphene is 0.34nm, the light absorption is only 2.3% in a wide band, and the intrinsic carrier mobility is as high as 2.0×10 ⁵ cm ² ·V ^-1 ·s ^-1 , which makes graphene In essence, it has high transmittance and good conductivity at the same time, and can be used as a transparent conductive material.

At present, the preparation methods of graphene films mainly include chemical vapor deposition method. Generally, the graphene prepared by this method cannot be used directly on copper substrates, and needs to be transferred to other substrates for better application. The transfer process will cause some damage to the quality of graphene, and certain doping methods are required to make the square resistance of graphene meet the use requirements. The existing doping technology is generally doping modification on the surface of graphene. The dopant attached to the surface of graphene is easily affected by various impurities in the air. As time goes by, the doping effect decreases or even disappears, thus affecting The stability of square resistance limits the application of graphene films in industrial fields such as display technology that require high square resistance of transparent conductive films.

Contents of the invention

The technical problem to be solved by the present invention is to provide a stable doping method for graphene, so that the doping reagent does not directly contact with the air, significantly improves the doping stability, and heats at 80-120 degrees Celsius for 3-5 hours. The resistance change is small, which promotes the industrialization process of graphene film.

The technical scheme of the present invention to solve the above-mentioned technical problems is as follows: a stable doping method of graphene, comprising the steps of wrapping dopant reagent molecules between graphene and graphene and/or wrapping dopant reagent molecules between substrate and steps between graphene; where,

The step of wrapping dopant reagent molecules between graphene and graphene is specifically as follows:

Step 1) Graphene is grown on the copper foil by CVD, and then the temporary substrate is pasted on the graphene;

Step 2) Put the copper foil into an etching solution, etch, wash and dry the copper foil to obtain a temporary substrate/graphene layer sample, and connect the graphene side of the sample to the substrate Bonding, and then remove the temporary substrate, then put the graphene surface into the doping solution for doping, after washing and drying, a sample with dopant on the graphene surface is obtained;

Step 3) the sample sheet that is provided with dopant on the graphene surface is pasted on the sample sheet of another temporary substrate/graphene layer, and then removes described temporary substrate, obtains successively from bottom to top as substrate, Sample form of graphene, dopant and graphene sequence;

The step of wrapping the dopant reagent molecules between the substrate and the graphene is specifically as follows:

1.1) Graphene is grown on the copper foil by CVD, and then the temporary substrate is pasted on the graphene;

1.2) Put the copper foil into the etching solution, etch the copper foil to obtain a temporary substrate/graphene sample, and then put the graphene surface of the sample into the doping solution for doping, Then bond one side of the doped graphene to the substrate, then remove the temporary substrate to obtain a sample sheet with a dopant on the graphene surface, and finally obtain the substrate, dopant and graphene from bottom to top. sequential dailies; or,

Put the copper foil/graphene into the mixed solution composed of etching solution and doping solution, etch and dope at the same time, then attach the doped graphene side to the substrate, and then remove the temporary substrate , to obtain a sample sheet with a dopant on the graphene surface, and finally obtain a sample sheet in the order of substrate, dopant and graphene from bottom to top.

The beneficial effects of the present invention are:

1. The present invention achieves a stable doping effect by covering the dopant molecules between the graphene and the base layer and between the graphene and the graphene, avoiding direct contact between the air and the dopant molecules, and maintaining the doping effect for a long time. The original doping state of the dopant molecules on the graphene surface can maintain the long-term stability of the doping effect.

When the present invention covers the dopant molecules between the graphene and the base layer, a temporary substrate is used, which provides a temporary attachment surface for the graphene during the transfer process, and completely transfers the graphene from the copper substrate to the substrate. On the required substrate, the structural integrity of graphene is maintained during the transfer process, and the transfer quality of graphene is improved.

2. The present invention provides a method for improving the time stability of the graphene doping effect, thereby improving the quality of graphene and promoting the use of graphene films in industrial fields such as display technology that require higher square resistance of transparent conductive films. for wide application.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, in the step of wrapping the dopant reagent molecules between the graphene and the graphene, repeat step 3) to obtain a sample sheet with a dopant on the n-layer graphene surface, and the range of the n-layer is 2 to 10 layer.

Further, in the step of wrapping the dopant reagent molecules between graphene and graphene, n layers of graphene are superimposed on the topmost layer of graphene, and the range of n layers is 2-10 layers.

Further, in the step of wrapping the dopant reagent molecules between the substrate and the graphene, repeat step 1.2) to obtain a sample sheet with dopants on the n-layer graphene surface, and the range of n layers is 2-10 layers.

Further, in the step of wrapping the dopant reagent molecules between the graphene and the step combination of wrapping the dopant reagent molecules between the substrate and the graphene, stack n layers of graphene on the top graphene , and the range of n layers is 2 to 10 layers.

Further, the specific method for fixing the temporary substrate on the graphene includes any one of spin coating, spray coating, evaporation, CVD deposition or bonding.

Further, the specific method for removing the temporary substrate includes any one of dissolution, peeling or thermal release.

Further, the specific method for doping includes any one of immersion, spray coating, spin coating or drop coating.

Further, the active ingredients of the dopant in the doping solution are nitrogen dioxide, gold chloride, concentrated nitric acid of chloroauric acid, naphthalene diamine, 2,3,5,6-tetrafluoro-7,7',8 ,8'-tetracyanodimethyl-p-benzoquinone (F4-TCNQ), ammonium persulfate, ethylenediamine, triethylenetetramine, imidazole compounds and their derivatives, triazole compounds and all derivatives, tetrazole Any one or a mixture of two or more of these compounds and their derivatives, benzimidazole and its derivatives, and bistrifluoromethylsulfonimide;

The solvent in the dope liquid is any of water, ethanol, dichloromethane, nitromethane, chloroform, acetone, N,N-dimethylformamide, dimethyl sulfoxide, ethylene glycol, and glycerol One or a mixture of two or more;

The dopant concentration is 0.001˜1 g/L.

The further beneficial effect of adopting the above is that the doping structure improves the stability of the square resistance of doped graphene, the number of layers of graphene that can be superimposed is 2 to 10 layers, and the square resistance range is 10 to 150 ohms. The rate is 75-95%.

Further, the main components of the etchant in the etching solution are any one or both of ferric chloride, ferric nitrate, ammonium persulfate, sulfuric acid, hydrogen peroxide, copper chloride, ammonium chloride, ammonia water, and sodium hydroxide. a mixture of the above,

The concentration of the etchant is 0.05-3.00g/L.

Description of drawings

Fig. 1 is the graphene stable doping structure schematic diagram of dopant of the present invention between substrate and graphene;

Fig. 2 is the schematic diagram of the stable doping mechanism of dopant of the present invention between graphene and graphene layer;

Fig. 3 is the schematic diagram of the double-layer stable doping structure between substrate and graphene, graphene and graphene of dopant of the present invention;

Fig. 4 is the schematic diagram of the multi-layer full doping structure between substrate and graphene, graphene and graphene of dopant of the present invention;

Fig. 5 is a schematic diagram of the multi-layer incomplete doping structure of the dopant of the present invention between the substrate and graphene, graphene and graphene;

Fig. 6 is a schematic diagram of a multi-layer stable fully doped structure between graphene and graphene of the dopant of the present invention;

Fig. 7 is a schematic diagram of the multi-layer incomplete doping structure of dopant of the present invention between graphene and graphene;

Fig. 8 is a schematic flow chart of the steps of wrapping dopant reagent molecules between graphene and graphene in the present invention;

Fig. 9 is a schematic flow chart of the step of wrapping dopant reagent molecules between the substrate and graphene in the present invention.

detailed description

The principles and features of the present invention are described below in conjunction with the accompanying drawings, and the examples given are only used to explain the present invention, and are not intended to limit the scope of the present invention.

Example 1

As shown in Figure 1, the graphene stable doping structure of the dopant between the substrate and the graphene, the flow process is shown in Figure 8, and the specific steps are as follows:

1.1) Graphene is grown on the copper foil by CVD, and then the temporary substrate is pasted on the graphene;

1.2) Put the copper foil into the etching solution, etch the copper foil to obtain a temporary substrate/graphene sample, and then put the graphene surface of the sample into the doping solution for doping, Then bond one side of the doped graphene to the substrate, then remove the temporary substrate to obtain a sample sheet with a dopant on the graphene surface, and finally obtain the substrate, dopant and graphene from bottom to top. sequential dailies; or,

Put the copper foil/graphene into the mixed solution composed of etching solution and doping solution, etch and dope at the same time, then attach the doped graphene side to the substrate, and then remove the temporary substrate , to obtain a sample sheet with a dopant on the graphene surface, and finally obtain a sample sheet in the order of substrate, dopant and graphene from bottom to top.

Example 2

As shown in Figure 2, the stable doping structure of dopant between graphene and graphene layers, the flow process is shown in Figure 9, and the specific steps are as follows:

Step 1) Graphene is grown on the copper foil by CVD, and then the temporary substrate is pasted on the graphene;

Step 2) Put the copper foil into an etching solution, etch, wash and dry the copper foil to obtain a temporary substrate/graphene layer sample, and connect the graphene side of the sample to the substrate Bonding, and then remove the temporary substrate, then put the graphene surface into the doping solution for doping, after washing and drying, a sample with dopant on the graphene surface is obtained;

Step 3) the sample sheet that is provided with dopant on the graphene surface is pasted on the sample sheet of another temporary substrate/graphene layer, and then removes described temporary substrate, obtains successively from bottom to top as substrate, Sample form of graphene, dopant, and graphene sequence.

Example 3

As shown in Figure 3, the double-layer stable doping structure of the dopant between the substrate and graphene, graphene and graphene, the flow process is shown in Figure 8 and Figure 9, and the specific steps are as follows:

The step of wrapping dopant reagent molecules between graphene and graphene is specifically as follows:

Step 1) Graphene is grown on the copper foil by CVD, and then the temporary substrate is pasted on the graphene;

Step 2) Put the copper foil into an etching solution, etch, wash and dry the copper foil to obtain a temporary substrate/graphene layer sample, and connect the graphene side of the sample to the substrate Bonding, and then remove the temporary substrate, then put the graphene surface into the doping solution for doping, after washing and drying, a sample with dopant on the graphene surface is obtained;

Step 3) the sample sheet that is provided with dopant on the graphene surface is pasted on the sample sheet of another temporary substrate/graphene layer, and then removes described temporary substrate, obtains successively from bottom to top as substrate, Sample form of graphene, dopant and graphene sequence;

The step of wrapping the dopant reagent molecules between the substrate and the graphene is specifically as follows:

1.1) Graphene is grown on the copper foil by CVD, and then the temporary substrate is pasted on the graphene;

1.2) Put the copper foil into the etching solution, etch the copper foil to obtain a temporary substrate/graphene sample, and then put the graphene surface of the sample into the doping solution for doping, Then bond one side of the doped graphene to the substrate, then remove the temporary substrate to obtain a sample sheet with a dopant on the graphene surface, and finally obtain the substrate, dopant and graphene from bottom to top. sequential dailies; or,

Put the copper foil/graphene into the mixed solution composed of etching solution and doping solution, etch and dope at the same time, then attach the doped graphene side to the substrate, and then remove the temporary substrate , to obtain a sample sheet with a dopant on the graphene surface, and finally obtain a sample sheet in the order of substrate, dopant and graphene from bottom to top.

Example 4

As shown in Figure 4, the dopant is in the multilayer fully doped structure between the substrate and graphene, graphene and graphene, and the specific method steps are on the basis of Example 1, repeating step 1.2) to obtain n-layer graphite A sample sheet with a dopant on the surface of the graphene, and the range of n layers is 2-10 layers; in Figure 4, A represents graphene and the dopant repeating unit.

Example 5

As shown in Figure 5, the dopant is between the substrate and graphene, and the multi-layer incomplete doping structure between graphene and graphene. The specific method steps are based on Example 3, and then superimposed on the top graphene. n-layer graphene, and the range of n-layer is 2-10 layers; in Fig. 5, B represents graphene repeating unit.

Example 6

Dopant as shown in Figure 6 is between graphene and graphene multi-layer stable fully doped structure, concrete method steps are on the basis of embodiment 2, repeat step 3), obtain n-layer graphene surface A sample piece with a dopant, and the range of n layers is 2-10 layers; in Figure 6, A represents graphene and dopant repeating unit.

Example 7

As shown in Figure 7, the multi-layer incomplete doping structure between graphene and graphene, the specific method steps are on the basis of embodiment 2, on the top graphene, superimpose n layers of graphene, and the n layer The range is 2-10 layers; in Figure 4, B represents the graphene repeat unit.

In above-mentioned Fig. 1 to Fig. 9, each label represents as follows:

1 represents graphene, 2 represents copper foil, 3 represents temporary substrate, 4 represents etching solution, 5 represents doping liquid, 6 represents dopant, 7 represents substrate, 8 represents etching liquid and doping liquid mixture;

In Fig. 8, the label in brackets represents the specific process steps, as follows:

(1) represents temporary substrate fixation, such as spin coating, spray coating, evaporation, CVD deposition, bonding, etc.; (2) represents etching; (3) represents doping; (4) represents substrate bonding; (5) represents removal Temporary substrates, such as dissolution, peeling, release and other methods; (6) represents repeating the process of (2) to (5) to obtain multi-layer doped graphene, and (7) represents the simultaneous process of etching and doping.

In Fig. 9, the label in brackets represents the specific process steps, as follows:

(8) represents temporary substrate fixation, such as spin coating, spray coating, evaporation, CVD deposition, lamination, etc.; (9) represents etching copper foil; (10) represents water washing and drying; (11) represents lamination; ( 12) represents removal of temporary substrates, such as dissolution, peeling, heat release, etc.; (13) represents doping processes, such as soaking, spraying, spin coating, drip coating, etc.; (14) represents washing and drying; (15) represents Lay the second layer of graphene film on the temporary substrate to obtain a double-layer doped structure; (16) represents the removal of the temporary substrate, such as dissolution, peeling, heat release, etc.; (17) represents the execution of repeated operation units to obtain multiple layer doping structure.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (9)

1. A stable doping method of graphene is characterized by comprising the following steps: the method comprises the steps of wrapping doping reagent molecules between graphene and/or wrapping the doping reagent molecules between a substrate and the graphene; wherein,

the step of wrapping the doping reagent molecules between the graphene and the graphene specifically comprises the following steps:

step 1), growing graphene on a copper foil through a CVD method, and then attaching a temporary substrate to the graphene;

step 2) placing the copper foil into etching liquid, etching, washing and drying the copper foil to obtain a temporary substrate/graphene layer sample, attaching one surface of graphene of the sample to the substrate, removing the temporary substrate, placing the graphene surface into doping liquid for doping, and washing and drying to obtain a sample with a doping agent on the graphene surface;

step 3) attaching the sample wafer with the dopant on the graphene surface to a sample wafer of another temporary substrate/graphene layer, and then removing the temporary substrate to obtain a sample wafer form in which the substrate, the graphene, the dopant and the graphene are in sequence from bottom to top;

the steps of wrapping the doping reagent molecules between the substrate and the graphene are as follows:

1.1) growing graphene on a copper foil through a CVD method, and then attaching a temporary substrate to the graphene;

1.2) placing the copper foil into an etching solution, etching the copper foil to obtain a temporary substrate/graphene sample wafer, placing the graphene surface of the sample wafer into a doping solution for doping, attaching one surface of the doped graphene to the substrate, removing the temporary substrate to obtain a sample wafer with a dopant on the graphene surface, and finally obtaining a sample wafer form with the substrate, the dopant and the graphene in sequence from bottom to top; or,

placing the copper foil/graphene into a mixed solution composed of an etching solution and a doping solution, simultaneously etching and doping, attaching one surface of the doped graphene to a substrate, removing the temporary substrate to obtain a sample wafer with a dopant on the graphene surface, and finally obtaining a sample wafer form which is sequentially the substrate, the dopant and the graphene from bottom to top,

the active ingredients of the dopant in the doping liquid are the mixture of more than two of naphthalene diamine, 2,3,5, 6-tetrafluoro-7, 7',8,8' -tetracyanoldimethyl p-benzoquinone, ethylenediamine, triethylene tetramine, imidazole compounds and derivatives thereof, triazole compounds and all derivatives thereof, tetrazole compounds and derivatives thereof, benzimidazole and derivatives thereof and bis (trifluoromethyl) sulfonyl imide; the solvent in the doping liquid is any one or the mixture of more than two of water, ethanol, dichloromethane, nitromethane, chloroform, acetone, N-dimethylformamide, dimethyl sulfoxide, ethylene glycol and glycerol; the concentration of the dopant is 0.001-1 g/L.

2. The method for stably doping graphene according to claim 1, wherein: in the step of wrapping the doping reagent molecules between the graphene and the graphene, repeating the step 3) to obtain sample sheets with the doping agents on n layers of graphene surfaces, wherein the range of the n layers is 2-10 layers.

3. The method for stably doping graphene according to claim 1, wherein: in the step of wrapping the doping reagent molecules between the graphene and the graphene, n layers of graphene are overlapped on the topmost graphene, and the range of the n layers is 2-10 layers.

4. The method for stably doping graphene according to claim 1, wherein: and in the step of wrapping the doping reagent molecules between the substrate and the graphene, repeating the step 1.2) to obtain sample sheets with the doping agents on n layers of graphene surfaces, wherein the range of the n layers is 2-10 layers.

5. The method for stably doping graphene according to claim 1, wherein: in the step of wrapping the doping reagent molecules between the graphene and the step of wrapping the doping reagent molecules between the substrate and the graphene, n layers of graphene are further overlapped on the topmost graphene, and the range of the n layers is 2-10 layers.

6. The method for stably doping graphene according to any one of claims 1 to 5, wherein: specific methods for fixing the temporary substrate on the graphene include any one of spin coating, spray coating, evaporation, CVD deposition, or bonding.

7. The method for stably doping graphene according to any one of claims 1 to 5, wherein: the specific method of removing the temporary substrate includes any one of dissolution, peeling, or heat release.

8. The method for stably doping graphene according to any one of claims 1 to 5, wherein: the specific method for doping comprises any one of soaking, spraying, spin coating or dripping.

9. The method for stably doping graphene according to any one of claims 1 to 5, wherein: the main components of the etching agent in the etching liquid are one or a mixture of more than two of ferric chloride, ferric nitrate, ammonium persulfate, sulfuric acid, hydrogen peroxide, copper chloride, ammonium chloride, ammonia water and sodium hydroxide, and the concentration of the etching agent is 0.05-3.00 g/L.