CN104817073B - Method for transferring graphene film to TEM copper net - Google Patents

Abstract

The invention discloses a method for transferring a graphene film to a TEM copper net, which is characterized in that: firstly, the TEM copper net is adsorbed on an electrostatic adsorption film, and then the graphene film is transferred thereon. By adsorbing the TEM copper mesh on the electrostatic adsorption film, the present invention indirectly expands the surface area of the copper mesh macroscopically, making it easy to clamp, and does not directly contact the TEM copper mesh during clamping, avoiding damage to its structure; Using this composite substrate to transfer the graphene film can easily realize the transfer of graphene to the TEM copper grid, solve the difficulty that the graphene film is not easy to transfer to the small-area TEM copper grid, and the operation is simple.

Description

A Method for Transferring Graphene Films to TEM Copper Grids

technical field

The invention relates to a method for transferring a graphene thin film material to a TEM copper grid so as to carry out a transmission electron microscope test.

technical background

Graphene is a two-dimensional planar material with a thickness of one atom formed by the hexagonal arrangement of carbon atoms. In 2004, Novoselov and Geim of the University of Manchester successfully exfoliated graphene from highly oriented pyrolytic graphite by means of micromechanical exfoliation, which opened up the possibility of experimental investigation of graphene, a two-dimensional material.

Due to its excellent electrical, optical, thermal, and mechanical properties, graphene has a very broad application prospect in the fields of nanoelectronics, sensors, optical devices, energy conversion and storage, environmental governance, composite materials, and biotechnology.

There are two main ways to prepare graphene: bottom-up and top-down. Among them, the bottom-up method mainly includes epitaxial growth method, chemical vapor deposition (CVD), chemical small molecule synthesis method; the top-down method mainly includes liquid phase exfoliation method, mechanical exfoliation method, etc. At present, the CVD method is the most commonly used method for growing graphene. This method can not only grow large-area graphene films, but also control the number of layers of graphene within a certain range. Graphene films prepared by this method have been applied to scientific research fields such as transparent electrodes, solar cells, field effect transistors and supercapacitors.

However, no matter which method is used to prepare graphene, some necessary characterization must be carried out to observe its morphology, crystallization properties, optical properties, electrical properties, and defects, etc., to assist the next step of research. At present, the characterization technology of two-dimensional materials such as graphene has been perfected, mainly including scanning electron microscope (SEM) characterization, transmission electron microscope (TEM) characterization, Raman (Raman) characterization, XPS characterization, XRD characterization, Fourier transform infrared characterization Spectral characterization, etc. In the process of characterization and testing, it is generally necessary to attach the material to the substrate first. For example, when using Raman to characterize the properties of the film, the film needs to be attached to a silicon substrate or a silicon dioxide substrate, which has almost no restrictions on the size of the material and the size of the substrate. , the base area can be any size within the required range.

However, the copper grid substrate is used in the test of the transmission electron microscope to characterize the material properties, and people need to transfer the material to be tested to the TEM copper grid for testing. At present, the steps of transferring graphene to TEM copper grid are as follows: first, suspend the graphene film spin-coated with a protective layer in deionized water, use tweezers to clamp the TEM copper grid, and dip it into deionized water to remove the graphene , and then soaked in acetone to remove the protective adhesive layer, and then use tweezers to remove the graphene-transferred copper grid from the acetone. This method has the following problems:

1. The area of the TEM copper mesh is only a few millimeters, and it is very easy to damage its structure by directly clamping it with tweezers, making the graphene film unable to self-support on the damaged copper mesh, and it is easier to break, and at the same time affects the observation of the graphene morphology; And clamping is difficult;

2. Use tweezers to hold a very small area of TEM copper mesh and extend it into deionized water to fish out graphene. The operation is extremely difficult and time-consuming. It takes several hours or even more than ten hours to complete a transfer. The technical level of the operator is required. high;

3. After removing the protective film, it is necessary to use tweezers to remove the graphene-transferred copper grid from the acetone. The graphene structure caught by the tweezers is basically destroyed, and the graphene area on the copper grid itself is limited. affect the effectiveness of the test;

4. Use tweezers to directly contact the TEM copper mesh and graphene many times, which is very easy to introduce pollutants.

Therefore, an efficient and convenient method for transferring graphene films to TEM copper grids needs to be discovered urgently.

Contents of the invention

The present invention provides a method for efficiently and conveniently transferring a graphene film to a TEM copper grid in order to avoid the disadvantages of the above-mentioned prior art.

The present invention adopts following technical scheme for solving technical problems:

The present invention transfers the method for graphene thin film to TEM copper net, and its feature is to carry out as follows:

Step a, the graphene film that is spin-coated with the protective adhesive layer is suspended in deionized water with the protective adhesive layer facing up;

Step b, adsorbing the TEM copper mesh on the electrostatic adsorption film, the area of the electrostatic adsorption film is at least 4 times the area of the TEM copper mesh, and the area of the electrostatic adsorption film is not smaller than the graphene described in step a the area of the film;

Step c, with the TEM copper mesh facing up, extend the electrostatic adsorption film in step b into the deionized water in step a with tweezers, pull out the graphene film, and make the graphene film cover the TEM copper mesh, A composite structure of protective adhesive layer/graphene film/TEM copper mesh/electrostatic adsorption film is formed from top to bottom;

Step d, after naturally drying the protective adhesive layer/graphene film/TEM copper mesh/electrostatic adsorption film composite structure obtained in step c, soak in acetone to remove the protective adhesive layer to obtain the graphene film/TEM copper mesh/ Electrostatic adsorption film composite structure;

Step e, on the graphene film/TEM copper mesh/electrostatic adsorption film composite structure obtained in step d, the TEM copper mesh is taken off from the electrostatic adsorption film together with the graphene film positioned thereon with tweezers, and the graphene film That is, it is transferred to the TEM copper grid.

The method for transferring the graphene film to the TEM copper grid in the present invention is also characterized in that the electrostatic adsorption film is a PET film, a PE film or a PVC film, preferably a PET film.

The method of the present invention can also transfer it to other smaller substrates, such as silicon chips, silicon oxide, glass sheets, plastic sheets, sapphire sheets, and quartz sheets, except that the graphene film can be transferred to the TEM copper grid. , metal flakes, etc., which solve the problem of difficult transfer of small-area graphene.

In addition, the method of the present invention can also be used to transfer other thin-film materials to TEM copper grids or other small-area substrates, such as boron nitride thin films, molybdenum disulfide thin films, and the like.

Compared with the prior art, the beneficial effects of the present invention are reflected in:

1. The present invention indirectly expands the surface area of the copper mesh macroscopically by adsorbing the TEM copper mesh on the electrostatic adsorption film, making it easy to clamp, and does not directly contact the TEM copper mesh when clamping, avoiding damage to its structure Destruction; use this composite substrate to transfer graphene film, it is easy to realize the transfer of graphene to TEM copper grid, solve the difficulty that graphene film is not easy to transfer to small area TEM copper grid, and the operation is simple, reducing the time of traditional transfer method Reduced from tens of hours to a few minutes, greatly improving the efficiency of graphene for TEM testing;

2. The method of the present invention does not introduce any pollutants during the operation process, nor will it destroy the morphology and structural properties of graphene, and is environmentally friendly and efficient;

Description of drawings

Fig. 1 is the photo that the graphene film that is coated with PMMA is suspended in deionized water;

Fig. 2 is the photograph that copper mesh is adsorbed on the PET film;

Fig. 3 and Fig. 4 are the photograph that fishes the graphene film in deionized water with the PET film that is adsorbed with copper mesh;

Fig. 5 is the photo of the graphene film/TEM copper mesh/PET film composite structure after etching away PMMA with acetone;

Fig. 6 is to take off the photo of the copper grid that transfers graphene thin film with tweezers;

Fig. 7 is the photograph that _SiO2 is adsorbed on the PET film;

Fig. 8 and Fig. ₉ are to use the PET film that is adsorbed with SiO to fish for the photo of the graphene film in deionized water;

Fig. 10 is the photo of the graphene film/SiO ₂ /PET film composite structure after etching away PMMA with acetone;

Figure 11 is a photo of _SiO2 transferred with graphene film removed with tweezers.

detailed description

Example 1

In this embodiment, the graphene film is transferred to the TEM copper grid according to the following steps:

Step a, as shown in Figure 1, will be spin-coated with the graphene film of PMMA protective adhesive layer to be suspended in deionized water upwards with protective adhesive layer;

Step b, as shown in Figure 2, the TEM copper mesh is adsorbed on the PET film;

Step c, as shown in Figure 3 and Figure 4, with the TEM copper grid facing up, use tweezers to extend the electrostatic adsorption film in step b into the deionized water in step a, pull out the graphene film, and make the graphite Graphene film covers TEM copper mesh, forming a composite structure of protective adhesive layer/graphene film/TEM copper mesh/PET film from top to bottom;

Step d, as shown in Figure 5, after naturally drying the protective adhesive layer/graphene film/TEM copper mesh/PET film composite structure obtained in step c, soak in acetone to remove the protective adhesive layer to obtain a graphene film /TEM copper mesh/PET film composite structure;

Step e, as shown in Figure 6, on the graphene film/TEM copper mesh/electrostatic adsorption film composite structure obtained in step d, use tweezers to remove the TEM copper mesh together with the graphene film on it from the electrostatic adsorption film Take it off, and the graphene film is transferred to the TEM copper grid.

Example 2

The method of the present invention is also suitable for transferring the graphene film to a small-area silicon dioxide substrate, so that it can be tested by Raman, and the specific steps are as follows:

a, the graphene film that will be spin-coated with PMMA protective adhesive layer is suspended in deionized water with protective adhesive layer upwards;

b. As shown in Figure 7, adsorb the SiO ₂ sheet on the PET film with the smooth side of the SiO ₂ sheet facing upward.

c. As shown in Figure 8 and Figure 9, with the _SiO2 sheet facing up, use tweezers to extend the electrostatic adsorption film in step b into step a

In the deionized water in , remove the graphene film, and make the graphene film cover the SiO ₂ sheet to form a protection from top to bottom

Adhesive layer/graphene film/SiO ₂ sheets/PET film composite structure;

d, as shown in Figure 10, after the protective adhesive layer/graphene film/SiO ₂ sheets/PET film composite structure obtained in step c is naturally dried, soak in acetone to remove the protective adhesive layer, and obtain the graphene film/ SiO ₂ pieces/PET film composite structure;

e, as shown in Figure 11, on the graphene film/SiO ₂ sheet/PET film composite structure obtained in step d, use tweezers to remove the SiO ₂ sheet together with the graphene film on it from the electrostatic adsorption film , the graphene film is transferred onto the _SiO2 sheet.

Claims (2)

1. a kind of method that graphene thin film is transferred to TEM copper net, it is characterized in that carry out as follows: Step a, the graphene film that is spin-coated with the protective adhesive layer is suspended in deionized water with the protective adhesive layer facing up; Step b, adsorbing the TEM copper mesh on the electrostatic adsorption film, the area of the electrostatic adsorption film is at least 4 times the area of the TEM copper mesh, and the area of the electrostatic adsorption film is not smaller than the graphene described in step a The area of the film; the electrostatic adsorption film is PET film, PE film or PVC film; Step c, with the TEM copper mesh facing up, extend the electrostatic adsorption film in step b into the deionized water in step a with tweezers, pull out the graphene film, and make the graphene film cover the TEM copper mesh, A composite structure of protective adhesive layer/graphene film/TEM copper mesh/electrostatic adsorption film is formed from top to bottom; Step d, after naturally drying the protective adhesive layer/graphene film/TEM copper mesh/electrostatic adsorption film composite structure obtained in step c, soak in acetone to remove the protective adhesive layer to obtain the graphene film/TEM copper mesh/ Electrostatic adsorption film composite structure; Step e, on the graphene film/TEM copper mesh/electrostatic adsorption film composite structure obtained in step d, the TEM copper mesh is taken off from the electrostatic adsorption film together with the graphene film positioned thereon with tweezers, and the graphene film That is, it is transferred to the TEM copper grid. 2. the method that graphene thin film is transferred to TEM copper net according to claim 1, is characterized in that: described electrostatic adsorption film is PET film.