WO2017049682A1 - Manufacturing method of solar panel having graphene coating - Google Patents

Abstract

A manufacturing method of a solar panel having a graphene coating. The manufacturing method comprises: coating a graphene coating material on a surface layer of a solar panel, wherein the graphene coating material is prepared by dispersing graphene, oxidized graphene, or modified oxidized graphene in a solvent, and the solvent is selected from ethanol, water, N-methylpyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide, methylbenzene, dimethylbenzene, and n-butanol. The manufacturing method adds only one spraying procedure before packaging a solar panel, thereby having a simple process. In addition, the coating can dry by itself in a short time without affecting subsequent processing. Furthermore, an average photoelectric conversion efficiency of the solar panel can be improved by 3% or more by spraying the graphene coating material.

Description

Method for preparing solar panel with graphene coating Technical field

The invention relates to the technical field of solar cells, and in particular to a method for preparing a solar panel with a graphene coating.

Background technique

With the development of society, human beings have more and more demand for energy. However, the earth's non-renewable energy sources are limited. In order to reduce the consumption of non-renewable energy and reduce environmental pollution, solar power generation is an emerging one. Renewable energy is of great significance, and with the advancement of related technologies, the application range of solar cells is becoming more and more extensive.

The most basic components of solar photovoltaic power generation are solar cell cells. The most common ones are monocrystalline silicon, polycrystalline silicon, amorphous silicon and thin film cells. Modules consisting of one or more solar cells are called solar modules or solar cells. board. The power generation efficiency of solar cells depends largely on their photoelectric conversion efficiency; however, due to the limitations of materials and structures, the photoelectric conversion efficiency of current solar cells still needs to be improved.

Take thin film solar cells as an example. The front electrode of a thin film solar cell uses a transparent conductive oxide (TCO) glass, and its performance plays a vital role in the conversion efficiency of the battery. The most widely studied transparent conductive thin film material is ZnO-based TCO thin film material, which is stable to hydrogen ions and has better light transmittance than FTO. However, in practical applications, the interface matching process between the ZnO-based transparent conductive film and the photoelectric conversion region film is not perfect, and there is no obvious advantage in the contribution of the FTO conductive film to the photoelectric conversion efficiency, in order to completely balance the theoretically existing advantages. It is necessary to improve the structure and composition of the TCO film.

According to the search of the prior art, the application number is 201210095209.1, and the invention name is a Chinese patent for improving the photoelectric conversion efficiency of a solar panel. In order to solve the interface matching process between the ZnO-based transparent conductive film and the photoelectric conversion zone film, A technical problem that affects the photoelectric conversion efficiency is imperfect, and a method based on the improved TCO film layer to improve the photoelectric conversion efficiency of the solar panel is designed. The method improves the light transmittance and conductivity of the panel by effectively designing the TCO film layer into a multi-layer composite structure and controlling the doping concentration of each layer to form a gradient gradient, thereby effectively improving the solar cell photoelectricity. Conversion efficiency. However, the method is complicated in process and high in cost, and is only applicable to ZnO-based TCO thin film solar cells, and is not suitable for silicon solar cells.

Summary of the invention

It is an object of the present invention to provide a method of preparing a solar cell panel having a graphene coating in view of the deficiencies of the prior art described above. The invention forms a graphene coating by spraying a layer of graphene coating on the surface of the silicon solar panel, thereby improving the photoelectric conversion efficiency of the solar panel. In addition, the process of the present invention is extremely simple, the sprayed material is excellent in performance and low in cost, and has a positive effect on subsequent processing after spraying.

The object of the present invention is achieved by the following technical solutions:

The invention relates to a method for preparing a solar panel with a graphene coating, the preparation method comprising coating a surface of a solar panel with a graphene coating; the graphene coating is composed of graphene and graphene oxide (including The graphene oxide is prepared by dispersing in a solvent.

Preferably, the solvent is selected from the group consisting of ethanol, water, N-methylpyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide, toluene, xylene, n-butanol.

Preferably, the concentration of graphene or graphene oxide in the graphene coating is from 0.08 to 0.4 mg/ml. More preferably, it is 0.12-0.40 mg/ml.

Preferably, the dispersion of graphene is selected by using different solvents, such as the surface tension of the lossless single crystal graphene is similar to that of graphite, and belongs to a material which is neither lipophilic nor hydrophilic. The solvent is generally selected by NMP, and since the specific surface tension of the solvent is similar to that of graphite (46 dyn/cm), the graphene has a good dispersion effect. In order to increase the evaporation rate of the solvent, the NMP dispersion of the dispersed graphene is diluted with ethanol to obtain a spray agent of a desired concentration. Graphene oxide has a large amount of hydroxyl, carboxyl and epoxy groups due to its oxidation on the surface, and it can be well dispersed in polar solvents such as water, ethanol and DMF, and the dispersion concentration reaches 10 mg/ml. It can be directly configured to form a dispersion in a polar solvent such as ethanol, water or DMF. Also, in order to increase the evaporation rate of the solvent, a solvent having a large saturated vapor pressure (referring to a solvent having a low boiling point such as ethanol, methanol, tetrahydrofuran, etc.) may be selected and diluted and then sprayed. Further, the organo-modified graphene oxide can be sprayed after being dispersed in an oily solvent. Toluene and xylene are ideal organic solvents.

Further preferably, the graphene coating is prepared by dispersing graphene in a mixed solution of N-methylpyrrolidone and ethanol; and the volume ratio of the N-methylpyrrolidone to ethanol is 1:1 to 5.

Further preferably, the graphene coating is prepared by dispersing unmodified graphene oxide in water, ethanol, dimethyl sulfoxide or N,N-dimethylformamide.

Further preferably, the graphene coating is prepared by dispersing modified graphene oxide in an oil solvent and adding an appropriate amount of a high saturated vapor pressure solvent; the oil solvent includes one or more of toluene and xylene. Mixed Compound. The volume ratio of the oily solvent to the high saturated vapor pressure solvent is 1:0.5-2. The high saturated vapor pressure solvent is selected from the group consisting of alkane solvents such as tetrahydrofuran, hexane, and pentane.

Preferably, the graphene is selected from the group consisting of CVD growth graphene, carbon dioxide supercritical expansion stripping graphene, electrochemical stripping graphene, mechanical ball mill stripping graphene, and three roll mechanical stripping graphene.

Preferably, the graphene oxide is selected from the group consisting of chemically oxidized and exfoliated graphene oxide, a coupling agent-modified graphene oxide, a high-temperature thermally expanded reduced graphene oxide, and reduced graphene oxide obtained by low-temperature thermal expansion.

Preferably, the coating is selected from atomized spraying, and the pressure of the spray gun is 0.2-0.3 MPa. When spraying, adjust the pressure of the gun. If the pressure is too high, the silver wire on the surface of the board will be broken. Therefore, the pressure should be 2 to 3 kg, that is, 0.2 to 0.3 Mpa. If the pressure is too small, the spray cannot be atomized due to insufficient pressure, which affects the spraying effect.

Preferably, the coating is specifically: coating the surface of the solar panel with 50 to 250 mL of the graphene coating per square meter.

Compared with the prior art, the present invention has the following beneficial effects:

1. The process is extremely simple, only one step of spraying before the solar panel is packaged, and the coating can be automatically dried in a short time without affecting the subsequent processing.

2. Select the graphene material with the most potential application, mainly based on its excellent natural light transmittance (97.7%), superior thermal conductivity (3000W·m ^-1 ·K ^-1 ) and high carrier mobility. (15000cm ² ·V ^-1 ·s ^-1 ), which has unparalleled properties and advantages over other coating materials, and has absolute advantages in both light transmission and substrate thermal conduction applications.

3. Graphene coating is also a thermally stable material in terms of material properties. Therefore, even the subsequent thermal baking process of the cell sheet has no effect on the structure and properties of the coated graphene. And for graphene oxide, the slightly higher temperature post-treatment has the effect of high-temperature thermal reduction, that is, the high-temperature treatment can remove the oxygen-containing group on the surface of the graphene oxide and reduce the structural defects of the graphene oxide sheet layer, thereby The conductive property of the graphene oxide coating is enhanced, and the photoelectric conversion efficiency of the solar panel after spraying graphene oxide is further improved. The good dispersibility of graphene oxide in the solvent used in this patent and its uniform film formation after spraying play an important role in improving the photoelectric conversion performance of photovoltaic panels. Therefore, the monodispersity of graphene in the solvent, the uniformity and thickness of the sprayed film determine the determinant of the increase in the photoelectric conversion performance of the solar panel after the coating of the graphene coating.

4. In terms of solvent preparation, the invention invents a formula for using a plurality of solvents according to the specific experience of actual operation, increases the dispersibility of graphene, improves the drying rate of the coating, uniformity of film formation, and greatly improves Processing efficiency.

5. After spraying the "ink" of the graphene coating of the present invention, the average photoelectric conversion efficiency of the panel is increased by 3%.

DRAWINGS

Other features, objects, and advantages of the present invention will become apparent from the Detailed Description of Description

Figure 1 is a SEM photograph of the surface of a panel after spraying graphene;

2 is an AFM photograph of an ultra-clean surface of sprayed graphene oxide; wherein (a) is a two-dimensional planar structure diagram of graphene, and (b) is a thickness diagram of a graphene sheet;

3 is an AFM photograph of an ultra-clean surface of a sprayed graphene; wherein (a) is a two-dimensional planar structure diagram of graphene, and (b) is a thickness diagram of a graphene sheet.

detailed description:

The invention will now be described in detail in connection with the embodiments. The following examples are intended to further understand the invention, but are not intended to limit the invention in any way. It should be noted that a number of adjustments and improvements may be made by those skilled in the art without departing from the inventive concept. These are all within the scope of protection of the present invention.

The invention is to form a graphene surface layer by spraying a layer of graphene "ink" on the surface of the silicon solar panel, thereby improving the photoelectric conversion efficiency of the solar panel.

The best choice for spray coating is graphene due to its large specific surface area (2600 m ² /g) and excellent light transmission (97.7%), which provides for its coating on solar panels. It is possible and laid a good foundation. For solar panels in the 1 m ² region, theoretically only 0.38 mg of graphene is required, which reduces the threshold for its industrial application. Different types of graphene (chemically prepared graphene oxide, graphene, and organically modified graphene oxide) were placed in different solvents in different concentrations. The general solvent is selected from the group consisting of ethanol, water, N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), toluene, xylene, n-butanol, etc. According to different graphenes, different solvents are selected. Unmodified graphene has poor dispersibility in polar solvents due to its low polarity, so it is first dispersed in NMP, and in order to increase the evaporation rate of the solvent and reduce its saturated vapor pressure, it can be mixed in NMP. Several times the volume of ethanol is finally formulated into the desired amount of spray "ink". The graphene oxide itself can be well dispersed in a polar solvent such as water, ethanol or DMF, and thus can be directly disposed as a dispersion in ethanol, water or DMF. In addition, the surface-organized modified graphene oxide can also be sprayed after being dispersed in an oily solvent, and toluene and xylene are the optimum organic solvents. After selecting a solvent according to the type of graphene, it is configured to be a spray "ink" (i.e., graphene paint) of 0.08 to 0.4 mg/ml. Compared with other existing methods, the process of the present invention is extremely simple, excellent in material properties and inexpensive. Specific application implementations are as follows:

Examples 1-20

Embodiments 1-20 relate to a method for preparing a solar panel having a graphene surface layer, comprising the following steps:

1. Formulate "ink" for graphene coatings.

The graphenes in Examples 1 to 10 were selected by CVD growth of graphene, carbon dioxide supercritical expansion stripping graphene, electrochemical stripping graphene, modified electrochemical stripping graphene, mechanical ball-milling stripping graphene, and three-roll mechanical stripping. Graphene, chemically oxidized and exfoliated graphene oxide, reduced-temperature graphene oxide which is thermally expanded at a high temperature, reduced graphene oxide obtained by low-temperature thermal expansion, and oxidized graphene modified by a silane coupling agent.

The CVD growth graphene was dispersed in an NMP solvent, and in order to increase the evaporation rate of the solvent, the NMP dispersion of the dispersed graphene was diluted with 3 times the volume of NMP, and the graphene concentration corresponding to Example 1 was 0.12 mg/ Mm of graphene coating. The composition and formulation of the graphene coating in Example 11 was the same as in Example 1, except that the graphene concentration in the graphene coating was 0.24 mg/ml.

The graphene coatings corresponding to Examples 2 to 6 were prepared in the same manner as in Example 1, except that the corresponding graphene materials were carbon dioxide supercritical expansion stripped graphene, electrochemical stripped graphene, and modified electrochemical stripped graphite. Aene, mechanical ball milling, stripping of graphene, three-roll mechanical stripping of graphene. The compositions and formulations of the graphene coatings of Examples 12 to 16 correspond one-to-one with Examples 2 to 6, respectively, except that the graphene concentration in the graphene coating was 0.20 mg/ml.

The chemically oxidized and exfoliated graphene oxide was dispersed in water to prepare a graphene coating having a graphene concentration of 0.20 mg/ml corresponding to Example 7. The composition and formulation of the graphene coating of Example 17 was the same as that of Example 7, except that the graphene concentration in the graphene coating was 0.40 mg/ml.

The graphene paint having a graphene concentration of 0.16 mg/ml corresponding to Example 8 was prepared by dispersing the reduced-temperature graphene oxide which was thermally expanded at a high temperature in ethanol. The composition and formulation of the graphene coating of Example 18 was the same as in Example 8, except that the graphene concentration in the graphene coating was 0.20 mg/ml.

The reduced graphene oxide obtained by low-temperature thermal expansion was dispersed in DMF to prepare a graphene coating having a graphene concentration of 0.16 mg/ml corresponding to Example 9. The composition and formulation of the graphene coating of Example 19 was the same as that of Example 19 except that the graphene concentration in the graphene coating was 0.32 mg/ml.

The silane coupling agent-modified graphene oxide was dispersed in a mixed solvent of benzene and xylene in a mass ratio of 2:1 to prepare a graphene coating having a graphene concentration of 0.20 mg/ml corresponding to Example 10. Modification of silane coupling agent Graphene was dispersed in xylene to prepare a graphene coating having a graphene concentration of 0.30 mg/ml corresponding to Example 20.

2. The surface of the silicon solar panel before packaging in the conventional process (any solar panel, the package of the sandwich structure is suitable for the invention) the atomized sprayed graphene coating; wherein the graphene coatings of the examples 1 to 10 are sprayed When the pressure of the spray gun is 0.2Mpa; when the graphene paint of Examples 11-20 is sprayed, the pressure of the spray gun is 0.3Mpa.

3. After the spraying is completed, the solar panel is placed in a clean environment to dry, and the solvent is naturally evaporated.

Graphene is easily compounded with the matrix material due to its large specific surface area and low specific surface tension, as shown in Figures 1, 2 and 3. 1 is a SEM photograph of a surface of a panel after spray coating CVD for graphene corresponding to Example 1; FIG. 2 is an AFM photograph of an ultraclean surface of sprayed graphene oxide corresponding to Example 7; AFM photograph of the ultra-clean surface of the spray-extracted graphene; as shown in Figures 1, 2 and 3, graphene has good dispersion and bonding on the solar cell wafer, and also has a high degree of uniformity in thickness distribution. As shown in Fig. 1, under the scanning electron microscope, graphene is compactly combined on the silicon wafer, and is connected to each other, and pores are locally formed, which is related to the concentration of the sprayed graphene and the probability of contact, and the reliability of the spray film formation is reflected. Figure 2 shows the distribution of graphene oxide on a single crystal silicon wafer. It can be seen from the photo that there is not only a large distribution of graphene, but also a single layer, which provides evidence for the improvement of the photoelectric conversion efficiency of the graphene oxide. . Figure 3 shows the distribution of graphene on a single crystal silicon wafer. The graphene is smaller than the graphene oxide sheet, and its good electrical conductivity improves the photoelectric conversion efficiency.

The photoelectric conversion rates of the solar panels before and after coating the graphene corresponding to the above Examples 1 to 20 were tested (using the solar cell tester of the model HSC1 commonly used in the art, the results are shown in Table 1:

Table 1

Example	Photoelectric conversion rate (%)	Photoelectric conversion rate after spraying (%)
1	17.42	18.04
2	17.70	18.19
3	17.70	18.14
4	17.76	18.19
5	17.68	18.21
6	17.74	18.13
7	17.75	18.33
8	17.7	18.32
9	17.71	18.29
10	17.76	18.36

11	17.74	18.30
12	17.75	18.25
13	17.78	18.24
14	17.79	18.29
15	17.59	18.28
16	17.67	18.22
17	17.60	18.30
18	17.65	18.34
19	17.65	18.35
20	17.50	18.22

It can be seen from Table 1 that after the graphene coating is sprayed on the surface of the silicon solar panel, the average photoelectric conversion efficiency of the solar panel is significantly improved. It should be emphasized that due to the large specific surface area of the graphene (2600 m ² /g) and the extremely excellent light transmittance (97.7%), this makes it possible to coat the solar panel. However, the surface of the silicon solar panel is sprayed to form a graphene film, and the photoelectric conversion efficiency of the solar panel is significantly improved by the multi-effect synergistic effect of the light transmission and high-speed electron transmission of the graphene film, and a good technical effect is achieved.

In summary, the present invention provides a method for preparing a solar cell panel having a graphene coating, which specifically relates to a graphene ink (graphene coating) for surface coating of a panel for improving the efficiency of a solar cell. Preparation method and coating method. The coating material is graphene, graphene oxide, and modified graphene oxide, and the method is an atomized spray method. The method has the advantages of simple and easy process, seamless connection with the manufacturing process of the existing battery sheet, no need to modify the existing equipment, and additionally requires few raw materials, cost saving, easy mass production, and good feasibility. Compared with the prior art, the mechanism of the present invention exerting an unexpected technical effect may also be that after spraying graphene, the presence of single-layer graphene increases the secondary absorption of sunlight by the solar panel, and increases the photoelectric conversion efficiency. . In addition, the good thermal conductivity of graphene has a good heat dissipation effect on the surface of the solar panel, thereby prolonging the service life of the solar panel and further improving its photoelectric conversion efficiency. Graphene-coated panels improved their average photoelectric conversion efficiency by 3% compared to conventional cells.

The specific embodiments of the present invention have been described above. It is to be understood that the invention is not limited to the specific embodiments described above, and various modifications and changes may be made by those skilled in the art without departing from the scope of the invention.

Claims (10)

1. A method for preparing a solar panel with a graphene coating, characterized in that the preparation method comprises coating a surface of a solar panel with a graphene coating; the graphene coating is dispersed by graphene and graphene oxide Prepared in a solvent.
2. The method for preparing a solar cell panel with a graphene coating according to claim 1, wherein the solvent is selected from the group consisting of ethanol, water, N-methylpyrrolidone, N,N-dimethylformamide, and Methyl sulfoxide, toluene, xylene or n-butanol.
3. The method for preparing a solar cell panel having a graphene coating according to claim 1, wherein the graphene coating has a concentration of graphene or graphene oxide of 0.08 to 0.4 mg/ml.
4. The method for preparing a solar cell panel with a graphene coating according to claim 1, wherein the graphene coating is prepared by dispersing graphene in a mixed solution of N-methylpyrrolidone and ethanol. The volume ratio of the N-methylpyrrolidone to ethanol is 1:1 to 5.
5. The method for preparing a solar cell panel with a graphene coating according to claim 1, wherein the graphene coating is dispersed in water, ethanol, dimethyl sulfoxide or unmodified graphene oxide. Formulated in N,N-dimethylformamide.
6. The method for preparing a solar cell panel with a graphene coating according to claim 1, wherein the graphene coating is dispersed in an oily solvent by a modified graphene oxide, and an appropriate amount of a high saturated vapor pressure solvent is added. Prepared; the oily solvent comprises one or a mixture of toluene and xylene.
7. The method for preparing a solar cell panel having a graphene coating according to claim 1, wherein the graphene is selected from the group consisting of CVD growth graphene, carbon dioxide supercritical expansion stripping graphene, electrochemical stripping graphene, and mechanical Ball mill stripped graphene or three rolls mechanically stripped graphene.
8. The method for preparing a solar cell panel with a graphene coating according to claim 1, wherein the graphene oxide is selected from the group consisting of chemically oxidized and exfoliated graphene oxide, a coupling agent-modified graphene oxide, and high-temperature thermal expansion. Reduction of graphene oxide or reduced graphene oxide obtained by low temperature thermal expansion.
9. The method for preparing a solar cell panel with a graphene coating according to claim 1, wherein the coating is selected from atomized spraying, and the pressure of the spray gun is 0.2-0.3 MPa.
10. The method for preparing a solar panel with a graphene coating according to claim 1, wherein the coating is specifically: coating a surface of the solar panel of 50 to 250 mL per square meter of the solar panel.

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