Small velvet surface texturing method for solar cell and solar cell preparation method

Abstract

The present invention relates to a method for texturing a small velvet surface of a solar cell and a method for preparing a solar cell, and belongs to the technical field of preparing solar cells. It comprises: configuring a solution of a texturing tank, wherein the solution of the texturing tank is composed of the following raw materials in weight percentage: NaOH 1.0%-1.5%, texturing additive 0.55%-0.75%, and the rest is pure water solvent; pre-cleaning; water washing; texturing: the texturing reaction temperature is 82-83°C, so that the surface of the single crystal silicon wafer is corroded to form a pyramid-shaped velvet surface; water washing; post-cleaning; acid washing; water washing; pre-dehydration; drying. The present invention increases the mass percentage of the texturing additive in the solution of the texturing tank and increases the texturing reaction temperature, so that the velvet surface obtained by the texturing process is small and uniform, which not only increases the uniformity of the velvet surface of the single crystal silicon wafer, but also reduces the surface reflectivity, and can improve the photoelectric conversion efficiency of the solar cell.

Description

Technical Field

[0001] The invention relates to the technical field of solar cell preparation, and in particular to a method for making a small velvet surface of a solar cell and a method for preparing the solar cell. Background Art

[0002] As the global demand for clean energy grows, photovoltaic power generation, as an efficient and environmentally friendly form of energy, is gradually becoming an important part of energy strategy. However, the rapid development of the photovoltaic industry is currently facing an important challenge, namely, reducing costs and improving efficiency. To this end, the photovoltaic industry continues to explore and apply various advanced technologies to achieve the goal of reducing costs and increasing efficiency.

[0003] In the production of solar cells, the texturing process is a crucial process, the purpose of which is to form an uneven velvet surface to increase the silicon wafer's absorption of sunlight, reduce reflectivity, and thus improve the photovoltaic conversion efficiency of the cell. However, in the existing texturing process, velvet defects are a problem that cannot be ignored. At the same time, in actual production, due to improper control of process parameters or insufficient equipment precision, the velvet surface may become uneven. This uneven velvet surface will affect the silicon wafer's absorption efficiency of sunlight, thereby reducing the photovoltaic conversion efficiency of the cell. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for making a small velvet surface of a solar cell and a method for preparing a solar cell. The technical solution of the present invention is as follows:

[0005] In a first aspect, a method for making a small velvet surface of a solar cell is provided, comprising:

[0006] S1, preparing a texturing tank solution, the texturing tank solution is composed of the following raw materials in weight percentage: NaOH 1.0%-1.5%, texturing additive 0.55%-0.75%, and the rest is pure water solvent;

[0007] S2, pre-cleaning;

[0008] S3, water washing;

[0009] S4, texturing: placing the single crystal silicon wafer in the solution of the texturing tank for reaction, the reaction time is 420s, the reaction temperature is 82-83°C, so that the surface of the single crystal silicon wafer is corroded to form a pyramid-shaped texturing morphology;

[0010] S5, water washing;

[0011] S6, post-cleaning;

[0012] S7, pickling;

[0013] S8, water washing;

[0014] S9, pre-dehydration;

[0015] S10, drying.

[0016] Optionally, the pre-cleaning in S2 and the post-cleaning in S6 both include: immersing the single crystal silicon wafer in a mixed aqueous solution of 0.3-0.5% by mass of NaOH and 0.9-1.5% by mass of H2O2 at 60-70°C for 100-140s.

[0017] Optionally, the water washing in S3, S5 and S8 all include: immersing the single crystal silicon wafer in flowing deionized water for 100-140 seconds.

[0018] Optionally, the pickling in S7 includes: immersing the single crystal silicon wafer in a mixed aqueous solution of 0.2-0.6% by mass HF and 0.8-1.2% by mass HCl at 15-30° C. for 100-160 seconds.

[0019] Optionally, the pre-dehydration in S9 includes: immersing the single crystal silicon wafer in flowing deionized water at 60-80° C. for 20-60 seconds.

[0020] Optionally, the drying in S10 includes: drying the single crystal silicon wafer in an oven at a temperature of 85-95° C. for 600-800 seconds.

[0021] In a second aspect, a method for preparing a solar cell is provided, wherein the texturing process is performed using the small texturing method for the solar cell described in the first aspect.

[0022] All the above optional technical solutions can be combined arbitrarily, and the present invention does not provide detailed descriptions of the structures after the combinations.

[0023] By means of the above scheme, the beneficial effects of the present invention are as follows:

[0024] By setting the weight percentage of the texturing additive in the solution of the texturing tank to 0.55%-0.75%, and setting the reaction temperature in the texturing step to 82-83°C, the mass percentage of the texturing additive is increased and the texturing reaction temperature is increased compared to the traditional texturing process, so that the velvet surface obtained by the texturing process is small and uniform, which not only increases the uniformity of the velvet surface of the single crystal silicon wafer, but also reduces the surface reflectivity, thereby improving the photoelectric conversion efficiency of solar cells.

[0025] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1It is a flow chart of a method for making small velvet surface of a solar cell provided by an embodiment of the present invention.

[0027] Figure 2 It is a schematic diagram of the suede surface prepared in an embodiment of the present invention.

[0028] Figure 3 It is a schematic diagram of the suede obtained by the comparative example of the present invention. DETAILED DESCRIPTION

[0029] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0030] like Figure 1 As shown, the method for making a small velvet surface of a solar cell provided by an embodiment of the present invention is characterized by comprising:

[0031] S1, preparing a texturing tank solution, the texturing tank solution is composed of the following raw materials in weight percentage: NaOH 1.0%-1.5%, texturing additive 0.55%-0.75%, and the rest is pure water solvent.

[0032] As for the specific components of the texturing additive, the texturing additive available on the market can be used, and the embodiment of the present invention does not specifically limit this.

[0033] S2, front cleaning.

[0034] Pre-cleaning is used to clean impurities, oxides and damaged layers on the surface of single crystal silicon wafers.

[0035] S3, water washing.

[0036] S4, texturing: placing the single crystal silicon wafer in the solution of the texturing tank for reaction, the reaction time is 420s, the reaction temperature is 82-83°C, so that the surface of the single crystal silicon wafer is corroded to form a pyramid-shaped texturing morphology;

[0037] S5, water washing.

[0038] S6, post-cleaning.

[0039] Post-cleaning is used to clean impurities, oxides and damaged layers on the surface of single crystal silicon wafers.

[0040] S7, pickling.

[0041] S8, water washing.

[0042] S9, pre-dehydration.

[0043] S10, drying.

[0044] In a specific embodiment, the pre-cleaning in S2 and the post-cleaning in S6 both include: immersing the single crystal silicon wafer in a mixed aqueous solution of 0.3-0.5% by mass NaOH and 0.9-1.5% by mass H2O2 at 60-70°C for 100-140s.

[0045] In a specific embodiment, the water washing in S3, S5 and S8 all include: immersing the single crystal silicon wafer in flowing deionized water for 100-140 seconds.

[0046] In a specific embodiment, the pickling in S7 includes: immersing the single crystal silicon wafer in a mixed aqueous solution of 0.2-0.6% by mass HF and 0.8-1.2% by mass HCl at 15-30° C. for 100-160 seconds.

[0047] In a specific embodiment, the pre-dehydration in S9 includes: immersing the single crystal silicon wafer in flowing deionized water at 60-80° C. for 20-60 seconds.

[0048] In a specific embodiment, the drying in S10 includes: drying the single crystal silicon wafer in an oven at a temperature of 85-95° C. for 600-800 seconds.

[0049] In order to verify the beneficial effects of the small velvet surface texturing method for solar cells provided by the embodiments of the present invention, the following embodiments and comparative examples are provided below.

[0050] Example

[0051] The method for making a small velvet surface of a solar cell provided in this embodiment comprises the following steps:

[0052] (a) preparing a texturing tank solution: the texturing tank solution is composed of the following raw materials in weight percentage: 1.2% NaOH, 0.6% texturing additive, and the rest being pure water solvent;

[0053] (b) Pre-cleaning: Immerse the single crystal silicon wafer in a mixed aqueous solution of 0.35% by mass NaOH and 1.2% by mass H2O2 at 64°C for 120s;

[0054] (c) Water washing: immerse the single crystal silicon wafer in flowing deionized water for 100 s;

[0055] (d) Texturing: placing a single crystal silicon wafer in a solution in a texturing tank for reaction at a temperature of 82° C. for a reaction time of 420 seconds, so that the surface of the single crystal silicon wafer is corroded to form a pyramid-shaped texturing morphology;

[0056] (e) Water washing: immerse the single crystal silicon wafer in flowing deionized water for 100 s;

[0057] (f) Post-cleaning: The single crystal silicon wafer was immersed in a mixed aqueous solution of 0.35% by mass NaOH and 1.2% by mass H2O2 at 64°C for 120s;

[0058] (g) pickling: the single crystal silicon wafer was immersed in a mixed aqueous solution of 0.35% by mass HF and 1.0% by mass HCl for 120 s at 25° C.;

[0059] (h) Water washing: immerse the single crystal silicon wafer in flowing deionized water for 100 s;

[0060] (i) Pre-dehydration: The single crystal silicon wafer was immersed in flowing deionized water at 68 °C for 50 s;

[0061] (j) Drying: Dry in an oven at 95°C for 720 s.

[0062] Comparative Example

[0063] The texturing method of the solar cell provided in this comparative example comprises the following steps:

[0064] (a) preparing a texturing tank solution: the texturing tank solution is composed of the following raw materials in weight percentage: 1.2% NaOH, 0.5% texturing additive, and the rest being pure water solvent;

[0065] (b) Pre-cleaning: Immerse the single crystal silicon wafer in a mixed aqueous solution of 0.35% by mass NaOH and 1.2% by mass H2O2 at 64°C for 120s;

[0066] (c) Water washing: immerse the single crystal silicon wafer in flowing deionized water for 100 s;

[0067] (d) Texturing: placing a single crystal silicon wafer in a solution in a texturing tank for reaction at a temperature of 81° C. for a reaction time of 420 seconds, so that the surface of the single crystal silicon wafer is corroded to form a pyramid-shaped texturing morphology;

[0068] (e) Water washing: immerse the single crystal silicon wafer in flowing deionized water for 100 s;

[0069] (f) Post-cleaning: The single crystal silicon wafer was immersed in a mixed aqueous solution of 0.35% by mass NaOH and 1.2% by mass H2O2 at 64°C for 120s;

[0070] (g) pickling: the single crystal silicon wafer was immersed in a mixed aqueous solution of 0.35% by mass HF and 1.0% by mass HCl for 120 s at 25° C.;

[0071] (h) Water washing: immerse the single crystal silicon wafer in flowing deionized water for 100 s;

[0072] (i) Pre-dehydration: The single crystal silicon wafer was immersed in flowing deionized water at 68 °C for 50 s;

[0073] (j) Drying: Dry in an oven at 95°C for 720 s.

[0074] The above-mentioned embodiment and comparative example adopt the same source and same line type of single crystal silicon wafers. The texture conditions of the solar cells after the reaction of the embodiment and comparative example are shown in Table 1.

[0075] Table 1

[0076] Group Weight loss Reflectivity size high Specific surface area Velvet density Comparative example (large velvet) 0.48 10.265 1.857 1.156 1.323 156005 Embodiment (small suede) 0.423 9.75 1.592 0.874 1.261 210937

[0077] like Figure 2 As shown in Table 1, Figure 2 and Figure 3 It can be seen that due to the increase in the concentration of the texturing additive in the embodiment, the size of the formed suede surface is smaller due to its protective effect. At the same time, due to the increase in the texturing reaction temperature, the suede surface is more uniform as a whole, and the light trapping effect is significantly improved.

[0078] The embodiment of the present invention further provides a method for preparing a solar cell, which adopts the small velvet surface texturing method of the solar cell described in the above embodiment to perform the texturing process.

[0079] The electrical properties of the solar cells formed by subjecting the single crystal silicon wafers after texturing in the embodiment and the comparative example to the same wet process, diffusion, coating and screen making processes are compared as shown in Table 2.

[0080] Table 2

[0081] Electrical properties Eta Uoc Isc FF R R IRV2 Example 3518 26.447 0.73386 18.0721 87.93 0.00416 1221.35 Comparative Example 3680 26.424 0.73393 18.0788 87.82 0.00395 1243.09 Gain(%) 0.023 -0.0001 -0.007 0.116 0.0002 -21.738 0.030

[0082] As shown in Table 2, the efficiency gain of the embodiment (small velvet surface) is 0.023% compared with the comparative example (large velvet surface), and the overall opening voltage and current change are small, mainly manifested in the FF filling height of 0.116. The improvement in efficiency is caused by the smoother surface structure of the small velvet surface of the cell, which makes the contact between the screen and the silicon wafer more compact and uniform during the screen printing process.

[0083] In summary, the embodiments of the present invention increase the nucleation points on the surface of the single crystal silicon wafer and improve the pyramid density by adjusting the formula of the texturing process (increasing the mass percentage of the texturing additive) and the texturing reaction temperature, thereby obtaining a small and uniform texturing surface, which can improve the conversion efficiency of solar cells.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the technical principles of the present invention, and these improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for making a small velvet surface of a solar cell, characterized in that: include: S1, preparing a texturing tank solution, the texturing tank solution is composed of the following raw materials in weight percentage: NaOH 1.0%-1.5%, texturing additive 0.55%-0.75%, and the rest is pure water solvent; S2, pre-cleaning; S3, water washing; S4, texturing: placing the single crystal silicon wafer in the solution of the texturing tank for reaction, the reaction time is 420s, the reaction temperature is 82-83°C, so that the surface of the single crystal silicon wafer is corroded to form a pyramid-shaped texturing morphology; S5, water washing; S6, post-cleaning; S7, pickling; S8, water washing; S9, pre-dehydration; S10, drying.

2. The method for making small velvet surface of a solar cell according to claim 1, characterized in that: The pre-cleaning in S2 and the post-cleaning in S6 both include: The single crystal silicon wafer is immersed in a mixed aqueous solution of 0.3-0.5% by mass of NaOH and 0.9-1.5% by mass of H2O2 for 100-140 seconds at 60-70°C.

3. The method for making small velvet surface of a solar cell according to claim 1, characterized in that: The water washing in S3, S5 and S8 all includes: Immerse the single crystal silicon wafer in flowing deionized water for 100-140 seconds.

4. The method for making small velvet surface of a solar cell according to claim 1, characterized in that: The pickling in S7 includes: The single crystal silicon wafer is immersed in a mixed aqueous solution of 0.2-0.6% by mass HF and 0.8-1.2% by mass HCl at 15-30° C. for 100-160 seconds.

5. The method for making small velvet surface of a solar cell according to claim 1, characterized in that: The pre-dehydration in S9 includes: Immerse the single crystal silicon wafer in flowing deionized water at 60-80°C for 20-60s.

6. The method for making small velvet surface of a solar cell according to claim 1, characterized in that: The drying in S10 includes: Dry the single crystal silicon wafer in an oven at a temperature of 85-95°C for 600-800s.

7. A method for preparing a solar cell, characterized in that: The texturing process is carried out using the small texturing method for the solar cell surface according to any one of claims 1 to 6.

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