A crystalline silicon cell side passivation coating and passivation method

Abstract

The invention relates to the technical field of silicon cells, and proposes a side passivation coating for a crystalline silicon cell, comprising a (2-(9H-carbazole-9-yl)ethyl)phosphonic acid solution and an active agent, which can be directly applied to the side of the crystalline silicon. Through the above technical solution, the influence of the side recombination of the crystalline silicon cell caused by laser cutting is reduced, the power conversion efficiency of the component is improved, the process is simple, the cost is low, and large-scale production can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon cells, and in particular to a crystalline silicon cell side passivation coating and a passivation method. Background Art

[0002] As the global shortage of disposable energy becomes more and more severe, the development and utilization of clean energy has become an urgent problem to be solved in various industries around the world. Solar cells are devices that can convert light energy into electrical energy. Silicon-based solar cells are the main ones, which can effectively reduce environmental pollution and the crisis of energy consumption. In order to improve the efficiency of cells to modules, a half-cell and shingled technology has emerged. At present, due to the popularity of half-cells and shingles, the use of lasers to cut whole cells has become one of the important application technologies in the industrial field. After cutting, very serious laser loss is caused at the cross-section of the two cells, resulting in a large number of dangling bonds and defect states on the side of the cell, causing serious recombination, and then seriously losing the efficiency of the battery module. Figure 1 As shown in the figure, based on the data comparison between laser cutting and non-destructive cutting, we can clearly see that laser cutting causes greater damage to silicon wafers. Therefore, solving the side problems of crystalline silicon after laser cutting has become a crucial issue in the industry.

[0003] In order to solve the side problems of crystalline silicon after laser cutting, there are two main methods in the industry:

[0004] (1) Natural oxidation method in the atmosphere

[0005] This method can reduce surface recombination to a certain extent, but there is a serious problem during natural oxidation, which is that this method is inevitably doped with impurities in the air, and the ability to repair losses is very limited. In fact, the efficiency loss problem of the battery cell has not been substantially solved, which ultimately leads to the inability to further increase the power of the component.

[0006] (2) Deposition Alumina Method

[0007] This method is to deposit an aluminum oxide passivation layer on the edge of the cell, and then anneal the passivation layer at a temperature above 220°C to activate the passivation layer and reduce edge composite damage. However, since the passivation mechanism of aluminum oxide deposited by this technology relies on the expulsion of electrons by internal negative charges (field effect passivation mechanism), it can only passivate p-type silicon, and the passivation layer cannot be precisely grown only on the edge. In fact, thin films will grow on the edges of the front and back surfaces, resulting in poor light absorption and conductivity on other surfaces. In addition, since this method requires a high temperature of more than 220°C, but too high a temperature will cause hydrogen to leak out, reducing the performance of the solar cell, so this technology is also extremely strict with temperature requirements, which ultimately leads to high costs and low production capacity of ALD equipment.

[0008] Therefore, how to develop a passivation method with low cost, simple process and good passivation effect has become a technical problem in this industry. Summary of the invention

[0009] The present invention provides a crystalline silicon cell side passivation coating and a passivation method, which solves the problems of poor effect, complex process and high cost of the passivation method in the prior art.

[0010] The technical solution of the present invention is as follows:

[0011] A crystalline silicon cell side passivation coating comprises a (2-(9H-carbazole-9-yl)ethyl)phosphonic acid solution and an activator.

[0012] As a further technical solution, the solvent of the (2-(9H-carbazole-9-yl)ethyl)phosphonic acid solution includes one of isopropanol, ethanol, water, ethylene glycol and toluene.

[0013] As a further technical solution, the solvent is isopropanol or ethylene glycol.

[0014] As a further technical solution, the mass concentration of the (2-(9H-carbazole-9-yl)ethyl)phosphonic acid solution is 0.5%-6%.

[0015] As a further technical solution, the mass concentration of the (2-(9H-carbazole-9-yl)ethyl)phosphonic acid solution is 1.5%.

[0016] As a further technical solution, the active agent is trimethylolpropane triglycidyl ether.

[0017] As a further technical solution, the mass ratio of the (2-(9H-carbazole-9-yl)ethyl)phosphonic acid to the active agent is (15-20):1.

[0018] As a further technical solution, the mass ratio of the (2-(9H-carbazole-9-yl)ethyl)phosphonic acid to the active agent is 18:1.

[0019] The present invention also provides a method for preparing a side passivation coating of a crystalline silicon cell, comprising the following steps:

[0020] S1, preparing a solution of (2-(9H-carbazole-9-yl)ethyl)phosphonic acid;

[0021] S2, adding an active agent to the solution to obtain a mixture;

[0022] S3. Stir the mixture with a magnetic stirrer for 5-6 hours in an environment with a temperature of 25° C. and a humidity of 35%-40%.

[0023] The present invention also provides a method for passivating the side of a crystalline silicon cell. The passivation is completed by brushing the side passivation coating of the crystalline silicon cell on the side of the crystalline silicon in an atmospheric environment until it is evenly applied.

[0024] The beneficial effects of the present invention are:

[0025] 1. (2-(9H-carbazole-9-yl)ethyl)phosphonic acid, referred to as 2PACZ, is a white powder solid that not only has a passivation effect, but also has the characteristics of self-assembly. 2PACZ can spontaneously associate to form a stable, perfectly structured two-dimensional or three-dimensional supramolecule through covalent or non-covalent bond interactions under equilibrium conditions, and can also passivate the side defects of crystalline silicon caused by cutting. The passivating groups in the 2PACZ material are combined with the dangling bonds on the side of the crystalline silicon after laser cutting. At the same time, due to the self-assembly characteristics of the material, the ordered molecular film formed by adsorption on the silicon surface is immersed in the molecules to be assembled by adding active agents, solvents and regulating the concentration, so that the molecules spontaneously adsorb firmly on the solid surface through chemical bonds to form an ordered molecular assembly, in which the molecules are arranged in an orderly manner and have few defects, so that most of the molecules are better combined with the dangling bonds on the side of the silicon, and the passivation effect is better.

[0026] 2. The passivation coating prepared by (2-(9H-carbazole-9-yl)ethyl)phosphonic acid, solvent and active agent of the present invention is applied to the laser cutting process in half-cell and shingled components. It can be directly coated on the side of the crystalline silicon cell and operated in the atmospheric environment. There are no special restrictions on the passivation conditions. At the same time, no heavy equipment is required. The process is simple, the cost is low, and large-scale production can be achieved. In addition, the passivation coating and passivation method of the present invention can greatly reduce the impact of the side recombination of the crystalline silicon cell caused by laser cutting, and improve the power conversion efficiency of the component. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0028] Figure 1 It is the efficiency loss caused by the side of crystalline silicon after laser cutting;

[0029] Figure 2 A comparison chart of minority carrier lifetimes of Examples 1-5;

[0030] Figure 3 This is a comparison diagram of the opening pressure of Example 1 and Examples 6-10;

[0031] Figure 4 This is a comparison diagram of the photovoltaic performance of the cells obtained after passivation between the present invention and the prior art. In the figure, the solid line represents the present invention, and the dotted line represents the prior art. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] A method for side passivation of crystalline silicon cells:

[0035] S1, dissolving 2PACZ in isopropanol solvent to prepare a solution with a mass concentration of 1.5%;

[0036] S2, adding trimethylolpropane triglycidyl ether to the dissolved solution, wherein the mass ratio of trimethylolpropane triglycidyl ether to 2PACZ is 1:18;

[0037] S3. Stirring with a magnetic stirrer for 5 hours in an environment with a temperature of 25° C. and a humidity of 35%-40% to obtain a solution for a passivation coating.

[0038] Example 2

[0039] The difference from Example 1 is that the solvent is ethylene glycol, and the rest is the same as Example 1.

[0040] Example 3

[0041] The difference from Example 1 is that the solvent is ethanol, and the rest is the same as Example 1.

[0042] Example 4

[0043] The difference from Example 1 is that the solvent is water, and the rest is the same as Example 1.

[0044] Example 5

[0045] The difference from Example 1 is that the solvent is toluene, and the rest is the same as Example 1.

[0046] Experimental Example 1

[0047] The minority carrier lifetime was tested using the solution of the passivation coating obtained in Examples 1-5.

[0048] Test process: Use a double-polished silicon wafer with a resistivity of 3k-5kΩ·cm and a thickness of 400±10um. First, clean the double-polished silicon wafer with hydrofluoric acid for 3 minutes, then take 50uL of solution with a pipette, turn on the glue machine, set the speed to 7500r / min, and rotate the solution of the pipette gun at high speed to form a film containing solvent. Use WCT-120Sinton minority carrier lifetime tester for testing.

[0049] Figure 2 This is a comparison chart of minority carrier lifetimes in Examples 1-5. The lifetime of the uncoated silicon wafer is 0.02 ms. The passivation solution obtained by the present invention can increase the minority carrier lifetime. Ethylene glycol and isopropyl alcohol have better effects, and the minority carrier lifetime of isopropyl alcohol reaches the highest at about ten minutes, which is about 1.95 ms.

[0050] Example 6

[0051] Compared with Example 1, a solution with a concentration of 0.5% is prepared in step S1, and the rest is the same as Example 1.

[0052] Example 7

[0053] Compared with Example 1, a solution with a concentration of 1% is prepared in step S1, and the rest is the same as Example 1.

[0054] Example 8

[0055] Compared with Example 1, a solution with a concentration of 2% is prepared in step S1, and the rest is the same as Example 1.

[0056] Example 9

[0057] Compared with Example 1, a solution with a concentration of 4% is prepared in step S1, and the rest is the same as Example 1.

[0058] Example 10

[0059] Compared with Example 1, a solution with a concentration of 6% is prepared in step S1, and the rest is the same as Example 1.

[0060] Experimental Example 2

[0061] Testing process: Select heterojunction cells and cut them into 3*3cm pieces by laser 2 The solutions prepared in Example 1 and Examples 6-10 are brushed onto the newly added side surfaces of the crystalline silicon after laser cutting.

[0062] Test results such as Figure 3 As shown, it can be found that when the measured concentration is 1.5wt%, that is, the heterojunction cell of Example 1 has the highest opening voltage (that is, the passivation effect is significant).

[0063] Experimental Example 3

[0064] The passivation coating solution obtained in Example 1 was brush-coated on the newly added side of the crystalline silicon after laser cutting, and the cell was subjected to IV test (testing the photovoltaic performance of the cell). The test results are as follows: Figure 4 And as shown in Table 1. Among them, the prior art in the table is the performance of non-passivated batteries:

[0065] Table 1 Statistics of photovoltaic performance data of batteries

[0066]

[0067]

[0068] When the coating of the present invention is applied to the newly added side surface of the crystalline silicon cell after laser cutting, the opening voltage and filling factor of the cell are significantly improved, and the final efficiency is improved.

[0069] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A crystalline silicon cell side passivation coating, characterized in that: The invention comprises a (2-(9H-carbazole-9-yl)ethyl)phosphonic acid solution and an active agent; The solvent of the (2-(9H-carbazole-9-yl)ethyl)phosphonic acid solution is isopropanol or ethylene glycol; The active agent is trimethylolpropane triglycidyl ether; The side of the crystalline silicon cell is the side of the crystalline silicon formed after the entire cell is cut by laser; The mass concentration of the (2-(9H-carbazole-9-yl)ethyl)phosphonic acid solution is 1.5%; The mass ratio of the (2-(9H-carbazole-9-yl)ethyl)phosphonic acid to the active agent is 18:

1.

2. The method for preparing a crystalline silicon cell side passivation coating according to claim 1, characterized in that: The following steps are involved: S1, preparing a solution of (2-(9H-carbazole-9-yl)ethyl)phosphonic acid; S2, adding an active agent to the solution to obtain a mixture; S3. Stir the mixture with a magnetic stirrer for 5-6 hours in an environment with a temperature of 25° C. and a humidity of 35%-40%.

3. A method for side passivation of a crystalline silicon cell, characterized in that: The passivation can be completed by brushing the crystalline silicon cell side passivation coating as claimed in claim 1 onto the side of the crystalline silicon in an atmospheric environment until it is evenly applied.

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