Preparation method and application of positive and negative electrode insulation isolation layer of solar cell

Abstract

The invention discloses a preparation method of a positive and negative electrode insulation isolation layer of a solar cell. The preparation method comprises the following steps: S1, placing the back surface of a back contact solar cell on an ink-jet printing platform deck; s2, arranging an insulation isolation area in parallel on a metal auxiliary grid line on the back surface of the back contact solar cell and a welding contact area; carrying out insulation ink-jet printing in the insulation isolation area; and curing the solar cell after ink-jet printing of the insulation isolation area under an ultraviolet lamp. According to the invention, the graph is digitally printed, and the manufacturing time is shortened from several weeks to several hours; the film forming thickness of 1-50 microns can be realized through one-time ink-jet printing, and the problem of bubbles can be solved at the same time; precision of ink-jet printing graph capable of being controlled within range

Description

Technical Field

[0001] The invention relates to a preparation method and application of a positive and negative electrode insulating isolation layer of a solar cell, relates to H01L, and specifically relates to the field of semiconductor devices. Background Art

[0002] In order to transfer the ink from the printing equipment to the battery substrate, the traditional process mostly adopts the method of screen printing to heat and cure the ink. However, due to its own thermal contact printing method, screen printing will cause the silicon wafer to break during the printing process, the silicon crystal surface will be contaminated, and the shaping effect after the graphics are printed will be poor. In addition, the ink used in screen printing is mostly epoxy resin, which has certain limitations in terms of adhesion to the silicon wafer and insulation performance. In addition, due to the external pressure of 40-100N for contact printing, bubbling problems are also inevitable during the printing process, which will affect the stability and reliability of the final product solar cell.

[0003] Chinese invention patent CN202210738287.2 discloses an inkjet printing device and a method for inkjet printing a graphic layer, which overcomes the defects of the existing solar cell electrode grid line having a small aspect ratio and high cost. Without increasing the width of the graphic layer, the height of the graphic layer is increased, thereby improving the aspect ratio of the graphic layer. However, a thermal curing method is adopted, which has high energy consumption. Chinese invention patent CN202011494726.7 discloses a solar cell metal electrode mesh, a manufacturing method, and a solar cell manufacturing method using a solar cell metal electrode mesh, a metal seed layer is arranged on the surface of a roll-shaped carrier, and an insulating layer with a hollow grid line pattern is arranged on the surface of the metal seed layer. The copper grid line of the battery production line only needs to transfer the metal electrode mesh on the roll-shaped carrier, and the cost is reduced. However, the damage to the silicon wafer caused by ink printing cannot be avoided, resulting in a loss of battery efficiency. Summary of the invention

[0004] In order to solve the problems of silicon wafer breakage and surface contamination in the screen printing process, improve the printing accuracy and avoid the bubbling problem during the printing process, the first aspect of the present invention provides a method for preparing an insulating isolation layer of positive and negative electrodes of a solar cell, comprising the following steps:

[0005] S1 Place the back side of the back-contact solar cell on the inkjet printing stage, with the back side facing up and facing the inkjet head, with the middle distance > 200 μm;

[0006] S2 is fixedly arranged and positioned, and an insulating isolation area is arranged parallel to the metal secondary grid line and the welding contact area on the back side of the back contact solar cell;

[0007] S3 performs inkjet printing of insulating ink in the insulating isolation area;

[0008] S4 places the solar cell with the insulating isolation area printed by inkjet printing under ultraviolet light for curing.

[0009] In step S2 of the present application, the positive secondary grid line is set to n, the negative secondary grid line is set to n+1, the positive welding strip is set to N, and the negative welding strip is set to N+1; the secondary grid line and the welding strip are vertically cross-lapped, and an insulating isolation layer is set at the positive secondary grid line n and the negative welding strip N+1, and at the same time, an insulating isolation layer is set at the negative secondary grid line n+1 and the positive welding strip N, so that the positive welding strip N and the positive secondary grid line n are metallized in contact, and all the current of the positive secondary grid line n is collected through the positive welding strip, and the negative welding strip N+1 is metallized in contact with the negative secondary grid line n+1, and all the current of the negative secondary grid line n+1 is collected through the negative welding strip. The short circuit between the negative welding strip N+1 and the positive secondary grid line n and the positive welding strip N and the negative secondary grid line n+1 is eliminated due to the set insulating isolation layer.

[0010] As a preferred implementation, the working temperature of the insulating ink is 20-65° C., and the viscosity of the insulating ink at the working temperature is 5-100 cp.

[0011] As a preferred implementation, the ink droplet size of the insulating ink is 3-80 pL; when the insulating ink is inkjetted, the ink droplets are arranged in an overlapping manner, and the overlapping area of ​​each ink droplet accounts for 10-50% of the entire ink drop area.

[0012] As a preferred embodiment, the inkjet head arranges the ink droplets in a linear and / or cross-shaped manner.

[0013] As a preferred embodiment, the absolute distance between the inkjet head and the metal secondary grid line of the battery is 1-50 mm, and the thickness of the formed insulating isolation area is 0.02-0.2 mm.

[0014] During the experiment, the applicant found that the electronic inkjet printing method has a stable printing effect and high printing efficiency, and can solve the problem of printing bubbles at the same time, reduce the fragmentation rate of silicon wafers, and improve the yield rate. The possible reason is guessed: the electronic inkjet printing method does not contact the solar cell silicon wafer during the printing process, replacing the contact printing of screen printing, and avoiding the breakage of the silicon wafer. The ink viscosity used in the printing of this application is 5-100cp, the working temperature of the ink is 20-65℃, and the ink printing droplet size is 3-80pL, which can achieve good adhesion on the solar silicon wafer. Only by using small ink droplets while maintaining a high ink viscosity can printing be achieved on the solar silicon wafer. Only by using a small amount of ink droplets can a high printing resolution be achieved. However, if the ink droplets are too small, the adhesion on the silicon wafer is small, which may cause the printing to become flowery when printing without contact. The printing temperature of 20-65℃ and the printing ink with a viscosity of 5-100cp can achieve fast contactless printing while maintaining a high printing resolution.

[0015] As a preferred embodiment, the curing wavelength of the insulating ink is 365-405nm, and the curing energy of the insulating ink is 100-2000mj / cm 2 .

[0016] As a preferred implementation, the resolution of the inkjet head is 100-1800 dpi.

[0017] As a preferred embodiment, the inkjet head is selected from one or a combination of Ricoh G5, Ricoh G6, Konica 1024, Konica 1800, Xaar 1003, and Xaar 2002.

[0018] The second aspect of the present invention provides an application of a method for preparing an insulating isolation layer of positive and negative electrodes of a solar cell, which is applied to a back-connected cell or a multi-junction cell.

[0019] As a preferred implementation, diffusion is performed on the back side of the P-type or N-type silicon substrate of the back-connected cell or multi-junction cell to form P+ and N+ regions.

[0020] As a preferred implementation, the P+ and N+ regions are grooved by laser technology to isolate the regions;

[0021] As a preferred embodiment, a silicon oxide, silicon nitride or polysilicon layer is deposited on the back of the silicon substrate and diffused, and an N++ region is formed by a laser process or a wet chemical etching process;

[0022] As a preferred embodiment, screen printing of silver paste / silver aluminum paste / aluminum paste is performed in the P+ and N++ regions and thermal curing or sintering is performed to form positive and negative electrode grid lines;

[0023] As a preferred embodiment, a copper seed layer is formed by a deposition process in the P+ and N++ regions and then electroplated; a mask patterned region is formed by printing, coating or other processes and then the excess region is removed by acid etching, leaving the positive and negative electrode grid lines;

[0024] As a preferred embodiment, the positive and negative electrode grid lines are connected by welding strips, and an insulating layer is formed between the positive and negative electrode grid lines in the crossing region using the method of the present invention.

[0025] As a preferred embodiment, the insulating isolation layer prepared in the back-connected cell or multi-junction cell has an insulating property of >10 11 ohm, breakdown voltage>1000V.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The insulating isolation layer of the positive and negative electrodes of the solar cell described in the present invention is printed by electronic inkjet printing, which has a stable printing effect and high printing efficiency. It can also solve the problem of printing bubbles, reduce the fragmentation rate of silicon wafers, and improve the quality of finished products. The insulating isolation layer formed has excellent insulation properties and high breakdown voltage.

[0028] (2) The insulating isolation layer of the positive and negative electrodes of the solar cell described in the present invention uses an ink with a viscosity of 5-100cp, an ink working temperature of 20-65°C, and an ink droplet size of 3-80pL. It can achieve good adhesion on the solar silicon wafer and can achieve fast contactless printing while maintaining high printing resolution.

[0029] (3) The insulating isolation layer of the positive and negative electrodes of the solar cell of the present invention adopts non-contact ink printing, which can avoid the contact between the screen and the silicon wafer and reduce the ink contamination of the silicon wafer in the non-printing area. The ultraviolet curing ink is adopted, which is cured by ultraviolet light in the 365-405nm band, has low energy density, and the energy consumption required for ink curing is saved by more than 60% compared with the traditional screen printing thermosetting type. In terms of equipment investment, material utilization, maintenance cost and energy consumption, it has obvious cost savings and performance improvement compared with the existing process.

[0030] (4) The method for preparing the insulating isolation layer of the positive and negative electrodes of the solar cell of the present invention can print the graphics digitally. The production of new graphics only needs to be done by using CAD software on a computer, which shortens the original screen printing screen production time from several weeks to several hours. The inkjet printing can achieve a film thickness of 1-50 microns in one printing, and can also solve the bubble problem at the same time. The accuracy of the inkjet printed graphics can be controlled within +Within 5 microns; inkjet printing has no organic emissions, which is more environmentally friendly and energy-saving; during the production process of inkjet printing, the printing effect is stable and consistent, and the printing quality will not be reduced due to the increase in the number of prints; the silicon wafer will not be broken due to the process during the printing process, and the fragmentation rate is 0; there is no waste of ink, and the ink utilization rate reaches 100%. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a top view of the back side of the solar cell in Example 1 of the present application;

[0032] Figure 2 A three-dimensional diagram of a solar cell according to Example 1 of the present application;

[0033] Figure 3 This is a flow chart of the equipment for printing solar cells in Example 1 of the present application;

[0034] Figure 4 The ink accuracy of the solar cell printed in Example 1 of the present application;

[0035] Figure 5 This is the actual printing effect of the solar cell printing in Example 1 of the present application;

[0036] Figure 6 This is an adhesion test effect diagram of the solar cell printed in Example 1 of the present application;

[0037] Figure 7 This is a breakdown voltage test effect diagram printed for the solar cell in Example 1 of the present application.

[0038] In the figure: 1. Insulation isolation area; 2. Metal secondary grid line; 3. Welding contact area; 4. Conveyor belt; 5. UV module; 6. Printing module; 7. CCD photosensitive coupling component; 8. Material handling module. DETAILED DESCRIPTION

[0039] The technical scheme of the present invention is further illustrated by specific embodiments below. In order to facilitate understanding of the present invention, the present invention is described more comprehensively below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0040] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0042] Example 1

[0043] A method for preparing a positive and negative electrode insulating isolation layer of a solar cell comprises the following steps:

[0044] S1 Place the back side of the back-contact solar cell on the inkjet printing stage, with the back side facing up and facing the inkjet head, with the middle distance > 200 μm;

[0045] S2 is fixedly arranged and positioned, and an insulating isolation area 1 is arranged parallel to the metal secondary grid line 2 and the welding contact area 3 on the back side of the back contact solar cell;

[0046] S3 performs inkjet printing of insulating ink in the insulating isolation area 1;

[0047] S4: placing the solar cell in the insulating isolation area 1 after inkjet printing under a UV lamp for curing.

[0048] The back contact solar cell is 182*192mm 2 Rectangular solar cell.

[0049] The specific operation of step S3 is: open the operation control interface of the printing device, and the system completes the parameter inspection. Import the file to be printed, and set the printing resolution accordingly as required. Use the camera to grab points or find edges for alignment, and after the alignment is completed, the device prints as required.

[0050] The insulating ink is an epoxy-modified acrylic resin system ink purchased from Foshan Yalanshi IU10C.

[0051] The working temperature of the insulating ink is 45° C., and the viscosity of the insulating ink at the working temperature is 55 cp.

[0052] The size of the ink droplets of the insulating ink is 40 pL; when the insulating ink is jetted, the ink droplets are arranged in an overlapping manner, and the overlapping area of ​​each ink droplet accounts for 30% of the entire ink drop area.

[0053] The inkjet head ejects ink droplets in a linear arrangement.

[0054] The absolute distance between the inkjet head and the metal secondary grid line of the battery is 30 mm, and the thickness of the formed insulating isolation area is 0.1 mm.

[0055] The curing wavelength of the insulating ink is 385nm, and the curing energy of the insulating ink is 1000mj / cm 2 .

[0056] The inkjet head is Konica 1024, and the resolution of the inkjet head is 850dpi.

[0057] Example 2

[0058] A method for preparing a positive and negative electrode insulating isolation layer of a solar cell comprises the following steps:

[0059] S1 Place the back side of the back-contact solar cell on the inkjet printing stage, with the back side facing up and facing the inkjet head, with the middle distance > 200 μm;

[0060] S2 is fixedly arranged and positioned, and an insulating isolation area 1 is arranged parallel to the metal secondary grid line 2 and the welding contact area 3 on the back side of the back contact solar cell;

[0061] S3 performs inkjet printing of insulating ink in the insulating isolation area 1;

[0062] S4: placing the solar cell in the insulating isolation area 1 after inkjet printing under a UV lamp for curing.

[0063] The back contact solar cell is 182*182mm 2 Square solar cells.

[0064] The specific operation of step S3 is: open the operation control interface of the printing device, and the system completes the parameter inspection. Import the file to be printed, and set the printing resolution accordingly as required. Use the camera to grab points or find edges for alignment, and after the alignment is completed, the device prints as required.

[0065] The insulating ink is an amino-modified acrylic resin system ink purchased from Foshan Yalanshi IU20C.

[0066] The working temperature of the insulating ink is 30° C., and the viscosity of the insulating ink at the working temperature is 60 cp.

[0067] The size of the ink droplets of the insulating ink is 60 pL; when the insulating ink is jetted, the ink droplets are arranged in an overlapping manner, and the overlapping area of ​​each ink droplet accounts for 40% of the entire ink drop area.

[0068] The inkjet head ejects ink droplets in a cross-shaped arrangement.

[0069] The absolute distance between the inkjet head and the metal secondary grid line of the battery is 30 mm, and the thickness of the formed insulating isolation area is 0.03 mm.

[0070] The curing wavelength of the insulating ink is 395nm, and the curing energy of the insulating ink is 2000mj / cm 2 .

[0071] The inkjet head is Ricoh G5, and the resolution of the inkjet head is 850dpi.

[0072] Example 3

[0073] A method for preparing a positive and negative electrode insulating isolation layer of a solar cell comprises the following steps:

[0074] S1 Place the back side of the back-contact solar cell on the inkjet printing stage, with the back side facing up and facing the inkjet head, with the middle distance > 200 μm;

[0075] S2 is fixedly arranged and positioned, and an insulating isolation area 1 is arranged parallel to the metal secondary grid line 2 and the welding contact area 3 on the back side of the back contact solar cell;

[0076] S3 performs inkjet printing of insulating ink in the insulating isolation area 1;

[0077] S4: placing the solar cell in the insulating isolation area 1 after inkjet printing under a UV lamp for curing.

[0078] The back contact solar cell is 210*210mm 2 Square solar cells.

[0079] The specific operation of step S3 is: open the operation control interface of the printing device, and the system completes the parameter inspection. Import the file to be printed, and set the printing resolution accordingly as required. Use the camera to grab points or find edges for alignment, and after the alignment is completed, the device prints as required.

[0080] The insulating ink is an amino-modified acrylic resin system ink purchased from Foshan Yalanshi IU10G.

[0081] The working temperature of the insulating ink is 25° C., and the viscosity of the insulating ink at the working temperature is 45 cp.

[0082] The size of the ink droplets of the insulating ink is 50 pL; when the insulating ink is jetted, the ink droplets are arranged in an overlapping manner, and the overlapping area of ​​each ink droplet accounts for 10% of the entire ink drop area.

[0083] The inkjet head ejects ink droplets in a cross-shaped arrangement.

[0084] The absolute distance between the inkjet head and the metal secondary grid line of the battery is 30 mm, and the thickness of the formed insulating isolation area is 0.06 mm.

[0085] The curing wavelength of the insulating ink is 365nm, and the curing energy of the insulating ink is 3000mj / cm 2 .

[0086] The inkjet head is Ricoh G5, and the resolution of the inkjet head is 850dpi.

[0087] Comparative Example 1

[0088] A method for preparing an insulating isolation layer of positive and negative electrodes of a solar cell, the specific implementation method is the same as that of Example 1, except that in step S3, screen printing of insulating ink is performed in the insulating isolation area. The screen-related parameters are: mesh number is 250μm, yarn thickness is 60μm, film thickness is 20μ, printing pressure is 60N, mesh spacing is 1.8mm, printing speed is 500mm / s, and ink return speed is 1400mm / s.

[0089] Performance Testing

[0090] 1. Adhesion: Adhesion of the cross-cut test example of the paint and varnish film of GBT 9286-1998. The performance test results of Example 1 are shown in the figure Figure 6 .

[0091] 2. Insulation: The insulation is tested using the GB1410-1989 solid insulating material volume resistivity and surface resistivity test method.

[0092] 3. Breakdown voltage: The breakdown voltage of the embodiment is tested using the method for determining the power frequency breakdown voltage strength and withstand voltage of vulcanized rubber in accordance with GB / T 1695-2005.

[0093] Result analysis:

[0094] In Example 1, the breakage rate of the silicon wafer is 0%, the printing accuracy is ±5μm, the straightness is <1μm, there are no bubbles in the printing, and the ink utilization rate is 100%; the ink adhesion after curing is 5B, and the insulation is ≥10 12 Ω, breakdown voltage>1000V, no obvious bubbles.

[0095] In Example 2, the breakage rate of the silicon wafer is 0%, the printing accuracy is ±5μm, the straightness is <1μm, there are no bubbles in the printing, and the ink utilization rate is 100%; the ink adhesion after curing is 5B, and the insulation is ≥10 12 Ω, breakdown voltage>1000V, no obvious bubbles.

[0096] In Example 3, the breakage rate of the silicon wafer is 0%, the printing accuracy is ±5μm, the straightness is <1μm, there are no bubbles in the printing, and the ink utilization rate is 100%; the ink adhesion after curing is 5B, and the insulation is ≥10 12 Ω, breakdown voltage>1000V, no obvious bubbles.

[0097] In the comparative example, the breakage rate of the silicon wafer is 1‰, the printing accuracy is ±15μm, the straightness is 3-5μm, the edge is uneven, there are bubbles in the screen printing, the number of bubbles with diameters greater than 5μm is 45, and the maximum bubble diameter reaches 24.5μm.

[0098] The performance test results of Examples 1 to 3 and Comparative Example 1 are shown in Table 1. From the statistical data, it can be seen that the use of inkjet printing to prepare the positive and negative electrode insulating isolation layer can improve the adhesion, insulation and breakdown voltage of the insulating isolation layer. At the same time, compared with screen printing, inkjet printing technology is a non-contact coating, which can achieve no bubbles after the isolation layer is cured, and the silicon chip fragmentation rate is 0%.

[0099] Table 1

[0100]

Claims

1. A method for preparing an insulating isolation layer of positive and negative electrodes of a solar cell, characterized in that: The following steps are involved: S1 Place the back side of the back-contact solar cell on the inkjet printing stage, with the back side facing up and facing the inkjet head, with the middle distance > 200 μm; S2 is fixedly arranged and positioned, and an insulating isolation area is arranged parallel to the metal secondary grid line and the welding contact area on the back side of the back contact solar cell; S3 performs inkjet printing of insulating ink in the insulating isolation area; S4 places the solar cell with the insulating isolation area printed by inkjet printing under ultraviolet light for curing.

2. The method for preparing the positive and negative electrode insulating isolation layer of a solar cell according to claim 1, characterized in that: The working temperature of the insulating ink is 20-65° C., and the viscosity of the insulating ink at the working temperature is 5-100 cp.

3. The method for preparing the positive and negative electrode insulating isolation layer of a solar cell according to claim 1, characterized in that: The size of the ink droplets of the insulating ink is 3-80 pL; when the insulating ink is jetted, the ink droplets are arranged in an overlapping manner, and the overlapping area of ​​each ink droplet accounts for 10-50% of the entire ink drop area.

4. The method for preparing the positive and negative electrode insulating isolation layer of a solar cell according to claim 1, characterized in that: The absolute distance between the inkjet head and the metal secondary grid line of the battery is 1-50 mm, and the thickness of the formed insulating isolation area is 0.02-0.2 mm.

5. The method for preparing the positive and negative electrode insulating isolation layer of a solar cell according to claim 1, characterized in that: The curing wavelength of the insulating ink is 365-405nm, and the curing energy of the insulating ink is 100-2000mj / cm 2 .

6. The method for preparing the positive and negative electrode insulating isolation layer of a solar cell according to claim 1, characterized in that: The resolution of the inkjet head is 100-1800 dpi.

7. The method for preparing the positive and negative electrode insulating isolation layer of a solar cell according to claim 1, characterized in that: The inkjet head is selected from one of Ricoh G5, Ricoh G6, Konica 1024, Konica 1800, Xaar 1003, and Xaar 2002, or a combination of several of them.

8. An application of the method for preparing the positive and negative electrode insulating isolation layer of a solar cell according to any one of claims 1 to 7, characterized in that: Applicable to back-contact cells or multi-junction cells.

9. The use of the method for preparing the positive and negative electrode insulating isolation layer of a solar cell according to claim 8, characterized in that: Diffusion is performed on the back side of the P-type or N-type silicon substrate of the back-connected cell or multi-junction cell to form P+ and N+ regions.

10. The use of the method for preparing the positive and negative electrode insulating isolation layer of a solar cell according to claim 9, characterized in that: The insulation performance of the insulating isolation layer prepared in the back-connected cell or multi-junction cell is greater than 10 11 ohm, breakdown voltage>1000V.

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