Preparation method of poly-finger structure battery, photovoltaic module and photovoltaic system

Abstract

The present application discloses a preparation method, a photovoltaic module and a photovoltaic system of a Poly-finger structure battery, and relates to the field of photovoltaic technology. The preparation method of the Poly-finger structure battery includes: providing a battery blue film, at least one side of the battery blue film includes a Poly-finger area and a non-finger area, the Poly-finger area protrudes from the battery blue film setting, and forms a step with the non-finger area; preparing a mask in the circumference of the Poly-finger area to widen the Poly-finger area, and to form a first area partially covered by the mask and a second area not covered by the mask on the side of the Poly-finger area away from the battery blue film; preparing a surface electrode in the second area, removing the mask, and obtaining a Poly-finger structure battery. Therefore, the battery prepared by the method of the present application can effectively solve the problem that the slurry of the printed surface electrode hits the edge of the step and falls into the non-finger area, and the obtained Poly-finger structure battery has high efficiency.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular, to a preparation method of a Poly-finger structure battery, a photovoltaic module and a photovoltaic system. Background Art

[0002] Poly-finger structure cells are a type of solar cell technology that only prepares polycrystalline silicon (Polycrystalline Silicon, referred to as Poly or Poly-Si) in the metal contact area. In order to effectively solve the problems of high composite current density in the metallized area of ​​solar cells and serious parasitic absorption of the entire Poly surface, the industry has gradually adopted the metallized area passivation contact technology, that is, forming a Poly-finger structure instead of the entire Poly surface. The specific preparation process is to first deposit the tunneling layer and the polysilicon layer on the entire surface, and then remove the tunneling layer and the polysilicon layer in the non-gate line area by means of laser film opening and wet etching, and then use screen printing to obtain the metallized area passivation contact structure.

[0003] However, due to the processes of film opening and wet etching, the height of the Poly-finger area on the surface of the cell will be significantly higher than that of the non-finger area, thus forming up and down micro-steps. During the screen printing step, due to the deformation of the screen opening, the slurry of the surface electrode easily touches the edge of the step and then falls on the non-gridline area (non-finger area) near the Poly-finger, resulting in a sharp increase in metal recombination and a significant decrease in the electrical performance of the cell, especially the open circuit voltage. Summary of the invention

[0004] In the first aspect of the present application, the present application proposes a method for preparing a Poly-finger structure battery, comprising: providing a battery blue diaphragm, at least one side of the battery blue diaphragm includes a Poly-finger area and a non-finger area, and the Poly-finger area protrudes from the battery blue diaphragm; preparing a mask in the circumferential direction of the Poly-finger area to widen the Poly-finger area, and to form a first area partially covered by the mask and a second area not covered by the mask on the side of the Poly-finger area away from the battery blue diaphragm; preparing a surface electrode in the second area, removing the mask, and obtaining a Poly-finger structure battery. Therefore, the Poly-finger structure battery prepared by the method of the present application can effectively solve the problem that the slurry is easy to fall into the non-grid line area during screen printing under the condition that the width of the Poly-finger area is narrow, resulting in a decrease in the electrical performance of the battery cell. On the one hand, the Poly-finger structure design has practical value, and on the other hand, it matches the actual production conditions well.

[0005] In some embodiments, the material of the mask includes thermosetting organic ink.

[0006] In some embodiments, the curing temperature of the thermosetting organic ink is less than 250°C.

[0007] In some embodiments, the carbonization temperature of the thermosetting organic ink is less than 750°C.

[0008] In some embodiments, the thermosetting organic ink includes at least one of epoxy resin, polyurethane and acrylic resin.

[0009] In some embodiments, the width of the Poly-finger region is 10 μm-130 μm.

[0010] In some embodiments, the width of the second region is 5 μm-40 μm.

[0011] In some embodiments, the mask is prepared by the following method: using thermosetting organic ink as the mask material, using a mask screen, aligning the openings with the circumferential printing of the Poly-finger area, and drying to widen the Poly-finger area and form a first area and a second area on one side of the Poly-finger area away from the battery blue film.

[0012] In some embodiments, a surface electrode is prepared in the second area, and the mask is removed to obtain a Poly-finger structure battery, including: using a screen printing screen, aligning the opening to the second area, printing the surface electrode slurry, sintering to solidify the surface electrode slurry, and carbonizing and removing the mask to obtain a Poly-finger structure battery.

[0013] In some embodiments, the opening of the screen printing screen has a diameter smaller than the width of the second region.

[0014] In some embodiments, the opening of the screen printing screen has a diameter of 2 μm-30 μm.

[0015] In some embodiments, the sintering temperature is greater than 750°C.

[0016] In some embodiments, the battery blue film is prepared by the following method:

[0017] A poly-Si layer is prepared on the back side of the silicon substrate and is doped with boron to form a P-poly-Si layer and a BSG layer;

[0018] A velvet surface is prepared on the front side of the silicon substrate, and a tunnel oxide layer and a poly-Si layer are deposited, and phosphorus is doped to form an N-poly-Si layer and a PSG layer;

[0019] Using laser film opening to remove the PSG layer in the non-finger area on the front side of the silicon substrate;

[0020] Removing the N-poly-Si layer in the non-finger area on the front side of the silicon substrate, and performing texturing on the non-finger area, so that the front side of the silicon substrate has a Poly-finger area and a non-finger area;

[0021] Removing the remaining PSG layer and BSG layer;

[0022] Sequentially preparing an aluminum oxide layer and an anti-reflection layer on the front side of the silicon substrate;

[0023] A passivation layer is prepared on the back side of the silicon substrate to obtain a battery blue film.

[0024] In a second aspect of the present application, the present application provides a photovoltaic module, comprising at least one cell string, wherein the cell string comprises at least two aforementioned Poly-finger structure cells.

[0025] In a third aspect of the present application, the present application proposes a photovoltaic system, comprising the aforementioned photovoltaic component. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0027] Figure 1 A structural diagram of a Poly-finger structure battery according to an embodiment of the present application;

[0028] Figure 2 A flow chart of a method for preparing a Poly-finger structure battery according to an embodiment of the present application;

[0029] Figure 3 This is a structural diagram of the battery blue film according to an embodiment of the present application.

[0030] Description of reference numerals:

[0031] 1 is silicon substrate, 2 is non-finger area, 3 is Poly-finger area, 4 is mask, 5 is surface electrode, 6 is mask screen, 7 is screen printing screen;

[0032] 01 is an N-type silicon wafer, 11 is a silicon oxide layer, 12 is an N-poly-Si layer, 13 is an aluminum oxide layer, 14 is a silicon nitride layer, 21 is a silicon oxide layer, 22 is a P-poly-Si layer, and 23 is a silicon nitride layer. DETAILED DESCRIPTION

[0033] The embodiments of the present application are described in detail below. Examples of the embodiments are shown in the drawings, but unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of actually identical structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0034] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field to which this application belongs; the terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application; unless otherwise specified, the numerical values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the embodiments of this application).

[0035] The terms "including" and "having" in the specification and claims of the present application and any modifications thereof are open expressions, that is, including the contents specified in the present application but not excluding other contents.

[0036] In the description of the present application, it should be understood that the terms "width", "thickness", etc. indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0037] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. "First feature" and "second feature" may include one or more of the features.

[0038] In the description of the present application, “plurality” means two or more.

[0039] In the description of the present application, "A and / or B" may include the case of A alone, the case of B alone, or any of the cases of A and B, where A and B are only used for examples and may be any technical feature connected by "and / or" in the present application.

[0040] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0041] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0042] In order to continuously improve the efficiency of batteries, the Poly-finger structure of passivated contacts in the metallized area is gradually being adopted by the industry. In theory, the narrower the Poly-finger area structure, the finer the metal grid lines (i.e., surface electrodes) can match, which can further reduce the problems of shading and parasitic light absorption, and can better improve the efficiency of the battery cell. However, in practice, it has been found that the narrower the width of the Poly-finger area, the closer it is to the deformation at the opening of the screen during printing, and the easier it is for the slurry to hit the edge of the step and then fall into the non-grid line area (non-finger area) near the Poly-finger area, resulting in a sharp increase in metal recombination and a significant decrease in the electrical performance of the battery cell, especially the open circuit voltage.

[0043] How to improve the slurry falling problem while keeping the width of the Poly-finger area narrow? Although electroplating or steel screen printing can avoid or alleviate screen printing deformation to a certain extent, the electroplated grid lines are easy to fall off and the steel mesh screen has a short service life, which cannot meet actual production needs.

[0044] In the present application, a mask is first prepared in the circumferential direction of the Poly-finger area to widen the Poly-finger area. The subsequent surface electrode slurry will only contact the second area not covered by the mask, thereby effectively solving the problem of the surface electrode slurry hitting the edge of the step and falling into the non-grid line area. By adding a simple method of mask preparation, the current process conditions can effectively solve the problem that under the condition of a narrow width of the Poly-finger area, the surface electrode slurry is easy to fall into the non-grid line area during printing, resulting in a decrease in the electrical performance of the battery cell. On the one hand, the Poly-finger structure design has practical value, and on the other hand, it matches the actual production conditions very well.

[0045] In the first aspect of the present application, the present application proposes a method for preparing a Poly-finger structure battery, referring to Figure 1 , the method comprising:

[0046] Process step ①: providing a battery blue film, wherein at least one side of the battery blue film comprises a Poly-finger area 3 and a non-finger area 2, and the Poly-finger area 3 protrudes from the battery blue film.

[0047] In some embodiments, the battery blue film is prepared by the following method:

[0048] A poly-Si layer is prepared on the back side of the silicon substrate 1 and is doped with boron to form a P-poly-Si layer and a BSG layer;

[0049] A velvet surface is prepared on the front side of the silicon substrate 1 and a tunnel oxide layer and a poly-Si layer are deposited, and phosphorus is doped to form an N-poly-Si layer and a PSG layer;

[0050] Using laser film opening to remove the PSG layer in the front non-finger area 2 of the silicon substrate 1;

[0051] The N-poly-Si layer of the non-finger area 2 on the front side of the silicon substrate 1 is removed, and the non-finger area 2 is textured, so that the front side of the silicon substrate 1 has a Poly-finger area 3 and a non-finger area 2;

[0052] Removing the remaining PSG layer and BSG layer;

[0053] An aluminum oxide layer and an anti-reflection layer are sequentially prepared on the front side of the silicon substrate 1;

[0054] A passivation layer is prepared on the back side of the silicon substrate 1 to obtain a battery blue film.

[0055] The structure of the battery blue film prepared by the above method is as follows Figure 3 As shown. The obtained battery blue film, wherein 01 is an N-type silicon wafer, 11 is a silicon oxide layer, 12 is an N-poly-Si layer, 13 is an aluminum oxide layer, 14 is an anti-reflection layer silicon nitride layer, 21 is a silicon oxide layer, 22 is a P-poly-Si layer, and 23 is a passivation layer silicon nitride layer. The N-poly-Si layer 12, the aluminum oxide layer 13 and the silicon nitride layer 14 form a Poly-finger region, and the Poly-finger structure is adopted to optimize the passivation and contact characteristics of the battery, and achieve high efficiency and high fill factor.

[0056] Process step ②: Prepare a mask 4 in the circumferential direction of the Poly-finger area 3 to widen the Poly-finger area 3 and form a first area partially covered by the mask 4 and a second area not covered by the mask 4 on the side of the Poly-finger area 3 away from the battery blue film.

[0057] Specifically, in this step, a mask 4 is prepared in the circumferential direction of the Poly-finger area 3 to widen the Poly-finger area 3 so that the overall width of the Poly-finger area 3 is greater than the deformation at the opening of the silk screen, thereby providing good support for the screen. Subsequently, the slurry of the surface electrode 5 will only contact the second area not covered by the mask 4, thereby effectively solving the problem of the slurry of the surface electrode 5 hitting the edge of the step and falling into the non-gate line area.

[0058] In some embodiments, the material of the mask 4 includes thermosetting organic ink. Thermosetting organic ink refers to an organic ink that can be cured under heating conditions. When heated, the thermal initiator contained in the thermosetting organic ink decomposes to generate free radicals, and the resin undergoes a cross-linking reaction under the action of the free radicals and solidifies, thereby forming a solidified film on the surface of the substrate. The use of thermosetting organic ink as the raw material of the mask 4 is convenient for curing to achieve the widening of the Poly-finger area 3. In addition, after the slurry of the surface electrode 5 is prepared, when heated and cured, the thermosetting organic ink is carbonized and removed under heating conditions, so that the surface electrode 5 forms a good ohmic contact with the Poly-finger area 3, and there is no need to set an additional step to remove the mask 4, which can well match the actual production conditions.

[0059] In some embodiments, the curing temperature of the thermosetting organic ink is less than 250° C. For example, the curing temperature of the thermosetting organic ink can be 70° C., 100° C., 150° C., 200° C., 249° C., etc. The curing temperature of the thermosetting organic ink is controlled within the above range to facilitate curing to form the mask 4 layer, thereby widening the Poly-finger area 3, thereby effectively solving the problem that the slurry of the surface electrode 5 hits the step edge and falls into the non-gridline area (non-finger area 2), thereby improving the performance of the Poly-finger structure battery.

[0060] In some embodiments, the carbonization temperature of the thermosetting organic ink is less than 750° C. For example, it can be 250° C., 300° C., 400° C., 500° C., 600° C., 700° C., 749° C., etc. The carbonization temperature of the thermosetting organic ink is controlled within the above range. After the slurry of the surface electrode 5 is prepared, during heating and curing, the thermosetting organic ink is carbonized and removed under heating conditions, so that the surface electrode 5 forms a good ohmic contact with the Poly-finger area 3, and there is no need to set an additional step to remove the mask 4, which can well match the actual production conditions and improve the performance of the Poly-finger structure battery.

[0061] In some embodiments, the thermosetting organic ink includes at least one of epoxy resin, polyurethane and acrylic resin. The above substances are used as the raw materials of the mask 4, which is convenient for curing to achieve the widening of the Poly-finger area 3. In addition, after the slurry of the surface electrode 5 is prepared, during heating and curing, the thermosetting organic ink is carbonized and removed under heating conditions, so that the surface electrode 5 forms a good ohmic contact with the Poly-finger area 3, and there is no need to set an additional step to remove the mask 4, which can well match the actual production conditions.

[0062] In some embodiments, the width of the Poly-finger region 3 is 10 μm-130 μm. For example, the width of the Poly-finger region 3 can be 10 μm, 30 μm, 50 μm, 70 μm, 100 μm, 130 μm, etc. It can be understood that the width of the Poly-finger region 3 is as follows: Figure 2 As shown in (a), it is the width of the mask 4 before widening. The width of the Poly-finger area 3 is controlled within the above range. The Poly-finger area 3 is narrower and matches the finer metal grid line (ie, the surface electrode 5), which can reduce the shading and parasitic light absorption problems and better improve the efficiency of the battery cell.

[0063] In some embodiments, the width of the second region is 5 μm-40 μm. For example, the width of the second region can be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, etc. By controlling the width of the second region within the above range, a narrower surface electrode 5 can be prepared in the second region later, which can further reduce the shading problem and better improve the efficiency of the battery cell.

[0064] In some embodiments, see Figure 1 , the mask 4 is prepared by the following method:

[0065] Thermosetting organic ink is used as the mask 4 material, and a mask stencil 6 is used, with the opening aligned with the circumferential printing of the Poly-finger area 3, and then dried to widen the Poly-finger area 3 and form a first area and a second area on the side of the Poly-finger area 3 away from the battery blue film.

[0066] Specifically, a mask screen 6 with a specific opening position is made according to the Poly-finger pattern, and thermosetting organic ink is used as the mask 4 material for circumferential printing of the Poly-finger area 3. The film is then passed through a drying furnace to solidify the thermosetting organic ink, thereby widening the Poly-finger area 3.

[0067] Process steps ③ and ④: prepare a surface electrode 5 in the second area, remove the mask 4, and obtain a Poly-finger structure battery.

[0068] Specifically, the preparation of the surface electrode 5 and the removal of the mask 4 are carried out by the following method:

[0069] See also Figure 1 In process steps ③ and ④, a screen printing screen 7 is used with the opening aligned with the second area to print the slurry of the surface electrode 5, and sintering is performed to solidify the slurry of the surface electrode 5, and the mask 4 is carbonized and removed to obtain a Poly-finger structure battery.

[0070] The opening of the screen printing screen 7 is positioned opposite to the Poly-finger area 3 (i.e., the second area) in the middle of the Poly-finger area 3 that is not covered by the mask 4, and then the slurry of the surface electrode 5 is printed; after the screen printing is completed, the mask 4 formed by the thermosetting organic ink is removed by high-temperature carbonization in the slurry sintering step, and at the same time, the formed surface electrode 5 and the Poly-finger area 3 form a good ohmic contact to obtain a complete battery cell.

[0071] In some embodiments, the opening of the screen printing screen 7 has a diameter smaller than the width of the second region. In this way, the slurry of the printed surface electrode 5 is not easy to cover the mask 4, and the slurry of the surface electrode 5 is not easy to hit the edge of the step and then fall on the non-gridline area (non-finger area 2) near the Poly-finger, ensuring that the battery cell has excellent performance.

[0072] In some embodiments, the opening of the screen printing screen 7 has a diameter of 2 μm-30 μm. For example, the opening of the screen printing screen 7 may have a diameter of 2 μm, 4 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, etc. Figure 1 As shown in (b), controlling the opening diameter of the screen printing screen 7 within the above range is conducive to preparing a finer surface electrode 5, which can further reduce the shading problem and better improve the efficiency of the battery cell.

[0073] In some embodiments, the sintering temperature is greater than 750° C. For example, the sintering temperature may be 750° C., 760° C., 770° C., 780° C., 790° C., 800° C., 810° C., 820° C., 830° C., 840° C., 850° C. Controlling the sintering temperature within the above range is conducive to high-temperature carbonization to remove the mask 4 formed by the thermosetting organic ink, while allowing the formed surface electrode 5 to form a good ohmic contact with the Poly-finger region 3, thereby obtaining a complete battery cell.

[0074] In summary, the preparation method of the Poly-finger structure battery proposed in the present application first prepares a mask 4 in the circumferential direction of the Poly-finger area 3 to widen the Poly-finger area 3, and the subsequent slurry of the surface electrode 5 will only contact the second area not covered by the mask 4, thereby effectively solving the problem that the slurry of the surface electrode 5 hits the edge of the step and falls into the non-grid line area. By adding a simple method of mask 4 preparation, the current process conditions can effectively solve the problem that under the condition that the width of the Poly-finger area 3 is narrow, the slurry of the surface electrode 5 is easy to fall into the non-grid line area during printing, resulting in a decrease in the electrical performance of the battery cell. On the one hand, the Poly-finger structure design has practical value, and on the other hand, it matches the actual production conditions very well, and the prepared Poly-finger structure battery has high efficiency.

[0075] The Poly-finger structure battery prepared in this application is as follows Figure 2 As shown, under the condition that the width of the Poly-finger area 3 is relatively narrow, the slurry of the surface electrode 5 is not easy to fall into the non-grid area during printing, thereby improving the battery performance. On the one hand, the Poly-finger structure design has practical value, and on the other hand, it is well matched to the actual production conditions, and the prepared Poly-finger structure battery has high efficiency.

[0076] In a second aspect of the present application, the present application proposes a photovoltaic module, comprising at least one battery string, wherein the battery string comprises at least two Poly-finger structure batteries prepared by the method described in the first aspect.

[0077] In some embodiments, the back-contact solar cells may be connected together by serial welding, so that the electrical energy generated by the individual back-contact solar cells can be collected for subsequent transmission.

[0078] In some embodiments, the back contact solar cells may be arranged in an alternate manner or stacked in a shingled manner.

[0079] For example, the photovoltaic module further includes an encapsulation layer and a cover plate, wherein the encapsulation layer is used to cover the surface of the battery string, and the cover plate is used to cover the surface of the encapsulation layer away from the battery string.

[0080] In a third aspect of the present application, the present application provides a photovoltaic system, comprising the aforementioned photovoltaic component.

[0081] Photovoltaic systems can be used in photovoltaic power stations, such as ground power stations, rooftop power stations, water power stations, etc., and can also be used in equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it is understandable that the application scenarios of photovoltaic systems are not limited to this, that is to say, photovoltaic systems can be used in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple photovoltaic components. For example, multiple photovoltaic components can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid, and then connected to the mains network to realize solar power supply.

[0082] The scheme of the present application is described below by specific examples. It should be noted that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If no specific technology or conditions are specified in the examples, the technology or conditions described in the literature in this area or the product instructions are used. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be obtained commercially.

[0083] Example 1

[0084] Step A: Clean and polish the N-type silicon wafer to form a flat surface.

[0085] Step B: depositing a poly-Si layer on the back side of the silicon substrate and performing boron doping, and sequentially forming a silicon oxide layer, a P-poly-Si layer and a BSG layer away from the silicon substrate.

[0086] Step C: remove the front wrap plating, use a chain cleaning machine to remove the front BSG layer, use a mixed solution of KOH and additives to remove the front P-poly-Si layer, and use HF solution to remove the front silicon oxide layer.

[0087] Step D: Prepare a pyramid velvet surface on the front side using a mixed solution of KOH and additives.

[0088] Step E: depositing a poly-Si layer on the front surface, followed by phosphorus doping, and sequentially forming a silicon oxide layer, an N-poly-Si layer and a PSG layer away from the front surface.

[0089] Step F: Remove the back-side wrap-around plating, use a chain cleaning machine to remove the back PSG layer, use a mixed solution of KOH and additives to remove the back N-poly-Si layer, and use HF solution to remove the back silicon oxide layer.

[0090] Step G: Use laser film opening to remove the PSG layer in the non-finger area on the front side.

[0091] Step H: Use a mixed solution of KOH and additives to remove the N-poly-Si layer and silicon oxide layer in the non-finger area on the front side, and further etch the substrate to remove the inner expansion layer formed by phosphorus doping, and then use a mixed solution of KOH and additives to texturize the non-finger area. After this step, the front side of the cell has a Poly-finger structure, there is a height difference between the Poly-finger area and the non-Poly-finger area, and the surface of the cell forms undulating micro-steps; the width of a single Poly-finger area is 40μm.

[0092] Step I: Clean and remove residual PSG and BSG.

[0093] Step J: Front ALD deposition of aluminum oxide layer.

[0094] Step K: depositing a silicon nitride anti-reflection layer by PECVD on the front side.

[0095] Step L: Deposition of silicon nitride passivation layer by PECVD on the back side. After this step, a blue film of the battery is obtained.

[0096] Step M: The back side of the blue film is metallized to form a back electrode.

[0097] Step N: The front side of the blue film is metallized to form a front electrode 5 .

[0098] Specifically, Figure 1 As shown, the detailed steps of the blue film front metallization process are as follows:

[0099] Process step ①: Battery blue film with Poly-finger structure;

[0100] Process step ②: Use the mask screen 6 to print the mask layer 4, and the mask screen opening position is as follows: Figure 1 As shown in the process step ②, a thermosetting organic ink (epoxy resin, purchased from Nantong Synasia New Materials Co., Ltd., Syna Epoxy S-100) is used as a mask material to align the Poly-finger area for circumferential printing, and then the film passes through a drying oven to cure the ink to achieve a widening of the Poly-finger area to 130 μm; wherein the curing temperature of the thermosetting organic ink is 200°C;

[0101] Process step ③: Make the opening position of the screen printing screen face the Poly-finger area (second area) not covered by the mask in the middle of the Poly-finger area, and then print the slurry; wherein the width of the Poly-finger area (second area) not covered by the mask is 20 μm, and the opening size of the screen printing screen is 8 μm;

[0102] Process step ④: After screen printing is completed, high-temperature carbonization is used to remove the organic mask in the slurry sintering step. The sintering temperature is 750°C. At the same time, a good ohmic contact is formed between the slurry and the Poly-finger area to obtain a complete battery cell.

[0103] Examples 2-10 and Comparative Example 1 are the same as Example 1, except that the specific parameters are different, see Table 1. The polyurethane in Example 2 was purchased from Ube Industries, UW-1005D-C1, the acrylic resin in Example 3 was purchased from Nengda Chemical Co., Ltd., AC1061, in Example 5, the Poly-finger area in process step ② was widened to 140 μm, and after the blue film of the battery was obtained in Comparative Example 1, the slurry was directly screen-printed with a silk screen in step M, and then the battery was obtained by high-temperature sintering.

[0104] Table 1

[0105]

[0106] In accordance with IEC 60904 and 61853 standards, the open circuit voltage Voc, short circuit current density Jsc, fill factor FF (Fill Factor), and energy conversion efficiency Eff (Efficiency) of the above-mentioned Poly-finger structure battery were tested. The test results are shown in Table 2.

[0107] Table 2

[0108] Eff(%) Voc(mV) <![CDATA[Jsc(mA / cm 2 )]]> FF(%) Example 1 25.07 736 40.89 83.3 Example 2 25.08 735 40.86 83.5 Example 3 25.05 737 40.90 83.1 Example 4 25.43 735 41.32 83.7 Example 5 24.72 737 40.55 82.7 Example 6 25.11 736 40.95 83.3 Example 7 25.06 736 40.88 83.3 Example 8 25.01 737 40.76 83.3 Example 9 25.06 736 40.89 83.3 Example 10 25.07 736 40.88 83.3 Comparative Example 1 20.18 694 37.60 77.09

[0109] As can be seen from Table 2, in Examples 1-10 of the present application, a mask is first prepared in the circumferential direction of the Poly-finger area to widen the Poly-finger area, and the subsequent surface electrode slurry will only contact the second area not covered by the mask, thereby effectively solving the problem of the printed slurry hitting the edge of the step and falling into the non-grid area, and the obtained Poly-finger structure battery has a higher efficiency. Comparative Example 1 does not pre-widen the Poly-finger area, and the efficiency and open-circuit voltage of the battery are significantly reduced. It can be seen that the Poly-finger structure battery prepared by the method described in this application has significantly improved efficiency and open-circuit voltage.

[0110] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing a Poly-finger structure battery, characterized in that: include: A battery blue film is provided, wherein at least one side of the battery blue film comprises a Poly-finger area and a non-finger area, and the Poly-finger area protrudes from the battery blue film; A mask is prepared in the circumferential direction of the Poly-finger region to widen the Poly-finger region and form a first region partially covered by the mask and a second region not covered by the mask on a side of the Poly-finger region away from the battery blue film; A surface electrode is prepared in the second region, and the mask is removed to obtain a Poly-finger structure battery.

2. The method according to claim 1, characterized in that The material of the mask includes thermosetting organic ink.

3. The method according to claim 2, characterized in that The curing temperature of the thermosetting organic ink is less than 250° C.; and / or, The carbonization temperature of the thermosetting organic ink is less than 750° C.; and / or, The thermosetting organic ink includes at least one of epoxy resin, polyurethane and acrylic resin.

4. The method according to any one of claims 1 to 3, characterized in that The width of the Poly-finger region is 10 μm-130 μm; and / or, The width of the second region is 5 μm-40 μm.

5. The method according to any one of claims 1 to 3, characterized in that: The mask is prepared by the following method: Thermosetting organic ink is used as a mask material, a mask screen is used, and the opening is aligned with the circumferential printing of the Poly-finger area, and then dried to widen the Poly-finger area and form a first area and a second area on a side of the Poly-finger area away from the battery blue film.

6. The method according to any one of claims 1 to 3, characterized in that A surface electrode is prepared in the second region, and the mask is removed to obtain a Poly-finger structure battery, comprising: A screen printing screen is used, the opening is aligned with the second area, the slurry of the surface electrode is printed, sintering is performed to solidify the slurry of the surface electrode, and the mask is carbonized and removed to obtain a Poly-finger structure battery.

7. The method according to claim 6, characterized in that The opening of the screen printing screen has a diameter smaller than the width of the second area; and / or, The opening of the screen printing screen has a diameter of 2 μm-30 μm; and / or, The sintering temperature is greater than 750°C.

8. The method according to any one of claims 1 to 3, characterized in that The battery blue film is prepared by the following method: A poly-Si layer is prepared on the back side of the silicon substrate and is doped with boron to form a P-poly-Si layer and a BSG layer; A velvet surface is prepared on the front side of the silicon substrate, and a tunnel oxide layer and a poly-Si layer are deposited, and phosphorus is doped to form an N-poly-Si layer and a PSG layer; Using laser film opening to remove the PSG layer in the non-finger area on the front side of the silicon substrate; Removing the N-poly-Si layer in the non-finger area on the front side of the silicon substrate, and texturing the non-finger area, so that the front side of the silicon substrate has a Poly-finger area and a non-finger area; Removing the remaining PSG layer and BSG layer; Sequentially preparing an aluminum oxide layer and an anti-reflection layer on the front side of the silicon substrate; A passivation layer is prepared on the back side of the silicon substrate to obtain a battery blue film.

9. A photovoltaic module, characterized in that: The invention comprises at least one battery string, wherein the battery string comprises at least two Poly-finger structure batteries prepared by the method according to any one of claims 1 to 8.

10. A photovoltaic system, characterized in that: The photovoltaic module according to claim 9 is included.

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