Back contact solar cell, preparation method thereof and photovoltaic module

Abstract

The invention relates to the technical field of batteries, in particular to a back contact solar battery, a preparation method thereof and a photovoltaic module. The method comprises the following steps: providing a silicon substrate, wherein the silicon substrate is provided with a first surface and a second surface which are opposite to each other; sequentially preparing a passivation layer and an antireflection layer on the first surface; a tunneling oxide layer and a first intrinsic layer are sequentially prepared on the second surface, local grooving is carried out on the second surface, the non-grooved area is a first area, and the grooved area is a second area; preparing a second intrinsic layer and a second doped layer in the second region in sequence; preparing transparent conductive film layers in the first area and the second area; printing ink is arranged on the surface of the transparent conductive film layer; removing the transparent conductive film layer at the junction of the first region and the second region, and forming an isolation region between the first region and the second region; removing the printing ink; and preparing a silver electrode on the surface of the transparent conductive film layer. According to the invention, the ink coverage area is reduced, the plate sticking risk is reduced, and the battery conversion efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a back-contact solar cell and a preparation method thereof, and a photovoltaic module. Background Art

[0002] BC cells (Back Contact) are a type of back-contact solar cell technology. Their key feature is the placement of both the PN junction and metal contacts on the back of the cell, leaving the front of the cell unobstructed by electrodes. This increases the area available for the cell to absorb sunlight, thereby improving conversion efficiency and generating more power. They are expected to become the mainstream of crystalline silicon cells. However, the BC cell manufacturing process presents issues such as sticking to the substrate, which require further improvement. Therefore, the development of a method for fabricating back-contact solar cells is urgently needed. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the present invention provides a back-contact solar cell and a method for preparing the same, and a photovoltaic module.

[0004] To this end, the first aspect of the present invention provides a method for preparing a back-contact solar cell, comprising the following steps: Providing a silicon substrate having a first surface and a second surface opposite to each other; sequentially preparing a passivation layer and an anti-reflection layer on the first surface; A tunneling oxide layer and a first intrinsic layer are sequentially formed on the second surface, the first intrinsic layer is doped to form a first doped layer, and a local groove is formed on the second surface, where the ungrooved area is the first area and the grooved area is the second area; a second intrinsic layer and a second doped layer are sequentially formed on the second area; a transparent conductive film layer is formed on the first area and the second area; ink is provided on the surface of the transparent conductive film layer; the transparent conductive film layer at the junction of the first area and the second area is removed to form an isolation area between the first area and the second area; and the ink is removed; preparing a silver electrode on the surface of the transparent conductive film layer; Based on the area of the transparent conductive film layer, the area of the ink is 50%-90%; In parts by mass, the ink includes 15-45 parts by mass of acrylic resin, 0-75 parts by mass of solvent and 0-5 parts by mass of filler.

[0005] The present invention provides a method for preparing a back-contact solar cell. During the preparation process, ink containing acrylic resin is used as a physical barrier to reduce the coverage area of the ink. This not only prevents the area where the ink is set from being too large, thereby affecting light reflection, but also reduces the risk of board sticking and ink consumption, thereby saving costs and shortening time. Ink residue will introduce impurities, and reducing the printing area of the ink can reduce pollution and improve the conversion efficiency of the battery.

[0006] In some embodiments of the present invention, the solvent includes one or more of ethylene glycol butyl ether, diethylene glycol monobutyl ether acetate, and propylene glycol diacetate. Ethylene glycol butyl ether has a moderate volatility, which can improve the printability of the ink and prevent skinning or poor leveling caused by excessive drying. Diethylene glycol monobutyl ether acetate has good compatibility with acrylic resins and can also improve leveling and wettability, reducing surface defects. Propylene glycol diacetate facilitates uniform coating and curing of the ink.

[0007] In some embodiments of the present invention, the mass ratio of ethylene glycol butyl ether, diethylene glycol monobutyl ether acetate, and propylene glycol diacetate is 1:(0.1-5):(0.1-5). Therefore, the simultaneous use of ethylene glycol butyl ether, diethylene glycol monobutyl ether acetate, and propylene glycol diacetate as a solvent system can produce a synergistic effect, improving the spreadability and adhesion of the ink on the surface of the transparent conductive film layer.

[0008] In some embodiments of the present invention, the filler includes one or more of silicon dioxide, calcium carbonate, talc, kaolin, and barium sulfate. The filler can reduce ink sedimentation during storage and improve the anti-sagging property of the ink during setting.

[0009] In some embodiments of the present invention, the ink includes, by weight, 30-45 parts of acrylic resin, 10-25 parts of ethylene glycol butyl ether, 10-25 parts of diethylene glycol monobutyl ether acetate, 10-25 parts of propylene glycol diacetate, and 3-5 parts of silicon dioxide. This can further improve the conversion efficiency of the battery.

[0010] In some embodiments of the present invention, the area of the ink is 70%-80% based on the area of the transparent conductive film layer, thereby further improving the conversion efficiency of the battery.

[0011] In some embodiments of the present invention, the thickness of the ink provided on the surface of the transparent conductive film layer is 5-10 μm. This controls the thickness of the ink, improves the uniformity of the ink on the transparent conductive film layer, allows the ink to fully wet the substrate, and forms a dense film layer after curing.

[0012] In some embodiments of the present invention, the doping element of the first doping layer includes phosphorus and / or arsenic, thereby forming an n+ type semiconductor by doping phosphorus (P) and / or arsenic (As) to collect photogenerated electrons (negative charges).

[0013] In some embodiments of the present invention, the doping element of the second doping layer includes boron, thereby forming a p+ type semiconductor by doping with boron (B) to collect photogenerated holes (positive charges).

[0014] A second aspect of the present invention provides a back-contact solar cell manufactured by the above-mentioned preparation method.

[0015] A third aspect of the present invention provides a photovoltaic module, comprising the back-contact solar cell produced by the above-mentioned preparation method, and / or the above-mentioned back-contact solar cell.

[0016] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which: Figure 1 A printed pattern of an ink according to an embodiment of the present invention is shown; Figure 2 A flow chart showing a printing ink according to one embodiment of the present invention.

[0018] Description of reference numerals: N region 1; P region 2; transparent conductive film layer 3; ink 4; isolation region 5. DETAILED DESCRIPTION

[0019] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0020] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more of such features. Furthermore, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0021] During the BC cell manufacturing process, the back surface needs to be patterned, with screen-printed ink used as a mask to protect the transparent conductive film layer in the P / N region. The ink at the PN junction is then removed using a wet process to form the PN region insulation groove. However, due to the large printing area, the printing process can easily cause board sticking, and ink consumption increases, increasing costs. Therefore, the present invention provides a method for preparing a back-contact solar cell. During the preparation process, ink containing acrylic resin is used as a physical barrier to reduce the ink coverage area. This not only avoids the impact of excessive ink coverage on light reflection, but also reduces the risk of board sticking and ink consumption, thereby saving costs and time. Ink residue can introduce impurities, and reducing the ink printing area can reduce the probability of contamination and improve the cell's conversion efficiency.

[0022] A first aspect of the present invention provides a method for preparing a back-contact solar cell, comprising the following steps: S100 , providing a silicon substrate, wherein the silicon substrate has a first surface and a second surface opposite to each other.

[0023] The present invention has no particular restrictions on the specific type and size (such as thickness, diameter, etc.) of the silicon substrate, which can be selected according to actual needs.

[0024] It is understood that the silicon substrate of the present invention may be a double-sided polished and clean silicon substrate obtained after double-sided cleaning and polishing, and removal of surface organic matter, metal impurities and surface damage layers.

[0025] The present invention does not specifically limit the process for cleaning the silicon substrate, and it can be any cleaning process, such as standard cleaning 1 or standard cleaning 2; wherein, standard cleaning 1 can include a mixture of ammonium hydroxide, hydrogen peroxide and water, and standard cleaning 2 can include a mixture of hydrochloric acid, hydrogen peroxide and water.

[0026] In some embodiments of the present invention, a double-sided polished, clean silicon substrate can be textured. Specifically, texture formation involves forming a microscopic velvet structure on the surface of the silicon substrate through chemical etching or physical methods. This structure increases the residence time of light on the silicon surface, reduces light reflection, and thus improves light absorption efficiency.

[0027] In some embodiments of the present invention, the texturing can be performed by chemically etching with an alkaline solution (such as sodium hydroxide or potassium hydroxide), utilizing the anisotropic etching characteristics of silicon in the alkaline solution to form a pyramid-shaped textured surface structure.

[0028] S200, sequentially preparing a passivation layer and an anti-reflection layer on the first surface; sequentially preparing a tunneling oxide layer and a first intrinsic layer on the second surface, doping the first intrinsic layer to form a first doped layer, and locally grooved the second surface, with the ungrooved area being the first area and the grooved area being the second area; sequentially preparing a second intrinsic layer and a second doped layer in the second area; preparing a transparent conductive film layer in the first area and the second area; arranging ink on the surface of the transparent conductive film layer; removing the transparent conductive film layer at the junction of the first area and the second area to form an isolation area between the first area and the second area; and then removing the ink; based on the area of the transparent conductive film layer, the area of the ink is 50%-90%; in parts by mass, the ink comprises 15-45 parts by mass of acrylic resin, 0-75 parts by mass of solvent, and 0-5 parts by mass of filler.

[0029] In some embodiments of the present invention, the passivation layer includes one or more of aluminum oxide, amorphous silicon, silicon nitride, silicon dioxide, hafnium oxide, tantalum oxide, and gallium oxide.

[0030] In some embodiments of the present invention, the passivation layer may be formed by plasma enhanced chemical vapor deposition (PECVD), hot filament chemical vapor deposition (HWCVD), or low pressure chemical vapor deposition (LPCVD).

[0031] In some embodiments of the present invention, the thickness of the passivation layer is 2-10 nm, for example, 2, 3, 4, 5, 6, 7, 8, 9 or 10 nm.

[0032] In some embodiments of the present invention, the antireflection layer comprises one or more of silicon nitride (SiNx), silicon oxynitride (SiOxNy), and silicon oxide (SiOx). The antireflection layer can be a combination of SiOx, SiNx, and SiOxNy layers, or a single layer. Those skilled in the art can flexibly select the appropriate layer based on specific needs. This effectively reduces light reflection, increases light transmittance, and improves the passivation effect.

[0033] In some embodiments of the present invention, the anti-reflection layer may be prepared by plasma enhanced chemical vapor deposition (PECVD), hot filament chemical vapor deposition (HWCVD), or low pressure chemical vapor deposition (LPCVD).

[0034] In some embodiments of the present invention, the thickness of the antireflection layer is 10-100 nm, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 nm, etc. By controlling the thickness of the antireflection layer, its reflectivity can be adjusted to achieve the desired antireflection effect.

[0035] In some embodiments of the present invention, the solvent includes one or more of ethylene glycol butyl ether, diethylene glycol monobutyl ether acetate, and propylene glycol diacetate. Ethylene glycol butyl ether has a moderate volatility, which can improve the printability of the ink and prevent skinning or poor leveling caused by excessive drying. Diethylene glycol monobutyl ether acetate has good compatibility with acrylic resins and can also improve leveling and wettability, reducing surface defects. Propylene glycol diacetate facilitates uniform coating and curing of the ink.

[0036] In some embodiments of the present invention, the mass ratio of ethylene glycol butyl ether, diethylene glycol monobutyl ether acetate, and propylene glycol diacetate is 1:(0.1-5):(0.1-5). Therefore, the simultaneous use of ethylene glycol butyl ether, diethylene glycol monobutyl ether acetate, and propylene glycol diacetate as a solvent system can produce a synergistic effect, improving the spreadability and adhesion of the ink on the surface of the transparent conductive film layer.

[0037] In some embodiments of the present invention, the filler includes one or more of silicon dioxide, calcium carbonate, talc, kaolin, and barium sulfate. The filler can reduce ink sedimentation during storage and improve the anti-sagging property of the ink during setting.

[0038] In some embodiments of the present invention, the ink includes, by weight, 30-45 parts of acrylic resin, 10-25 parts of ethylene glycol butyl ether, 10-25 parts of diethylene glycol monobutyl ether acetate, 10-25 parts of propylene glycol diacetate, and 3-5 parts of silicon dioxide. This can further improve the conversion efficiency of the battery.

[0039] In some embodiments of the present invention, as an example, based on the area of the transparent conductive film layer, the area of the ink can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%.

[0040] In some preferred embodiments of the present invention, the area of the ink is 70%-80% based on the area of the transparent conductive film layer, thereby further improving the conversion efficiency of the battery.

[0041] In some embodiments of the present invention, the ink is applied to the surface of the transparent conductive film layer to a thickness of 5-10 μm, for example, 5, 6, 7, 8, 9, or 10 μm. This allows the thickness of the ink to be controlled, improving its uniformity across the transparent conductive film layer and allowing the ink to fully wet the substrate, forming a dense film layer after curing.

[0042] In some embodiments of the present invention, the ink can be disposed on the surface of the transparent conductive film layer by screen printing, inkjet printing, laser transfer, photoresist-assisted deposition, electrophoretic deposition, atomic layer deposition, roll-to-roll coating, or laser sintering-assisted deposition.

[0043] In some preferred embodiments of the present invention, the screen printing solution is lower in cost than exposure and development; at the same time, it reduces the printing area and consumption, reduces the problem of plate sticking during the preparation process, and improves printing efficiency.

[0044] In some embodiments of the present invention, the ink is prepared by screen printing and specifically includes: inking; scraping; demoulding; and curing. Furthermore, the curing temperature is 80-200° C. and the curing time is 2-10 minutes.

[0045] In some embodiments of the present invention, the present invention has no special requirements for the printing pattern of the ink, and conventional printing patterns in the art can be used.

[0046] In some embodiments of the present invention, an acidic substance may be used to perform wet etching to form an isolation region. The isolation region is used to isolate the first region from the second region to reduce leakage caused by a short circuit.

[0047] In some embodiments of the present invention, the acidic substance includes one or more of perchloric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, hydrochloric acid, nitric acid, and iodic acid.

[0048] In some embodiments of the present invention, an alkaline substance may be used to remove the ink; the alkaline substance includes sodium hydroxide and / or potassium hydroxide.

[0049] In some embodiments of the present invention, the tunnel oxide layer may be formed by atmospheric pressure chemical vapor deposition (APCVD), radio frequency magnetron sputtering (PVD), or reactive plasma deposition (RPD).

[0050] In some embodiments of the present invention, the thickness of the tunnel oxide layer is 0.5-3 nm, for example, 0.5, 1, 1.5, 2, 2.5, 3 nm, etc. Thus, efficient carrier transport can be achieved, and carrier recombination can be suppressed to enhance the passivation effect.

[0051] In some embodiments of the present invention, the first intrinsic layer includes a polysilicon layer and can be formed by plasma enhanced chemical vapor deposition (PECVD), hot filament chemical vapor deposition (HWCVD), or low pressure chemical vapor deposition (LPCVD).

[0052] In some embodiments of the present invention, the thickness of the first intrinsic layer is 1-200 nm, for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 nm, etc.

[0053] In some embodiments of the present invention, the second intrinsic layer includes a microcrystalline silicon layer or an amorphous silicon layer, or a composite layer of one or more of the above. The second intrinsic layer can be formed using plasma-enhanced chemical vapor deposition (PECVD), hot-wire chemical vapor deposition (HWCVD), or low-pressure chemical vapor deposition (LPCVD).

[0054] In some embodiments of the present invention, the thickness of the second intrinsic layer is 1-100 nm, for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 nm, etc.

[0055] In some embodiments of the present invention, the doping element of the first doping layer includes phosphorus and / or arsenic, thereby forming an n+ type semiconductor by doping phosphorus (P) and / or arsenic (As) to collect photogenerated electrons.

[0056] In some embodiments of the present invention, the doping element of the second doping layer includes boron, thereby forming a p+ type semiconductor by doping with boron (B) to collect photogenerated holes.

[0057] In some embodiments of the present invention, the first doping layer or the second doping layer may be prepared by plasma enhanced chemical vapor deposition (PECVD), hot filament chemical vapor deposition (HWCVD), or low pressure chemical vapor deposition (LPCVD).

[0058] In some embodiments of the present invention, the thickness of the first doped layer is 1-200 nm, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 nm, etc. This can optimize carrier transport and collection, further improving the passivation effect.

[0059] In some embodiments of the present invention, the thickness of the second doped layer is 1-100 nm, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 nm, etc. This can optimize carrier transport and collection, further enhancing the passivation effect.

[0060] In some embodiments of the present invention, after preparing the first doping layer, a mask layer is prepared on the surface of the first doping layer, the second surface is locally grooved, and then the mask layer is removed. Subsequently, a second intrinsic layer and a second doping layer are sequentially prepared in the second area.

[0061] In some embodiments of the present invention, the material of the mask layer includes one or more of silicon nitride (SiNx), silicon oxynitride (SiOxNy), and silicon oxide (SiOx).

[0062] In some embodiments of the present invention, the mask layer may be prepared by plasma enhanced chemical vapor deposition (PECVD), hot filament chemical vapor deposition (HWCVD), or low pressure chemical vapor deposition (LPCVD).

[0063] In some embodiments of the present invention, the thickness of the mask layer is 10-100 nm, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 nm, etc.

[0064] In some embodiments of the present invention, the material of the transparent conductive film layer includes one or more of indium tin oxide (ITO), lanthanide metal-doped indium oxide, fluorine-doped tin oxide (FTO), antimony-doped tin oxide, boron-doped zinc oxide (BZO), aluminum zinc oxide (AZO), indium zinc oxide (IZO), gallium zinc oxide (GZO), and indium tungsten oxide (IWO).

[0065] In some embodiments of the present invention, the transparent conductive film layer may be prepared by atmospheric pressure chemical vapor deposition (APCVD), radio frequency magnetron sputtering (PVD) or reactive plasma deposition (RPD).

[0066] In some embodiments of the present invention, the thickness of the transparent conductive film layer is 50-150 nm. As an example, the thickness of the transparent conductive film layer is 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, or 150 nm.

[0067] S300 , preparing a silver electrode on the surface of the transparent conductive film layer.

[0068] In some embodiments of the present invention, silver electrodes may be prepared by electroplating, screen printing, or laser transfer of low-temperature silver paste.

[0069] In some embodiments of the present invention, a fine gate, an insulating layer and a main gate are sequentially prepared on the surface of the transparent conductive film layer.

[0070] In some embodiments of the present invention, the insulating layer is prepared by printing insulating ink; in parts by mass, the insulating ink includes 80-100 parts by mass of a main agent and 1-10 parts by mass of a curing agent; the main agent includes an epoxy resin and an auxiliary agent; the auxiliary agent includes dicyandiamide, dimethyl diacid, phthalocyanine green, barium sulfate, silica and dimethylpolysiloxane; the curing agent includes imidazole or its derivatives and talc.

[0071] A second aspect of the present invention provides a back-contact solar cell manufactured by the above-mentioned preparation method.

[0072] A third aspect of the present invention provides a photovoltaic module, comprising the back-contact solar cell produced by the above-mentioned preparation method, and / or the above-mentioned back-contact solar cell.

[0073] The scheme of the present disclosure will be explained below in conjunction with the examples. Those skilled in the art will understand that the following examples are only used to illustrate the present disclosure and should not be considered to limit the scope of the present disclosure. Where specific techniques or conditions are not specified in the examples, they are carried out according to the techniques or conditions described in the literature in this area or according to the product instructions. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially.

[0074] Example 1 The back contact solar cell of this embodiment is prepared by the method comprising the following steps: (1) Polishing and cleaning: Provide an N-type silicon wafer as a silicon substrate, use KOH solution to texture the silicon wafer to form a pyramid texture structure, and then use dilute HF to clean it to obtain a polished and cleaned N-type silicon wafer.

[0075] (2) Preparation of a tunneling oxide layer on the back side: A tunneling oxide layer is prepared on the back side of the silicon wafer obtained in step (1) by low pressure chemical vapor deposition (LPCVD). The thickness of the tunneling oxide layer is 2 nm.

[0076] (3) Preparation of an intrinsic polysilicon layer (i-poly-Si): An intrinsic polysilicon layer is prepared on the surface of the silicon wafer obtained in step (2) by low-pressure chemical vapor deposition (LPCVD). The thickness of the intrinsic polysilicon layer is 180 nm.

[0077] (4) Preparation of doped polysilicon layer: Place the deposited polysilicon (poly) layer in a tubular diffusion furnace, introduce a phosphorus source, and perform phosphorus doping at 880°C to complete the doping of poly silicon to form N-poly. Use wet etching (dilute HF) to remove the PSG layer generated in this step.

[0078] (5) Preparation of mask layer: A SiNx layer (20 nm) is deposited on the surface of the doped polysilicon layer of the silicon wafer obtained in step (4) by plasma enhanced chemical vapor deposition (PECVD) as a mask layer, and then a laser is used to perform local grooving to remove the tunneling oxide layer, the intrinsic amorphous silicon layer (10 nm) and the doped amorphous silicon layer (20 nm) on the local surface of the silicon wafer. The ungrooved area is the first area, and the area formed after the grooving is the second area. The width ratio of the second area to the first area is 1.5:1.

[0079] (6) Cleaning and texturing: Clean and texturize the silicon wafer obtained in step (5), and remove the mask layer on the surface of the silicon wafer.

[0080] (7) Using plasma enhanced chemical vapor deposition (PECVD), an amorphous silicon layer (5 nm thick) and a boron-doped amorphous silicon layer (10 nm thick) are sequentially deposited on the back of the silicon wafer obtained in step (6); an amorphous silicon passivation layer (5 nm thick) and a SiNx layer (80 nm thick) are sequentially deposited on the front, with the SiNx layer serving as an anti-reflection layer.

[0081] (8) The silicon wafer obtained in step (7) is laser-processed to remove the amorphous silicon layer and the boron-doped amorphous silicon layer in the first region, with the removal width being greater than 100 μm. The first region is the N region, and the second region is the P region.

[0082] (9) The silicon wafer obtained in step (8) is wet cleaned and then subjected to physical vapor deposition (PVD) coating to coat a transparent conductive film layer on the back with a thickness of 80 nm.

[0083] (10) Metal protective ink (hereinafter referred to as ink) is printed on the transparent conductive film layer by screen printing. First, the ink is evenly coated on the screen with a scraper angle of 60°. Then, the scraper is printed at a speed of 50 mm / s and a scraper pressure of 0.5 MPa. Then, the mold is demoulded and the screen is slowly lifted (at a speed of 1 mm / s). Finally, the printed pattern is dried and solidified. Figure 1 As shown, based on the area of the transparent conductive film layer, the printing area of the ink is 80%, and the thickness of the ink is 5 μm. Figure 1 In the figure, 1 is the N region; 2 is the P region; 3 is the transparent conductive film layer; 4 is the ink. Subsequently, it is cured and dried at 150°C for 5 minutes. Then, it passes through an acid tank to remove the transparent conductive film layer at the junction of the N region and the P region. Subsequently, it passes through an alkaline tank and uses a KOH solution to remove the ink. The preparation process is as follows. Figure 2 As shown, an isolation region 5 is finally formed; The ink comprises the following components: 45 parts by mass of acrylic resin, 10 parts by mass of ethylene glycol butyl ether, 10 parts by mass of diethylene glycol monobutyl ether acetate, 10 parts by mass of propylene glycol diacetate and 3 parts by mass of silicon dioxide.

[0084] (11) Wet-cleaning the silicon wafer obtained in step (10), screen-printing silver paste and curing to form a fine grid, applying insulating ink on the fine grid by screen printing, curing to form an insulating layer, and then screen-printing silver paste and curing to form a main grid; The insulating ink consists of 92 parts by mass of a main agent and 8 parts by mass of a curing agent. The main agent includes 85 parts by mass of epoxy resin and 10 parts by mass of auxiliary agents. The auxiliary agents include 1 part by mass of dicyandiamide, 2 parts by mass of dimethyl diacid, 2 parts by mass of phthalocyanine green, 2 parts by mass of barium sulfate, 2 parts by mass of silica and 1 part by mass of dimethyl polysiloxane. The curing agent includes 4 parts by mass of imidazole and 4 parts by mass of talc.

[0085] Example 2 This embodiment is carried out with reference to the steps in embodiment 1. The only difference from embodiment 1 is that in this embodiment, the printing area of the ink is 50% based on the area of the transparent conductive film layer.

[0086] Example 3 This embodiment is carried out with reference to the steps in embodiment 1. The only difference from embodiment 1 is that in this embodiment, the printing area of the ink is 90% based on the area of the transparent conductive film layer.

[0087] Comparative Example 1 This comparative example was carried out with reference to the steps in Example 1. The only difference from Example 1 was that in this comparative example, the printing area of the ink was 100% based on the area of the transparent conductive film layer.

[0088] Test Case The solar cells obtained in Examples 1-3 and Comparative Example 1 were subjected to IV tests. The IV tests were performed in accordance with the third edition of IEC 60904-9.2020. The test results are shown in Table 1. In Table 1, Eta refers to the photoelectric conversion efficiency of the cell, Voc refers to the open circuit voltage of the solar cell, Isc refers to the short circuit current, and FF refers to the fill factor.

[0089] Table 1

[0090] As can be seen from Table 1, compared with Example 1 (printing area 80%), Example 2 (printing area 50%) has insufficient metal protection ink in some areas, resulting in defective spots on the transparent conductive film layer, which causes a 3mV drop in open circuit voltage, a 0.19% drop in fill factor, and a 0.2% drop in photoelectric conversion efficiency. Compared with Example 1, there is no essential difference between Example 3 and Example 1, but Example 1 saves ink costs compared with Example 3. Compared with Example 1, Comparative Example 1 has an increased printing area, making it difficult to remove the metal protection ink and requiring a longer time, which has some impact on passivation. The subsequent metal protection ink is not completely removed, resulting in an increase in series resistance and a significant decrease in fill factor.

[0091] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", "some implementation plans" or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0092] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a back-contact solar cell, characterized in that: The following steps are involved: Providing a silicon substrate having a first surface and a second surface opposite to each other; sequentially preparing a passivation layer and an anti-reflection layer on the first surface; A tunneling oxide layer and a first intrinsic layer are sequentially formed on the second surface, the first intrinsic layer is doped to form a first doped layer, and the second surface is partially grooved, with the ungrooved area being the first area and the grooved area being the second area; a second intrinsic layer and a second doped layer are sequentially formed on the second area; and a transparent conductive film layer is formed on the first area and the second area. Disposing ink on the surface of the transparent conductive film layer; removing the transparent conductive film layer at the junction of the first region and the second region to form an isolation region between the first region and the second region; and then removing the ink; preparing a silver electrode on the surface of the transparent conductive film layer; Based on the area of the transparent conductive film layer, the area of the ink is 50%-90%; In parts by mass, the ink includes 15-45 parts by mass of acrylic resin, 0-75 parts by mass of solvent and 0-5 parts by mass of filler.

2. The method for preparing a back-contact solar cell according to claim 1, wherein: The solvent includes one or more of ethylene glycol butyl ether, diethylene glycol monobutyl ether acetate, and propylene glycol diacetate.

3. The method for preparing a back-contact solar cell according to claim 2, wherein: The mass ratio of the ethylene glycol butyl ether, the diethylene glycol monobutyl ether acetate and the propylene glycol diacetate is 1:(0.1-5):(0.1-5).

4. The method for preparing a back-contact solar cell according to claim 1, wherein: The filler includes one or more of silicon dioxide, calcium carbonate, talc, kaolin, and barium sulfate.

5. The method for preparing a back-contact solar cell according to claim 1, wherein: In parts by mass, the ink comprises 30-45 parts by mass of acrylic resin, 10-25 parts by mass of ethylene glycol butyl ether, 10-25 parts by mass of diethylene glycol monobutyl ether acetate, 10-25 parts by mass of propylene glycol diacetate and 3-5 parts by mass of silicon dioxide.

6. The method for preparing a back-contact solar cell according to claim 1, wherein: Based on the area of the transparent conductive film layer, the area of the ink is 70%-80%.

7. The method for preparing a back-contact solar cell according to claim 1, wherein: The thickness of the ink set on the surface of the transparent conductive film layer is 5-10 μm.

8. The method for preparing a back-contact solar cell according to claim 1, wherein: The doping element of the first doping layer includes phosphorus and / or arsenic; And / or, the doping element of the second doping layer includes boron.

9. A back-contact solar cell produced by the method for producing a back-contact solar cell according to any one of claims 1 to 8.

10. A photovoltaic module, characterized in that: A back-contact solar cell prepared by the preparation method according to any one of claims 1 to 8, and / or a back-contact solar cell according to claim 9.

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