Back contact battery and preparation method thereof

Abstract

The invention discloses a back contact cell and a preparation method thereof, and is applied to the field of photovoltaic cells. In the first direction, the back surface of the back contact battery comprises first areas and second areas which are alternately distributed, in the second direction, the first areas are provided with first type structures and second type structures which are stacked from inside to outside, and first isolation protection layers are distributed between the first type structures and the second type structures; the second area is provided with a second type structure; a first isolation protection layer is distributed on the side wall of the second type structure between the first region and the second region; in the first region, the second type structure is provided with an isolation groove; a notch of the isolation groove faces one side far away from the battery substrate; the first electrode is arranged in the first area, the second electrode is arranged in the second area, and the isolation groove is located between the first electrode and the second electrode. By arranging the first isolation protection layer and the isolation groove, effective isolation between the first type structure and the second type structure is realized, and the photoelectric conversion efficiency of the back contact cell is improved.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic cells, and in particular to a back contact cell and its preparation method. Background Technology

[0002] Photovoltaic solar cells are devices that convert sunlight into electrical energy. When both the positive and negative electrodes of a solar cell are located on the back side of the cell, it is called a BC cell (BC cell is a back-contact cell). Because there is no metal electrode obstructing the front side of the BC cell, it has a higher conversion efficiency and is one of the current technological directions for achieving high-efficiency crystalline silicon cells.

[0003] However, existing BC batteries rely on the GAP area on the back for P and N separation. But because the GAP area is textured and its depth is difficult to control, the BC battery has poor isolation effect and unstable leakage current.

[0004] Therefore, how to provide a structure that can effectively isolate BC batteries is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a back contact battery and its preparation method, which solves the problems of poor isolation effect and unstable leakage current in the prior art BC battery.

[0006] To solve the above-mentioned technical problems, the present invention provides a back contact battery including a battery substrate;

[0007] In a first direction, the back side of the back contact battery includes an alternately distributed first region and a second region. In a second direction, the first region is provided with a stacked first type structure and a second type structure from the inside to the outside, and a first isolation protective layer is distributed between the first type structure and the second type structure; the second region is provided with the second type structure.

[0008] The first isolation and protective layer is distributed on the sidewall of the second type structure between the first region and the second region;

[0009] The first type of structure includes a first dielectric layer and a first type of polycrystalline silicon layer formed from the inside to the outside on the back surface of the battery substrate, and the second type of structure includes a second dielectric layer and a second type of polycrystalline silicon layer formed from the inside to the outside away from the back surface of the battery substrate.

[0010] In the first region, the second type of structure is provided with an isolation groove; the opening of the isolation groove faces away from the battery substrate;

[0011] A first electrode is provided in the first region and a second electrode is provided in the second region, with an isolation trench located between the first electrode and the second electrode; the first electrode is in contact with a first-type polysilicon layer, and the second electrode is in contact with a second-type polysilicon layer; the first-type polysilicon layer and the second-type polysilicon layer have opposite electrical properties; the first direction is perpendicular to the second direction.

[0012] Optionally, it further includes: a second isolation protective layer; the second isolation protective layer is located on the surface of the second type structure opposite to the battery substrate; and / or, the second isolation protective layer is located on the front surface of the battery substrate;

[0013] The second isolation protection layer includes a passivation layer and an anti-reflection layer stacked in the direction away from the battery substrate.

[0014] Optionally, in the first region, the first isolation protective layer is provided with an opening, through which the second type structure contacts the first type structure.

[0015] Optionally, the width of the opening is 200 micrometers to 500 micrometers.

[0016] Optionally, the width of the isolation groove ranges from 30 micrometers to 150 micrometers.

[0017] Optionally, the front surface of the battery substrate has a textured surface; and / or, the portion of the back surface of the battery substrate corresponding to the second region has a textured surface.

[0018] This application also provides a method for preparing a back contact battery, including:

[0019] A battery substrate is provided, and a first type structure is fabricated on the back surface of the battery substrate; the first type structure includes a first dielectric layer and a first type polycrystalline silicon layer stacked from the inside to the outside along the back surface of the battery substrate; the back surface of the battery substrate includes a first region and a second region alternately distributed in a first direction;

[0020] Remove the first type structure and part of the battery substrate located in the second region;

[0021] A first isolation protective layer and a second type structure are grown on one side of the back surface of the battery substrate; the second type structure includes a second dielectric layer and a second type polysilicon layer stacked from the inside to the outside away from the back surface of the battery substrate; the first type polysilicon layer and the second type polysilicon layer have opposite electrical properties;

[0022] An isolation groove is formed in the portion of the second type structure corresponding to the first region; the opening of the isolation groove faces away from the battery substrate;

[0023] A first electrode is fabricated in the first region and a second electrode is fabricated in the second region, with the isolation trench located between the first electrode and the second electrode; the first electrode is in contact with the first type of polysilicon layer and the second electrode is in contact with the second type of polysilicon layer.

[0024] Optionally, after fabricating the isolation groove in the portion of the second type structure corresponding to the first region, it further includes:

[0025] A second isolation protective layer is grown on the surface of the second type structure opposite to the battery substrate; and / or, an isolation protective layer is grown on the front surface of the battery substrate.

[0026] Optionally, the first insulating protective layer and the second type of structure grown on one side of the back surface of the battery substrate include:

[0027] A first insulating protective layer is grown on one side of the back surface of the battery substrate;

[0028] In the first region, a portion of the first protective layer is removed to form an opening;

[0029] The second type structure is grown on one side of the back surface of the battery substrate, and the second type structure contacts the first type structure through the opening.

[0030] Optionally, after removing the first-type structure and part of the battery substrate located in the second region, the method further includes:

[0031] The front surface of the battery substrate is texturized to form a textured structure; and / or,

[0032] The back surface of the battery substrate is partially texturized in the area corresponding to the second region to form a texturized structure.

[0033] The back side of the back contact battery provided by this invention includes alternating first and second regions. The first region has a stacked first type structure, a second type structure, and a first electrode, while the second region has a second type structure and a second electrode. A first insulating protective layer is distributed between the stacked first and second type structures, and on the sidewalls of the second type structure between the first and second regions, to isolate the first and second type structures. Furthermore, in the first region, the second type structure has an isolation groove that separates the second type structure in the first and second regions, preventing short circuits between them. Therefore, this application effectively and completely isolates the first and second type structures through the first insulating protective layer and the isolation groove, improving the isolation effect between the first and second type structures and thus enhancing the photoelectric conversion efficiency of the back contact battery.

[0034] In addition, the present invention also provides a method for preparing a back contact battery, which also has the above-mentioned beneficial effects. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of a back contact battery provided in an embodiment of the present invention;

[0037] Figure 2 A flowchart of a back contact battery fabrication method provided in an embodiment of the present invention;

[0038] Figures 3 to 10 This is a flowchart of a back contact battery manufacturing process provided in an embodiment of the present invention.

[0039] The annotations in the attached figures are explained as follows:

[0040] 1. Battery substrate; 2. Type I structure; 21. First dielectric layer; 22. Type I polycrystalline silicon layer; 3. Type II structure; 31. Second dielectric layer; 32. Type II polycrystalline silicon layer; 4. First isolation protection layer; 5. First electrode; 6. Second electrode; 7. Second isolation protection layer; 71. Passivation layer; 72. Anti-reflection layer; 8. BSG layer; 9. PSG layer; 10. Opening; 11. Isolation trench. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a back contact battery provided in an embodiment of the present invention. The back contact battery may include a battery substrate 1;

[0043] In the first direction, the back side of the back contact battery includes an alternately distributed first region S1 and second region S2. In the second direction, the first region S1 is provided with a stacked first type structure 2 and second type structure 3 from the inside to the outside, and a first isolation protective layer 4 is distributed between the first type structure 2 and the second type structure 3; the second region is provided with the second type structure 3.

[0044] The first isolation and protection layer 4 is distributed on the sidewall of the second type structure 3 between the first region S1 and the second region S2;

[0045] The first type structure 2 includes a first dielectric layer 21 and a first type polycrystalline silicon layer 22 formed from the inside to the outside on the back surface of the battery substrate 1, and the second type structure 3 includes a second dielectric layer 31 and a second type polycrystalline silicon layer 32 formed from the inside to the outside away from the back surface of the battery substrate 1.

[0046] In the first region S1, the second type structure 3 is provided with an isolation groove 11; the opening of the isolation groove 11 faces away from the battery substrate 1.

[0047] A first electrode 5 is provided in the first region S1 and a second electrode 6 is provided in the second region S2, and the isolation trench 11 is located between the first electrode 5 and the second electrode 6; the first electrode 5 is in contact with the first type polysilicon layer 22, and the second electrode 6 is in contact with the second type polysilicon layer 32; the first type polysilicon layer 22 and the second type polysilicon layer 32 have opposite electrical properties; the first direction is perpendicular to the second direction.

[0048] The first direction is the X direction, and the second direction is the Y direction. The first direction X and the second direction Y are perpendicular to each other.

[0049] The battery substrate 1 can be N-type monocrystalline silicon with a resistivity ranging from 2 Ω·cm to 20 Ω·cm and a thickness ranging from 150 ± 10 μm. The first dielectric layer 21 and the second dielectric layer 31 can be silicon oxide layers. The thickness of the first dielectric layer 21 can range from 0.1 nm to 5 nm, and the thickness of the second dielectric layer 31 can range from 0.1 nm to 5 nm.

[0050] Of the first region S1 and the second region S2, one is an N-type region on the back of the battery, and the other is a P-type region. Correspondingly, of the first type polycrystalline silicon layer 22 and the second type polycrystalline silicon layer 32, one is an N-type polycrystalline silicon layer, and the other is a P-type polycrystalline silicon layer.

[0051] For example, when the first region S1 is a P-type region and the second region S2 is an N-type region, the first type polysilicon layer 22 is a P-type polysilicon layer and the second type polysilicon layer 32 is an N-type polysilicon layer.

[0052] The function of the first isolation protective layer 4 is to isolate the first type structure 2 and the second type structure 3. The material of the first isolation protective layer 4 can be silicon oxynitride, etc.

[0053] The first isolation and protection layer 4 is distributed between the stacked first type structure 2 and the second type structure 3, as well as on the side wall of the second type structure 3, to completely isolate the first type structure 2 and the second type structure 3.

[0054] The function of the isolation groove 11 is to isolate the second type structure 3 in the first region S1 and the second region S2.

[0055] It should be noted that the width of the isolation groove 11 in the first direction is not limited in this application, but depends on the specific circumstances.

[0056] As one possible implementation, the width of the isolation groove 11 ranges from 30 micrometers to 150 micrometers, ensuring the isolation effect while ensuring that the first type structure 2 in the first region S1 has sufficient width, thereby ensuring contact with the first electrode 5.

[0057] In one embodiment of this application, in the first region S1, the first isolation protective layer 4 is provided with an opening 10, and the second type structure 3 contacts the first type structure 2 through the opening 10.

[0058] In this embodiment, by providing an opening 10, the first electrode 5 is made to contact the first type of polysilicon layer 22 in the first region.

[0059] It should be noted that the width of the opening 10 in the first direction X is not limited in this application, but depends on the specific circumstances.

[0060] As one possible implementation, the width of the opening 10 is 200 micrometers to 500 micrometers to facilitate the fabrication of the first electrode 5.

[0061] The back side of the back contact battery provided in this embodiment includes an alternately distributed first region S1 and second region S2. The first region S1 is provided with a stacked first type structure 2, a second type structure 3, and a first electrode 5. The second region is provided with a second type structure 3 and a second electrode 6. A first isolation protective layer 4 is distributed between the stacked first type structure 2 and second type structure 3, and on the sidewalls of the second type structure 3 between the first region S1 and the second region S2, to isolate the first type structure 2 and the second type structure 3. Furthermore, in the first region S1, the second type structure 3 is provided with an isolation groove 11, which can isolate the second type structure 3 in the first region S1 and the second region S2, preventing short circuits between the first region S1 and the second region S2. Therefore, in this application, the first isolation protective layer 4 and the isolation groove 11 effectively and completely isolate the first type structure 2 and the second type structure 3, improving the isolation effect between the first type structure 2 and the second type structure 3, thereby improving the photoelectric conversion efficiency of the back contact battery.

[0062] Based on the above embodiments, in one embodiment of this application, the back contact battery may further include: a second isolation protection layer 7; the second isolation protection layer 7 is located on the surface of the second type structure 3 away from the battery substrate 1; and / or, the second isolation protection layer 7 is located on the front surface of the battery substrate 1; the second isolation protection layer 7 includes a passivation layer 71 and an anti-reflection layer 72 stacked in the direction away from the battery substrate 1.

[0063] The second isolation layer 7 can be configured in three ways: first, the second isolation layer 7 is located on the surface of the second type structure 3 away from the battery substrate 1; second, the second isolation layer 7 is located on the front surface of the battery substrate 1; and third, the second isolation layer 7 is located on the surface of the second type structure 3 away from the battery substrate 1 and on the front surface of the battery substrate 1.

[0064] The passivation layer 71 can reduce the recombination rate of charge carriers on the back surface of the battery, and the antireflection layer 72 can significantly reduce the reflection loss of incident light on the battery surface, allowing more light to enter the battery and improving the battery conversion efficiency.

[0065] The thickness of the passivation layer 71 can range from 1 nm to 10 nm, and the passivation layer 71 can be an aluminum oxide layer; the thickness of the passivation layer 71 can range from 50 nm to 150 nm, and the anti-reflection layer 72 can be a silicon nitride layer.

[0066] By providing a second protective layer 7 on the back and / or front surface of the battery, not only can the battery be protected, but the absorption of light by the battery can also be improved, thereby improving the photoelectric conversion efficiency of the battery.

[0067] Based on any of the above embodiments, in one embodiment of this application, the front surface of the battery substrate 1 has a textured structure; and / or, the back surface of the battery substrate 1 corresponding to the second region S2 has a textured structure.

[0068] This embodiment includes three cases: First, the back surface of the battery substrate 1 corresponding to the second region S2 has a textured structure, while the front surface of the battery substrate 1 does not have a textured structure; Second, the back surface of the battery substrate 1 corresponding to the second region S2 does not have a textured structure, while the front surface of the battery substrate 1 has a textured structure; Third, the back surface of the battery substrate 1 corresponding to the second region S2 has a textured structure, and the front surface of the battery substrate 1 also has a textured structure.

[0069] The textured surface can give the surface of the battery substrate 1 a light-trapping effect, which can significantly reduce the reflectivity of the surface of the battery substrate 1 and improve the light absorption effect.

[0070] This application also provides a method for preparing a back contact battery; please refer to [reference needed]. Figure 2 The method may include:

[0071] Step S101: Provide a battery substrate and fabricate a first type structure on the back surface of the battery substrate; the first type structure includes a first dielectric layer and a first type polycrystalline silicon layer stacked from the inside to the outside along the back surface of the battery substrate; the back surface of the battery substrate includes a first region and a second region alternately distributed in a first direction.

[0072] It should be noted that before preparing the first type of structure, the battery substrate needs to be pre-cleaned to remove the damaged layer on the surface of the battery substrate.

[0073] In one embodiment of this application, before fabricating the first type structure on the back surface of the battery substrate, the process may further include: cleaning the battery substrate to remove the damaged layer of the battery substrate.

[0074] The cleaning process involves placing the battery substrate in an alkaline solution of 5% to 20% NaOH or KOH, with polishing additives added, and removing the damaged layer at a temperature of 50℃ to 100℃.

[0075] Removing the damaged layer can improve the quality of the battery substrate, thereby improving the efficiency of the back contact battery.

[0076] The deposition method of the first dielectric layer is not limited in this application and can be selected by the applicant. For example, the first dielectric layer can be deposited using LPCVD (low pressure chemical vapor deposition) or PECVD (plasma enhanced chemical vapor deposition), etc.

[0077] The fabrication process of the first type of polycrystalline silicon layer includes: depositing an intrinsic polycrystalline silicon (i-poly-Si) layer with a thickness of 10 nm to 1000 nm on the surface of the first dielectric layer. The deposition method of the intrinsic polycrystalline silicon layer can be LPCVD or PECVD, etc., and then performing boron doping, with a doping concentration of 1E18 atoms / cm3 to 1E22 atoms / cm3, to obtain the first type of polycrystalline silicon layer.

[0078] Understandably, when boron doping occurs, a BSG (borosilicate glass) layer will also be formed on the back side.

[0079] Step S102: Remove the first type structure and part of the battery substrate located in the second region.

[0080] A first laser can be used to remove the first-type structure and part of the battery substrate on the back side. The first laser includes, but is not limited to, any one of nanosecond green light, nanosecond ultraviolet light, picosecond green light, picosecond ultraviolet light, femtosecond green light, and femtosecond ultraviolet light. The spot diameter of the first laser is 100μm to 300μm, and the removal width of the BSG layer can be 200μm to 800μm. Then, the back side is polished to a depth of 2μm to 5μm.

[0081] Step S103: A first isolation protective layer and a second type structure are grown on one side of the back surface of the battery substrate; the second type structure includes a second dielectric layer and a second type polysilicon layer stacked from the inside to the outside away from the back surface of the battery substrate; the first type polysilicon layer and the second type polysilicon layer have opposite electrical properties.

[0082] As one possible implementation, growing a first insulating protective layer and a second type of structure on one side of the back surface of the battery substrate includes:

[0083] Step S1031: A first isolation protective layer is grown on one side of the back surface of the battery substrate.

[0084] The first protective layer can be grown by PECVD or other methods, which are not limited in this application, and its thickness can be 3nm-30nm.

[0085] Step S1032: In the first region, remove part of the first isolation protective layer to form an opening.

[0086] It should be noted that when an opening is formed in the first isolation protective layer of the first region, the first isolation protective layer of the second region is simultaneously etched to expose the battery substrate.

[0087] This step can use a second laser to etch the first isolation protective layer, forming a first opening in the first isolation protective layer in the first region. The second laser includes, but is not limited to, any one of picosecond green light, picosecond ultraviolet light, femtosecond green light, and femtosecond ultraviolet light. The spot diameter of the second laser can be 100μm~300μm, and the removal width (i.e., the opening width) of the first isolation protective layer in the first region can be 200μm~500μm.

[0088] Step S1033: The second type structure is grown on one side of the back surface of the battery substrate, and the second type structure contacts the first type structure through the opening.

[0089] The deposition method of the second dielectric layer is not limited in this application and can be selected by the applicant. For example, the second dielectric layer can be deposited using LPCVD or PECVD.

[0090] The fabrication process of the second type of polycrystalline silicon layer includes: depositing an intrinsic polycrystalline silicon (i-poly-Si) layer with a thickness of 10nm~1000nm on one side of the back side of the battery substrate. The intrinsic polycrystalline silicon layer can be deposited by LPCVD or PECVD, etc., and then doping with P element, the doping concentration can be 1E18 atoms / cm3~1E22 atoms / cm3, to obtain the second type of polycrystalline silicon layer.

[0091] Understandably, when performing P doping, a PSG (phosphosilicate glass) layer will also be formed on the back side.

[0092] Step S104: An isolation groove is formed in the portion of the second type structure corresponding to the first region; the opening of the isolation groove faces away from the battery substrate.

[0093] This step can use a third laser to etch the portion of the second-type structure corresponding to the first region to form an isolation trench. The third laser includes, but is not limited to, any one of picosecond green light, picosecond ultraviolet light, femtosecond green light, and femtosecond ultraviolet light, with a spot diameter of 30μm~150μm.

[0094] The remaining PSG layer was removed using an alkaline solution, exposing the type II polysilicon layer.

[0095] Step S105: A first electrode is fabricated in the first region and a second electrode is fabricated in the second region, with the isolation trench located between the first electrode and the second electrode; the first electrode is in contact with the first type of polysilicon layer and the second electrode is in contact with the second type of polysilicon layer.

[0096] Each polarity burn-through paste is printed in the first region and the second region respectively, and sintered and solidified to form an ohmic contact, thus obtaining the first electrode and the second electrode.

[0097] The back side of the back contact battery fabricated in this embodiment includes alternating first and second regions. The first region has a stacked first-type structure, a second-type structure, and a first electrode, while the second region has a second-type structure and a second electrode. A first insulating protective layer is distributed between the stacked first-type and second-type structures, and on the sidewalls of the second-type structure between the first and second regions, to isolate the first-type and second-type structures. Furthermore, in the first region, the second-type structure has an isolation groove that separates the second-type structure in the first and second regions, preventing short circuits between them. Therefore, in this application, the first insulating protective layer and the isolation groove effectively and completely isolate the first-type and second-type structures, improving the isolation effect between them and thus enhancing the photoelectric conversion efficiency of the back contact battery.

[0098] Based on the above embodiments, in one embodiment of this application, after the isolation groove is fabricated in the portion of the second type structure corresponding to the first region, it may further include: growing a second isolation protective layer on the surface of the second type structure away from the battery substrate; and / or growing an isolation protective layer on the front surface of the battery substrate.

[0099] By growing an isolation protective layer, not only can the battery be protected, but the battery's absorption of light can also be improved, thereby increasing the battery's photoelectric conversion efficiency.

[0100] The second protective isolation layer includes a passivation layer and an antireflection layer. The passivation layer can be grown by PECVD, ALD (atomic layer deposition), or PEALD (plasma enhanced atomic layer deposition), etc., and is not specifically limited in this application. The antireflection layer can be grown by PECVD, ALD, or PEALD, etc., and is not specifically limited in this application.

[0101] The passivation layer can reduce the recombination rate of charge carriers on the back surface of the battery, and the antireflection layer can significantly reduce the reflection loss of incident light on the battery surface, allowing more light to enter the battery and improving the battery conversion efficiency.

[0102] Based on any of the above embodiments, in one embodiment of this application, after removing the first type structure located in the second region and part of the battery substrate, it may further include: texturing the front surface of the battery substrate to form a textured structure; and / or, texturing a portion of the back surface of the battery substrate corresponding to the second region to form a textured structure.

[0103] By utilizing the different corrosion rates of alkaline solutions on silicon surfaces, a tank-type texturing machine can be used to texturize the front and / or back of the battery substrate to form a textured surface structure.

[0104] In this embodiment, by creating a textured surface on the battery substrate, the reflectivity of the battery substrate surface can be significantly reduced, thereby improving the light absorption effect.

[0105] Based on any of the above embodiments, in one embodiment of this application, the back contact battery preparation method includes:

[0106] Step 1, as follows Figure 3 As shown, an N-type monocrystalline silicon wafer is selected as the battery substrate 1. The battery substrate 1 is pre-cleaned using an alkaline solution with added polishing additives to remove the damaged layer on the surface of the battery substrate 1.

[0107] Step 2: Sequentially deposit a first silicon oxide layer and a first intrinsic polysilicon layer on the back surface of the battery substrate 1, with the first silicon oxide layer serving as the first dielectric layer 21;

[0108] Step 3, as follows Figure 4 As shown, the first intrinsic polysilicon layer is doped with B to form a first type doped polysilicon layer. The first type doped polysilicon layer and the first dielectric layer 21 form the first type structure 2. At the same time, a BSG layer 8 is formed on the surface of the first type doped polysilicon layer.

[0109] Step 4, as follows Figure 5 As shown, the BSG layer 8 of the second region S2 is removed, and then the first type structure 2 and part of the battery substrate 1 of the second region S2 are removed by the first laser, and the back side is polished.

[0110] Step 5, as follows Figure 6 As shown, a first isolation protective layer 4 is grown on one side of the back surface of the battery substrate 1 using PECVD.

[0111] Step 6, as follows Figure 7 As shown, the first isolation protective layer 4 of the first region S1 is etched by the second laser to form an opening 10 in the isolation layer 4, and the first isolation protective layer 4 of the second region S2 is etched. Then, the positive surface of the battery substrate 1 and part of the second region S2 are texturized by the alkaline solution to form a textured surface structure.

[0112] Step 7, as follows Figure 8As shown, a second silicon oxide layer and a second intrinsic polysilicon layer are deposited by LPCVD, with the second silicon oxide layer serving as the second dielectric layer 31; then, the second intrinsic polysilicon layer is P-doped to form a second type polysilicon layer 32. The second type doped polysilicon layer and the second dielectric layer 31 serve as the second type structure 3, while a PSG layer 9 is formed on the surface of the second type doped polysilicon layer.

[0113] Step 8, as follows Figure 9 As shown, the PSG layer 9 is removed, and the width of the removal is the same as the width of the isolation trench 11. The second type structure 3 of the first region S1 is etched using a third laser to form the isolation trench 11 in the second type structure 3. Then, the remaining PSG layer is removed using an alkaline solution to expose the second type polysilicon layer 32.

[0114] Step 9, as follows Figure 10 As shown, a passivation layer 71 is deposited on the front surface of the battery substrate 1 and the surface of the second type structure 3 opposite to the battery substrate 1 using ALD, and an antireflection layer 72 is deposited on the surface of the passivation layer 71 using PECVD.

[0115] Step 10, as follows Figure 1 As shown, polarity burn-through pastes are printed in the first region S1 and the second region S2 respectively, and sintered and solidified to form ohmic contacts, thus obtaining the first electrode 5 and the second electrode 6.

[0116] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0117] Furthermore, it should be noted that in this document, relationships such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0118] The foregoing has provided a detailed description of a back contact battery and its preparation method. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A back-contact battery, characterized in that, Including the battery substrate; In a first direction, the back side of the back contact battery includes an alternately distributed first region and a second region. In a second direction, the first region is provided with a stacked first type structure and a second type structure from the inside out, and a first isolation protective layer is distributed between the first type structure and the second type structure; the second region is provided with the second type structure. The first isolation and protective layer is distributed on the sidewall of the second type structure between the first region and the second region; The first type of structure includes a first dielectric layer and a first type of polycrystalline silicon layer formed from the inside to the outside on the back surface of the battery substrate, and the second type of structure includes a second dielectric layer and a second type of polycrystalline silicon layer formed from the inside to the outside away from the back surface of the battery substrate. In the first region, the second type of structure is provided with an isolation groove; the opening of the isolation groove faces away from the battery substrate; A first electrode is provided in the first region and a second electrode is provided in the second region, and an isolation trench is located between the first electrode and the second electrode; the first electrode is in contact with the first type of polysilicon layer, and the second electrode is in contact with the second type of polysilicon layer; the first type of polysilicon layer and the second type of polysilicon layer have opposite electrical properties; the first direction is perpendicular to the second direction.

2. The back contact battery according to claim 1, characterized in that, Also includes: A second isolation protective layer; the second isolation protective layer is located on the surface of the second type structure opposite to the battery substrate; And / or, the second protective layer is located on the front surface of the battery substrate; The second isolation protection layer includes a passivation layer and an anti-reflection layer stacked in the direction away from the battery substrate.

3. The back contact battery according to claim 1, characterized in that, In the first region, the first isolation protective layer is provided with an opening, through which the second type structure contacts the first type structure.

4. The back contact battery according to claim 3, characterized in that, The width of the opening is 200 micrometers to 500 micrometers.

5. The back contact battery according to claim 1, characterized in that, The width of the isolation groove ranges from 30 micrometers to 150 micrometers.

6. The back contact battery according to claim 1, characterized in that, The front surface of the battery substrate has a textured surface; and / or, the portion of the back surface of the battery substrate corresponding to the second region has a textured surface.

7. A method for preparing a back contact battery, characterized in that, include: A battery substrate is provided, and a first type structure is fabricated on the back surface of the battery substrate; the first type structure includes a first dielectric layer and a first type polycrystalline silicon layer stacked from the inside to the outside along the back surface of the battery substrate; the back surface of the battery substrate includes a first region and a second region alternately distributed in a first direction; Remove the first type structure and part of the battery substrate located in the second region; A first isolation protective layer and a second type structure are grown on one side of the back surface of the battery substrate; the second type structure includes a second dielectric layer and a second type polysilicon layer stacked from the inside to the outside away from the back surface of the battery substrate; the first type polysilicon layer and the second type polysilicon layer have opposite electrical properties; An isolation groove is formed in the portion of the second type structure corresponding to the first region; the opening of the isolation groove faces away from the battery substrate; A first electrode is fabricated in the first region and a second electrode is fabricated in the second region, with the isolation trench located between the first electrode and the second electrode; the first electrode is in contact with the first type of polysilicon layer and the second electrode is in contact with the second type of polysilicon layer.

8. The method for preparing a back contact battery according to claim 7, characterized in that, After fabricating the isolation groove in the portion of the second type structure corresponding to the first region, it further includes: A second isolation protective layer is grown on the surface of the second type structure opposite to the battery substrate; and / or, an isolation protective layer is grown on the front surface of the battery substrate.

9. The method for preparing a back contact battery according to claim 7, characterized in that, The first insulating protective layer and the second type structure grown on one side of the back surface of the battery substrate include: A first insulating protective layer is grown on one side of the back surface of the battery substrate; In the first region, a portion of the first protective layer is removed to form an opening; The second type structure is grown on one side of the back surface of the battery substrate, and the second type structure contacts the first type structure through the opening.

10. The method for preparing a back contact battery according to claim 7, characterized in that, After removing the first-type structure and part of the battery substrate located in the second region, the method further includes: The front surface of the battery substrate is texturized to form a textured structure; and / or, The back surface of the battery substrate is partially texturized in the area corresponding to the second region to form a texturized structure.

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