Back contact battery and preparation method thereof

Abstract

The invention discloses a back contact cell and a preparation method, and is applied to the field of photovoltaic cells. In the first direction, the back surface of the cell substrate is provided with first areas and second areas which are alternately arranged, the first areas are provided with first type structures, and the second areas are provided with second type structures; in the second direction, a first type structure and a second type structure are partially stacked between the first region and the second region, and an isolation layer is arranged between the first type structure and the second type structure which are stacked; the first type structure comprises a first dielectric layer and a first type polycrystalline silicon layer, and the second type structure comprises a second dielectric layer and a second type polycrystalline silicon layer; the first region is provided with a first electrode which is in contact with the first type polycrystalline silicon layer, and the second region is provided with a second electrode which is in contact with the second type polycrystalline silicon layer. The first type structure and the second type structure are effectively isolated through the isolation layer, and the photoelectric conversion efficiency of the 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 problem that in the prior art, BC batteries use GAP areas to isolate P and N regions, but because the GAP area is a textured surface and its depth is difficult to control, the isolation effect of BC batteries is poor and there is unstable leakage current.

[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 surface of the battery substrate has alternating first and second regions, the first region being provided with a first type structure and the second region being provided with a second type structure; in a second direction, the first type structure and the second type structure are partially stacked between the first region and the second region, and an isolation layer is provided between the stacked first type structure and the second type structure.

[0008] 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 in a direction away from the back surface of the battery substrate.

[0009] The first region is provided with a first electrode, which is in contact with the first type of polycrystalline silicon layer; the second region is provided with a second electrode, which is in contact with the second type of polycrystalline silicon layer.

[0010] The first type of polysilicon layer has opposite electrical properties to the second type of polysilicon layer; the first direction is perpendicular to the second direction.

[0011] Optionally, the insulating layer has a first opening, and the second type structure has a second opening, wherein the projection of the first opening onto the battery substrate is within the projection range of the second opening onto the battery substrate, so that a portion of the first type structure is exposed.

[0012] Optionally, it further includes: an isolation protective layer located on the surface of the second type structure opposite to the battery substrate, and in the regions of the first opening and the second opening; and / or, the isolation protective layer located on the front surface of the battery substrate.

[0013] Optionally, the isolation protection layer includes a passivation layer and an antireflection layer stacked in the direction away from the battery substrate.

[0014] Optionally, the difference between the width of the first opening and the width of the second opening ranges from 20 micrometers to 200 micrometers.

[0015] Optionally, the portion of the back surface of the battery substrate corresponding to the second region has a textured surface, and / or the front surface of the battery substrate has a textured surface.

[0016] This application also provides a method for preparing a back contact battery, including:

[0017] 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 from the inside to the outside in a direction away from the battery substrate; the back surface of the battery substrate includes alternating first and second regions;

[0018] Remove the first-type structure and part of the battery substrate located in the second region;

[0019] An insulating layer is grown on one side of the back surface of the battery substrate;

[0020] The isolation layer is etched to form a second type structure, the second type structure including a second dielectric layer and a second type polysilicon layer from the inside out in the direction away from the battery substrate; the first type polysilicon layer and the second type polysilicon layer have opposite electrical properties;

[0021] A first electrode is grown in a first region and a second electrode is grown in a second region, wherein 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.

[0022] Optionally, the isolation layer has a first opening, the second type structure has a second opening, and after etching the isolation layer and forming the second type structure, the method further includes:

[0023] An isolation protective layer is grown on the surface of the second type structure opposite to the battery substrate, and in the regions of the first and second openings; and / or, an isolation protective layer is grown on the front surface of the battery substrate.

[0024] Optionally, growing an isolation protective layer on the surface of the second type structure opposite to the battery substrate, and in the regions of the first and second openings, includes:

[0025] A passivation layer is grown on the surface of the second type structure opposite to the battery substrate, and in the regions of the first and second openings;

[0026] An antireflection layer is grown on the surface of the passivation layer that is opposite to the battery substrate.

[0027] Optionally, before fabricating the first type structure on the back surface of the battery substrate, the method further includes: cleaning the battery substrate to remove the damaged layer of the battery substrate.

[0028] Optionally, after etching the isolation layer, the process further includes: 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.

[0029] The back-contact battery of this application includes a battery substrate with alternating first and second regions on its back surface. A first-type structure and a first electrode are disposed in the first region, and a second-type structure and a second electrode are disposed in the second region. The first-type structure and the second-type structure are stacked in the portion between the first and second regions, and an isolation layer is disposed between the stacked first-type structure and the second-type structure. The isolation layer can effectively isolate the first-type structure and the second-type structure, improving the isolation effect between the first-type structure and the second-type structure, thereby improving the photoelectric conversion efficiency of the back-contact battery.

[0030] 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

[0031] 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.

[0032] Figure 1This is a schematic diagram of the structure of a back contact battery provided in an embodiment of the present invention;

[0033] Figure 2 A flowchart of a back contact battery fabrication method provided in an embodiment of the present invention;

[0034] Figures 3 to 10 This is a flowchart of a back contact battery manufacturing process provided in an embodiment of the present invention.

[0035] The annotations in the attached figures are explained as follows:

[0036] 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. Separator layer; 5. First electrode; 6. Second electrode; 7. Separator layer; 71. Passivation layer; 72. Antireflection layer; 8. BSG layer; 9. PSG layer; 10. First opening; 11. Second opening. Detailed Implementation

[0037] 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.

[0038] Please refer to Figure 1 This application provides a back contact battery, which may include a battery substrate 1;

[0039] In a first direction, the back surface of the battery substrate 1 has an alternately arranged first region S1 and second region S2, the first region S1 is provided with a first type structure 2, and the second region S2 is provided with a second type structure 3; in a second direction, the first type structure 2 and the second type structure 3 are partially stacked between the first region S1 and the second region S2, and an isolation layer 4 is provided between the stacked first type structure 2 and the second type structure 3.

[0040] 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 in the direction away from the back surface of the battery substrate 1.

[0041] The first region S1 is provided with a first electrode 5, which is in contact with the first type of polysilicon layer 22; the second region S2 is provided with a second electrode 6, which is in contact with the second type of polysilicon layer 32.

[0042] The first type of polysilicon layer 22 and the second type of polysilicon layer 32 have opposite electrical properties; the first direction is perpendicular to the second direction.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] For example, when the first region S1 is an N-type region and the second region S2 is a P-type region, the first type polysilicon layer 22 is an N-type polysilicon layer and the second type polysilicon layer 32 is a P-type polysilicon layer.

[0047] The function of the isolation layer 4 is to isolate the first type structure 2 and the second type structure 3. The material of the isolation layer 4 can be silicon oxynitride, etc.

[0048] It should be noted that the first type structure 2 and the second type structure 3 also have an isolation layer 4 in the areas where they are opposite each other on the sides, so as to achieve better isolation between the first type structure 2 and the second type structure 3.

[0049] In one embodiment of this application, the insulating layer 4 has a first opening 10, and the second type structure 3 has a second opening 11. The projection of the first opening 10 onto the battery substrate 1 is located within the projection range of the second opening 11 onto the battery substrate 1, so that a portion of the first type structure 2 is exposed.

[0050] The width of the first opening 10 is smaller than the width of the second opening 11, which can expose the isolation layer 4 between the first type structure 2 and the second type structure 3, thereby ensuring that the first type structure 2 and the second type structure 3 are completely isolated by the isolation layer 4, and further ensuring the isolation effect between the first type structure 2 and the second type structure 3.

[0051] It should be noted that this application does not limit the difference between the width of the first opening 10 and the width of the second opening 11, but depends on the specific circumstances.

[0052] As one possible implementation, the difference between the width of the first opening 10 and the width of the second opening 11 can be between 20 micrometers and 200 micrometers. This ensures that the first type structure 2 and the second type structure 3 are isolated while avoiding excessive removal of the second type structure 3, thus ensuring the functionality of the second type structure 3 on the back of the battery substrate 1.

[0053] The back-contact battery of this embodiment includes a battery substrate 1. The back surface of the battery substrate 1 has alternately distributed first regions S1 and second regions S2. A first-type structure 2 and a first electrode 5 are disposed in the first region S1, and a second-type structure 3 and a second electrode 6 are disposed in the second region S2. The first-type structure 2 and the second-type structure 3 are stacked in the portion between the first region S1 and the second region S2, and an isolation layer 4 is disposed between the stacked first-type structure 2 and the second-type structure 3. The isolation layer 4 effectively isolates 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.

[0054] Based on the above embodiments, in one embodiment of this application, the back contact battery may further include: an isolation protection layer 7, the isolation protection layer 7 being located on the surface of the second type structure 3 away from the battery substrate 1, and in the areas of the first opening 10 and the second opening 11; and / or, the isolation protection layer 7 being located on the front surface of the battery substrate 1.

[0055] The isolation protection layer 7 can be configured in three ways: first, the isolation protection layer 7 is located on the surface of the second type structure 3 away from the battery substrate 1; second, the isolation protection layer 7 is located on the front surface of the battery substrate 1; and third, the isolation protection 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.

[0056] By setting an isolation protective layer 7 on the back and / or front of the battery, the battery can not only be protected, but also its light absorption can be improved, thereby improving the battery's photoelectric conversion efficiency.

[0057] As one possible implementation, the isolation protection layer 7 includes a passivation layer 71 and an antireflection layer 72 stacked in the direction away from the battery substrate 1.

[0058] 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.

[0059] 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.

[0060] Based on any of the above embodiments, in one embodiment of this application, the back surface of the battery substrate 1 corresponding to the second region S2 has a textured structure, and / or the front surface of the battery substrate 1 has a textured structure.

[0061] 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.

[0062] 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.

[0063] This application also provides a method for preparing a back contact battery; please refer to [reference needed]. Figure 2 The method may include:

[0064] 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 from the inside to the outside in a direction away from the battery substrate; the back surface of the battery substrate includes alternating first and second regions.

[0065] 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.

[0066] 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.

[0067] 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℃.

[0068] Removing the damaged layer can improve the quality of the battery substrate, thereby improving the efficiency of the back contact battery.

[0069] 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.

[0070] 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.

[0071] Understandably, when boron doping occurs, a BSG (borosilicate glass) layer will also be formed on the back side.

[0072] Step S102: Remove the first type structure and part of the battery substrate located in the second region.

[0073] The 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~300μm, and the removal width of the BSG layer can be 200μm~800μm. Then, the back side is polished to a depth of 2μm~5μm.

[0074] Step S103: An insulating layer is grown on one side of the back surface of the battery substrate.

[0075] The growth method of the isolation layer can be PECVD, etc., which is not limited in this application, and the thickness can be 3nm-30nm.

[0076] Step S104: Etch the isolation layer and form a second type structure, the second type structure including a second dielectric layer and a second type polysilicon layer from the inside to the outside in the direction away from the battery substrate.

[0077] The first type of polysilicon layer and the second type of polysilicon layer have opposite electrical properties. A second laser can be used to etch the isolation layer in the first region, forming a first opening in the isolation layer, and then etch the isolation layer in the second region. The second laser can be any one of picosecond green light, picosecond ultraviolet light, femtosecond green light, or femtosecond ultraviolet light. The spot diameter of the second laser can be 100μm to 300μm, and the removal width of the isolation layer in the first region (i.e., the width of the first opening) can be 200μm to 500μm.

[0078] 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.

[0079] 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.

[0080] Understandably, when performing P doping, a PSG (phosphosilicate glass) layer will also be formed on the back side.

[0081] After the second type of polysilicon layer is fabricated, the PSG layer and the second type of structure in the first region are etched using a third laser to form a second opening in the second type of structure. 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. The diameter of the third laser spot is 100μm to 300μm. The removal width of the second type of structure is 20μm to 200μm greater than the removal width of the isolation layer.

[0082] The remaining PSG layer was removed using an alkaline solution, exposing the type II polysilicon layer.

[0083] Step S105: A first electrode is grown in a first region and a second electrode is grown in a second region. 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.

[0084] 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.

[0085] The back-contact battery prepared in this embodiment includes a battery substrate with alternating first and second regions on its back surface. A first-type structure and a first electrode are disposed in the first region, and a second-type structure and a second electrode are disposed in the second region. The first-type structure and the second-type structure are stacked in the portion between the first and second regions, and an isolation layer is disposed between the stacked first-type structure and the second-type structure. The isolation layer effectively isolates the first-type structure and the second-type structure, improving the isolation effect between the first-type structure and the second-type structure, thereby improving the photoelectric conversion efficiency of the back-contact battery.

[0086] Based on the above embodiments, in one embodiment of this application, the isolation layer has a first opening and the second type structure has a second opening. After etching the isolation layer and forming the second type structure, the back contact battery fabrication method may further include: growing an isolation protective layer on the surface of the second type structure away from the battery substrate, and in the regions of the first and second openings; and / or growing an isolation protective layer on the front surface of the battery substrate.

[0087] 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.

[0088] This application does not impose any restrictions on the structure of the isolation and protective layer; it can be designed as desired.

[0089] As one possible implementation, growing an isolation protective layer on the surface of the second type structure away from the battery substrate, and in the regions of the first and second openings, includes: growing a passivation layer on the surface of the second type structure away from the battery substrate, and in the regions of the first and second openings; and growing an anti-reflection layer on the surface of the passivation layer away from the battery substrate.

[0090] As one possible implementation, growing an isolation and protective layer on the front surface of a battery substrate includes: growing a passivation layer on the front surface of the battery substrate; and growing an anti-reflection layer on the surface of the passivation layer opposite to the battery substrate.

[0091] The passivation layer can be grown using methods such as PECVD, ALD (atomic layer deposition), or PEALD (plasma enhanced atomic layer deposition), and no specific limitation is made in this application.

[0092] The antireflection layer can be grown by PECVD, ALD, or PEALD, etc., and no specific limitation is made in this application.

[0093] 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.

[0094] Based on any of the above embodiments, in one embodiment of this application, after etching the isolation layer, the process 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.

[0095] 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.

[0096] 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.

[0097] Based on any of the above embodiments, in one embodiment of this application, the back contact battery preparation method includes:

[0098] 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.

[0099] 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;

[0100] 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.

[0101] Step 4, as follows Figure 5 As shown, the BSG layer 8 of the second region S2 is removed, and the first type structure 2 and part of the battery substrate 1 of the second region S2 are removed using the first laser, and the back side is polished.

[0102] Step 5, as follows Figure 6 As shown, an isolation layer 4 is grown on one side of the back surface of the battery substrate 1 using PECVD.

[0103] Step 6, as follows Figure 7As shown, the isolation layer 4 of the first region S1 is etched by the second laser to form the first opening 10 in the isolation layer 4, and the isolation 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 structure.

[0104] Step 7, as follows Figure 8 As 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.

[0105] Step 8, as follows Figure 9 As shown, the PSG layer 9 is removed with a width equal to the width of the second opening. The second type structure 3 of the first region S1 is etched using a third laser to form the second opening 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] The foregoing has provided a detailed description of a back contact battery and a method for preparing a back contact battery. 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 surface of the battery substrate has alternating first and second regions, the first region being provided with a first type structure and the second region being provided with a second type structure; in a second direction, the first type structure and the second type structure are partially stacked between the first region and the second region, and an isolation layer is provided between the stacked first type structure and the second type structure. 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 in a direction away from the back surface of the battery substrate. The first region is provided with a first electrode, which is in contact with the first type of polycrystalline silicon layer; the second region is provided with a second electrode, which is in contact with the second type of polycrystalline silicon layer. The first type of polysilicon layer has opposite electrical properties to the second type of polysilicon layer; the first direction is perpendicular to the second direction.

2. The back contact battery according to claim 1, characterized in that, The insulating layer has a first opening, and the second type structure has a second opening. The projection of the first opening onto the battery substrate is located within the projection range of the second opening onto the battery substrate, so that a portion of the first type structure is exposed.

3. The back contact battery according to claim 2, characterized in that, Also includes: An isolation protective layer is located on the surface of the second type structure opposite to the battery substrate, and in the areas of the first opening and the second opening; And / or, the protective isolation layer is located on the front surface of the battery substrate.

4. The back contact battery according to claim 3, characterized in that, The isolation and protection layer includes a passivation layer and an anti-reflection layer stacked in the direction away from the battery substrate.

5. The back contact battery according to claim 2, characterized in that, The difference between the width of the first opening and the width of the second opening ranges from 20 micrometers to 200 micrometers.

6. The back contact battery according to any one of claims 1 to 5, characterized in that, The portion of the back surface of the battery substrate corresponding to the second region has a textured surface, and / or the front surface of the battery substrate 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 from the inside to the outside in a direction away from the battery substrate; the back surface of the battery substrate includes alternating first and second regions; Remove the first-type structure and part of the battery substrate located in the second region; An insulating layer is grown on one side of the back surface of the battery substrate; The isolation layer is etched to form a second type structure, the second type structure including a second dielectric layer and a second type polysilicon layer from the inside out in the direction away from the battery substrate; the first type polysilicon layer and the second type polysilicon layer have opposite electrical properties; A first electrode is grown in a first region and a second electrode is grown in a second region, wherein 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.

8. The method for preparing a back contact battery according to claim 7, characterized in that, The isolation layer has a first opening, the second type structure has a second opening, and after etching the isolation layer and forming the second type structure, the method further includes: An isolation protective layer is grown on the surface of the second type structure opposite to the battery substrate, and in the regions of the first and second openings; and / or, An isolation and protective layer is grown on the positive surface of the battery substrate.

9. The method for preparing a back contact battery according to claim 8, characterized in that, An isolation protective layer is grown on the surface of the second type structure opposite to the battery substrate, and in the regions of the first and second openings, comprising: A passivation layer is grown on the surface of the second type structure opposite to the battery substrate, and in the regions of the first and second openings; An antireflection layer is grown on the surface of the passivation layer that is opposite to the battery substrate.

10. The method for preparing a back contact battery according to claim 7, characterized in that, Before fabricating the first type structure on the back surface of the battery substrate, the method further includes: Clean the battery substrate to remove the damaged layer.

11. The method for preparing a back contact battery according to any one of claims 7 to 10, characterized in that, After etching the isolation layer, the process 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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