Back contact battery and preparation method thereof

Abstract

The present disclosure relates to the photovoltaic field and provides a back-contact cell and a method for preparing the same. The method comprises: providing a substrate, the substrate comprising a first surface and a second surface opposite each other; providing alternating first and second regions on the second surface, and a spacer region between the first and second regions; providing a first emitter on the first region, and providing a second emitter on the second region; the doping element in the first emitter and the doping element in the second emitter having different conductivity types, and the thickness of the first emitter being less than the thickness of the second emitter; printing a first grid line on the first region of the second surface using a first screen, the first grid line being in electrical contact with the first emitter; and printing a second grid line on the second region of the second surface using a second screen, the second grid line being in electrical contact with the second emitter. The present disclosure can at least improve the reliability of preparing the back-contact cell.

Description

Technical Field

[0001] The present disclosure relates to the field of photovoltaics, and in particular to a back-contact cell and a method for preparing the same. Background Art

[0002] As fossil fuels gradually deplete, solar energy is becoming increasingly popular as a new energy alternative. Solar cells convert sunlight into electrical energy. They utilize the photovoltaic principle to generate charge carriers and then use electrodes to extract these charge carriers, effectively utilizing solar energy.

[0003] Current solar cells primarily include back-contact cells, TOPCON (Tunnel Oxide Passivated Contact) cells, PERC (Passivated Emitter and Real Cell), and heterojunction cells. Back-contact cells have both positive and negative grid lines on the back, leaving the front unobstructed. Compared to conventional solar cells, these cells can reduce light energy loss caused by grid line obstruction and achieve higher photoelectric conversion efficiency.

[0004] However, the back-contact battery in the related art has problems when printing the grid lines, resulting in poor reliability in preparing the back-contact battery. Summary of the Invention

[0005] The embodiments of the present disclosure provide a back-contact battery and a method for preparing the same, which can at least improve the reliability of preparing the back-contact battery.

[0006] According to some embodiments of the present disclosure, on the one hand, an embodiment of the present disclosure provides a method for preparing a back-contact battery, which includes: providing a substrate, the substrate including a first surface and a second surface relative to each other; the second surface is provided with a first area and a second area arranged alternately, and a spacer area located between the first area and the second area, a first emitter is provided on the first area, and a second emitter is provided on the second area, the doping element in the first emitter and the doping element in the second emitter have different conductivity types, and the thickness of the first emitter is less than the thickness of the second emitter; using a first screen to print a first gate line on the first area of ​​the second surface, the first gate line is electrically contacted with the first emitter; using a second screen to print a second gate line on the second area of ​​the second surface, the second gate line is electrically contacted with the second emitter.

[0007] In some embodiments, before printing the first gate line, the method for preparing the back-contact battery further includes: forming a first passivation layer, the first passivation layer being located on the surface of the first emitter and the second emitter facing away from the substrate, and also being located on the spacer area of ​​the second surface; the height of the surface of the first gate line facing away from the substrate relative to the second surface is a first height, the height of the surface of the first passivation layer on the second area facing away from the substrate relative to the second surface is a second height, the first height is greater than the second height, and the difference between the first height and the second height is less than or equal to 4 μm.

[0008] In some embodiments, before printing the first gate line, the method for preparing the back-contact battery also includes: forming a first passivation layer, the first passivation layer is located on the surface of the first emitter and the second emitter facing away from the substrate, and is also located on the spacer area of ​​the second surface; the height of the surface of the first gate line facing away from the substrate relative to the second surface is a first height, the height of the surface of the first passivation layer on the second area facing away from the substrate relative to the second surface is a second height, and the first height is equal to the second height.

[0009] In some embodiments, a difference between a thickness of the first emitter and a thickness of the second emitter is less than or equal to 100 nm.

[0010] In some embodiments, the thickness of the first emitter is 60 nm to 380 nm, and the thickness of the second emitter is 60 nm to 400 nm.

[0011] In some embodiments, the thickness of the first gate line is less than the thickness of the second gate line.

[0012] In some embodiments, the thickness of the first gate line is 2 μm to 20 μm, and the thickness of the second gate line is 5 μm to 30 μm.

[0013] In some embodiments, the ratio of the projected area of ​​the first emitter on the second surface to the area of ​​the second surface is 0.1-0.4, and the ratio of the projected area of ​​the second emitter on the second surface to the area of ​​the second surface is 0.1-0.4.

[0014] In some embodiments, along the first direction, the width of the first emitter is 150 μm-300 μm, and the width of the second emitter is 150 μm-300 μm.

[0015] According to some embodiments of the present disclosure, on the other hand, the embodiments of the present disclosure further provide a back-contact battery, which includes: a substrate, the substrate including a first surface and a second surface relative to each other; a first region and a second region alternately arranged on the second surface, and a spacing region between the first region and the second region, a first emitter is provided on the first region, and a second emitter is provided on the second region, the doping elements in the first emitter and the doping elements in the second emitter have different conductivity types, and the thickness of the first emitter is less than the thickness of the second emitter; a first gate line, the first gate line is located on the first region and is electrically contacted with the first emitter; a second gate line, the second gate line is located on the second region and is electrically contacted with the second emitter.

[0016] The technical solution provided by the embodiments of the present disclosure has at least the following advantages:

[0017] The technical solution of the preparation method of the back-contact battery provided by the embodiment of the present disclosure includes: providing a substrate, the substrate including a first surface and a second surface relative to each other; providing a first area and a second area alternately arranged on the second surface, and a spacer area located between the first area and the second area, a first emitter is provided on the first area, and a second emitter is provided on the second area, the doping element in the first emitter and the doping element in the second emitter have different conductivity types, and the thickness of the first emitter is less than the thickness of the second emitter; using a first screen to print a first gate line on the first area of ​​the second surface, the first gate line is electrically contacted with the first emitter; using a second screen to print a second gate line on the second area of ​​the second surface, the second gate line is electrically contacted with the second emitter.

[0018] In the embodiment of the present disclosure, a first screen is first used to print a first grid line on a first area provided with a first emitter of smaller thickness, and then a second screen is used to print a second grid line on a second area provided with a second emitter of larger thickness, so that the height of the first grid line away from the surface of the substrate can be smaller, which can avoid the problem of printing offset caused by the first grid line first printed on the emitter of larger thickness having a higher height away from the surface of the substrate, resulting in the second screen needing to be set at a higher height when printing the second grid line, so that the distance between the second screen and the emitter of smaller thickness is larger. That is, in the embodiment of the present disclosure, when the second screen is used to print the second grid line, the distance between the second screen and the second emitter can be smaller, which is conducive to the second screen aligning the second emitter with the second emitter to print the second grid line, thereby improving the reliability of the preparation of the back contact battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the traditional technology, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 A schematic diagram of the structure of a back contact battery in the related art;

[0021] Figure 2 A schematic structural diagram of forming a first emitter in the method for preparing a solar cell provided by an embodiment of the present disclosure;

[0022] Figure 3 A schematic structural diagram of the solar cell manufacturing method according to an embodiment of the present disclosure, wherein the spacer region and the first emitter on the second region are removed;

[0023] Figure 4 A schematic structural diagram of forming a second emitter in the method for preparing a solar cell provided by an embodiment of the present disclosure;

[0024] Figure 5 A schematic structural diagram of removing the spacer region and the second emitter on the first region in the method for preparing a solar cell provided by an embodiment of the present disclosure;

[0025] Figure 6 A schematic structural diagram of forming a first passivation layer in the method for preparing a solar cell provided in an embodiment of the present disclosure;

[0026] Figure 7 A schematic structural diagram of forming a first grid line in the method for preparing a solar cell provided by an embodiment of the present disclosure;

[0027] Figure 8 Another structural schematic diagram of forming a first grid line in the method for preparing a solar cell provided by an embodiment of the present disclosure.

[0028] Description of reference numerals:

[0029] 100, substrate; 110, front side; 120, back side; 130, first region; 140, second region; 150, spacing region; 101, first emitter electrode; 102, second emitter electrode; 103, passivation film; 104, first fine gate; 200, base; 210, first surface; 220, second surface; 230, first region; 240, second region; 250, spacing region; 201, first emitter; 211, first doped silicon glass layer; 202, second emitter; 212, second doped silicon glass layer; 203, first passivation layer; 213, aluminum oxide film layer; 223, silicon nitride film layer; 204, second passivation layer; 214, aluminum oxide layer; 224, silicon nitride layer; 234, silicon oxide layer; 205, first gate line; 206, second gate line. DETAILED DESCRIPTION

[0030] Figure 1 This is a structural diagram of a back-contact battery in the related art.

[0031] refer to Figure 1 A back-contact cell in the related art includes a substrate 100, a first emitter electrode 101, a second emitter electrode 102, a passivation film 103, and a first fine gate 104. The substrate 100 includes a front surface 110 and a back surface 120. The back surface 120 is provided with alternating first and second regions 130, 140, and a spacing region 150 between the first and second regions 130, 140. The first emitter electrode 101 is located on the first region 130, and the second emitter electrode 102 is located on the second region 140. The passivation film 103 is located on the surfaces of the first and second emitter electrodes 101, 102 facing away from the substrate 100. The passivation film 103 is also located on the spacing region 150. The first fine gate 104 is located on the first region 130 and is in electrical contact with the first emitter electrode 101.

[0032] The thickness of the first emitting electrode 101 is greater than that of the second emitting electrode 102. When the first fine grid 104 is first printed on the first region 130 using a first screen, and then the second fine grid (not shown) is printed on the second region 140 using a second screen (not shown), the height H0 of the first fine grid 104 on the first emitting electrode 101, facing away from the substrate 100, is too high. The height H0 of the first fine grid 104 facing away from the substrate 100 is the height of the first fine grid 104 facing away from the substrate 100 relative to the back surface 120. The height of the second screen is the height of the second screen relative to the back surface 120. The height H0 of the first fine grid 104 facing away from the substrate 100 affects the height of the second screen. Specifically, to prevent the second screen from directly contacting and damaging the first fine grid 104, the second screen is positioned higher than the first fine grid 104. In other words, a higher first fine grid 104 results in a higher second screen, while a lower first fine grid 104 allows the second screen to be positioned lower. Therefore, the height H0 of the first fine grid 104 from the surface of the substrate 100 is relatively high, which requires that the second screen be set at a relatively high height. The high height of the second screen increases the distance between the second screen and the passivation film 103 on the second emitter electrode 102, making it difficult to align the second fine grid printed on the second screen with the second emitter electrode 102. The slurry of the second fine grid may diffuse into other areas, introducing more charge recombination areas, or causing gate breakage or virtual printing, thereby reducing the reliability of the back-contact cell.

[0033] In other words, in the related art, the first fine grid 104 is first printed on the first region 130 where the thicker emitting electrode is provided, and then the second fine grid is printed on the second region 140 where the thinner emitting electrode is provided. The first fine grid 104 first printed on the thicker emitting electrode is at a greater height away from the surface of the substrate 100, making it difficult to align the printing when using the second screen printing of the second fine grid, resulting in the reliability of the preparation of the back-contact battery to be improved.

[0034] Compared to the solution in the related art in which the gate lines are first printed on the region of the emitter with a larger thickness, resulting in the first-printed gate lines being at a higher height from the surface of the substrate, in the method for preparing a back-contact battery provided in the embodiment of the present disclosure, a first screen is first used to print the first gate lines on a first region provided with a first emitter with a smaller thickness, and then a second screen is used to print the second gate lines on a second region provided with a second emitter with a larger thickness. The height of the first gate lines on the first emitter with a smaller thickness printed first from the surface of the substrate can be smaller, so that when the second screen is used to print the second gate lines, the distance between the second screen and the second emitter can be smaller, which is beneficial for the second screen to align the second emitter with the second emitter to print the second gate lines, thereby improving the reliability of the preparation of the back-contact battery.

[0035] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are used solely to distinguish between different objects and should not be understood to indicate or imply relative importance or to implicitly specify the quantity, specific order, or primary and secondary relationship of the technical features indicated. In the description of the embodiments of the present disclosure, "plurality" means more than two, unless otherwise specifically defined.

[0036] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present disclosure. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0037] In the description of the embodiments of the present disclosure, the term "and / or" is merely a description of an association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B can represent the following three situations: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0038] In the description of the embodiments of the present disclosure, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0039] In the description of the embodiments of the present disclosure, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the embodiments of the present disclosure.

[0040] In the description of the embodiments of the present disclosure, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and can refer to internal connectivity between two components or interaction between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present disclosure based on specific circumstances.

[0041] In the accompanying drawings corresponding to the embodiments of the present disclosure, the thickness and area of ​​the layers are exaggerated for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) as being on another component or on the surface of another component, the component may be "directly" located on the surface of the other component, or a third component may be present between the two components. Conversely, when describing a component as being on the surface of another component, or when describing a component as being formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component as being "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0042] In the description of the embodiments of the present disclosure, when a component is referred to as "including" another component, unless otherwise specified, other components are not excluded, and other components may be further included. In addition, when a component such as a layer, film, region, or plate is referred to as being "on" another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component can be present between them. In addition, when a component such as a layer, film, region, or plate is "directly on" another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it means that no other components are located between them.

[0043] The following describes various embodiments of the present disclosure in detail with reference to the accompanying drawings. However, those skilled in the art will appreciate that many technical details are provided in the various embodiments of the present disclosure to facilitate a better understanding of the present disclosure. However, even without these technical details and the various variations and modifications based on the following embodiments, the technical solutions claimed in the present disclosure can still be implemented.

[0044] Figures 2 to 8 Schematic diagram of the corresponding structures formed in each step of the preparation method of the back contact battery provided in the embodiment of the present disclosure.

[0045] Combined with reference Figures 2 to 5 The preparation method of the back-contact battery includes: providing a substrate 200, the substrate 200 including a first surface 210 and a second surface 220 relative to each other; the second surface 220 is provided with first areas 230 and second areas 240 arranged alternately, and a spacer area 250 located between the first areas 230 and the second areas 240, a first emitter 201 is provided on the first area 230, and a second emitter 202 is provided on the second area 240, the doping element in the first emitter 201 and the doping element in the second emitter 202 have different conductivity types, and the thickness of the first emitter 201 is less than the thickness of the second emitter 202.

[0046] The substrate 200 is used to receive incident light and generate photogenerated carriers. In some embodiments, the substrate 200 may be a semiconductor substrate.

[0047] In some embodiments, the substrate 200 may be made of an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. The elemental semiconductor material may be in a single crystalline state, a polycrystalline state, an amorphous state, or a microcrystalline state (a state having both single crystalline and amorphous states is referred to as a microcrystalline state). For example, silicon may be at least one of single crystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0048] In some embodiments, the substrate 200 may be made of a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanium, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, copper indium selenide, and the like.

[0049] The substrate 200 may also be a sapphire substrate, a silicon-on-insulator substrate, or a germanium-on-insulator substrate.

[0050] The substrate 200 may be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with an N-type dopant element, which may be at least one of Group V elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate is doped with a P-type dopant element, which may be at least one of Group III elements such as boron (B), aluminum (Al), gallium (Ga), or indium (In).

[0051] The substrate 200 includes a first surface 210 and a second surface 220 that are opposite to each other. In some embodiments, the back-contact cell is a single-sided cell, in which case the first surface 210 of the substrate 200 can serve as a light-receiving surface for receiving incident light, and the second surface 220 can serve as a backlight surface. In some embodiments, the back-contact cell is a double-sided cell, in which case both the first surface 210 and the second surface 220 of the substrate 200 can serve as light-receiving surfaces for receiving incident light. It is understood that the backlight surface referred to in the embodiments of the present disclosure can also receive incident light, but the degree of reception of the incident light is weaker than that of the light-receiving surface, and is therefore defined as a backlight surface.

[0052] Continue to refer Figures 2 to 5 The doping element in the first emitter 201 is one of a P-type doping element and an N-type doping element, and the doping element in the second emitter 202 is the other of the P-type doping element and the N-type doping element.

[0053] In some embodiments, the difference between the thickness of the first emitter 201 and the thickness of the second emitter 202 is less than or equal to 100 nm, such as 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 95 nm, or 100 nm. The thickness of the first emitter 201 and the thickness of the second emitter 202 being within the above ranges ensures that the first emitter 201 can effectively collect and transport carriers while also preventing the second surface 220 from absorbing sunlight due to an excessively thick second emitter 202, or reducing the carrier collection efficiency due to an increased carrier transmission path.

[0054] In some embodiments, the thickness of the first emitter 201 is 60 nm to 380 nm, for example, 60 nm, 80 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 370 nm, or 380 nm. The thickness of the first emitter 201 within the above range can ensure that the first emitter 201 can effectively collect and transmit carriers while also preventing the first emitter 201 from being too thick, which could affect the second surface 220's absorption of sunlight, or reduce the carrier collection efficiency due to an increased carrier transmission path.

[0055] In some embodiments, the thickness of the second emitter 202 is 60 nm to 400 nm, such as 61 nm, 65 nm, 70 nm, 80 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 370 nm, 390 nm, or 400 nm. The thickness of the second emitter 202 within the above range can ensure that the second emitter 202 can effectively collect and transport carriers while also preventing excessive thickness of the second emitter 202 from affecting solar light absorption by the second surface 220 or increasing the carrier transmission path, thereby reducing carrier collection efficiency.

[0056] In some embodiments, the ratio of the projected area of ​​the first emitter 201 on the second surface 220 to the area of ​​the second surface 220 is 0.1-0.4, for example, 0.1, 0.2, 0.3, or 0.4. When the ratio of the projected area of ​​the first emitter 201 on the second surface 220 to the area of ​​the second surface 220 is within this range, the projected area of ​​the first emitter 201 is smaller, which can reduce parasitic absorption caused by the first emitter 201, thereby improving the performance of the back-contact cell.

[0057] The ratio of the projected area of ​​the second emitter 202 on the second surface 220 to the area of ​​the second surface 220 is 0.1 to 0.4, for example, 0.1, 0.2, 0.3, or 0.4. When the ratio of the projected area of ​​the second emitter 202 on the second surface 220 to the area of ​​the second surface 220 is within this range, the projected area of ​​the second emitter 202 is small, which can reduce parasitic absorption caused by the second emitter 202, thereby improving the performance of the back-contact cell.

[0058] In some embodiments, the width of the first emitter 201 along the first direction X is 150 μm to 300 μm, for example, 150 μm, 180 μm, 200 μm, 220 μm, 240 μm, 250 μm, 260 μm, 280 μm, or 300 μm. When the width of the first emitter 201 is within the above range, the smaller the width of the first emitter 201, the smaller the width of the first emitter 201, and thus the better the performance of the back-contact solar cell.

[0059] Along the first direction X, the width of the second emitter 202 is 150 μm to 300 μm, for example, 150 μm, 180 μm, 200 μm, 220 μm, 240 μm, 250 μm, 260 μm, 280 μm, or 300 μm. When the width of the second emitter 202 is within the above range, the smaller the width of the second emitter 202, the smaller the width of the second emitter 202, and thus the performance of the back-contact cell can be improved.

[0060] The first direction X is the direction from the first emitter 201 to the second emitter 202 .

[0061] Combined with reference Figure 2 and Figure 3 In some embodiments, the step of forming the first emitter 201 may include: depositing a first crystalline silicon layer (not shown) on the second surface 220; performing a doping treatment on the first crystalline silicon layer to convert the first crystalline silicon layer into the first emitter 201 and forming a first doped silicon glass layer 211 on the surface of the first emitter 201 facing away from the substrate 200; and removing the first doped silicon glass layer 211 and the first emitter 201 on the spacer 250 and the second region 240.

[0062] The material of the first crystalline silicon layer can be polysilicon or amorphous silicon.

[0063] The first crystalline silicon layer may be formed by chemical vapor deposition.

[0064] Doping treatment includes high-temperature diffusion method or ion implantation method.

[0065] In some embodiments, the first doped silicate glass layer 211 may be a borosilicate glass layer or a phosphosilicate glass layer, where "boron" or "phosphorus" depends on the doping element used in the doping process to form the first emitter 201. For example, if the doping element is boron, the first doped silicate glass layer 211 is a borosilicate glass layer.

[0066] In some embodiments, the thickness of the first doped silicate glass layer 211 is 20 nm to 80 nm, such as 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, or 80 nm.

[0067] In some embodiments, the method for removing the first doped silica glass layer 211 and the first emitter 201 on the spacer 250 and the second region 240 may include: using a laser process to transform the first doped silica glass layer 211 on the spacer 250 and the second region 240 into a first loose structure; and then using wet etching to remove the first loose structure and the first emitter 201 on the spacer 250 and the second region 240. The laser process transforms the first doped silica glass layer 211 on the spacer 250 and the second region 240 into the first loose structure, allowing the subsequent wet etching to remove the first loose structure and the first emitter 201 on the spacer 250 and the second region 240. The first emitter 201 on the first region 230 remains protected by the first doped silica glass layer 211 on the first region 230 that has not undergone the laser process.

[0068] refer to Figure 3 and Figure 4 In some embodiments, the step of forming the second emitter 202 may include: forming a second crystalline silicon layer (not shown) on the surface of the first doped silicon glass layer 211 in the first region 230 facing away from the substrate 200, as well as on the second region 240 and the spacer region 250; performing a doping treatment on the second crystalline silicon layer to convert the second crystalline silicon layer into the second emitter 202 and forming a second doped silicon glass layer 212 on the surface of the second emitter 202 facing away from the substrate 200; and removing the second doped silicon glass layer 212 and the second emitter 202 on the spacer region 250 and the first region 230.

[0069] The material of the second crystalline silicon layer can be polysilicon or amorphous silicon.

[0070] The second crystalline silicon layer may be formed by chemical vapor deposition.

[0071] Doping treatment includes high-temperature diffusion method or ion implantation method.

[0072] In some embodiments, the second doped silicate glass layer 212 may be a borosilicate glass layer or a phosphosilicate glass layer, where "boron" or "phosphorus" depends on the doping element used in the doping process to form the second emitter 202. For example, if the doping element is phosphorus, the second doped silicate glass layer 212 is a phosphosilicate glass layer.

[0073] In some embodiments, the second doped silicate glass layer 212 has a thickness of 20 nm to 80 nm, such as 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, or 80 nm.

[0074] In some embodiments, the method of removing the second doped silicon glass layer 212 and the second emitter 202 on the spacer region 250 and the first region 230 includes: using a laser process to transform the second doped silicon glass layer 212 on the spacer region 250 and the first region 230 into a second loose structure; and wet etching to remove the second loose structure and the second emitter 202 located on the spacer region 250 and the first region 230.

[0075] In some embodiments, when forming the first emitter 201 and the second emitter 202 on the second surface 220, a wrap-around coating layer (not shown) is formed on the first surface 210 and side surfaces of the substrate 200. The wrap-around coating layer includes at least the first emitter 201 and the second emitter 202. The back-contact cell fabrication method further includes removing the wrap-around coating layer. This prevents the wrap-around coating layer from adding additional recombination centers on the substrate 200 and affecting the performance of the back-contact cell.

[0076] The method for removing the coating layer can be acid wet etching.

[0077] refer to Figure 5 In some embodiments, the method for preparing a back-contact cell may further include: performing a texturing treatment on the spacer 250 of the second surface 220 and the first surface 210 to form a textured structure on the spacer 250 of the second surface 220 and the first surface 210. The textured structure can increase the number of refractions of light on the surface of the back-contact cell, which is beneficial to the absorption of light by the back-contact cell, thereby improving the performance of the back-contact cell.

[0078] Among them, the first doped silicon glass layer 211 on the first area 230 and the second doped silicon glass layer 212 on the second area 240 will protect the first emitter 201 and the second emitter 202 so that the texturing treatment will not damage the first emitter 201 and the second emitter 202, and no film layer is set on the spacer area 250 and the first surface 210. Under the texturing treatment, the first surface 210 and the spacer area 250 will form a velvet structure.

[0079] In some embodiments, a solution texturing method can be used to prepare the textured structure. For example, if the substrate 200 is single-crystal silicon, a mixture of an alkaline solution and an alcohol solution can be used to texturize the surface of the substrate 200; if the substrate 200 is polycrystalline silicon, an acid solution can be used to texturize the surface of the substrate 200.

[0080] In some embodiments, a laser texturing process or a reactive ion etching (RIE) process may be used to prepare the textured surface structure.

[0081] Combined with reference Figure 5 and Figure 6 In some embodiments, the method for preparing a back-contact cell may further include removing the first doped silica glass layer 211 and the second doped silica glass layer 212. Specifically, a mask may be placed on the spacer 250 to protect the substrate 200 of the spacer 250, and the first doped silica glass layer 211 and the second doped silica glass layer 212 may be removed by wet etching, and finally, the mask may be removed. Removing the first doped silica glass layer 211 and the second doped silica glass layer 212 can avoid the compounding problem caused by the first doped silica glass layer 211 and the second doped silica glass layer 212, thereby improving the performance of the back-contact cell.

[0082] In other embodiments, the first doped silica glass layer and the second doped silica glass layer may not be removed.

[0083] refer to Figure 6 In some embodiments, the method for preparing a back-contact battery may further include: forming a first passivation layer 203 on the second surface 220; the first passivation layer 203 is located on the surface of the first emitter 201 and the second emitter 202 away from the substrate 200, and is also located on the spacer area 250 of the second surface 220.

[0084] The first passivation layer 203 is used to passivate the second surface 220 of the substrate 200 to reduce surface recombination of the second surface 220 and improve the carrier collection efficiency, thereby improving the photoelectric conversion efficiency of the back contact cell.

[0085] The first passivation layer 203 may be formed by atomic layer deposition or chemical vapor deposition.

[0086] The first passivation layer 203 may be a single-layer structure or a stacked-layer structure. The material of the first passivation layer 203 may be one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride oxide, titanium oxide, hafnium oxide, aluminum oxide, and the like.

[0087] In some embodiments, the first passivation layer 203 includes an aluminum oxide film layer 213 and a silicon nitride film layer 223. The silicon nitride film layer 223 is located on a surface of the aluminum oxide film layer 213 facing away from the substrate 200.

[0088] Continue to refer Figure 6 In some embodiments, the method for preparing a back-contact battery may further include: forming a second passivation layer 204 on the first surface 210 .

[0089] The second passivation layer 204 is used to passivate the first surface 210 of the substrate 200 to reduce surface recombination of the first surface 210 and improve the carrier collection efficiency, thereby improving the photoelectric conversion efficiency of the back contact cell.

[0090] The second passivation layer 204 may be formed by atomic layer deposition or chemical vapor deposition.

[0091] The second passivation layer 204 may be a single-layer structure or a stacked-layer structure. The material of the second passivation layer 204 may be one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride oxide, titanium oxide, hafnium oxide, aluminum oxide, and the like.

[0092] In some embodiments, the second passivation layer 204 includes an aluminum oxide layer 214, a silicon nitride layer 224, and a silicon oxide layer 234. The aluminum oxide layer 214 is located between the substrate 200 and the silicon nitride layer 224, and the silicon nitride layer 224 is located between the aluminum oxide layer 214 and the silicon oxide layer 234.

[0093] Combined with reference Figures 6 to 8 The preparation method of the back-contact battery also includes: using a first screen to print a first gate line 205 on the first area 230 of the second surface 220, and the first gate line 205 is in electrical contact with the first emitter 201; using a second screen to print a second gate line 206 on the second area 240 of the second surface 220, and the second gate line 206 is in electrical contact with the second emitter 202.

[0094] A first gate line 205 is formed by printing a metal paste on the first region 230 using a first screen.

[0095] In some embodiments, the metal paste may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel.

[0096] In some embodiments, the metal paste contains a material with a highly corrosive component such as glass. Thus, during the sintering process, the corrosive component will corrode the first passivation layer 203 and the first emitter 201, thereby causing the metal paste to penetrate the first passivation layer 203 and a portion of the first emitter 201, so that the metal paste burns through from the side of the first emitter 201 away from the substrate 200 to a portion of the thickness of the first emitter 201, thereby forming the first gate line 205.

[0097] A second gate line 206 is formed by printing metal paste on the second area 240 using a second screen.

[0098] In some embodiments, the metal paste may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel.

[0099] In some embodiments, the metal paste contains a material with a highly corrosive component such as glass. Thus, during the sintering process, the corrosive component will corrode the first passivation layer 203 and the second emitter 202, thereby causing the metal paste to penetrate the first passivation layer 203 and a portion of the second emitter 202, so that the metal paste burns through from the side of the second emitter 202 away from the substrate 200 to a portion of the thickness of the second emitter 202, thereby forming a second gate line 206.

[0100] The height of the first gate line 205 facing away from the substrate 200 relative to the second surface 220 is a first height H1 , and the height of the first passivation layer 203 on the second region 240 facing away from the substrate 200 relative to the second surface 220 is a second height H2 .

[0101] Combined with reference Figure 6 and Figure 7 In some embodiments, the first height H1 may be greater than the second height H2, and the difference between the first height H1 and the second height H2 is less than or equal to 4 μm, such as 0.5 μm, 1 μm, 2 μm, 3 μm, or 4 μm. Within this range, the difference can avoid the problem of the second screen being too high relative to the second surface 220 when printing the second gate line 206 due to the first height H1 of the first gate line 205 being too large, resulting in an excessive distance between the second screen and the first passivation layer 203 on the second emitter 202, making it difficult for the second screen to align with the second gate line 206. In other words, the difference between the first height H1 and the second height H2 is within the above range, which can ensure that when printing the second gate line 206, the distance between the second screen and the first passivation layer 203 on the second emitter 202 is small, making it easier for the second screen to align with the second emitter 202 to print the second gate line 206.

[0102] Combined with reference Figure 6 and Figure 8 In some embodiments, the first height H1 can be equal to the second height H2. In this way, when the second gate line 206 is printed using the second screen, the first gate line 205 does not lift up the second screen, resulting in a large distance between the second screen and the first passivation layer 203 on the second emitter 202, causing difficulty in alignment and printing.

[0103] In some embodiments, the thickness of first gate line 205 is less than the thickness of second gate line 206. That is, the thickness of first gate line 205 is relatively small, and the thickness of first gate line 205 is positively correlated with first height H1 of first gate line 205. The smaller thickness of first gate line 205 allows first height H1 of first gate line 205 to be smaller, thereby allowing the height of the second screen relative to second surface 220 to be smaller. Therefore, when the second screen is used to print second gate line 206, the distance between the second screen and first passivation layer 203 on second emitter 202 can be smaller, which facilitates alignment of the second screen with the second emitter 202 when printing second gate line 206, thereby improving the reliability of the back-contact battery.

[0104] In some embodiments, the thickness of first gate line 205 is 2 μm to 20 μm, for example, 2 μm, 4 μm, 5 μm, 8 μm, 10 μm, 11 μm, 12 μm, 15 μm, or 20 μm. When the thickness of first gate line 205 is within the above range, the thickness of first gate line 205 is relatively small. The smaller thickness of first gate line 205 allows first height H1 to be smaller, thereby allowing the height of the second screen relative to second surface 220 to be smaller. Therefore, when the second screen is used to print second gate line 206, the distance between the second screen and the first passivation layer 203 on the second emitter 202 can be smaller, which facilitates the second screen to align the second emitter 202 with the second gate line 206 when printing, thereby improving the reliability of the back-contact battery.

[0105] In some embodiments, the thickness of the second gate line 206 is 5 μm to 30 μm, for example, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 25 μm, or 30 μm. When the thickness of the second gate line 206 is within the above range, the thickness of the second gate line 206 can be larger, and the second gate line 206 can provide a larger current transmission channel, thereby improving the efficiency of the second gate line 206 in collecting current.

[0106] In the above-mentioned method for preparing a back-contact battery, a first screen is first used to print a first gate line 205 on a first region 230 provided with a first emitter 201 having a smaller thickness, and a second screen is then used to print a second gate line 206 on a second region 240 provided with a second emitter 202 having a larger thickness. The first gate line 205 printed on the first emitter 201 having a smaller thickness can be at a smaller height relative to the surface of the substrate 200. Therefore, when the second screen is used to print the second gate line 206, the distance between the second screen and the second emitter 202 can be reduced, which facilitates alignment of the second screen with the second emitter 202 when printing the second gate line 206, thereby improving the reliability of the back-contact battery.

[0107] Accordingly, another aspect of the present disclosure further provides a back-contact battery manufactured by the method for manufacturing a back-contact battery according to any of the above embodiments. It should be noted that for the parts that are identical or corresponding to the above embodiments, reference can be made to the corresponding descriptions of the above embodiments and will not be repeated below.

[0108] Combined with reference Figures 6 to 8 The back-contact cell includes a substrate 200, which includes a first surface 210 and a second surface 220 that oppose each other. The second surface 220 is provided with alternating first and second regions 230, 240, and a spacer 250 between the first and second regions 230, 240. A first emitter 201 is provided on the first region 230, and a second emitter 202 is provided on the second region 240. The dopant element in the first emitter 201 and the dopant element in the second emitter 202 have different conductivity types, and the thickness of the first emitter 201 is smaller than that of the second emitter 202. The back-contact cell also includes a first gate line 205 and a second gate line 206. The first gate line 205 is located on the first region 230 and is in electrical contact with the first emitter 201. The second gate line 206 is located on the second region 240 and is in electrical contact with the second emitter 202.

[0109] Those skilled in the art will appreciate that the above-described embodiments are specific examples for implementing the present disclosure, and that in actual applications, various changes in form and detail may be made thereto without departing from the spirit and scope of the present disclosure. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure shall be subject to the scope defined in the claims.

Claims

1. A method for preparing a back contact battery, characterized in that: include: A substrate is provided, the substrate comprising a first surface and a second surface opposite to each other; the second surface is provided with first and second regions alternately arranged, and a spacer region located between the first and second regions; a first emitter is provided on the first region, and a second emitter is provided on the second region; an impurity element in the first emitter and an impurity element in the second emitter have different conductivity types, and a thickness of the first emitter is smaller than a thickness of the second emitter; First, a first gate line is printed on the first area of ​​the second surface using a first screen, wherein the first gate line is in electrical contact with the first emitter; Then, using a second screen to print a second gate line on the second area of ​​the second surface, the second gate line being in electrical contact with the second emitter, and the thickness of the first gate line being smaller than that of the second gate line; Before printing the first gate line, the method for preparing the back contact battery further includes: A first passivation layer is formed, and the first passivation layer is located on the surface of the first emitter and the second emitter facing away from the substrate, and is also located on the spacer area of ​​the second surface; the height of the surface of the first gate line facing away from the substrate relative to the second surface is a first height, the height of the surface of the first passivation layer on the second area facing away from the substrate relative to the second surface is a second height, the height of the surface of the first passivation layer on the first area facing away from the substrate relative to the second surface is less than the second height, and the difference between the first height and the second height is less than or equal to 4μm.

2. The method for preparing a back contact battery according to claim 1, wherein: The first height is equal to the second height.

3. The method for preparing a back contact battery according to claim 1, wherein: A difference between a thickness of the first emitter and a thickness of the second emitter is less than or equal to 100 nm.

4. The method for preparing a back contact battery according to claim 3, wherein: The thickness of the first emitter is 60 nm to 380 nm, and the thickness of the second emitter is 60 nm to 400 nm.

5. The method for preparing a back contact battery according to claim 4, characterized in that: The thickness of the first gate line is 2 μm to 20 μm, and the thickness of the second gate line is 5 μm to 30 μm.

6. The method for preparing a back contact battery according to any one of claims 1 to 5, characterized in that: The ratio of the projected area of ​​the first emitter on the second surface to the area of ​​the second surface is 0.1-0.4, and the ratio of the projected area of ​​the second emitter on the second surface to the area of ​​the second surface is 0.1-0.

4.

7. The method for preparing a back contact battery according to claim 6, characterized in that: Along the first direction, the width of the first emitter is 150 μm-300 μm, and the width of the second emitter is 150 μm-300 μm.

8. A back contact battery, characterized in that: The back-contact battery is prepared by the method for preparing a back-contact battery according to any one of claims 1 to 7, and the back-contact battery comprises: A substrate comprising a first surface and a second surface opposite to each other; the second surface being provided with alternating first and second regions, and a spacer region between the first and second regions; a first emitter being provided on the first region, and a second emitter being provided on the second region; a dopant element in the first emitter and a dopant element in the second emitter having different conductivity types; and a thickness of the first emitter being smaller than a thickness of the second emitter; a first gate line, the first gate line being located on the first region and electrically contacting the first emitter; A second gate line is located on the second region and is electrically connected to the second emitter.

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