Preparation method of back contact solar cell and back contact solar cell

Abstract

The invention discloses a preparation method of a back contact solar cell and the back contact solar cell. The method comprises the following steps: preparing a first doping structure on one main surface of a silicon substrate; removing a part of the first doping structure to obtain a part of exposed region of the silicon substrate and a first doping region with the first doping structure; preparing an inclined plane structure connected with the first doped structure in the partially exposed region; preparing a second doped region in other exposed regions except the slope structure; and respectively forming a first conductive thin film in the first doped region, forming a second conductive thin film in the second doped region, and forming a third conductive thin film with a discontinuous structure in the inclined plane structure. According to the embodiment, the process of forming an isolation groove through laser can be omitted, the preparation process of the back contact solar cell is simplified, and the photoelectric conversion efficiency of the back contact solar cell is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a method for preparing a back-contact solar cell and a back-contact solar cell. Background Art

[0002] With the development of solar cell technology, back contact (BC) cells came into being. BC cells are cells in which all electrodes are set on the backlight side of the cell, so that the light-facing side of the cell is completely exposed to the sun, thereby improving the light absorption efficiency. Since both N-type and P-type regions are set on the back of BC solar cells, for BC solar cells with conductive films, the two regions will be electrically conductive, which will lead to short circuit or leakage of the positive and negative electrodes. Therefore, most of the current methods are to insulate the two regions by opening an isolation groove between the N-type region and the P-type region. The isolation groove is generally opened by laser. In the process of opening the isolation groove, there may be errors that make it impossible to effectively isolate the two regions. In addition, the laser film opening process will inevitably cause laser damage to the cell, reducing the photoelectric conversion efficiency of the BC cell. Therefore, there is an urgent need for a BC cell that does not require laser opening of the isolation groove. Summary of the invention

[0003] In view of this, an embodiment of the present invention provides a method for preparing a back-contact solar cell and a back-contact solar cell, which can eliminate the process of laser opening of isolation grooves, simplify the preparation process of the back-contact solar cell, and improve the photoelectric conversion efficiency of the back-contact solar cell.

[0004] To achieve the above object, according to one aspect of an embodiment of the present invention, a method for preparing a back-contact solar cell is provided. The method for preparing a back-contact solar cell according to an embodiment of the present invention comprises:

[0005] Step A1, preparing a first doping structure on a main surface of a silicon substrate;

[0006] Step A2, removing part of the first doping structure to obtain a partially exposed area of ​​the silicon substrate and a first doping area having the first doping structure; and preparing an inclined surface structure connected to the first doping structure in the partially exposed area;

[0007] Step A3, preparing a second doped region in other exposed regions outside the above-mentioned inclined surface structure;

[0008] Step A4, forming a first conductive film in the first doped region, forming a second conductive film in the second doped region, and forming a third conductive film with a discontinuous structure in the inclined structure.

[0009] To achieve the above objective, according to another aspect of an embodiment of the present invention, a back-contact solar cell is provided. A back-contact solar cell according to an embodiment of the present invention comprises:

[0010] Silicon substrate;

[0011] The first doped regions and the second doped regions are alternately arranged on the first main surface of the silicon substrate, the isolation region is located between the first doped regions and the second doped regions, the first conductive film is arranged in the first doped regions, the second conductive film is arranged in the second doped regions, and the third conductive film is arranged in the isolation region; wherein:

[0012] The first doping region and the second doping region have a height difference, and the first doping region and the second doping region have opposite doping types;

[0013] The isolation region includes an inclined surface structure arranged obliquely relative to the first doping region and the second doping region;

[0014] The third conductive film has a discontinuous structure, and the third conductive film with the inclined surface structure has a thickness smaller than that of the first conductive film and the second conductive film.

[0015] An embodiment of the above invention has the following advantages or beneficial effects: by forming a slope structure between a first doped region and a second doped region with a height difference, the thickness of the conductive film deposited on the slope structure is relatively thin, and a conductive film with an intermittent structure can be formed through a simple process, while achieving effective electrical isolation between the first doped region and the second doped region. On the one hand, for the method of opening an isolation groove by laser, the process of laser opening an isolation groove in the isolation area is eliminated, thereby reducing the laser damage to the back-contact solar cell and further improving the photoelectric conversion efficiency of the back-contact solar cell. On the other hand, for the method of forming an isolation groove by etching, the process of forming a mask layer in the first doped region and the second doped region before etching the entire surface and removing the mask layer is eliminated, thereby simplifying the preparation process of the back-contact solar cell.

[0016] The further effects of the above-mentioned non-conventional optional manner will be described below in conjunction with the specific implementation manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to better understand the present invention and do not constitute an improper limitation of the present invention.

[0018] Figure 1 It is a schematic diagram of the structure of a back contact solar cell in the prior art;

[0019] Figure 2is a schematic flow chart of a method for preparing a back-contact solar cell according to an embodiment of the present invention;

[0020] Figure 3 is a schematic diagram of a first structure of a back-contact solar cell according to an embodiment of the present invention;

[0021] Figure 4 4 is a schematic diagram of a second structure of a back-contact solar cell according to an embodiment of the present invention.

[0022] Reference numerals:

[0023] 10-silicon substrate; 21-first conductive film; 22-tunneling oxide layer; 23-doped polysilicon layer; 24-first intrinsic silicon-containing film; 25-first doped silicon-containing film; 31-second conductive film; 32-second intrinsic silicon-containing film; 33-second doped silicon-containing film; 41-third conductive film; 42-insulating isolation layer; 50-passivation layer; 51-third intrinsic silicon-containing film; 52-third doped silicon-containing film; 60-anti-reflection layer; 70-first metal electrode; 80-second metal electrode. DETAILED DESCRIPTION

[0024] For a back-contact solar cell, in order to prevent the first doped region A and the second doped region B from being electrically connected via the conductive film, the first doped region A and the second doped region B need to be electrically isolated. Figure 1 As shown, in the back-contact solar cell of the prior art, an isolation region C composed of a first doping structure, an insulating isolation layer 42, a second doping structure and a conductive film is arranged between the first doping region A and the second doping region B, and the first doping region A and the second doping region B are electrically isolated by opening an isolation groove in the isolation region C. However, since the planes where the first doping region A, the second doping region B and the third doping region are located are parallel to each other, when preparing the conductive film, the thickness of the conductive film in the above three regions is substantially the same, and the conductive film in the isolation region C needs to be disconnected by opening an isolation groove by laser, resulting in laser damage to the cell, thereby reducing the photoelectric conversion efficiency of the back-contact solar cell.

[0025] In addition, the isolation groove can also be formed by etching. Specifically, a mask layer is formed on the surface of the first doped region A having the first doping structure and the conductive film and on the surface of the second doped region B having the second doping structure and the conductive film to prevent the first doped region A and the second doped region B from being affected during the etching process. After the mask layer is formed, the conductive film of the isolation region C is etched to form an isolation groove. The mask layer is then removed. The formation and removal of the mask layer takes a lot of time, making the preparation process of the back contact solar cell cumbersome.

[0026] The following is a description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, including various details of the embodiments of the present invention to facilitate understanding, which should be considered as merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for clarity and conciseness, the description of well-known functions and structures is omitted in the following description.

[0027] It should be noted that, in the embodiment of the present invention, the direction from inside to outside refers to the direction away from the silicon substrate 10. The first main surface in the embodiment of the present invention refers to the side of the back contact solar cell facing away from the sunlight when working, and the second main surface refers to the side of the back contact solar cell facing the sunlight when working.

[0028] It should be pointed out that the embodiments of the present invention and the technical features therein may be combined with each other without conflict.

[0029] In order to avoid the above problems existing in the prior art, an embodiment of the present invention provides a method for preparing a back-contact solar cell which can avoid opening an isolation groove in the isolation region C and thus reduce the number of laser treatments.

[0030] Figure 2 FIG. 1 is a schematic diagram of a process for preparing a back-contact solar cell according to an embodiment of the present invention. Figure 2 As shown, an embodiment of the present invention provides a method for preparing a back-contact solar cell, comprising the following steps A1 to A4:

[0031] Step A1: prepare a first doping structure on a main surface of the silicon substrate 10.

[0032] The silicon substrate 10 is subjected to texturing treatment. A first doping structure is formed on the entire surface of one main surface of the silicon substrate 10 after texturing. The first doping structure is a tunneling oxide layer 22 and a doped polysilicon layer 23 stacked sequentially from the inside to the outside, or the first doping structure is a first intrinsic silicon-containing film 24 and a first doped silicon-containing film 25 stacked sequentially from the inside to the outside.

[0033] Step A2, removing part of the first doping structure to obtain a partially exposed area of ​​the silicon substrate 10 and a first doping area A having the first doping structure, and preparing an inclined surface structure connected to the first doping structure in the partially exposed area;

[0034] Specifically, part of the first doping structure is removed by polishing or texturing to obtain a partially exposed area of ​​the silicon substrate 10 and a first doping area A having the above-mentioned first doping structure; the above-mentioned partially exposed area is texturized; during the texturing process, a slope structure connected to the above-mentioned first doping structure is prepared.

[0035] The first doping structure at the position corresponding to the second doping region B and the bevel structure of the isolation region C is removed by polishing or texturing to obtain a partially exposed area not covered by the first doping structure and a first doping region A covering the first doping structure. When polishing is used to remove part of the first doping structure, the polishing solution can be prepared and / or the polishing time can be controlled; when texturing is used to remove part of the first doping structure, the texturing agent can be prepared and / or the texturing time can be controlled to form a height difference between the position corresponding to the second doping region B and the position of the first doping region A, so as to form a bevel structure connected to the first doping structure between the position corresponding to the second doping region B and the position of the first doping region A.

[0036] In an optional embodiment, when the isolation region C also includes a planar structure, the above-mentioned step A2 may include: preparing an insulating isolation layer 42 on the outside of the above-mentioned first doping structure; removing part of the insulating isolation layer 42 and part of the first doping structure to obtain a partially exposed area of ​​the silicon substrate 10 and an area having the above-mentioned insulating isolation layer 42 and the above-mentioned first doping structure; for the above-mentioned area having the above-mentioned insulating isolation layer 42 and the above-mentioned first doping structure, removing part of the insulating isolation layer 42 to obtain a first doping area A having the above-mentioned first doping structure and a planar structure having the above-mentioned insulating isolation layer 42 and the above-mentioned first doping structure; performing a texturing treatment on the above-mentioned partially exposed area; during the texturing treatment process, preparing a slope structure connected to the above-mentioned first doping structure.

[0037] The outer side of the first doping structure refers to the surface of the first doping structure away from the silicon substrate 10. Before removing the first doping structure at the position corresponding to the bevel structure of the second doping region B and the isolation region C, it is necessary to first perform laser processing on the insulating isolation layer 42 at the position corresponding to the bevel structure of the second doping region B and the isolation region C, and remove the insulating isolation layer 42 at the position corresponding to the bevel structure of the second doping region B and the isolation region C, without removing the insulating isolation layer 42 at the position corresponding to the plane structure and the first doping region A. Then, when removing the first doping structure at the position corresponding to the bevel structure of the second doping region B and the isolation region C, it is not necessary to remove the first doping structure at the position corresponding to the plane structure and the first doping region A, so as to obtain a partially exposed area not covered by the first doping structure, a plane structure covering the first doping structure and the insulating isolation layer 42, and the first doping region A.

[0038] Step A3: preparing a second doped region B in other exposed regions outside the above-mentioned inclined surface structure.

[0039] Specifically, a second doping structure is prepared in the first doping region A and a partially exposed region including the bevel structure; the second doping structure of the first doping region A is removed to obtain a bevel structure having a second doping structure and a second doping region B having a second doping structure.

[0040] A second doped structure is formed in other exposed areas and the inclined structure, that is, a second intrinsic silicon-containing film 32 and a second doped silicon-containing film 33 are stacked in sequence from inside to outside, thereby forming an inclined structure and a second doped region B including the second intrinsic silicon-containing film 32 and the second doped silicon-containing film 33.

[0041] In an optional embodiment, when the isolation region C also includes a planar structure, the above-mentioned step A3 includes: preparing a second doping structure in the above-mentioned planar structure, the above-mentioned first doping region A and a partially exposed area including the above-mentioned inclined surface structure; removing the second doping structure of the above-mentioned first doping region A to obtain an inclined surface structure having the above-mentioned second doping structure, a second doping region B having the above-mentioned second doping structure, and a planar structure having the above-mentioned second doping structure, the above-mentioned insulating isolation layer 42 and the above-mentioned first doping structure.

[0042] Step A4: forming a first conductive film 21 in the first doping region A, forming a second conductive film 31 in the second doping region B, and forming a third conductive film 41 with a discontinuous structure in the inclined structure.

[0043] The first conductive film 21 and the second conductive film 31 are continuous structures.

[0044] In an optional embodiment, the above-mentioned step A4 includes: synchronously preparing a conductive film (Transparent Conductive Oxide, TCO) in the above-mentioned first doping region A, the above-mentioned second doping region B and the above-mentioned bevel structure. Since the bevel structure has a certain inclination angle relative to other regions, when depositing the conductive film, the conductive film deposited by the bevel structure directly presents an intermittent structure, and at the same time, a conductive film presenting a continuous structure is deposited in other regions, thereby forming a first conductive film 21 in the above-mentioned first doping region A, forming a second conductive film 31 in the above-mentioned second doping region B, and forming a third conductive film 41 in the bevel structure.

[0045] In an optional embodiment, the above-mentioned step A4 includes: simultaneously preparing a conductive film in the above-mentioned first doping region A, the above-mentioned second doping region B and the above-mentioned bevel structure, and obtaining the first conductive film 21 of the above-mentioned first doping region A, the second conductive film 31 of the above-mentioned second doping region B and the third conductive film 41 of the above-mentioned bevel structure by etching the above-mentioned conductive film on the entire surface.

[0046] It can be understood that when the isolation region also includes a planar structure, step A4 includes synchronously preparing a conductive film in the above-mentioned first doping region A, the above-mentioned second doping region B, the above-mentioned inclined structure and the above-mentioned planar structure, forming a first conductive film 21 in the above-mentioned first doping region A, forming a second conductive film 31 in the above-mentioned second doping region B, forming a third conductive film 41 with an intermittent structure in the inclined structure, and forming a third conductive film 41 with a continuous structure in the planar structure.

[0047] In an optional embodiment, after step A3 and before step A4, the method further comprises: preparing a passivation layer 50 and an anti-reflection layer 60 on another main surface of the silicon substrate 10. Specifically, the passivation layer 50 may include a third intrinsic silicon-containing film 51.

[0048] Furthermore, the passivation layer 50 may further include a third doped silicon-containing film 52 disposed between the third intrinsic silicon-containing film 51 and the anti-reflection layer 60 .

[0049] In an optional embodiment, after the above step A4, the above method further includes: forming a first metal electrode 70 in the above first doping region A, and forming a second metal electrode 80 in the above second doping region B. The first metal electrode 70 is electrically connected to the first conductive film 21, and the second metal electrode 80 is electrically connected to the second conductive film 31.

[0050] It can be understood that, since the inclined structure has a certain inclination angle relative to other regions, when depositing the conductive film, the conductive film deposited on the inclined structure is thinner than the conductive film deposited on other regions, but the conductive films deposited on the inclined structure and other regions are both continuous structures. Then, the conductive films deposited on the inclined structure and other regions are etched by etching the entire surface, and the conductive films with thinner inclined structures are preferentially etched into discontinuous structures, while the conductive films in other regions are still continuous structures, and the entire surface etching is stopped, thereby forming the first conductive film 21 in the first doped region A, the second conductive film 31 in the second doped region B, and the third conductive film 41 in the inclined structure.

[0051] The method for preparing a back-contact solar cell in an embodiment of the present invention forms a slope structure between a first doped region A and a second doped region B having a height difference. The thickness of the conductive film deposited on the slope structure is relatively thin, and a conductive film with an intermittent structure can be formed through a simple process. While achieving effective electrical isolation between the first doped region A and the second doped region B, on the one hand, with respect to the method of opening an isolation groove by laser, the process of opening an isolation groove by laser in the isolation region C is omitted, thereby reducing the laser damage to the back-contact solar cell and further improving the photoelectric conversion efficiency of the back-contact solar cell. On the other hand, with respect to the method of forming the isolation groove by etching, the process of forming a mask layer in the first doped region A and the second doped region B and removing the mask layer before etching the entire surface is omitted, thereby simplifying the preparation process of the back-contact solar cell.

[0052] like Figure 3 As shown, the back-contact solar cell of the embodiment of the present invention mainly includes: a silicon substrate 10; a first doped region A and a second doped region B alternately arranged on the first main surface of the silicon substrate 10, an isolation region C located between the first doped region A and the second doped region B, a first conductive film 21 disposed in the first doped region A, a second conductive film 31 disposed in the second doped region B, and a third conductive film 41 disposed in the isolation region C.

[0053] The silicon substrate 10 may be a P-type silicon substrate 10 doped with a trivalent element, or an N-type silicon substrate 10 doped with a pentavalent element. The trivalent element may be boron, aluminum, etc., and the pentavalent element may be phosphorus, arsenic, etc.

[0054] The first doping region A and the second doping region B have a height difference, and the first doping region A and the second doping region B have opposite doping types. As an example, when the first doping region A is an N-type doping region, the second doping region B is a P-type doping region; when the first doping region A is a P-type doping region, the second doping region B is an N-type doping region.

[0055] The isolation region C includes an inclined surface structure that is arranged obliquely relative to the first doping region A and the second doping region B. The inclined surface structure may be connected to the first doping region A and the second doping region B, that is, by arranging the inclined surface structure between the first doping region A and the second doping region B, a height difference is provided between the first doping region A and the second doping region B. The height difference between the first doping region A and the second doping region B is the height of the inclined surface.

[0056] The third conductive film 41 is a discontinuous structure and the thickness of the third conductive film 41 of the inclined structure is less than the first conductive film 21 and the second conductive film 31. By providing a conductive film with good conductive properties in the first doping region A, the second doping region B and the isolation region C, it is helpful to improve the conductive properties and the photoelectric conversion efficiency of the back contact solar cell. In addition, the discontinuous structure can also achieve effective electrical isolation between the first doping region A and the second doping region B.

[0057] The first conductive film 21, the second conductive film 31 and the third conductive film 41 are obtained by etching the conductive films simultaneously prepared in the first doped region A, the second doped region B and the isolation region C on the entire surface.

[0058] It is understandable that when the conductive films of the above three regions are prepared simultaneously, since the isolation region C is provided with a bevel structure, the thickness of the conductive film deposited on the bevel structure will be less than the thickness of the conductive film deposited on the first doping region A and the second doping region B presenting a plane. At this time, the conductive film deposited on the bevel structure may directly present a discontinuous structure, or may present a continuous structure with a relatively thin thickness. When the conductive film deposited on the bevel structure presents a continuous structure with a relatively thin thickness, the first conductive film 21, the second conductive film 31 and the third conductive film 41 can be prepared by etching the entire surface, and the conductive film with a relatively thin bevel structure is first etched into a discontinuous structure by the etchant, and the etching is stopped at the same time, and the remaining conductive films that do not belong to the bevel structure are not etched into a discontinuous structure, thereby forming the third conductive film 41 of the discontinuous structure of the bevel structure of the isolation region C, the first conductive film 21 of the continuous structure of the first doping region A, and the second conductive film 31 of the continuous structure of the second doping region B, thereby avoiding laser grooving of the isolation region C.

[0059] In an optional embodiment, if Figure 3 and Figure 4 As shown, the inclination angle of the above-mentioned inclined surface structure relative to the above-mentioned first doped region A is 30°≤α≤80° or 100°≤α≤135°. As an example, the inclination angle of the inclined surface structure relative to the first doped region A can be 30°, 40°, 55°, 70°, 80°, 100°, 110°, 125°, 135°, etc.

[0060] Preferably, an inclination angle of the inclined surface structure relative to the first doping region A is 40°≤α≤70° or 100°≤α≤125°.

[0061] It should be noted that the first doped region A here refers to an N-type doped region.

[0062] In an optional embodiment, if Figure 3and Figure 4 As shown, the height of the inclined surface structure is greater than or equal to 3 μm and less than 10 μm. As an example, the height H of the inclined surface structure can be 3 μm, 5 μm, 6 μm, 7 μm or 10 μm.

[0063] Preferably, the height of the inclined surface structure is greater than or equal to 5 μm and less than 8 μm.

[0064] It can be understood that the height of the inclined surface structure is the height difference between the first doping region A and the second doping region. Generally, when the doping type of the first doping region A is N-type, the doping type of the second doping region B is P-type. Since the first doping structure of the N-type region is prepared first, the inclined surface structure is formed, and then the second doping structure of the P-type region is prepared, the height of the second doping region B from the second main surface of the silicon substrate 10 is less than the height of the first doping region A from the second main surface of the silicon substrate 10.

[0065] By controlling the inclination angle and height of the slope structure, the thickness of the conductive film deposited on the slope structure can be controlled, and then the thickness of the third conductive film 41 of the slope structure and the interval of the discontinuity can be controlled. On the one hand, the isolation area C can be used to better achieve electrical isolation between the first doped region A and the second doped region B. On the other hand, sufficient third conductive film 41 can be left on the slope structure to increase the effective area for carrier collection.

[0066] In an optional embodiment, if Figure 3 As shown, the first doped region A includes a tunneling oxide layer 22 and a doped polysilicon layer 23 stacked sequentially from the inside to the outside, wherein the first conductive film 21 is stacked outside the doped polysilicon layer 23 .

[0067] The tunnel oxide layer 22 may include silicon oxide. The thickness of the tunnel oxide layer 22 may be 0.5-3 nm. As an example, the thickness of the tunnel oxide layer 22 may be 0.5 nm, 1.5 nm, 2 nm, or 3 nm.

[0068] The doping type of the doped polysilicon layer 23 indicates the doping type of the first doped region A, and is opposite to the doping type of the second doped silicon-containing film 33. Generally, the doping type of the doped polysilicon layer 23 is N-type. Optionally, the doping type of the doped polysilicon layer 23 is the same as the conductivity type of the silicon substrate 10. As an example, when the conductivity type of the silicon substrate 10 is N-type, the doping type of the doped polysilicon layer 23 is N-type.

[0069] The first conductive film 21 disposed in the first doping region A is a continuous structure, which facilitates the lateral transmission of carriers in the first doping region A, so as to better collect the carriers in the first doping region A. The first conductive film 21 can be a film composed of a multilayer, stacked layer or mixture of one or more doped metal oxides or doped metal nitrides, wherein the metal oxides in the doped metal oxides include but are not limited to indium oxide, tin oxide, zinc oxide, cadmium oxide, titanium oxide; the metal nitrides in the doped metal amides include but are not limited to titanium nitride; the doping elements of the doped metal oxides or doped metal nitrides include but are not limited to indium, tin, calcium, aluminum, cadmium, zinc, cerium, and fluorine.

[0070] In an optional embodiment, if Figure 4 As shown, the first doped region A includes a first intrinsic silicon-containing film 24 and a first doped silicon-containing film 25 stacked sequentially from inside to outside, wherein the first conductive film 21 is stacked outside the first doped silicon-containing film 25 .

[0071] The first intrinsic silicon-containing film 24 includes but is not limited to a single layer, a multilayer or a stacked layer of one or more silicon-containing films, or a film composed of a mixture of any multiple of silicon, silicon oxide or silicon carbide. The silicon-containing film includes at least one of the films containing silicon, silicon oxide or silicon carbide. It should be noted that the silicon, silicon oxide or silicon carbide in the first intrinsic silicon-containing film 24 refers to microcrystalline, nanocrystalline or amorphous silicon, silicon oxide or silicon carbide.

[0072] The doping type of the first doped silicon-containing film 25 indicates the doping type of the first doped region A, and is opposite to the doping type of the second doped silicon-containing film 33. Generally, the doping type of the first doped silicon-containing film 25 can be N-type. The above-mentioned first doped silicon-containing film 25 includes but is not limited to a film composed of a single layer, a multilayer or a stacked layer of one or more doped silicon-containing films, or a film composed of a mixture of any multiple of doped silicon, doped silicon oxide or doped silicon carbide. Among them, the doped silicon-containing film includes at least one of the films containing doped silicon, doped silicon oxide or doped silicon carbide. It should be noted that the doped silicon, doped silicon oxide or doped silicon carbide in the first doped silicon-containing film 25 refers to microcrystalline, nanocrystalline or amorphous doped silicon, doped silicon oxide or doped silicon carbide.

[0073] Specifically, the thickness of the first doped silicon-containing film 25 is 1 nm-50 nm. As an example, the thickness of the first doped silicon-containing film 25 can be 1 nm, 3 nm, 10 nm, 25 nm, 40 nm or 50 nm.

[0074] The first conductive film 21 disposed in the first doping region A is a continuous structure, which facilitates the lateral transmission of carriers in the first doping region A, so as to better collect the carriers in the first doping region A. The first conductive film 21 can be a film composed of a multilayer, stacked layer or mixture of one or more doped metal oxides or doped metal nitrides, wherein the metal oxides in the doped metal oxides include but are not limited to indium oxide, tin oxide, zinc oxide, cadmium oxide, titanium oxide; the metal nitrides in the doped metal amides include but are not limited to titanium nitride; the doping elements of the doped metal oxides or doped metal nitrides include but are not limited to indium, tin, calcium, aluminum, cadmium, zinc, cerium, and fluorine.

[0075] In an optional embodiment, if Figure 3 and Figure 4 As shown, the second doped region B includes a second intrinsic silicon-containing film 32 and a second doped silicon-containing film 33 stacked sequentially from the inside to the outside, wherein the second conductive film 31 is stacked outside the second doped silicon-containing film 33 .

[0076] The second intrinsic silicon-containing film 32 includes but is not limited to a single layer, a multilayer or a stacked layer of one or more silicon-containing films, or a film composed of a mixture of any of silicon, silicon oxide or silicon carbide. The silicon-containing film includes at least one of the films containing silicon, silicon oxide or silicon carbide. It should be noted that the silicon, silicon oxide or silicon carbide in the second intrinsic silicon-containing film 32 refers to microcrystalline, nanocrystalline or amorphous silicon, silicon oxide or silicon carbide.

[0077] The doping type of the second doped silicon-containing film 33 indicates the doping type of the first doped region A, and is opposite to the doping type of the second doped silicon-containing film 33. Generally, the doping type of the second doped silicon-containing film 33 may be P-type. The above-mentioned second doped silicon-containing film 33 includes but is not limited to a film composed of a single layer, a multilayer or a stacked layer of one or more doped silicon-containing films, or a film composed of a mixture of any multiple of doped silicon, doped silicon oxide or doped silicon carbide. Among them, the doped silicon-containing film includes at least one of the films containing doped silicon, doped silicon oxide or doped silicon carbide. It should be noted that the doped silicon, doped silicon oxide or doped silicon carbide in the second doped silicon-containing film 33 refers to microcrystalline, nanocrystalline or amorphous doped silicon, doped silicon oxide or doped silicon carbide.

[0078] Specifically, the thickness of the second doped silicon-containing film 33 is 1 nm-50 nm. As an example, the thickness of the second doped silicon-containing film 33 may be 1 nm, 3 nm, 10 nm, 25 nm, 40 nm or 50 nm.

[0079] The second conductive film 31 disposed in the second doping region B is a continuous structure, which facilitates the lateral transmission of carriers in the second doping region B, so as to better collect the carriers in the second doping region B. The second conductive film 31 can be a film composed of a multilayer, stacked layer or mixture of one or more doped metal oxides or doped metal nitrides, wherein the metal oxides in the doped metal oxides include but are not limited to indium oxide, tin oxide, zinc oxide, cadmium oxide, titanium oxide; the metal nitrides in the doped metal amides include but are not limited to titanium nitride; the doping elements of the doped metal oxides or doped metal nitrides include but are not limited to indium, tin, calcium, aluminum, cadmium, zinc, cerium, and fluorine.

[0080] In an optional embodiment, the inclined surface structure may include a second intrinsic silicon-containing film 32 and a second doped silicon-containing film 33 extending from the second doped region and stacked sequentially from the inside to the outside, wherein the third conductive film 41 is stacked outside the second doped silicon-containing film 33. That is, the inclined surface structure may have the same second intrinsic silicon-containing film 32 and second doped silicon-containing film 33 as the second doped region B.

[0081] Among them, the second intrinsic silicon-containing film 32 of the bevel structure is the same as the second intrinsic silicon-containing film 32 of the second doped region B, and will not be repeated here. Similarly, the second doped silicon-containing film 33 of the bevel structure is the same as the second doped silicon-containing film 33 of the second doped region B, and will not be repeated here. It should be understood that in the case where the bevel structure includes the second intrinsic silicon-containing film 32 and the second doped silicon-containing film 33, the second intrinsic silicon-containing film 32 and the second doped silicon-containing film 33 extend from the second doped region to the bevel structure, that is, the second intrinsic silicon-containing film 32 of the bevel structure and the second intrinsic silicon-containing film 32 of the second doped region B are an integral structure; the second doped silicon-containing film 33 of the bevel structure and the second doped silicon-containing film 33 of the second doped region B are an integral structure.

[0082] Due to the setting of the inclined structure, the thickness of the conductive film deposited on the inclined structure is less than the thickness of the conductive film deposited in other regions, and thus the thickness of the third conductive film 41 formed in the inclined structure is less than the thickness of the first conductive film 21 and the second conductive film 31. The third conductive film 41 is a discontinuous structure, which ensures effective electrical isolation of the first doped region A and the second doped region B.

[0083] In an optional embodiment, if Figure 4As shown, the isolation region C further includes a planar structure, wherein the planar structure is located between the inclined structure and the first doped region. In order to better disconnect the functional layer of the first doped region A from the functional layer of the second doped region B, a planar structure may also be provided in the isolation region C, that is, the second intrinsic silicon-containing film 32 and the second doped silicon-containing film 33 in the inclined structure are extended to cover part of the functional layer belonging to the first doped region A.

[0084] Specifically, when the above-mentioned first doped region A includes the above-mentioned tunneling oxide layer 22 and the above-mentioned doped polysilicon layer 23, the planar structure includes the tunneling oxide layer 22 and the doped polysilicon layer 23 extending from the first doped region, which are stacked in sequence from the inside to the outside, the insulating isolation layer 42 stacked on the outside of the doped polysilicon layer 23, and the second intrinsic silicon-containing film 32 and the second doped silicon-containing film 33 extending from the second doped region; when the above-mentioned first doped region A includes the above-mentioned first intrinsic silicon-containing film 24 and the above-mentioned first doped silicon-containing film 25, the planar structure includes the first intrinsic silicon-containing film 24 and the first doped silicon-containing film 25 extending from the first doped region, which are stacked in sequence from the inside to the outside, the insulating isolation layer 42 stacked on the outside of the first doped silicon-containing film 25, and the second intrinsic silicon-containing film 32 and the second doped silicon-containing film 33 extending from the second doped region.

[0085] The third conductive film 41 is stacked on the outer side of the second doped silicon-containing film 33 .

[0086] Furthermore, the insulating isolation layer 42 includes one or more of silicon oxide, silicon nitride, and silicon oxynitride, but is not limited thereto.

[0087] It should be noted that the second intrinsic silicon-containing film 32 of the planar structure is the same as the second intrinsic silicon-containing film 32 of the second doped region B, and is an integral structure; the second doped silicon-containing film 33 of the planar structure is the same as the second doped silicon-containing film 33 of the second doped region B, and is an integral structure. In the case where the planar structure includes a tunneling oxide layer 22 and a doped polysilicon layer 23, the tunneling oxide layer 22 of the planar structure is the same as the tunneling oxide layer 22 of the first doped region A, and is an integral structure; the doped polysilicon layer 23 of the planar structure is the same as the doped polysilicon layer 23 of the first doped region A, and is an integral structure. In the case where the planar structure includes a first intrinsic silicon-containing film 24 and a first doped silicon-containing film 25, the first intrinsic silicon-containing film 24 of the planar structure is the same as the first intrinsic silicon-containing film 24 of the first doped region A, and is an integral structure; the first doped silicon-containing film 25 of the planar structure is the same as the first doped silicon-containing film 25 of the first doped region A, and is an integral structure. I will not repeat them one by one here.

[0088] In a possible implementation, the width of the insulating isolation layer 42 is greater than or equal to 20 μm and less than 200 μm. In fact, in order to avoid conduction between film layers with different doping types in the planar structure, a complete insulating isolation layer 42 should be provided between film layers with different doping types in the planar structure. Therefore, the width of the insulating isolation layer 42 indicates the width of the planar structure in the isolation region C.

[0089] In addition, the third conductive film 41 in the third conductive film covering the planar structure may be a continuous structure, and its thickness may be the same as that of the first conductive film 21 or the second conductive film 31. It can be understood that when the third conductive film 41 in the inclined structure is a discontinuous structure, effective electrical isolation between the first doped region A and the second doped region B is ensured, and the third conductive film 41 in the planar structure may not be set as a spacer structure.

[0090] In an optional embodiment, if Figure 3 and Figure 4 As shown, the back-contact solar cell may further include: a passivation layer 50 and an anti-reflection layer 60 which are sequentially arranged on the second main surface of the silicon substrate 10 in a direction away from the silicon substrate 10 .

[0091] Among them, Figure 3 As shown, the passivation layer 50 may include a third intrinsic silicon-containing film 51. Specifically, the third intrinsic silicon-containing film 51 includes but is not limited to a film composed of a single layer, a multilayer or a stack of one or more silicon-containing films, or a film composed of a mixture of any multiple of silicon, silicon oxide or silicon carbide. Among them, the silicon-containing film includes at least one of the films containing silicon, silicon oxide or silicon nitride. It should be noted that the silicon, silicon oxide or silicon carbide in the third intrinsic film refers to microcrystalline, nanocrystalline or amorphous silicon, silicon oxide or silicon carbide. The thickness of the third intrinsic silicon-containing film 51 is 1nm-15nm. As an example, the thickness of the third intrinsic film can be 1nm, 2nm, 7nm, 10nm or 15nm, etc.

[0092] The anti-reflection layer 60 is at least one of aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon oxynitride, aluminum nitride, magnesium fluoride, lithium fluoride, zinc oxide, and indium tin oxide semiconductor transparent conductive film (Indium Tin Oxides, ITO). The thickness of the anti-reflection layer 60 is 40nm-200nm. As an example, the thickness of the anti-reflection layer 60 can be 40nm, 80nm, 100nm, 150nm or 200nm, etc.

[0093] Furthermore, if Figure 4 As shown, the passivation layer 50 may further include a third doped silicon-containing film 52 disposed between the third intrinsic silicon-containing film 51 and the anti-reflection layer 60 .

[0094] Specifically, the third doped silicon-containing film 52 includes but is not limited to a film composed of a single layer, a multilayer or a stacked layer of one or more doped silicon-containing films, or a film composed of a mixture of any multiple of doped silicon, doped silicon oxide or doped silicon carbide. Among them, the doped silicon-containing film includes at least one of the films containing doped silicon, doped silicon oxide or doped silicon carbide. It should be noted that the doped silicon, doped silicon oxide or doped silicon carbide in the third doped silicon-containing film 52 refers to microcrystalline, nanocrystalline or amorphous doped silicon, doped silicon oxide or doped silicon carbide. The thickness of the third doped silicon-containing film 52 is 0-15nm. As an example, the thickness of the third doped silicon-containing film 52 can be 0.1nm, 2nm, 7nm, 10nm or 15nm, etc.

[0095] In an optional embodiment, if Figure 3 and Figure 4 As shown, the back contact solar cell may further include: a first metal electrode 70 disposed in the first doping region A and a second metal electrode 80 disposed in the second doping region B.

[0096] Specifically, the first metal electrode 70 is electrically connected to the first conductive film 21 of the first doping region A; the second metal electrode 80 is electrically connected to the second conductive film 31 of the second doping region B. The first metal electrode 70 and the second metal electrode 80 are a multilayer electrode composed of one of a silver electrode, a silver alloy electrode, a copper electrode and a copper alloy electrode, or any multiple of them, or a multilayer electrode composed of nickel, copper, and silver.

[0097] In an optional embodiment, the first main surface of the silicon substrate 10 is a suede surface.

[0098] The back-contact solar cell of the embodiment of the present invention sets a slope structure in the isolation region C between the first doping region A and the second doping region B, so that the thickness of the conductive film deposited in the slope structure is less than the conductive film deposited in the first doping region A and the second doping region B, so that a third conductive film 41 with an intermittent structure can be formed in the slope structure, eliminating the process of laser opening an isolation groove in the isolation region C, reducing laser damage to the back-contact solar cell, and further improving the photoelectric conversion efficiency of the back-contact solar cell.

[0099] In the embodiment of the present invention, the isolation region C may only include a slope structure of a third conductive film 41 provided with a first doping structure and a discontinuous structure. The first doping region A and the second doping region B can be effectively electrically isolated by the conductive film of the discontinuous structure, and the effective area for carrier collection can be increased. The prior art method of superimposing the first doping structure, the insulating isolation layer 42, the second doping structure and the conductive film at the position adjacent to the first doping region A and the second doping region B and then opening an isolation groove to form a structure of the isolation region C in which carrier collection is almost impossible is abandoned.

[0100] In summary, the embodiments of the present invention provide the following technical solutions:

[0101] Technical solution 1, a method for preparing a back contact solar cell, comprising:

[0102] Step A1, preparing a first doping structure on a main surface of the silicon substrate 10;

[0103] Step A2, removing part of the first doping structure to obtain a partially exposed area of ​​the silicon substrate 10 and a first doping area having the first doping structure, and preparing an inclined surface structure connected to the first doping structure in the partially exposed area;

[0104] Step A3, preparing a second doped region in other exposed regions outside the inclined surface structure;

[0105] Step A4: forming a first conductive film 21 in the first doping region, forming a second conductive film 31 in the second doping region, and forming a third conductive film 41 with a discontinuous structure in the inclined structure.

[0106] Technical solution 2: According to the method for preparing a back-contact solar cell according to technical solution 1, step A4 comprises:

[0107] Conductive films are simultaneously prepared in the first doped region, the second doped region and the slope structure, and the first conductive film 21, the second conductive film 31 and the third conductive film 41 are obtained by etching the conductive film entirely.

[0108] Technical solution 3: According to the method for preparing a back-contact solar cell according to technical solution 1, step A2 comprises:

[0109] Removing part of the first doping structure by polishing or texturing to obtain a partially exposed area of ​​the silicon substrate 10 and a first doping area having the first doping structure;

[0110] The partially exposed area is subjected to a texturing treatment; during the texturing treatment, a slope structure connected to the first doping structure is prepared.

[0111] Technical solution 4: According to the method for preparing a back-contact solar cell according to technical solution 1, step A3 comprises:

[0112] Prepare a second doping structure in the first doping region and a partially exposed region including the slope structure;

[0113] The second doping structure of the first doping region is removed to obtain a slope structure having the second doping structure and a second doping region having the second doping structure.

[0114] Technical solution 5: According to the method for preparing a back-contact solar cell according to technical solution 1, step A2 comprises:

[0115] Prepare an insulating isolation layer 42 outside the first doping structure;

[0116] Removing part of the insulating isolation layer 42 and part of the first doping structure to obtain a partially exposed area of ​​the silicon substrate 10 and an area having the insulating isolation layer 42 and the first doping structure;

[0117] For the region having the insulating isolation layer 42 and the first doping structure, a portion of the insulating isolation layer 42 is removed to obtain a first doped region having the first doping structure and a planar structure having the insulating isolation layer 42 and the first doping structure;

[0118] The partially exposed area is subjected to a texturing treatment; during the texturing treatment, a slope structure connected to the first doping structure is prepared.

[0119] Technical solution 6: According to the method for preparing a back-contact solar cell according to technical solution 5, step A3 comprises:

[0120] Prepare a second doping structure on the planar structure, the first doping region and a partially exposed region including the inclined structure;

[0121] The second doping structure of the first doping region is removed to obtain an inclined structure having the second doping structure, a second doping region having the second doping structure, and a planar structure having the second doping structure, the insulating isolation layer 42, and the first doping structure.

[0122] Technical solution 7, a back contact solar cell, comprising:

[0123] Silicon substrate 10;

[0124] A first doped region and a second doped region are alternately arranged on the first main surface of the silicon substrate 10, an isolation region between the first doped region and the second doped region, a first conductive film 21 is arranged in the first doped region, a second conductive film 31 is arranged in the second doped region, and a third conductive film 41 is arranged in the isolation region; wherein:

[0125] The first doping region and the second doping region have a height difference, and the first doping region and the second doping region have opposite doping types;

[0126] The isolation region includes a slope structure that is tilted relative to the first doping region and the second doping region;

[0127] The third conductive film 41 is a discontinuous structure, and the thickness of the third conductive film 41 with the inclined structure is smaller than that of the first conductive film 21 and the second conductive film 31 .

[0128] Technical solution 8: A back-contact solar cell according to technical solution 7,

[0129] The first conductive film 21, the second conductive film 31 and the third conductive film 41 are obtained by etching the conductive films simultaneously prepared in the first doped region, the second doped region and the isolation region.

[0130] Technical solution 9. A back-contact solar cell according to technical solution 7,

[0131] The inclination angle of the inclined surface structure relative to the first doped region is 30°≤α≤80° or 100°≤α≤135°;

[0132] Preferably, the inclination angle of the slope structure relative to the first doping region is 40°≤α≤70° or 100°≤α≤125°.

[0133] Technical solution 10. A back-contact solar cell according to technical solution 7,

[0134] The height of the slope structure is greater than or equal to 3 μm and less than 10 μm;

[0135] Preferably, the height of the inclined surface structure is greater than or equal to 5 μm and less than 8 μm.

[0136] Technical solution 11, a back contact solar cell according to technical solution 7,

[0137] The first doped region includes a tunneling oxide layer 22 and a doped polysilicon layer 23 stacked in sequence from the inside to the outside, wherein the first conductive film 21 is stacked on the outside of the doped polysilicon layer 23;

[0138] or,

[0139] The first doped region includes a first intrinsic silicon-containing film 24 and a first doped silicon-containing film 25 stacked in sequence from the inside to the outside, wherein the first conductive film 21 is stacked on the outside of the first doped silicon-containing film 25 .

[0140] Technical solution 12. A back-contact solar cell according to technical solution 11,

[0141] The second doped region includes a second intrinsic silicon-containing film 32 and a second doped silicon-containing film 33 stacked in sequence from the inside to the outside, wherein the second conductive film 31 is stacked on the outside of the second doped silicon-containing film 33 .

[0142] Technical solution 13. A back-contact solar cell according to technical solution 12,

[0143] The inclined surface structure includes a second intrinsic silicon-containing film 32 and a second doped silicon-containing film 33 extending from the second doped region and stacked sequentially from the inside to the outside, wherein the third conductive film 41 is stacked outside the second doped silicon-containing film 33;

[0144] and / or,

[0145] The isolation region further includes a planar structure, wherein the planar structure is located between the inclined structure and the first doped region;

[0146] When the first doped region includes the tunneling oxide layer 22 and the doped polysilicon layer 23, the planar structure includes the tunneling oxide layer 22 and the doped polysilicon layer 23 sequentially stacked from the inside to the outside extending from the first doped region, an insulating isolation layer 42 stacked on the outside of the doped polysilicon layer 23, and the second intrinsic silicon-containing film 32 and the second doped silicon-containing film 33 extending from the second doped region;

[0147] When the first doped region includes the first intrinsic silicon-containing film 24 and the first doped silicon-containing film 25, the planar structure includes the first intrinsic silicon-containing film 24 and the first doped silicon-containing film 25 sequentially stacked from the inside to the outside extending from the first doped region, the insulating isolation layer 42 stacked on the outside of the first doped silicon-containing film 25, and the second intrinsic silicon-containing film 32 and the second doped silicon-containing film 33 extending from the second doped region;

[0148] The third conductive film 41 is stacked on the outer side of the second doped silicon-containing film 33 .

[0149] Technical solution 14. A back-contact solar cell according to technical solution 13,

[0150] In the case where the isolation region also includes a planar structure,

[0151] The width of the insulating isolation layer 42 is greater than or equal to 20 μm and less than 200 μm.

[0152] Technical solution 15. A back-contact solar cell according to technical solution 13,

[0153] The portion of the third conductive film 41 covering the planar structure is a continuous structure.

[0154] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may occur depending on design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a back contact solar cell, characterized in that: include: Step A1, preparing a first doping structure on a main surface of a silicon substrate (10); Step A2, removing part of the first doping structure to obtain a partially exposed area of ​​the silicon substrate (10) and a first doping area having the first doping structure, and preparing an inclined surface structure connected to the first doping structure in the partially exposed area; Step A3, preparing a second doped region in other exposed regions outside the inclined surface structure; Step A4, forming a first conductive film (21) in the first doping region, forming a second conductive film (31) in the second doping region, and forming a third conductive film (41) with a discontinuous structure in the inclined structure.

2. The method for preparing a back contact solar cell according to claim 1, characterized in that: The step A4 comprises: Conductive films are simultaneously prepared in the first doped region, the second doped region and the inclined surface structure, and the first conductive film (21), the second conductive film (31) and the third conductive film (41) are obtained by etching the conductive film over its entire surface.

3. The method for preparing a back contact solar cell according to claim 1, characterized in that: The step A2 comprises: Removing part of the first doping structure by polishing or texturing to obtain a partially exposed area of ​​the silicon substrate (10) and a first doping area having the first doping structure; The partially exposed area is subjected to a texturing treatment; during the texturing treatment, a slope structure connected to the first doping structure is prepared.

4. The method for preparing a back contact solar cell according to claim 1, characterized in that: The step A3 comprises: Prepare a second doping structure in the first doping region and a partially exposed region including the bevel structure; The second doping structure of the first doping region is removed to obtain a slope structure having the second doping structure and a second doping region having the second doping structure.

5. The method for preparing a back contact solar cell according to claim 1, characterized in that: The step A2 comprises: Preparing an insulating isolation layer (42) outside the first doping structure; Removing part of the insulating isolation layer (42) and part of the first doping structure to obtain a partially exposed area of ​​the silicon substrate (10) and an area having the insulating isolation layer (42) and the first doping structure; For the region having the insulating isolation layer (42) and the first doping structure, a portion of the insulating isolation layer (42) is removed to obtain a first doping region having the first doping structure and a planar structure having the insulating isolation layer (42) and the first doping structure; The partially exposed area is subjected to a texturing treatment; during the texturing treatment, a slope structure connected to the first doping structure is prepared.

6. The method for preparing a back contact solar cell according to claim 5, characterized in that: The step A3 comprises: Prepare a second doping structure on the planar structure, the first doping region and a partially exposed region including the inclined structure; The second doping structure of the first doping region is removed to obtain an inclined structure having the second doping structure, a second doping region having the second doping structure, and a planar structure having the second doping structure, the insulating isolation layer (42), and the first doping structure.

7. A back contact solar cell, characterized in that: include: Silicon substrate (10); A first doping region and a second doping region are alternately arranged on a first main surface of the silicon substrate (10), an isolation region is located between the first doping region and the second doping region, a first conductive film (21) is arranged in the first doping region, a second conductive film (31) is arranged in the second doping region, and a third conductive film (41) is arranged in the isolation region; wherein: The first doping region and the second doping region have a height difference, and the first doping region and the second doping region have opposite doping types; The isolation region includes a slope structure that is tilted relative to the first doping region and the second doping region; The third conductive film (41) is a discontinuous structure, and the thickness of the third conductive film (41) with an inclined surface structure is smaller than that of the first conductive film (21) and the second conductive film (31).

8. The back contact solar cell according to claim 7, characterized in that: The first conductive film (21), the second conductive film (31) and the third conductive film (41) are obtained by etching the conductive films simultaneously prepared in the first doped region, the second doped region and the isolation region.

9. The back contact solar cell according to claim 7, characterized in that: The inclination angle of the inclined surface structure relative to the first doped region is 30°≤α≤80° or 100°≤α≤135°; Preferably, the inclination angle of the slope structure relative to the first doping region is 40°≤α≤70° or 100°≤α≤125°.

10. The back contact solar cell according to claim 7, characterized in that: The height of the slope structure is greater than or equal to 3 μm and less than 10 μm; Preferably, the height of the inclined surface structure is greater than or equal to 5 μm and less than 8 μm.

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