Back contact solar cell

Abstract

The utility model discloses a back contact solar cell. The cell includes: a silicon substrate; the first doped regions and the second doped regions are alternately arranged on the first main surface of the silicon substrate, the isolation regions are located between the first doped regions and the second doped regions, the first conductive thin films are arranged in the first doped regions, the second conductive thin films are arranged in the second doped regions, and the third conductive thin films are arranged in the isolation regions; wherein the first doped region and the second doped region have a height difference, and the doping types of the first doped region and the second doped region are opposite; the isolation region comprises an inclined plane structure which is obliquely arranged relative to the first doped region and the second doped region; the third conductive film is of a discontinuous structure, and the thickness of the third conductive film of the slope structure is smaller than that of the first conductive film and the second conductive film. 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 cell is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to solar cell technical field especially relates to a back contact solar cell. BACKGROUND

[0002] With the development of solar cell technology, back contact (BC) cell emerges as the times require. The BC cell is to set all electrodes on the back surface of the cell, so that the light surface of the cell is completely exposed to sunlight, thereby improving the light absorption efficiency. Because the BC solar cell back surface is provided with N type area and P type area at the same time, for the BC solar cell laid with conductive film, the phenomenon of two area electric conduction will appear, and then lead to positive and negative pole short circuit or electric leakage. Therefore, at present, the two areas are generally insulated by opening isolation groove between N type area and P type area. The isolation groove is generally opened by laser, and in the process of opening the isolation groove, there may be errors leading to the failure to realize the effective insulation of the two areas. In addition, the laser damage to the cell sheet is inevitable in the process of laser film opening, which reduces the photoelectric conversion efficiency of the BC cell. Therefore, at present, there is an urgent need for a BC cell without laser opening isolation groove. SUMMARY

[0003] Therefore, the utility model discloses a back contact solar cell, can dispense with the process of laser opening isolation groove, simplify the preparation process of back contact solar cell, improve the photoelectric conversion efficiency of back contact solar cell.

[0004] To achieve the above object, according to an aspect of the utility model embodiment, a back contact solar cell is provided. The utility model embodiment of a back contact solar cell includes:

[0005] Silicon base body;

[0006] The first doped region and the second doped region arranged alternately on the first main surface of the above-mentioned silicon base body, the isolation region between the first doped region and the second doped region, the first conductive film arranged on the first doped region, the second conductive film arranged on the second doped region and the third conductive film arranged on the isolation region;Wherein,

[0007] The first doped region and the second doped region have height difference, and the doping type of the first doped region and the second doped region is opposite;

[0008] The isolation region includes the inclined surface structure arranged obliquely relative to the first doped region and the second doped region;

[0009] The third conductive film is discontinuous, and the third conductive film of the inclined surface structure has a thickness less than the first conductive film and the second conductive film.

[0010] The embodiment of the utility model has the advantages or beneficial effects that: by arranging the inclined surface structure in the isolation region between the first doped region and the second doped region, the thickness of the conductive film deposited in the inclined surface structure is less than the conductive film deposited in the first doped region and the second doped region, and then the third conductive film of the discontinuous structure can be formed in the inclined surface structure, the process of laser opening the isolation groove in the isolation region is omitted, the laser damage to the back contact solar cell is reduced, and the photoelectric conversion efficiency of the back contact solar cell is further improved.

[0011] The further effects of the non-conventional optional mode will be described below in combination with the specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0012] The accompanying drawings are used to better understand the utility model and do not constitute undue limitations on the utility model. Among them:

[0013] Figure 1 is a structural schematic diagram of a back contact solar cell in the prior art;

[0014] Figure 2 is a flowchart of a preparation method of a back contact solar cell according to an embodiment of the utility model;

[0015] Figure 3 is a first structural schematic diagram of a back contact solar cell according to an embodiment of the utility model;

[0016] Figure 4 is a second structural schematic diagram of a back contact solar cell according to an embodiment of the utility model.

[0017] Reference signs:

[0018] 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-antireflection layer; 70-first metal electrode; 80-second metal electrode. DETAILED DESCRIPTION

[0019] For the back contact solar cell, in order to avoid the first doped region A and the second doped region B conduct electricity through the conductive film, the first doped region A and the second doped region B need to be electrically isolated. As shown in Figure 1 The first doped region A and the second doped region B are electrically isolated by setting the isolation area C composed of the first doped structure, the insulating isolation layer 42, the second doped structure and the conductive film between the first doped region A and the second doped region B, and by opening the isolation groove in the isolation area C. However, since the planes where the first doped region A, the second doped region B and the third doped region are located are parallel to each other, the thicknesses of the conductive films of the above three regions are basically the same when the conductive film is prepared, and the conductive film in the isolation area C needs to be disconnected by opening the isolation groove by laser, which causes laser damage to the cell piece and reduces the photoelectric conversion efficiency of the back contact solar cell.

[0020] 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 with the first doped structure and the conductive film and on the surface of the second doped region B with the second doped structure and the conductive film to prevent the first doped region A and the second doped region B from being affected during etching. After the mask layer is formed, the conductive film of the isolation area C is etched to form the isolation groove. Then the mask layer is removed. The formation and removal of the mask layer require a lot of time, making the preparation process of the back contact solar cell complicated.

[0021] The exemplary embodiments of the present application will be described below with reference to the accompanying drawings, which include various details of the present application embodiments to help understanding, and should be considered as merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Also, for the sake of clarity and conciseness, the description below omits the description of well-known functions and structures.

[0022] It should be noted that the inside-out direction referred to in the embodiments of the present application means the direction away from the silicon substrate 10. The first main surface referred to in the embodiments of the present application means the side of the back contact solar cell away from sunlight when working, and the second main surface means the side of the back contact solar cell facing sunlight when working.

[0023] It should be noted that the embodiments of the present application and the technical features in the embodiments can be combined with each other without conflict.

[0024] In order to avoid the above-mentioned problems in the prior art, the embodiments of the present application provide a preparation method of a back contact solar cell which can avoid opening an isolation groove in the isolation area C and thus reduce the number of lasers.

[0025] Figure 2 is a flowchart of a preparation method of a back contact solar cell according to an embodiment of the present application. As shown in the figure, the present embodiment provides a preparation method of a back contact solar cell, including the following steps A1~A4: Figure 2

[0026] Step A1, preparing a first doped structure on one main surface of a silicon substrate 10.

[0027] The silicon substrate 10 is subjected to texturing treatment. A first doped structure is formed on the entire surface of one main surface of the silicon substrate 10 after texturing. The first doped structure is a tunneling oxide layer 22 and a doped polysilicon layer 23 stacked in order from inside to outside, or the first doped structure is a first intrinsic silicon-containing thin film 24 and a first doped silicon-containing thin film 25 stacked in order from inside to outside.

[0028] Step A2, removing part of the first doped structure to obtain a partially exposed region of the silicon substrate 10 and a first doped region A with the first doped structure, and preparing a bevel structure connected to the first doped structure on the partially exposed region;

[0029] Specifically, part of the first doped structure is removed by polishing or texturing to obtain a partially exposed region of the silicon substrate 10 and a first doped region A with the first doped structure; the partially exposed region is subjected to texturing treatment; and a bevel structure connected to the first doped structure is prepared during the texturing treatment.

[0030] The first doped structure at the position corresponding to the bevel structure of the second doped region B and the isolation region C is removed by polishing or texturing to obtain a partially exposed region not covered by the first doped structure and a first doped region A covered by the first doped structure. When the part of the first doped structure is removed by polishing, the polishing solution can be adjusted and / or the polishing time can be controlled; when the part of the first doped structure is removed by texturing, the texturing agent can be adjusted and / or the texturing time can be controlled to form a height difference between the position corresponding to the second doped region B and the position of the first doped region A, so as to form a bevel structure connected to the first doped structure between the position corresponding to the second doped region B and the position of the first doped region A.

[0031] ​In an alternative embodiment, when the isolation region C further comprises a planar structure, the step A2 can comprise: preparing an insulating isolation layer 42 outside the first doped structure; removing part of the insulating isolation layer 42 and part of the first doped structure to obtain a partially exposed region of the silicon substrate 10 and a region with the insulating isolation layer 42 and the first doped structure; removing part of the insulating isolation layer 42 for the region with the insulating isolation layer 42 and the first doped structure to obtain a first doped region A with the first doped structure and a planar structure with the insulating isolation layer 42 and the first doped structure; performing a texturing process on the partially exposed region; and preparing a bevel structure connected to the first doped structure during the texturing process.

[0032] The outside of the first doped structure refers to the surface of the first doped structure away from the silicon substrate 10. Before removing the first doped structure at the positions corresponding to the second doped region B and the bevel structure of the isolation region C, the insulating isolation layer 42 at the positions corresponding to the second doped region B and the bevel structure of the isolation region C needs to be treated by laser to remove the insulating isolation layer 42 at the positions corresponding to the second doped region B and the bevel structure of the isolation region C, without removing the insulating isolation layer 42 at the positions corresponding to the planar structure and the first doped region A. Then, when removing the first doped structure at the positions corresponding to the second doped region B and the bevel structure of the isolation region C, the first doped structure at the positions corresponding to the planar structure and the first doped region A does not need to be removed, thereby obtaining a partially exposed region without the first doped structure, a planar structure covering the first doped structure and the insulating isolation layer 42, and a first doped region A.

[0033] Step A3: preparing a second doped region B on other exposed regions outside the bevel structure.

[0034] Specifically, a second doped structure is prepared on the first doped region A and the partially exposed region including the bevel structure; the second doped structure of the first doped region A is removed to obtain a bevel structure with the second doped structure and a second doped region B with the second doped structure.

[0035] The second doped structure is formed on the other exposed regions and the bevel structure, i.e., the second intrinsic silicon-containing film 32 and the second doped silicon-containing film 33 are sequentially stacked from inside to outside, thereby forming a bevel structure including the second intrinsic silicon-containing film 32 and the second doped silicon-containing film 33 and a second doped region B.

[0036] In an alternative embodiment, when the isolation region C further comprises a planar structure, the step A3 comprises: preparing a second doping structure on the planar structure, the first doped region A and the part of the exposed region comprising the inclined structure; removing the second doping structure of the first doped region A to obtain the inclined structure with the second doping structure, the second doped region B with the second doping structure and the planar structure with the second doping structure and the insulating isolation layer 42 and the first doping structure.

[0037] The step A4 comprises forming a first conductive film 21 on the first doped region A, forming a second conductive film 31 on the second doped region B and forming a third conductive film 41 with an intermittent structure on the inclined structure, respectively.

[0038] The first conductive film 21 and the second conductive film 31 are continuous structures.

[0039] In an alternative embodiment, the step A4 comprises: simultaneously preparing a transparent conductive oxide (TCO) film on the first doped region A, the second doped region B and the inclined structure. Since the inclined structure has a certain inclination angle relative to other regions, when the TCO film is deposited, the TCO film deposited on the inclined structure directly presents an intermittent structure, while the TCO film deposited on other regions presents a continuous structure, thereby forming the first conductive film 21 on the first doped region A, the second conductive film 31 on the second doped region B and the third conductive film 41 on the inclined structure.

[0040] In an alternative embodiment, the step A4 comprises: simultaneously preparing a TCO film on the first doped region A, the second doped region B and the inclined structure, and obtaining the first conductive film 21 of the first doped region A, the second conductive film 31 of the second doped region B and the third conductive film 41 of the inclined structure by whole surface etching the TCO film.

[0041] It can be understood that, when the isolation region further comprises a planar structure, the step A4 comprises: simultaneously preparing a TCO film on the first doped region A, the second doped region B, the inclined structure and the planar structure, thereby forming the first conductive film 21 on the first doped region A, the second conductive film 31 on the second doped region B, the third conductive film 41 with an intermittent structure on the inclined structure and the third conductive film 41 with a continuous structure on the planar structure.

[0042] In an alternative 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 can include a third intrinsic silicon-containing thin film 51.

[0043] Further, the passivation layer 50 can further include a third doped silicon-containing thin film 52 disposed between the third intrinsic silicon-containing thin film 51 and the anti-reflection layer 60.

[0044] In an alternative embodiment, after step A4, the method further comprises: forming a first metal electrode 70 on the first doped region A and forming a second metal electrode 80 on the second doped region B. The first metal electrode 70 is electrically connected to the first conductive thin film 21, and the second metal electrode 80 is electrically connected to the second conductive thin film 31.

[0045] It can be understood that, since the inclined surface structure has a certain inclination angle relative to other regions, when depositing the conductive thin film, the conductive thin film deposited on the inclined surface structure is thinner than the conductive thin film deposited on other regions, but the conductive thin film deposited on the inclined surface structure and other regions is in a continuous structure. Then, the conductive thin film deposited on the inclined surface structure and other regions is etched by full-area etching, the conductive thin film on the inclined surface structure is preferentially etched into an intermittent structure, the conductive thin film on other regions is still in a continuous structure, and the full-area etching is stopped, so that the first conductive thin film 21 is formed on the first doped region A, the second conductive thin film 31 is formed on the second doped region B, and the third conductive thin film 41 is formed on the inclined surface structure.

[0046] The preparation method of the back contact solar cell according to the embodiments of the present application forms an inclined surface structure between the first doped region A and the second doped region B with a height difference, the thickness of the conductive thin film deposited on the inclined surface structure is thinner, and the conductive thin film with an intermittent structure can be formed by a simple process. On the one hand, for the method of opening an isolation groove by laser, the process of opening an isolation groove by laser on the isolation region C is omitted, the laser damage to the back contact solar cell is reduced, and the photoelectric conversion efficiency of the back contact solar cell is further improved. On the other hand, for the method of forming an isolation groove by etching, the process of forming a mask layer on the first doped region A and the second doped region B before full-area etching and removing the mask layer is omitted, and the preparation process of the back contact solar cell is simplified.

[0047] As Figure 3As shown, the back contact solar cell of the embodiment of the utility model mainly includes: silicon base body 10;The first doped area A and the second doped area B of alternately arranged first main surface of above-mentioned silicon base body 10 are set, the isolation area C between above-mentioned first doped area A and above-mentioned second doped area B, the first conductive film 21 of above-mentioned first doped area A is set, the second conductive film 31 of above-mentioned second doped area B is set and the third conductive film 41 of above-mentioned isolation area C is set.

[0048] The silicon base body 10 can be a P-type silicon base body 10 doped with trivalent elements, or an N-type silicon base body 10 doped with pentavalent elements. The trivalent elements can be boron, aluminum, etc., and the pentavalent elements can be phosphorus, arsenic, etc.

[0049] The first doped area A and the second doped area B have a height difference, and the doping types of the first doped area A and the second doped area B are opposite. As an example, when the first doped area A is an N-type doped area, the second doped area B is a P-type doped area; when the first doped area A is a P-type doped area, the second doped area B is an N-type doped area.

[0050] The isolation area C includes an inclined surface structure inclinedly arranged with respect to the first doped area A and the second doped area B. The inclined surface structure can be connected with the first doped area A and the second doped area B, that is, by arranging the inclined surface structure between the first doped area A and the second doped area B, the first doped area A and the second doped area B have a height difference. The height difference between the first doped area A and the second doped area B is the height of the inclined surface.

[0051] The third conductive film 41 is an intermittent structure, and the thickness of the third conductive film 41 of the inclined surface structure is less than the first conductive film 21 and the second conductive film 31. By arranging the conductive film with good conductivity in the first doped area A, the second doped area B and the isolation area C, the conductivity is improved, the photoelectric conversion efficiency of the back contact solar cell is improved, and the intermittent structure can also realize effective electrical isolation of the first doped area A and the second doped area B.

[0052] The first conductive film 21, the second conductive film 31 and the third conductive film 41 are obtained by simultaneously preparing conductive films on the first doped area A, the second doped area B and the isolation area C by whole surface etching.

[0053] It can be understood that, when the conductive thin films of the three regions are synchronously prepared, the thickness of the conductive thin film deposited on the inclined surface structure is smaller than the thickness of the conductive thin film deposited on the first doped region A and the second doped region B which are flat. At this time, the conductive thin film deposited on the inclined surface structure can directly present an intermittent structure, or present a continuous structure with a small thickness. When the conductive thin film deposited on the inclined surface structure presents a continuous structure with a small thickness, the first conductive thin film 21, the second conductive thin film 31 and the third conductive thin film 41 can be prepared by full-area etching. The conductive thin film of the inclined surface structure with a small thickness is firstly etched into an intermittent structure by an etchant, and the etching is stopped at this time. The conductive thin film which does not belong to the inclined surface structure is not etched into an intermittent structure, thereby forming the third conductive thin film 41 of the intermittent structure of the inclined surface structure of the isolation region C, the first conductive thin film 21 of the continuous structure of the first doped region A and the second conductive thin film 31 of the continuous structure of the second doped region B, and avoiding laser grooving of the isolation region C.

[0054] In an alternative embodiment, as shown in Figure 3 and Figure 4 , the inclination angle of the inclined surface structure with respect to the first doped region A is 30°≤α≤80° or 100°≤α≤135°. For example, the inclination angle of the inclined surface structure with respect to the first doped region A can be 30°, 40°, 55°, 70°, 80°, 100°, 110°, 125°, 135°, etc.

[0055] Preferably, the inclination angle of the inclined surface structure with respect to the first doped region A is 40°≤α≤70° or 100°≤α≤125°.

[0056] It should be noted that the first doped region A refers to a doped region with an N-type doping type.

[0057] In an alternative embodiment, as shown in Figure 3 and Figure 4 , the height of the inclined surface structure is greater than or equal to 3μm and less than 10μm. For example, the height H of the inclined surface structure can be 3μm, 5μm, 6μm, 7μm or 10μm, etc.

[0058] Preferably, the height of the inclined surface structure is greater than or equal to 5μm and less than 8μm.

[0059] It is understandable that the height of the sloped structure is the height difference between the first doped region A and the second doped region. Generally, when the doping type of the first doped region A is N-type, the doping type of the second doped region B is P-type. Since the first doped structure of the N-type region is prepared first, and the sloped structure is formed before the second doped structure of the P-type region is prepared, the height of the second doped region B from the second main surface of the silicon substrate 10 is less than the height of the first doped region A from the second main surface of the silicon substrate 10.

[0060] By controlling the tilt angle and height of the inclined structure, the thickness of the conductive film deposited on the inclined structure can be controlled, thereby controlling the thickness and discontinuity of the third conductive film 41 of the inclined structure. On the one hand, the first doped region A and the second doped region B can be better electrically isolated through the isolation region C. On the other hand, sufficient third conductive film 41 can be left in the inclined structure to improve the effective area for carrier collection.

[0061] In one alternative embodiment, such as 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 on the outside of the doped polysilicon layer 23.

[0062] The tunneling oxide layer 22 may include silicon oxide. The thickness of the tunneling oxide layer 22 may be 0.5-3 nm. As an example, the thickness of the tunneling oxide layer 22 may be 0.5 nm, 1.5 nm, 2 nm, or 3 nm, etc.

[0063] The doping type of the 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 thin film 33. Generally, the doping type of the polysilicon layer 23 is N-type. Optionally, the doping type of the polysilicon layer 23 is the same as the conductivity type of the silicon substrate 10. As an example, if the conductivity type of the silicon substrate 10 is N-type, the doping type of the polysilicon layer 23 is also N-type.

[0064] The first conductive thin film 21 disposed in the first doped region A has a continuous structure, which facilitates the lateral transport of charge carriers in the first doped region A, thereby improving the collection of charge carriers in the first doped region A. The first conductive thin film 21 may be a thin film composed of multiple layers, stacks, or mixtures of one or more doped metal oxides or doped metal nitrides. The metal oxides among the doped metal oxides include, but are not limited to, indium oxide, tin oxide, zinc oxide, cadmium oxide, and titanium dioxide. The metal nitrides among the doped metal nitrides 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.

[0065] In an alternative embodiment, as shown in FIG. 1C, the first doped region A includes a first intrinsic silicon-containing thin film 24 and a first doped silicon-containing thin film 25 stacked in sequence from inside to outside, wherein the first conductive thin film 21 is stacked outside the first doped silicon-containing thin film 25. Figure 4

[0066] The first intrinsic silicon-containing thin film 24 includes, but is not limited to, one or more single layers, multiple layers, or stacked layers of silicon-containing thin films, or a mixture of any number of silicon, silicon oxide, or silicon carbide. The silicon-containing thin film includes at least one of a thin film containing silicon, silicon oxide, or silicon carbide. It is noted that the silicon, silicon oxide, or silicon carbide in the first intrinsic silicon-containing thin film 24 refers to microcrystalline, nanocrystalline, or amorphous silicon, silicon oxide, or silicon carbide.

[0067] The doping type of the first doped silicon-containing thin 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 thin film 33. Generally, the doping type of the first doped silicon-containing thin film 25 can be N-type. The first doped silicon-containing thin film 25 includes, but is not limited to, one or more single layers, multiple layers, or stacked layers of doped silicon-containing thin films, or a mixture of any number of doped silicon, doped silicon oxide, or doped silicon carbide. The doped silicon-containing thin film includes at least one of a thin film containing doped silicon, doped silicon oxide, or doped silicon carbide. It is noted that the doped silicon, doped silicon oxide, or doped silicon carbide in the first doped silicon-containing thin film 25 refers to microcrystalline, nanocrystalline, or amorphous doped silicon, doped silicon oxide, or doped silicon carbide.

[0068] Specifically, the thickness of the first doped silicon-containing thin film 25 is 1 nm to 50 nm. As an example, the thickness of the first doped silicon-containing thin film 25 can be 1 nm, 3 nm, 10 nm, 25 nm, 40 nm, or 50 nm, etc.

[0069] The first conductive thin film 21 disposed in the first doped region A is of a continuous structure, facilitating the lateral transport of carriers in the first doped region A for better collection of carriers in the first doped region A. The first conductive thin film 21 can be a thin film composed of one or more multiple layers, stacked layers, or mixtures of doped metal oxides or doped metal nitrides, wherein the metal oxide in the doped metal oxide includes, but is not limited to, indium oxide, tin oxide, zinc oxide, cadmium oxide, titanium oxide, and the metal nitride in the doped metal nitride includes, but is not limited to, titanium nitride; and the doping element in the doped metal oxide or the doped metal nitride includes, but is not limited to, indium, tin, calcium, aluminum, cadmium, zinc, cerium, and fluorine.

[0070] In an alternative embodiment, as shown in FIG. 1C, the first doped region A includes a first intrinsic silicon-containing thin film 24 and a first doped silicon-containing thin film 25 stacked in sequence from inside to outside, wherein the first conductive thin film 21 is stacked outside the first doped silicon-containing thin film 25. Figure 3 and Figure 4 ​As shown, the second doped region B includes a second intrinsic silicon-containing thin film 32 and a second doped silicon-containing thin film 33 stacked in order from inside to outside, wherein the second conductive thin film 31 is stacked outside the second doped silicon-containing thin film 33.

[0071] The second intrinsic silicon-containing thin film 32 includes, but is not limited to, one or more single layers, multiple layers, or stacked layers of silicon-containing thin films, or a mixture of any of silicon, silicon oxide, or silicon carbide. The silicon-containing thin film includes at least one of a thin film 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 thin film 32 refers to microcrystalline, nanocrystalline, or amorphous silicon, silicon oxide, or silicon carbide.

[0072] The doping type of the second doped silicon-containing thin 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 thin film 33. Generally, the doping type of the second doped silicon-containing thin film 33 can be P-type. The second doped silicon-containing thin film 33 includes, but is not limited to, one or more single layers, multiple layers, or stacked layers of doped silicon-containing thin films, or a mixture of any of doped silicon, doped silicon oxide, or doped silicon carbide. The doped silicon-containing thin film includes at least one of a thin film 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 thin film 33 refers to microcrystalline, nanocrystalline, or amorphous doped silicon, doped silicon oxide, or doped silicon carbide.

[0073] Specifically, the thickness of the second doped silicon-containing thin film 33 is 1 nm-50 nm. As an example, the thickness of the second doped silicon-containing thin film 33 can be 1 nm, 3 nm, 10 nm, 25 nm, 40 nm, or 50 nm, etc.

[0074] The second conductive thin film 31 provided in the second doped region B is of a continuous structure, facilitating the lateral transport of carriers in the second doped region B, so as to better collect the carriers in the second doped region B. The second conductive thin film 31 can be a thin film composed of one or more multiple layers, stacked layers, or mixtures of doped metal oxides or doped metal nitrides, wherein the metal oxide in the doped metal oxide includes, but is not limited to, indium oxide, tin oxide, zinc oxide, cadmium oxide, titanium oxide, and the metal nitride in the doped metal nitride includes, but is not limited to, titanium nitride; and the doping element of the doped metal oxide or the doped metal nitride includes, but is not limited to, indium, tin, calcium, aluminum, cadmium, zinc, cerium, and fluorine.

[0075] In an optional embodiment, the aforementioned sloped structure may include a second intrinsic silicon-containing thin film 32 and a second doped silicon-containing thin film 33, which are stacked sequentially from the inside to the outside extending from the second doped region, wherein the third conductive thin film 41 is stacked on the outside of the second doped silicon-containing thin film 33. That is, the sloped structure may have the same second intrinsic silicon-containing thin film 32 and second doped silicon-containing thin film 33 as the second doped region B.

[0076] The second intrinsic silicon-containing thin film 32 of the inclined structure is the same as the second intrinsic silicon-containing thin film 32 of the second doped region B, and will not be described again here. Similarly, the second doped silicon-containing thin film 33 of the inclined structure is the same as the second doped silicon-containing thin film 33 of the second doped region B, and will not be described again here. It should be understood that when the inclined structure includes the second intrinsic silicon-containing thin film 32 and the second doped silicon-containing thin film 33, wherein the second intrinsic silicon-containing thin film 32 and the second doped silicon-containing thin film 33 extend from the second doped region to the inclined structure, that is, the second intrinsic silicon-containing thin film 32 of the inclined structure and the second intrinsic silicon-containing thin film 32 of the second doped region B are an integral structure; the second doped silicon-containing thin film 33 of the inclined structure and the second doped silicon-containing thin film 33 of the second doped region B are an integral structure.

[0077] Due to the sloped structure, the thickness of the conductive film deposited on the sloped structure is less than the thickness of the conductive films deposited in other regions. Consequently, the thickness of the third conductive film 41 formed in the sloped structure is less than the thickness of the first conductive film 21 and the second conductive film 31. The third conductive film 41 has an intermittent structure, ensuring effective electrical isolation between the first doped region A and the second doped region B.

[0078] In one alternative embodiment, such as Figure 4 As 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. To better separate the functional layers of the first doped region A and the second doped region B, a planar structure can also be provided in the isolation region C, whereby the extended portions of the second intrinsic silicon-containing thin film 32 and the second doped silicon-containing thin film 33 in the inclined structure belong to the functional layer of the first doped region A.

[0079] Specifically, when the first doped region A 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 stacked in order from inside to outside, the insulating isolation layer 42 stacked outside the doped polysilicon layer 23, and the second intrinsic silicon-containing thin film 32 and the second doped silicon-containing thin film 33 extending from the second doped region; when the first doped region A includes the first intrinsic silicon-containing thin film 24 and the first doped silicon-containing thin film 25, the planar structure includes the first intrinsic silicon-containing thin film 24 and the first doped silicon-containing thin film 25 stacked in order from inside to outside, the insulating isolation layer 42 stacked outside the first doped silicon-containing thin film 25, and the second intrinsic silicon-containing thin film 32 and the second doped silicon-containing thin film 33 extending from the second doped region.

[0080] The third conductive thin film 41 is stacked outside the second doped silicon-containing thin film 33.

[0081] Further, the insulating isolation layer 42 includes one or more of silicon oxide, silicon nitride, and silicon oxynitride, but is not limited thereto.

[0082] It should be noted that the second intrinsic silicon-containing thin film 32 of the planar structure is the same as the second intrinsic silicon-containing thin film 32 of the second doped region B and is an integral structure; the second doped silicon-containing thin film 33 of the planar structure is the same as the second doped silicon-containing thin film 33 of the second doped region B and is an integral structure. When the planar structure includes the tunneling oxide layer 22 and the 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. When the planar structure includes the first intrinsic silicon-containing thin film 24 and the first doped silicon-containing thin film 25, the first intrinsic silicon-containing thin film 24 of the planar structure is the same as the first intrinsic silicon-containing thin film 24 of the first doped region A and is an integral structure; the first doped silicon-containing thin film 25 of the planar structure is the same as the first doped silicon-containing thin film 25 of the first doped region A and is an integral structure. Details are not repeated here.

[0083] 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 the film layers of different doping types in the planar structure, a complete insulating isolation layer 42 should be provided between the film layers of different doping types in the planar structure, and therefore, the width of the insulating isolation layer 42 indicates the width of the planar structure in the isolation region C.

[0084] In addition, the third conductive film 41 covering the planar structure can be a continuous structure, and the thickness thereof can 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 of the inclined plane structure is an intermittent structure, the effective electrical isolation of the first doped region A and the second doped region B has been ensured, and the third conductive film 41 of the planar structure can not be set as an intermittent structure.

[0085] In an alternative embodiment, as shown in FIG. 6, the back contact solar cell can further include a passivation layer 50 and an anti-reflection layer 60 arranged in sequence on the second main surface of the silicon substrate 10 away from the silicon substrate 10. Figure 3 Figure 4 In an alternative embodiment, as shown in FIG. 6, the back contact solar cell can further include a passivation layer 50 and an anti-reflection layer 60 arranged in sequence on the second main surface of the silicon substrate 10 away from the silicon substrate 10.

[0086] In an alternative embodiment, as shown in FIG. 6, the back contact solar cell can further include a passivation layer 50 and an anti-reflection layer 60 arranged in sequence on the second main surface of the silicon substrate 10 away from the silicon substrate 10. Figure 3 In an alternative embodiment, as shown in FIG. 6, the back contact solar cell can further include a passivation layer 50 and an anti-reflection layer 60 arranged in sequence on the second main surface of the silicon substrate 10 away from the silicon substrate 10. The passivation layer 50 can include a third intrinsic silicon-containing film 51. Specifically, the third intrinsic silicon-containing film 51 includes but is not limited to one or more single-layer, multi-layer or stacked films of 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 a film 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 1 nm-15 nm. As an example, the thickness of the third intrinsic film can be 1 nm, 2 nm, 7 nm, 10 nm or 15 nm, etc.

[0087] The anti-reflection layer 60 is at least one of aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon aluminum oxide, aluminum nitride, magnesium fluoride, lithium fluoride, zinc oxide, indium tin oxide (ITO) semiconductor transparent conductive film. The thickness of the anti-reflection layer 60 is 40 nm-200 nm. As an example, the thickness of the anti-reflection layer 60 can be 40 nm, 80 nm, 100 nm, 150 nm or 200 nm, etc.

[0088] Further, as shown in FIG. 6, the passivation layer 50 can further include a third doped silicon-containing film 52 arranged between the third intrinsic silicon-containing film 51 and the anti-reflection layer 60. Figure 4

[0089] ​​Specifically, the third-doped silicon-containing thin film 52 includes, but is not limited to, a thin film composed of a single layer, multiple layers, or stack of one or more doped silicon-containing thin films, or a thin film composed of any mixture of doped silicon, doped silicon oxide, or doped silicon carbide. The doped silicon-containing thin film includes at least one thin film 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 thin 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 thin film 52 is 0-15 nm. As an example, the thickness of the third-doped silicon-containing thin film 52 can be 0.1 nm, 2 nm, 7 nm, 10 nm, or 15 nm, etc.

[0090] In one alternative embodiment, such as Figure 3 and Figure 4 As shown, the aforementioned back-contact solar cell may further include: a first metal electrode 70 disposed in the first doped region A and a second metal electrode 80 disposed in the second doped region B.

[0091] Specifically, the first metal electrode 70 is electrically connected to the first conductive film 21 of the first doped region A; the second metal electrode 80 is electrically connected to the second conductive film 31 of the second doped region B. The first metal electrode 70 and the second metal electrode 80 are multilayer electrodes composed of one or more of the following: silver electrode, silver alloy electrode, copper electrode, or copper alloy electrode; or multilayer electrodes composed of nickel, copper, and silver.

[0092] In one alternative embodiment, the first primary surface of the silicon substrate 10 is textured.

[0093] The back-contact solar cell of this utility model has a sloped structure in the isolation region C between the first doped region A and the second doped region B. The thickness of the conductive film deposited in the sloped structure is smaller than that of the conductive film deposited in the first doped region A and the second doped region B. This allows a third conductive film 41 with a discontinuous structure to be formed in the sloped structure. This eliminates the need for laser-cut isolation trenches in the isolation region C, reduces laser damage to the back-contact solar cell, and further improves the photoelectric conversion efficiency of the back-contact solar cell.

[0094] The embodiment of the utility model discloses the isolation area C can only include the inclined plane structure of third conductive film 41 of being provided with first doped structure and intermittent structure, and the effective electrical isolation of first doped area A and second doped area B can be realized through the conductive film of intermittent structure, can increase the effective area of carrier collection, discarded the structure of isolation area C that present technique through first doped structure, insulating isolation layer 42, second doped structure and conductive film are mutually superimposed after setting isolation groove in the position of abutting of first doped area A and second doped area B, thereby forming almost impossible to realize carrier collection.

[0095] The above detailed description does not constitute a limitation on the scope of protection of the utility model. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can occur depending on design requirements and other factors. Any modification, equivalent substitution and improvement within the spirit and principle of the utility model should be included in the scope of protection of the utility model.

Claims

1. A back contact solar cell, characterized by, The back contact solar cell comprises: a silicon substrate (10); first and second doped regions arranged alternately on a first main surface of the silicon substrate (10), an isolation region between the first and second doped regions, a first conductive film (21) arranged on the first doped region, a second conductive film (31) arranged on the second doped region, and a third conductive film (41) arranged on the isolation region; wherein the first and second doped regions have a height difference, and the first and second doped regions have opposite doping types; the isolation region comprises a slope structure arranged obliquely relative to the first and second doped regions; the third conductive film (41) is in an intermittent structure, and the thickness of the third conductive film (41) of the slope structure is smaller than that of the first and second conductive films (21, 31).

2. The back contact solar cell according to claim 1, wherein the first, second and third conductive films (21, 31, 41) are obtained by etching the conductive film on the first, second and isolation regions synchronously.

3. The back contact solar cell according to claim 1, wherein the slope structure has an inclination angle of 30°≤α≤80° or 100°≤α≤135° relative to the first doped region.

4. The back contact solar cell according to claim 3, wherein the slope structure has an inclination angle of 40°≤α≤70° or 100°≤α≤125° relative to the first doped region.

5. The back contact solar cell according to claim 1, wherein the height of the slope structure is greater than or equal to 3μm and less than 10μm.

6. The back contact solar cell according to claim 5, wherein the height of the slope structure is greater than or equal to 5μm and less than 8μm.

7. The back contact solar cell according to claim 1, wherein the first doped region comprises a tunneling oxide layer (22) and a doped polysilicon layer (23) stacked in sequence from inside to outside, and the first conductive film (21) is stacked outside the doped polysilicon layer (23); or the first doped region comprises a first intrinsic silicon-containing film (24) and a first doped silicon-containing film (25) stacked in sequence from inside to outside, and the first conductive film (21) is stacked outside the first doped silicon-containing film (25).

8. The back contact solar cell according to claim 7, wherein the second doped region comprises a second intrinsic silicon-containing film (32) and a second doped silicon-containing film (33) stacked in sequence from inside to outside, and the second conductive film (31) is stacked outside the second doped silicon-containing film (33).

9. The back contact solar cell according to claim 8, wherein ​ The inclined surface structure comprises a second intrinsic silicon-containing thin film (32) and a second doped silicon-containing thin film (33) extending from the second doped region and stacked in sequence from inside to outside, wherein the third conductive thin film (41) is stacked outside the second doped silicon-containing thin film (33).

10. The back contact solar cell of claim 8, wherein, The isolation region further comprises a planar structure, wherein the planar structure is located between the inclined surface structure and the first doped region; When the first doped region comprises the tunneling oxide layer (22) and the doped polysilicon layer (23), the planar structure comprises the tunneling oxide layer (22) and the doped polysilicon layer (23) extending from the first doped region and stacked in sequence from inside to outside, an insulating isolation layer (42) stacked outside the doped polysilicon layer (23), and the second intrinsic silicon-containing thin film (32) and the second doped silicon-containing thin film (33) extending from the second doped region; When the first doped region comprises the first intrinsic silicon-containing thin film (24) and the first doped silicon-containing thin film (25), the planar structure comprises the first intrinsic silicon-containing thin film (24) and the first doped silicon-containing thin film (25) extending from the first doped region and stacked in sequence from inside to outside, the insulating isolation layer (42) stacked outside the first doped silicon-containing thin film (25), and the second intrinsic silicon-containing thin film (32) and the second doped silicon-containing thin film (33) extending from the second doped region; The third conductive thin film (41) is stacked outside the second doped silicon-containing thin film (33).

11. The back contact solar cell of claim 10, wherein, The width of the insulating isolation layer (42) is greater than or equal to 20 μm and less than 200 μm.

12. The back contact solar cell of claim 10, wherein, The portion of the third conductive thin film (41) covering the planar structure is a continuous structure.

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