Back contact heterojunction solar cell and preparation method therefor

Abstract

The present disclosure discloses a back contact heterojunction solar cell and a preparation method therefor. The back contact heterojunction solar cell comprises: a silicon substrate, having a first functional region, a second functional region, and an isolation region blocking the first functional region and the second functional region arranged on a first main surface thereof; a first carrier collection layer, disposed on the first functional region; an insulating layer, covering the first carrier collection layer; a second carrier collection layer, disposed on the second functional region and the insulating layer corresponding to the first functional region; and a conductive layer, disposed on the second carrier collection layer. The first carrier collection layer and the second carrier collection layer have opposite conductivity types. The second carrier collection layer and the insulating layer corresponding to the first functional region are provided with conductive holes. The conductive layer corresponding to the first functional region extends to the conductive holes and is in contact with the first carrier collection layer. The performance of the back contact heterojunction solar cell is effectively improved.

Description

Back contact heterojunction solar cell and preparation method

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese patent application No. 202410852673.3, filed on June 27, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure relates to a back contact heterojunction solar cell and a preparation method. BACKGROUND

[0004] For the back contact heterojunction solar cell, the heterojunction structure and the grid lines are arranged on the back surface of the solar cell, which removes the shading of the grid lines to the front surface of the back contact heterojunction solar cell, thereby increasing the absorption efficiency of the incident light.

[0005] The existing preparation process of the back contact heterojunction solar cell generally prepares functional layers on the entire main surface of the silicon substrate, and then removes the functional layers in a certain area by laser or chemical etching, so that two doped layers with opposite doping types are arranged side by side. For example, a P-type doped layer is prepared on the entire surface, and then the P-type doped layer in a certain area is removed by laser or chemical etching. Then, an N-type doped layer is prepared on the front surface, and the N-type doped layer stacked on the P-type doped layer is removed by laser or chemical etching. In the process of removing the N-type doped layer stacked on the P-type doped layer, the laser or chemical etching inevitably damages the integrity of the P-type doped layer, resulting in poor performance of the back contact heterojunction solar cell.

[0006] SUMMARY

[0007] Therefore, the present disclosure provides a back contact heterojunction solar cell, a photovoltaic module and a preparation method, which can avoid damaging the doped layer and effectively improve the performance of the back contact heterojunction solar cell.

[0008] To solve the above technical problems, the present disclosure provides the following technical solutions:

[0009] In a first aspect, the present disclosure provides a back contact heterojunction solar cell, comprising:

[0010] a silicon substrate, wherein a first main surface of the silicon substrate is arranged with a first functional region, an isolation region and a second functional region;

[0011] a first carrier collection layer arranged on the first functional region;

[0012] an insulating layer covering the first carrier collection layer;

[0013] a second carrier collection layer disposed on the second functional region and the insulating layer corresponding to the first functional region;

[0014] a conductive layer disposed on the second carrier collection layer;

[0015] the first carrier collection layer and the second carrier collection layer are opposite in conductive type;

[0016] the second carrier collection layer and the insulating layer corresponding to the first functional region are provided with a conductive hole;

[0017] the conductive layer corresponding to the first functional region extends to the conductive hole and contacts the first carrier collection layer.

[0018] In a second aspect, the embodiments of the present disclosure provide a preparation method of a back contact heterojunction solar cell, comprising:

[0019] Step A, providing a silicon substrate, the silicon substrate comprising opposite first and second main surfaces, the first main surface comprising a first functional region, an isolation region and a second functional region;

[0020] Step B, sequentially forming a first carrier collection layer and an insulating layer on the silicon substrate corresponding to the first functional region and the isolation region;

[0021] Step C, forming a second carrier collection layer opposite in conductive type to the first carrier collection layer on the silicon substrate corresponding to the second functional region and on the insulating layer;

[0022] Step D, using a laser to open a conductive hole on the second carrier collection layer and the insulating layer corresponding to the first functional region;

[0023] Step E, forming a conductive layer on the second carrier collection layer, wherein the conductive layer corresponding to the first functional region extends to the conductive hole and contacts the first carrier collection layer;

[0024] Step F, removing the second carrier collection layer and the conductive layer corresponding to the isolation region.

[0025] The technical solution of the first aspect of the above disclosure has the following advantages or beneficial effects:

[0026] The first functional area of the back contact heterojunction solar cell provided in the embodiments of the present disclosure is provided with a first carrier collection layer and a second carrier collection layer, and the two are separated by an insulating layer. A conductive hole is formed in the second carrier collection layer on the first functional area, and the conductive layer extends into the conductive hole and contacts the first carrier collection layer, so as to guide the current of the first carrier collection layer to the surface of the cell. The back contact heterojunction solar cell provided in the embodiments of the present disclosure can guide the current of the first carrier collection layer to the surface of the cell without removing the second carrier collection layer on the first carrier collection layer. Compared with removing the second carrier collection layer, the energy required for forming the hole in the second carrier collection layer is much smaller. Therefore, the damage to the first carrier collection layer can be reduced in the formation process of the back contact heterojunction solar cell structure, and the performance of the back contact heterojunction solar cell can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0027] FIG. 1 is a partial cross-sectional structure schematic diagram of a back contact heterojunction solar cell according to an embodiment of the present disclosure;

[0028] FIG. 2 is a main flow schematic diagram of a preparation method of a back contact heterojunction solar cell according to an embodiment of the present disclosure;

[0029] FIG. 3 is a structure variation diagram containing steps S201 to S202 according to an embodiment of the present disclosure;

[0030] FIG. 4 is a structure variation diagram of the processing process of steps S203 to S204 and a structure variation diagram of forming a passivation layer and an anti-reflection layer according to an embodiment of the present disclosure;

[0031] FIG. 5 is a structure variation diagram of steps S205 and S206 and a structure variation diagram of forming a metal electrode according to an embodiment of the present disclosure.

[0032] The reference signs are as follows: 10-silicon substrate; 11-first functional area; 12-isolation area; 13-second functional area; 20-first carrier collection layer; 21-tunneling oxide layer; 22-first doped layer; 30-second carrier collection layer; 31-second intrinsic silicon-containing film layer; 32-second doped layer; 40-insulating layer; 50-conductive layer; 60-passivation layer; 70-anti-reflection layer; 80-metal electrode. DETAILED DESCRIPTION

[0033] The structure involved in the embodiments of the present disclosure is generally referred to as the direction away from the structure from inside to outside. For example, the direction from inside to outside in the thickness direction of the silicon substrate 10 is referred to as the direction away from the main surface (such as the first main surface) of the silicon substrate 10.

[0034] The first main surface and the second main surface of the silicon substrate 10 refer to two opposite main surfaces of the silicon substrate 10, one of which is the first main surface, and the other is the second main surface.

[0035] It should be noted that the "first", "second", and the like mentioned in the embodiments of the present disclosure are used to distinguish different functional layers or functional parts or functional regions, and are not intended to sort or number the functional layers or functional parts or functional regions. For example, the first doped layer and the second doped layer are used to distinguish the doped layers formed by different doping elements or the doped layers with different doping types; for example, the first functional region and the second functional region are used to distinguish the p-type doped region and the n-type doped region (for example, the first functional region is a p-type doped region, and correspondingly, the second functional region is an n-type doped region; for example, the first functional region is an n-type doped region, and correspondingly, the first functional region is a p-type doped region)

[0036] The embodiments of the present disclosure refer to the laminated arrangement of multiple structures, which generally means that one structure is arranged above or below another structure.

[0037] It should be noted that the structure involved in the embodiments of the present disclosure is located on another structure, which is not specifically referred to as being located above another structure in the use process of the back contact heterojunction solar cell, but in the preparation process of the back contact heterojunction solar cell, the structure is formed above another structure under the condition that the main surface (such as the first main surface) of the two structures faces upward.

[0038] The back contact heterojunction solar cell has the characteristics of low preparation process temperature, high conversion efficiency, good high temperature characteristics, and high light absorption rate, and is more and more favored by the industry. However, due to the defects such as complex manufacturing process, multiple laser and chemical corrosion to remove functional layers, and large damage to functional layers, the current back contact heterojunction solar cell not only has the problem of poor performance, but also has low production yield and increased production cost.

[0039] The embodiments of the present disclosure improve the structure of the back contact heterojunction solar cell and the preparation method thereof to improve the performance of the back contact heterojunction solar cell, and can improve the yield of the back contact heterojunction solar cell, and effectively reduce the production cost of the back contact heterojunction solar cell.

[0040] Among them, FIG. 1 shows a partial cross-sectional structure schematic diagram of a back contact heterojunction solar cell provided by the embodiments of the present disclosure; FIG. 2 shows a main flow schematic diagram of a preparation method of a back contact heterojunction solar cell provided by the embodiments of the present disclosure; FIGS. 3 to 5 show structure change schematic diagrams corresponding to each step provided by the embodiments of the present disclosure.

[0041] As shown in FIG. 1, the present disclosure provides a back contact heterojunction solar cell. The back contact heterojunction solar cell can include:

[0042] a silicon substrate 10, wherein a first main surface of the silicon substrate 10 is arranged with a first functional region 11, an isolation region 12 and a second functional region 13;

[0043] a first carrier collection layer 20 disposed on the first functional region 11;

[0044] an insulating layer 40 covering the first carrier collection layer 20;

[0045] a second carrier collection layer 30 disposed on the second functional region 13 and the insulating layer 40 corresponding to the first functional region 11;

[0046] a conductive layer 50 disposed on the second carrier collection layer 30;

[0047] The conductive types of the first carrier collection layer 20 and the second carrier collection layer 30 are opposite;

[0048] The second carrier collection layer 30 and the insulating layer 40 corresponding to the first functional region 11 are provided with a conductive hole;

[0049] The conductive layer 50 corresponding to the first functional region 11 extends to the conductive hole and contacts the first carrier collection layer 20.

[0050] The second carrier collection layer 30 and the conductive layer 50 are disconnected at a position corresponding to the isolation region 12, for blocking the electrical connection between the first functional region 11 and the second functional region 13.

[0051] The silicon substrate 10 can be a p-type silicon substrate or an n-type silicon substrate. The main surface of the silicon substrate 10 can be a textured structure or a flat structure. The first functional region 11 can be an n-type functional region, and the first carrier collection layer 20 is an electron collection layer. Correspondingly, the second functional region 12 is a p-type functional region, and the second carrier collection layer 30 is a hole collection layer. The first functional region 11 can be a p-type functional region, and the first carrier collection layer 20 is a hole collection layer. Correspondingly, the second functional region 12 is an n-type functional region, and the second carrier collection layer 30 is an electron collection layer. The p-type functional region and the n-type functional region are mainly determined by the doping elements contained in the carrier collection layer. For example, in the p-type functional region, the doping elements contained in the carrier collection layer are p-type doping elements such as boron and the like. In the n-type functional region, the doping elements contained in the carrier collection layer are n-type doping elements such as phosphorus and the like.

[0052] The insulating layer 40 is generally formed by chemical vapor deposition, plasma vapor deposition, physical vapor deposition, or the like, and is a single layer or a laminated layer. Each layer of the single layer or the laminated layer can include one or more of silicon oxide, silicon nitride, and silicon oxynitride. The thickness of the insulating layer can be 0.5-3 nm, for example, 0.5 nm, 0.7 nm, 1 nm, 1.2 nm, 1.5 nm, 1.6 nm, 2 nm, 2.3 nm, 2.5 nm, 2.7 nm, 3 nm, or the like.

[0053] It should be noted that although FIG. 1 only shows the relative positions of the first functional region 11, the isolation region 12, and the second functional region 13, the first functional region 11, the isolation region 12, and the second functional region 13 can also be alternately arranged on the first main surface of the silicon substrate 10. Regardless of whether the first main surface is designed to have only one first functional region 11, one isolation region 12, and one second functional region 13, or the first main surface is designed to have the first functional region 11, the isolation region 12, and the second functional region 13 alternately arranged, the first main surface can be a polished surface with a tower base. That is, the first main surface is formed by polishing the textured structure.

[0054] In addition, as shown in FIG. 1, the first carrier collection layer 20 and the insulating layer 40 extend to the isolation region 12. That is, during the removal of the first carrier collection layer 20 and the insulating layer 40 on the second functional region 13, the first carrier collection layer 20 and the insulating layer 40 on the isolation region 12 are retained to avoid the removal process affecting the first carrier collection layer 20 on the first functional region 11, thereby ensuring the performance of the first carrier collection layer 20 on the first functional region 11.

[0055] Further, the conductive layer 50 is a single layer or a laminated layer of metal oxide and / or nitride doped with a metal element, wherein the metal oxide is one or more of indium oxide, tin oxide, zinc oxide, cadmium oxide, and titanium nitride, the metal nitride is titanium nitride, and the doped element is one or more of indium, tin, calcium, aluminum, cadmium, zinc, cerium, and fluorine.

[0056] For the conductive hole provided on the second carrier collection layer 30 and the insulating layer 40 corresponding to the first functional region 11, the aperture of the conductive hole and the distribution density of the conductive hole on the first functional region 11 can be obtained through experimental tests according to requirements.

[0057] The structure of the back contact heterojunction solar cell provided in the embodiment of the present disclosure has the first functional area with the first carrier collection layer and the second carrier collection layer arranged thereon, and the two are separated by the insulating layer. Meanwhile, the second carrier collection layer on the first functional area is provided with the conductive hole, and the conductive layer extends into the conductive hole and contacts the first carrier collection layer, so as to guide the current of the first carrier collection layer to the surface of the cell. The back contact heterojunction solar cell adopting the embodiment of the present disclosure can guide the current of the first carrier collection layer to the surface of the cell without removing the second carrier collection layer on the first carrier collection layer. Compared with removing the second carrier collection layer, the energy required for opening the hole on the second carrier collection layer is much smaller. Therefore, the structure of the back contact heterojunction solar cell provided in the embodiment of the present disclosure can reduce the damage to the first carrier collection layer during the forming process, and is beneficial to improving the performance of the back contact heterojunction solar cell.

[0058] In addition, due to the design of the insulating layer, the second carrier collection layer 30 can be reserved on the first functional area, which effectively simplifies the manufacturing process of the back contact heterojunction solar cell, reduces the production cost of the back contact heterojunction solar cell, and is beneficial to the popularization of the back contact heterojunction solar cell.

[0059] Specifically, the first carrier collection layer 20 can have two structures.

[0060] Specifically, the first carrier collection layer 20 can have two structures.

[0060] The first structure of the first carrier collection layer 20 is shown in FIG. 1. The first carrier collection layer 20 can include a tunneling oxide layer 21 and a first doped layer 22 arranged in the thickness direction of the silicon substrate 10 from inside to outside.

[0061] The tunneling oxide layer 21 is generally a silicon oxide layer formed by chemical vapor deposition, plasma vapor deposition, physical vapor deposition, etc. The thickness of the tunneling oxide layer 21 is generally 0.5-3 nm. For example, the thickness of the tunneling oxide layer 21 can be 0.5 nm, 0.8 nm, 1 nm, 1.3 nm, 1.5 nm, 1.8 nm, 2 nm, 2.2 nm, 2.5 nm, 2.8 nm, or 3 nm, etc.

[0062] The first doped layer 22 is generally a doped polysilicon layer with a thickness of 30-300 nm. For example, the thickness of the first doped layer 22 can be 30 nm, 35 nm, 40 nm, 50 nm, 70 nm, 90 nm, 100 nm, 120 nm, 150 nm, 180 nm, 200 nm, 220 nm, 240 nm, 250 nm, 270 nm, 280 nm, or 300 nm, etc.

[0063] The second structure of the first carrier collection layer 20 can include a first intrinsic silicon-containing thin film layer and a first doped layer 22 arranged in the thickness direction of the silicon substrate 10 from inside to outside. The first intrinsic silicon-containing thin film layer is generally intrinsic amorphous silicon, and the thickness of the intrinsic amorphous silicon is generally 0.5-3 nm. For example, the thickness of the intrinsic amorphous silicon can be 0.5 nm, 1 nm, 1.2 nm, 1.5 nm, 1.7 nm, 2 nm, 2.3 nm, 2.6 nm, 2.8 nm, or 3 nm, etc. Correspondingly, the first doped layer 22 corresponding to the first intrinsic silicon-containing thin film layer is a single layer or a laminated film layer formed by one or more of doped amorphous silicon, doped microcrystalline silicon, and doped nanocrystalline silicon. The thickness of the first doped layer 22 corresponding to the first intrinsic silicon-containing thin film layer can be 30-300 nm. For example, the thickness of the first doped layer 22 corresponding to the first intrinsic silicon-containing thin film layer can be 30 nm, 35 nm, 40 nm, 50 nm, 70 nm, 90 nm, 100 nm, 120 nm, 150 nm, 180 nm, 200 nm, 220 nm, 240 nm, 250 nm, 270 nm, 280 nm, or 300 nm, etc.

[0064] Further, on the basis of either of the two structures of the first carrier collection layer 20 described above, the second carrier collection layer 30 can include a second intrinsic silicon-containing thin film layer 31 and a second doped layer 32 arranged in the thickness direction of the silicon substrate 10 from inside to outside.

[0065] The second intrinsic silicon-containing thin film layer 31 arranged on the insulating layer 40 of the first functional area 11 is formed synchronously with the second intrinsic silicon-containing thin film layer 31 arranged on the second functional area 12. That is, the second intrinsic silicon-containing thin film layer 31 on the insulating layer 40 of the first functional area 11 is formed synchronously with the second intrinsic silicon-containing thin film layer 31 on the second functional area 12 during the formation of the second intrinsic silicon-containing thin film layer 31 on the second functional area 12, and the second intrinsic silicon-containing thin film layer 31 on the insulating layer 40 of the first functional area 11 does not need to be removed subsequently, thereby effectively reducing the processing procedures of the back contact heterojunction solar cell.

[0066] The back contact heterojunction solar cell provided by the embodiments of the present disclosure can obtain the second functional area by laying the intrinsic silicon-containing thin film and the second doped layer on the entire back surface of the silicon substrate, and after laying the intrinsic silicon-containing thin film and the second doped layer on the entire back surface of the silicon substrate, the intrinsic silicon-containing thin film and the second doped layer extending to the first functional area do not need to be removed by any means such as laser or chemical etching, so that the functional layer (the first carrier collection layer) of the first functional area is not damaged, and the performance of the back contact heterojunction solar cell is effectively improved.

[0067] The second intrinsic silicon-containing thin film layer 31 is generally formed by chemical vapor deposition, plasma vapor deposition, physical vapor deposition, or the like. The second intrinsic silicon-containing thin film layer 31 is a single layer or a stacked layer. Each layer of the second intrinsic silicon-containing thin film layer 31 includes one or more of microcrystalline silicon, nanosilicon, amorphous silicon, silicon oxide, and silicon carbide. The microcrystalline silicon, nanosilicon, and amorphous silicon are different structures or crystal forms of silicon. The thickness of the second intrinsic silicon-containing thin film layer 31 is generally 1-15 nm. For example, the thickness of the second intrinsic silicon-containing thin film layer 31 can be 1 nm, 1.5 nm, 3 nm, 1.7 nm, 5 nm, 7 nm, 8 nm, 10 nm, 12 nm, or 15 nm.

[0068] The second doped layer 32 is generally a single layer of doped silicon-containing thin film or a stacked layer of doped silicon-containing thin film. Each layer of the second doped layer 32 is formed by chemical vapor deposition, plasma vapor deposition, or the like. The thickness of the second doped layer 32 is 0-15 nm. For example, the thickness of the second doped layer 32 can be 0.2 nm, 0.5 nm, 0.8 nm, 1 nm, 1.4 nm, 1.8 nm, 2 nm, 4 nm, 5 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, or 15 nm.

[0069] Further, for the first structure of the first carrier collection layer 20, as shown in FIG. 1, the tunneling oxide layer 21, the first doped layer 22, and the insulating layer 40 are sequentially arranged in the thickness direction of the silicon substrate 10 from the inside to the outside for the isolation region 12. The tunneling oxide layer 21, the first doped layer 22, and the insulating layer 40 in the isolation region 12 are formed synchronously with the tunneling oxide layer 21, the first doped layer 22, and the insulating layer 40 in the first region 11. Through the structural design of the isolation region 12, each functional layer can be formed on the first main surface without removing all the functional layers of the isolation region 12, thereby effectively reducing the processing procedures and reducing the damage to the functional layers.

[0070] In addition, for the second structure of the first carrier collection layer 20, the first intrinsic silicon-containing thin film layer, the first doped layer 22, and the insulating layer 40 are sequentially arranged in the thickness direction of the silicon substrate 10 from the inside to the outside for the isolation region 12. The first intrinsic silicon-containing thin film layer, the first doped layer 22, and the insulating layer 40 in the isolation region 12 are formed synchronously with the first intrinsic silicon-containing thin film layer, the first doped layer 22, and the insulating layer 40 in the first region 11.

[0071] The back contact heterojunction solar cell structure provided by the embodiment of the present disclosure is shown in FIG. 1. The first functional region 11 and the second functional region 13 are misaligned in the thickness direction of the silicon substrate 10. That is, the first functional region 11 and the second functional region 13 are misaligned in the thickness direction. The first functional region 11 and the second functional region 13 are completely electrically isolated by the misalignment of the first functional region 11 and the second functional region 13 and the isolation region 12 between the first functional region 11 and the second functional region 13, thereby further improving the reliability of the back contact heterojunction solar cell.

[0072] Further, as shown in FIG. 1, the back contact heterojunction solar cell further includes a passivation layer 60 and an anti-reflection layer 70 stacked on the second main surface of the silicon substrate 10. The passivation layer 60 and the anti-reflection layer 70 can effectively improve the photoelectric conversion efficiency of the back contact heterojunction solar cell.

[0073] The anti-reflection layer 70 can be at least one of aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon oxynitride, aluminum oxynitride, magnesium fluoride, lithium fluoride, ITO, and zinc oxide. The thickness of the anti-reflection layer 70 can be 40-200 nm. For example, the thickness of the anti-reflection layer 70 can be 40 nm, 50 nm, 80 nm, 100 nm, 120 nm, 150 nm, 170 nm, 180 nm, or 200 nm.

[0074] Further, as shown in FIG. 1, the back contact heterojunction solar cell further includes a metal electrode 80 arranged in the first functional region 11 and the second functional region 13 and electrically connected to the conductive layer 50.

[0075] Further, FIG. 2 shows a main flowchart of a preparation method of a back contact heterojunction solar cell provided by the embodiment of the present disclosure. FIGS. 3-5 show structural changes based on the preparation method. As shown in FIG. 2, the preparation method can include:

[0076] Step S201: providing a silicon substrate 10 including opposite first and second main surfaces, the first main surface including a first functional region 11, an isolation region 12, and a second functional region 13.

[0077] After this step, before the following step S202, the silicon substrate 10 can be further subjected to a double-side texturing treatment. Through the double-side texturing treatment, the light-receiving surface of the prepared back contact heterojunction solar cell can be textured, the light-receiving surface can be light-limited, and the light utilization rate of the back contact heterojunction solar cell can be improved.

[0078] Further, on the basis of the above-mentioned double-side texturing silicon substrate 10, a polishing treatment is performed on the first main surface of the silicon substrate 10; the polishing treatment is generally performed by using an alkali solution. After the polishing treatment, the first main surface of the silicon substrate 10 forms a polished surface with a tower base, so as to ensure the uniformity of the subsequent preparation of the functional layers. In addition, the polishing treatment process can be completed by using the existing polishing process in the production process of the solar cell, without introducing new polishing materials and processes, thereby effectively controlling the cost.

[0079] Further, before step S202, a mask layer 14 can be further formed on the second main surface of the silicon substrate 10; specifically, for the silicon substrate 10 with a textured structure on the second main surface, the mask layer 14 is formed on the textured structure. For the silicon substrate 10 with a planar structure on the second main surface, the mask layer 14 is formed on the planar structure of the second main surface. By forming the mask layer 14, the first main surface of the silicon substrate 10 can face upward and the second main surface can face downward during the subsequent formation of the functional layers on the first main surface. The mask layer 14 protects the second main surface of the silicon substrate 10, so as to avoid damaging and contaminating the second main surface when the second main surface faces downward.

[0080] The mask layer 14 can be a film layer formed by deposition, and the film layer can include any one or more of silicon oxide, silicon nitride, and silicon oxynitride. That is, the materials used to form the mask layer 14, i.e., silicon oxide, silicon nitride, and silicon oxynitride, can be the same as the materials used in the subsequent functional layers, thereby avoiding the introduction of new materials and effectively controlling the production cost of the back contact heterojunction solar cell.

[0081] Step S202: sequentially forming a first carrier collection layer 20 and an insulating layer 40 on the silicon substrate 10 corresponding to the first functional region 11 and the isolation region 12.

[0082] Specifically, the specific implementation of step S202 can include: sequentially forming a tunneling oxide layer 21, a first doped layer 22, and an insulating layer 40 on the first main surface of the silicon substrate 10; removing the tunneling oxide layer 21, the first doped layer 22, and the insulating layer 40 corresponding to the second functional region 13 on the first main surface of the silicon substrate 10 by laser, so as to expose the silicon substrate 10 of the second functional region 13.

[0083] The sequentially formed tunneling oxide layer 21, first doped layer 22, and insulating layer 40 can all be completed by using the deposition process in the existing production process of the solar cell, without introducing new processing equipment.

[0084] Specifically, the tunneling oxide layer 21, the first doped layer 22, and the insulating layer 40 can be obtained by gas deposition, and all can be obtained by the existing preparation process, and the specific process is not limited herein.

[0085] For the processing procedure of the above steps S201 to S202, the structural change can be as shown in FIG. 3.

[0086] In addition, the step can also replace the tunneling oxide layer 21 with a first intrinsic silicon-containing thin film layer.

[0087] Further, after the step S202, before the step S203, it further includes: polishing the second functional area 13 with an alkali solution; and further removing the residual tunneling oxide layer 21, the first doped layer 22, etc. in the second functional area through the polishing treatment, so as to avoid the residual first doped layer 22 in the second functional area, thereby effectively improving the performance and yield of the produced back contact heterojunction solar cell.

[0088] Step S203: forming a second carrier collection layer 30 with a conductive type opposite to that of the first carrier collection layer 20 on the silicon substrate 10 corresponding to the second functional area 13 and on the insulating layer 40.

[0089] Specifically, the specific implementation of the step can include: sequentially forming a second intrinsic silicon-containing thin film layer 31 and a second doped layer 32 on the first main surface of the silicon substrate 10; and the second doped layer 32 is opposite in doping type to the first doped layer 22.

[0090] Both the sequentially forming the second intrinsic silicon-containing thin film layer 31 and the second doped layer 32 can be completed by using the existing process of forming the intrinsic silicon-containing thin film layer and the second doped layer in the solar cell production process, without introducing new processing equipment.

[0091] Step S204: using a laser to open a conductive hole on the second carrier collection layer 30 and the insulating layer 40 corresponding to the first functional area 11.

[0092] The laser opening is performed on the first functional area 11, and the opening region removes the insulating layer 40 and the second doped layer 32. The size of the laser opening in this step can be set according to requirements. Herein, the opening size is not limited.

[0093] In addition, after the step S204, before the step S205, it further includes: cleaning the silicon substrate 10 to remove the mask layer 14 on the second surface of the silicon substrate 10; and sequentially forming a passivation layer 60 and an anti-reflection layer 70 on the second surface of the silicon substrate 10.

[0094] The structural change corresponding to the processing procedure of the above steps S203 to S204 and the structural change of forming the passivation layer 60 and the anti-reflection layer 70 can be as shown in FIG. 4.

[0095] Step S205: Forming a conductive layer 50 on the second carrier collection layer 30, wherein the conductive layer 50 corresponding to the first functional area extends to the conductive hole and contacts the first carrier collection layer 20.

[0096] Step S206: Removing the second carrier collection layer 30 and the conductive layer 50 corresponding to the isolation area 13.

[0097] Specifically, the step of slotting removes the second carrier collection layer 30 and the conductive layer 50 in the region between the first functional area 11 and the second functional area 13 by laser. In addition, during the removal of the second carrier collection layer 30 corresponding to the isolation area 13, the second doped layer 32 and / or the second intrinsic silicon-containing thin film layer 31 can be allowed to remain, so that the process of removing the functional layer on the isolation area 13 by laser has a relatively wide operating window, which can effectively improve the yield of the back contact heterojunction solar cell.

[0098] Further, after the above step S206, a metal electrode 80 can be further formed on the first functional area 11 and the second functional area 13.

[0099] Corresponding to the structural changes of the above steps S205 and S206 and the structural changes of forming the metal electrode 80 can be shown in FIG. 5.

[0100] The preparation method of the back contact heterojunction solar cell provided by the embodiments of the present disclosure introduces an insulating layer, so that after the second intrinsic silicon-containing thin film layer 31 and the second doped layer 32 are formed on the entire first main surface, the second intrinsic silicon-containing thin film layer 31 and the second doped layer 32 on the first functional area do not need to be removed. Only the laser treatment is introduced in the hole forming process for the first functional area and the slotting process for the isolation area in the above step S204. The process of the two laser treatments has little damage to the functional layer, or even no damage, effectively improving the performance of the produced back contact heterojunction solar cell and improving the process reliability and stability of the preparation process. The preparation process has relatively high generalizability.

[0101] The above steps provide an introduction to help understand the method, structure and core idea of the present disclosure. For those skilled in the art, the present disclosure can be improved and modified without departing from the principles of the present disclosure, and these improvements and modifications also belong to the protection scope of the present disclosure.

Claims

1. A back contact heterojunction solar cell, comprising: a silicon substrate (10), wherein a first main surface of the silicon substrate (10) is arranged with a first functional region (11), an isolation region (12) and a second functional region (13) ; a first carrier collection layer (20) disposed on the first functional region (11) ; an insulating layer (40) covering the first carrier collection layer (20) ; a second carrier collection layer (30) disposed on the second functional region (13) and the insulating layer (40) corresponding to the first functional region (11) ; a conductive layer (50) disposed on the second carrier collection layer (30) ; the first carrier collection layer (20) and the second carrier collection layer (30) are opposite in conductive type; a conductive hole is disposed on the second carrier collection layer (30) and the insulating layer (40) corresponding to the first functional region (11) ; the conductive layer (50) corresponding to the first functional region (11) extends to the conductive hole and contacts the first carrier collection layer (20). 2.The back contact heterojunction solar cell of claim 1, wherein the first functional region (11), the isolation region (12) and the second functional region (13) are arranged alternately. 3.The back contact heterojunction solar cell of claim 1, wherein the first carrier collection layer (20) and the insulating layer (40) extend to the isolation region (12). 4.The back contact heterojunction solar cell of any one of claims 1 to 3, wherein the first carrier collection layer (20) comprises a first intrinsic silicon-containing thin film layer and a first doped layer (22) disposed in turn from inside to outside along the thickness direction of the silicon substrate (10) ; or the first carrier collection layer (20) comprises a tunneling oxide layer (21) and a first doped layer (22) disposed in turn from inside to outside along the thickness direction of the silicon substrate (10). 5.The back contact heterojunction solar cell of claim 4, wherein the second carrier collection layer (30) comprises a second intrinsic silicon-containing thin film layer (31) and a second doped layer (32) disposed in turn from inside to outside along the thickness direction of the silicon substrate (10). 6.The back contact heterojunction solar cell of any one of claims 1 to 3, further comprising: a passivation layer (60) and an anti-reflection layer (70) stacked on the second main surface of the silicon substrate (10). 7.The back contact heterojunction solar cell of any one of claims 1 to 3, further comprising: a metal electrode (80) separately disposed on the first functional region (11) and the second functional region (13) and electrically connected to the conductive layer (50). 8.The back contact heterojunction solar cell of any one of claims 1 to 3, wherein the first functional region (11) and the second functional region (13) are arranged in dislocation in the thickness direction of the silicon substrate (10). 9.The back contact heterojunction solar cell of claim 4, wherein The insulating layer (40) is one or more of silicon oxide, silicon nitride, and silicon oxynitride in combination; And / or, The structure includes a tunneling oxide layer (21) for the first carrier collection layer (20), and the first doped layer (22) is a doped polysilicon layer; And / or, The second doped layer (32) is one or more of microcrystalline, nanocrystalline, amorphous silicon, silicon oxide, and silicon carbide formed in a single layer or stacked silicon thin film layer doped with a doping element; And / or, The conductive layer (50) is a single layer or stacked thin film formed by a metal oxide and / or nitride doped with a metal element, wherein the metal oxide is one or more of indium oxide, tin oxide, zinc oxide, cadmium oxide, and titanium nitride, the metal nitride is titanium nitride, and the doping element doped in the conductive layer (50) is one or more of indium, tin, calcium, aluminum, cadmium, zinc, cerium, and fluorine.

10. A method for manufacturing a back contact heterojunction solar cell, comprising: Step A, providing a silicon substrate (10), the silicon substrate (10) comprising opposite first and second main surfaces, the first main surface comprising a first functional region (11), an isolation region (12), and a second functional region (13); Step B, sequentially forming a first carrier collection layer (20) and an insulating layer (40) on the silicon substrate (10) corresponding to the first functional region (11) and the isolation region (12); Step C, forming a second carrier collection layer (30) with a conductivity type opposite to that of the first carrier collection layer (20) on the silicon substrate (10) corresponding to the second functional region (13) and on the insulating layer (40); Step D, using a laser to open a conductive hole on the second carrier collection layer (30) and the insulating layer (40) corresponding to the first functional region (11); Step E, forming a conductive layer (50) on the second carrier collection layer (30), wherein the conductive layer (50) corresponding to the first functional region extends to the conductive hole and contacts the first carrier collection layer (20); Step F, removing the second carrier collection layer (30) and the conductive layer (50) corresponding to the isolation region (13). Step B includes:

11. The method of producing a back contact heterojunction solar cell according to claim 10, wherein, Step B1, sequentially forming a tunneling oxide layer (21), a first doped layer (22), and an insulating layer (40) on the first main surface of the silicon substrate (10); Step B2, removing the tunneling oxide layer (21), the first doped layer (22), and the insulating layer (40) on the first main surface of the silicon substrate (10) corresponding to the second functional region (13) by laser, so that the second functional region (13) is exposed to the silicon substrate (10). Step C includes:

12. The method of producing a back contact heterojunction solar cell according to claim 10 or 11, wherein, Sequentially forming a second intrinsic silicon-containing thin film layer (31) and a second doped layer (32) on the silicon substrate (10) corresponding to the second functional region (13) and on the insulating layer (40); In step D, a conductive hole is opened corresponding to the second intrinsic silicon-containing thin film layer (31) and the second doped layer (32). ​ 13. The method of claim 10 or 11, before the step B, further comprising: double-side texturing the silicon substrate (10).

14. The method of claim 10 or 11, before the step B, further comprising: forming a mask layer (14) on the second main surface of the silicon substrate (10); and polishing the first main surface of the silicon substrate (10).

15. The method of claim 11, wherein the second functional region (13) is polished by an alkali solution to form a polished surface with a tower base on the second functional region (13). After the step B2, before the step C, also comprising:

16. The method of claim 14, after the step D, before the step E, further comprising: cleaning the silicon substrate (10) to remove the mask layer (14) on the second surface of the silicon substrate (10); forming a passivation layer (60) and an anti-reflective layer (70) on the second surface of the silicon substrate (1) in sequence. ​ ​ ​

Images