Photovoltaic cell and photovoltaic cell assembly

Abstract

The utility model provides a photovoltaic cell and a photovoltaic cell assembly, and relates to the field of photovoltaic technology. The photovoltaic cell comprises a silicon substrate, a tunneling oxide layer, a doped polycrystalline silicon layer, at least one metal electrode and at least one blocking part, the blocking parts are provided with first surfaces deviating from the silicon substrate, and orthographic projections of the metal electrodes on the first surfaces of the corresponding blocking parts are located in the first surfaces of the corresponding blocking parts; the blocking part is embedded in the doped polycrystalline silicon layer, the blocking part is further provided with a second surface opposite to the first surface, the doped polycrystalline silicon layer is provided with a third surface facing the silicon substrate, and a preset distance is formed between the second surface of the blocking part and the third surface of the doped polycrystalline silicon layer; the total area of orthographic projections of the blocking parts on the third surface is smaller than the area of the third surface; the metal electrode is located on one side of the first surface of the corresponding blocking part, and a part of the metal electrode is embedded in the doped polycrystalline silicon layer. The passivation contact structure of the photovoltaic cell can ensure the passivation quality.

Description

Technical Field

[0001] The utility model relates to the technical field of photovoltaics, in particular to a photovoltaic cell and a photovoltaic cell assembly. Background Art

[0002] The statements in this section merely provide background technology related to the present invention and do not necessarily constitute prior art.

[0003] The Tunnel Oxide Passivated Contact (TOPCon) structure is a cell that prepares an ultra-thin silicon oxide layer and a highly doped polysilicon layer on the silicon surface. The selective permeability of ultra-thin silicon oxide to carriers and the good field passivation effect of highly doped polysilicon and substrate are used to effectively suppress the recombination of minority carriers on the silicon surface and improve the cell opening voltage.

[0004] In the related technology, the substrate of the N-type TopCon battery is an N-type silicon wafer, and the corresponding metal electrode is obtained on the back by screen printing. However, during the sintering process, the metal slurry will corrode the polysilicon layer inward, causing the metal slurry to pass through the polysilicon layer and directly contact the crystalline silicon substrate, forming a high-density defect state, causing a very large composite current, which seriously degrades the passivation quality and greatly reduces the open circuit voltage of the photovoltaic cell. Utility Model Content

[0005] The utility model aims to provide a photovoltaic cell and a photovoltaic cell assembly to solve the technical problem that the metal electrode of the photovoltaic cell is easy to directly contact with the silicon substrate and the passivation quality is reduced.

[0006] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0007] In a first aspect, the utility model provides a photovoltaic cell, comprising a silicon substrate, a tunneling oxide layer, a doped polysilicon layer, at least one metal electrode and at least one barrier, wherein the tunneling oxide layer and the doped polysilicon layer are distributed in a direction away from the silicon substrate;

[0008] The barrier portion has a first surface facing away from the silicon substrate, and the orthographic projection of the metal electrode on the first surface of the corresponding barrier portion is located within the first surface of the corresponding barrier portion;

[0009] The barrier portion is embedded in the doped polysilicon layer, the barrier portion further has a second surface opposite to the first surface, the doped polysilicon layer has a third surface facing the silicon substrate, and a preset distance exists between the second surface of the barrier portion and the third surface of the doped polysilicon layer;

[0010] The total area of ​​the orthographic projection of the blocking portion on the third surface is smaller than the area of ​​the third surface;

[0011] The metal electrode is located on one side of the first surface of the corresponding barrier portion, and a portion of the metal electrode is embedded in the doped polysilicon layer.

[0012] According to at least one embodiment of the present invention, the preset spacing is 10 nm to 80 nm.

[0013] According to at least one embodiment of the present utility model, the total area of ​​the orthographic projections of the blocking portions on the third surface is 5% to 99.8% of the area of ​​the third surface.

[0014] According to at least one embodiment of the present invention, the barrier portion is a barrier portion made of silicon dioxide or doped silicon dioxide.

[0015] According to at least one embodiment of the present invention, the doped silicon dioxide is phosphorus-doped silicon dioxide; and / or,

[0016] The silicon substrate is an N-type silicon substrate; and / or,

[0017] The doped polysilicon layer is an n+ doped polysilicon layer.

[0018] According to at least one embodiment of the present utility model, the doped polysilicon layer further has a fourth surface opposite to the third surface, and the second surface of the blocking portion and the fourth surface of the doped polysilicon layer have the preset distance therebetween.

[0019] According to at least one embodiment of the present utility model, the photovoltaic cell further includes a passivation anti-reflection layer disposed on one side of the fourth surface of the doped polysilicon layer.

[0020] According to at least one embodiment of the present utility model, there are multiple metal electrodes, there are multiple blocking parts, the multiple blocking parts are distributed at intervals, and each blocking part corresponds to one of the multiple metal electrodes; or,

[0021] The number of the metal electrodes is plural, the number of the blocking portion is one, and the blocking portion has a connecting portion for the doped polysilicon layer to penetrate.

[0022] According to at least one embodiment of the present invention, the metal electrode includes one or more of an aluminum electrode, a silver electrode or a silver-aluminum electrode.

[0023] In a second aspect, the utility model provides a photovoltaic cell assembly, comprising the photovoltaic cell described in the first aspect.

[0024] Among the one or more technical solutions provided in the exemplary embodiments of the present utility model, at least one of the following beneficial effects can be achieved.

[0025] The photovoltaic cell provided by the exemplary embodiment of the utility model includes a silicon substrate, a tunneling oxide layer, a doped polysilicon layer, at least one metal electrode and at least one barrier, wherein the tunneling oxide layer and the doped polysilicon layer are distributed in a direction away from the silicon substrate. Since the metal electrode is located on one side of the first surface of the barrier, and the orthographic projection of the metal electrode on the first surface of the corresponding barrier is located within the first surface of the corresponding barrier, that is, the barrier can completely block the end face of the metal electrode facing the silicon substrate, so that during the preparation of the metal electrode, the metal slurry will not corrode the second surface side of the barrier, and then penetrate the doped polysilicon layer and damage the silicon substrate. Based on this, the barrier of the photovoltaic cell can avoid the formation of high-density defect states on the silicon substrate, resulting in a very large composite current, thereby maintaining the passivation quality and open-circuit voltage of the photovoltaic cell. Based on this, the back metal electrode of the photovoltaic cell of the exemplary embodiment of the utility model can be prepared by selecting a lower-cost material, which will not affect the back passivation structure of the photovoltaic cell.

[0026] Furthermore, since the total area of ​​the positive projection of the blocking portion on the third surface is smaller than the area of ​​the third surface, that is, there is a through channel between the portion of the doped polysilicon layer on the first surface side of the blocking portion and the portion of the doped polysilicon layer on the second surface side, the metal electrode portion embedded in the portion of the doped polysilicon layer on the first surface side of the blocking portion can form an electrical contact with the portion of the doped polysilicon layer on the second surface side of the blocking portion through the through channel. At the same time, since there is a preset distance between the second surface of the blocking portion and the third surface of the doped polysilicon layer, the blocking portion will not destroy the passivation structure. Therefore, the metal electrode contact area can have good contact performance on the basis of ensuring the stability of the tunneling passivation structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings illustrate exemplary embodiments of the present invention and are used to explain the principles of the present invention together with the description thereof, wherein these drawings are included to provide a further understanding of the present invention, and the accompanying drawings are included in and constitute a part of this specification;

[0028] Figure 1 is a schematic diagram of a photovoltaic cell structure according to an embodiment of the utility model;

[0029] Figure 2 It is a schematic diagram of the explosion structure of a photovoltaic cell according to an embodiment of the utility model;

[0030] Figure 3 is a schematic diagram of an unmetallized structure of a photovoltaic cell according to an embodiment of the utility model;

[0031] Figure 4 is a schematic diagram of a plurality of blocking parts of a photovoltaic cell according to an embodiment of the present utility model;

[0032] Figure 5 is a schematic diagram of a single blocking portion structure of a photovoltaic cell according to an embodiment of the present utility model;

[0033] Figure 6 It is a schematic diagram of the structure of a single blocking portion of a photovoltaic cell according to another embodiment of the present utility model.

[0034] Figure numerals: 10, blocking part; 11, first surface; 12, second surface; 13, connecting part; 20, metal electrode; 30, doped polysilicon layer; 31, third surface; 32, fourth surface; 40, tunneling oxide layer; 50, passivation anti-reflection layer; 60, silicon substrate; 70, p+ emitter; 80, front anti-reflection layer; 90, front electrode. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] Before introducing the exemplary embodiments of the present utility model, the relevant terms involved in the exemplary embodiments of the present utility model are first explained as follows:

[0037] The bifaciality of a photovoltaic cell, also known as the bifaciality factor, is a measure of the ratio of the reverse illumination received by the back of the photovoltaic cell to the front illumination. Specifically, the bifaciality refers to the ratio of the reflected light received by the back of the photovoltaic cell and the reverse scattered light passing through the back of the cell to the front illumination intensity. Generally speaking, the front of the photovoltaic cell is the main surface that receives illumination, while the back can continue to generate electricity through reflected light or reverse scattered light. Therefore, improving the bifaciality of photovoltaic cells can increase the photoelectric conversion efficiency and improve the utilization rate of light energy.

[0038] Plasma Enhanced Chemical Vapor Deposition (PECVD) is a method of chemical vapor deposition that excites gas to produce low-temperature plasma, enhancing the chemical activity of the reactants, and thus performing epitaxy. This method can form a solid film at a relatively low temperature.

[0039] Low Pressure Chemical Vapor Deposition (LPCVD) uses chemical reactions to convert gaseous precursors into solid films under low pressure. It has the advantages of high purity, high uniformity, high quality, and high controllability. It is widely used in microelectronics, optoelectronics, materials science and other fields.

[0040] Atomic layer deposition (ALD) is a chemical vapor deposition thin film technology that forms a thin film by alternately introducing a vapor precursor into a reaction chamber and causing a gas-curing reaction on the surface of a substrate.

[0041] At present, with the development of monocrystalline solar cells, especially the successful industrialization of Passivated Emitter and Rear Cell (PERC) technology, the efficiency improvement of mass-produced cells on P-type silicon wafers is approaching a bottleneck. More investment has been made in N-type cells with higher body minority carrier lifetime and lower attenuation. Three types of cell structures, including N-type high-efficiency cell technology (Passivated Emitter, Rear Totally-diffused cell, N-PERT), heterojunction (Heterojunction Technology, HJT) and TOPCon, have gradually attracted attention from the industry.

[0042] TOPCon cells are cells that have an ultra-thin silicon oxide layer and a highly doped polysilicon layer prepared on the silicon surface. The selective permeability of ultra-thin silicon oxide to carriers and the good field passivation effect between highly doped polysilicon and the substrate effectively inhibit the recombination of minority carriers on the silicon surface, thereby increasing the cell opening voltage. The substrate of the N-type TopCon cell is an N-type silicon wafer, and a P+ doped layer is obtained on the front side by boron diffusion, and a corresponding passivation dielectric film is deposited on the front side by ALD or PECVD. On the back side, PECVD or LPCVD is used to deposit a corresponding ultra-thin silicon oxide passivation dielectric film and a highly doped N+ polysilicon layer. The front and back sides are usually screen-printed to obtain corresponding metal electrodes, with silver-aluminum paste used on the front side and silver paste used on the back side.

[0043] Compared with P-type PERC cells, the use of silver paste on the back of N-type TopCon cells can achieve a higher bifaciality, but it increases the manufacturing cost of the cells. In order to simultaneously meet the principles of improving efficiency and reducing costs for N-type TopCon cells, the use of silver paste on the back should be minimized. However, other metal pastes will corrode the inner layer during the sintering process. Since the thickness of the doped polysilicon layer is usually tens to hundreds of nanometers, the paste can easily penetrate the doped polysilicon layer and directly contact the crystalline silicon substrate. The direct contact between the metal paste and the crystalline silicon substrate will form a high-density defect state, resulting in a very large composite current, which will seriously reduce the passivation quality and greatly reduce the open circuit voltage of the cell.

[0044] In response to the above problems, the metal electrode of the photovoltaic cell provided in the exemplary embodiment of the utility model is partially arranged in the doped polysilicon layer, the blocking part is completely embedded in the doped polysilicon layer, and the blocking part is arranged between the metal electrode and the third surface of the doped polysilicon layer, thereby avoiding the metal electrode from damaging the passivation structure and ensuring good contact performance of the metal electrode contact area.

[0045] Figure 1 Schematic diagram of the photovoltaic cell structure according to the embodiment of the present utility model. Figure 1 As shown, the photovoltaic cell provided by the exemplary embodiment of the utility model includes a silicon substrate 60, a tunneling oxide layer 40, a doped polysilicon layer 30, at least one metal electrode 20 and at least one blocking portion 10, and the tunneling oxide layer 40 and the doped polysilicon layer 30 are distributed in a direction away from the silicon substrate 60.

[0046] Figure 2 Schematic diagram of the explosion structure of a photovoltaic cell according to the embodiment of the present utility model. Figure 1 and Figure 2 As shown, the blocking portion 10 has a first surface 11 facing away from the silicon substrate 60, and the orthographic projection of the metal electrode 20 on the first surface 11 of the corresponding blocking portion 10 is located within the first surface 11 of the corresponding blocking portion 10; the blocking portion 10 is embedded in the doped polysilicon layer 30, and the blocking portion 10 also has a second surface 12 opposite to the first surface 11, the doped polysilicon layer 30 has a third surface 31 facing the silicon substrate 60, and there is a preset distance between the second surface 12 of the blocking portion 10 and the third surface 31 of the doped polysilicon layer 30; the total area of ​​the orthographic projections of each blocking portion 10 on the third surface 31 is smaller than the area of ​​the third surface 31; the metal electrode 20 is located on one side of the first surface 11 of the corresponding blocking portion 10, and a part of the metal electrode 20 is embedded in the doped polysilicon layer 30.

[0047] In practical applications, the number of the metal electrodes 20 may be one or more, and the number of the barrier portions 10 may also be one or more. A portion of the metal electrode 20 extends outside the doped polysilicon layer 30, and another portion is embedded in the doped polysilicon layer 30. The barrier portion 10 is completely embedded in the doped polysilicon layer 30, and the second surface 12 of the barrier portion 10 is spaced a certain preset distance from the third surface of the doped polysilicon layer 30. Since the metal electrode 20 is located on one side of the first surface 11 of the blocking portion 10, and the orthographic projection of the metal electrode 20 on the first surface 11 of the corresponding blocking portion 10 is located within the first surface 11 of the corresponding blocking portion 10, that is, the blocking portion 10 can completely cover the end face of the metal electrode 20 facing the silicon substrate 60, so that during the manufacturing process of the metal electrode 20, for example, during the sintering process of the metal paste used, the blocking portion 10 can prevent the paste of the metal electrode 20 from penetrating the doped polysilicon layer 30 and then directly contacting the crystalline silicon substrate 60, thereby avoiding the formation of a high-density defect state on the crystalline silicon substrate 60, resulting in a very large recombination current, thereby maintaining the passivation quality and open-circuit voltage of the photovoltaic cell. On the other hand, since the total area of ​​the orthographic projection of each barrier portion 10 on the third surface 31 is smaller than the area of ​​the third surface 31, that is, each barrier portion 10 does not completely isolate the doped polysilicon layer 30, that is, the doped polysilicon layer 30 is not isolated into a portion located on the side of the first surface 11 of the barrier portion 10 and a portion located on the side of the second surface 12 of the barrier portion 10, but the portions of the doped polysilicon layer 30 located on both sides of the barrier portion 10 have interconnected parts, so that the metal electrode 20 forms an effective electrical connection with the portion located on the side of the second surface 12 of the barrier portion 10, thereby ensuring the stability of the tunneling passivation structure and enabling the metal electrode 20 to have good electrical contact performance.

[0048] Exemplarily, the tunneling oxide layer 40 , the doped polysilicon layer 30 , the metal electrode 20 and the blocking portion 10 of the photovoltaic cell provided by the exemplary embodiment of the utility model are all located on the back side of the photovoltaic cell.

[0049] like Figure 1 As shown, the front side of the silicon substrate 60 is also provided with a p+ emitter 70, a front anti-reflection layer 80 and a front electrode 90 in sequence, and the front electrode 90 penetrates the front anti-reflection layer 80 and contacts the p+ emitter 70; wherein the front anti-reflection layer 80 may include at least one of aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon oxynitride and aluminum oxynitride.

[0050] Figure 3 Schematic diagram of the unmetallized structure of a photovoltaic cell according to an embodiment of the present utility model. Figure 3As shown, the preset spacing L between the second surface 12 of the barrier 10 and the third surface 31 of the doped polysilicon layer 30 is specifically 10nm to 80nm. Within the preset spacing range, the passivation contact structure composed of the tunneling oxide layer 40 and the doped polysilicon layer 30 is not destroyed, and a good passivation contact effect can be obtained. It should be noted that the above-mentioned photovoltaic cell is not metallized, which means that the metal electrode 20 has not been installed or formed on the back of the photovoltaic cell.

[0051] In another embodiment, Figure 2 and Figure 3 As shown, the doped polysilicon layer 30 also has a fourth surface 32 opposite to the third surface 31, and there is a preset distance L between the second surface 12 of the barrier 10 and the fourth surface 32 of the doped polysilicon layer 30, specifically L is 10nm to 80nm. That is, the distances between the second surface 12 of the barrier 10 and the third surface 31 and the fourth surface 32 of the doped polysilicon layer 30 are both L, and the second surface 12 of the barrier 10 is located in the middle of the doped polysilicon layer 30. On the one hand, it can ensure that the part of the doped polysilicon layer 30 located on the side of the second surface 12 of the barrier 10 forms a stable and reliable passivation contact structure; on the other hand, the part of the doped polysilicon layer 30 located on the side of the first surface 11 of the barrier 10 has enough space to accommodate part of the metal electrode 20, so as to form a good electrical contact between the metal electrode 20 and the doped polysilicon layer 30.

[0052] Figure 4 Schematic diagram of multiple blocking structures of a photovoltaic cell according to an embodiment of the present utility model. Figure 4 As shown, there are multiple metal electrodes 20 and multiple blocking portions 10 . The multiple blocking portions 10 are distributed at intervals, and each blocking portion 10 corresponds to one of the multiple metal electrodes 20 .

[0053] Exemplarily, a plurality of metal electrodes 20 are evenly distributed on the back of the photovoltaic cell, and the barrier 10 corresponds to the metal electrode 20 one by one, that is, the first surface 11 of the barrier 10 is the same as the area of ​​the end face of the metal electrode 20 facing the silicon substrate 60, or the first surface 11 of the barrier 10 is slightly larger than the area of ​​the end face of the metal electrode 20 facing the silicon substrate 60. Since the metal electrodes 20 are spaced apart, the barrier 10 is also spaced apart, and the doped polysilicon layer 30 is connected at the position of the gap between the barrier 10. At this time, the amount of the barrier 10 is the least. Exemplarily, the total area of ​​the second surface 12 of each barrier 10 accounts for 5% of the area of ​​the third surface 31 of the doped polysilicon layer 30, which is low in cost and can ensure good contact performance of the metal electrode contact area on the basis of eliminating the damage of the metal electrode slurry to the passivation contact and the N-type silicon substrate. It should be noted that the area of ​​the third surface 31 of the doped polysilicon layer 30 is the same as the surface area of ​​the back of the silicon substrate 60.

[0054] Figure 5 It is a schematic diagram of a single blocking portion structure of a photovoltaic cell according to an embodiment of the present utility model. Figure 6 FIG. 1 is a schematic diagram of a single blocking portion structure of a photovoltaic cell according to another embodiment of the present invention. Figure 5 and Figure 6 As shown, there are a plurality of metal electrodes 20 and one barrier 10 , and the barrier 10 has a connecting portion 13 for the doped polysilicon layer 30 to penetrate.

[0055] Exemplarily, a plurality of metal electrodes 20 are evenly distributed on the back side of the photovoltaic cell, such as Figure 6 As shown, the area of ​​the first surface 11 of the barrier 10 is the same as the area of ​​the third surface 31 of the doped polysilicon layer 30. Considering that the portion of the doped polysilicon layer 30 located on the first surface 11 of the barrier 10 and the portion located on the second surface 12 of the barrier 10 need to be penetrated and electrically connected, it is necessary to provide one or more connecting portions 13 on the barrier 10 to form an electrical connection between the metal electrode 20 and the entire doped polysilicon layer 30. Exemplarily, the connecting portion 13 can be formed by a laser opening process, that is, the connecting portion 13 is a through hole. When the barrier 10 has a plurality of through holes, the through holes can be evenly distributed, and it can be understood that each through hole is provided outside the metal electrode 20. It can be understood that the through hole should not interfere with the orthographic projection of the metal electrode 20 on the first surface 11 of the barrier 10, so as to avoid the barrier 10 being unable to prevent the metal electrode 20 from damaging the passivation contact and the N-type silicon substrate 60. In this embodiment, the total area of ​​the orthographic projection of the barrier 10 on the third surface 31 can be 99.8% of the area of ​​the third surface 31.

[0056] It should be noted that when the number of the blocking portion 10 is single and the connecting portion 13 is a through hole, the total area of ​​the orthographic projection of the blocking portion 10 on the third surface 31 does not include the total area of ​​the orthographic projection of the connecting portion 13 on the third surface 31. Exemplarily, the total area of ​​each through hole accounts for 0.2% of the total area of ​​the first surface 11 of the blocking portion 10.

[0057] In other embodiments, Figure 5 As shown, when the number of the blocking portion 10 is single, the area of ​​the first surface 11 of the blocking portion 10 is smaller than the area of ​​the third surface 31 of the doped polysilicon layer 30. For example, when the shape of the third surface 31 is rectangular, the shape of the first surface 11 of the blocking portion 10 is rectangular, each side length of the first surface 11 of the blocking portion 10 is smaller than the corresponding side length of the third surface 31, and the first surface 11 is located near the center of the third surface 31, that is, when the blocking portion 10 is a complete plane, the doped polysilicon layer 30 can also pass through its edge portion, so that the part of the doped polysilicon layer 30 located on the first surface 11 side of the blocking portion 10 and the part located on the second surface 12 side of the blocking portion 10 are connected and electrically connected. The blocking portion 10 of this embodiment can be formed by mask plate evaporation.

[0058] In another optional embodiment, when the lengths of the sides of the first surface 11 of the blocking portion 10 are smaller than the corresponding lengths of the sides of the third surface 31, and the first surface 11 is located near the center of the third surface 31, the blocking portion 10 may also be a complete plane, or may be as follows: Figure 6 As shown, a plurality of through holes are provided on the barrier portion 10, thereby forming through channels of the doped polysilicon layer 30 on both sides of the barrier portion 10. At this time, the connecting portion 13 may include an edge channel formed by the barrier portion 10 having an area smaller than the third surface 31, or may include a channel formed by a through hole portion, so that the metal electrode 20 can form an effective and reliable electrical connection with the doped polysilicon layer 30. In this embodiment, the total area of ​​the orthographic projection of the barrier portion 10 on the third surface 31 is 5% to 99.8% of the area of ​​the third surface 31.

[0059] In order to obtain the desired damage prevention effect of the barrier 10, the barrier 10 is formed of an insulating material. For example, the barrier 10 is made of silicon dioxide or doped silicon dioxide, wherein the doped silicon dioxide may be phosphorus-doped silicon dioxide (PSG).

[0060] Exemplarily, the silicon substrate 60 is an N-type silicon substrate 60, which can be an N-type silicon wafer, and the front side thereof obtains a P+ doped layer by boron diffusion; the back side obtains a corresponding tunneling oxide layer 40 and a highly doped N+ polysilicon layer by PECVD or LPCVD deposition, wherein the highly doped N+ polysilicon layer is the doped polysilicon layer 30. Exemplarily, the tunneling oxide layer 40 is an ultra-thin silicon oxide passivation dielectric film, and the thickness of the tunneling oxide layer 40 is 0.5nm to 3nm.

[0061] Furthermore, the front and back sides of the silicon substrate 60 are usually screen-printed to obtain corresponding metal electrodes, wherein silver-aluminum paste is used on the front side and silver paste is used on the back side. Compared with P-type PERC cells, the use of silver paste on the back side of N-type TopCon cells can ensure a higher bifaciality, but it increases the manufacturing cost of the cells. In order to simultaneously meet the principles of improving efficiency and reducing costs for N-type TopCon cells, the use of silver paste on the back side should be minimized.

[0062] For example, the metal electrode 20 used on the back of the silicon substrate 60 of the exemplary embodiment of the utility model can be one or more of an aluminum electrode, a silver electrode or a silver-aluminum electrode, that is, a part of the low-cost aluminum electrode can be used, and the other part can use a silver electrode or a silver-aluminum electrode, or all of the aluminum electrode can be used. Due to the existence of the barrier 10 set in the photovoltaic cell of the exemplary embodiment of the utility model, in the preparation process of replacing the silver electrode with the aluminum electrode, the aluminum paste will not corrode the inner layer during the sintering process, and even if the thickness of the doped polysilicon layer 30 is tens to hundreds of nanometers, the aluminum paste cannot penetrate the doped polysilicon layer 30 and directly contact the silicon substrate 60, and the same passivation quality and open circuit voltage as the silver electrode can be achieved. Based on this, the back of the photovoltaic cell of the exemplary embodiment of the utility model uses a silver-aluminum electrode or an aluminum electrode to replace all or part of the silver electrode, so that the manufacturing cost is reduced while ensuring the passivation contact performance of the photovoltaic cell and having a higher double-sided rate.

[0063] In some embodiments, Figure 1 and Figure 2 As shown, in order to reduce reflection on the surface of the photovoltaic cell, the back side of the photovoltaic cell also includes a passivation anti-reflection layer 50 arranged on one side of the fourth surface 32 of the doped polysilicon layer 30. The passivation anti-reflection layer 50 has a similar function to the front anti-reflection layer 80 located on the front side of the photovoltaic cell, and the passivation anti-reflection layer 50 can be made of at least one of the following materials, for example, aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, silicon oxynitride and aluminum oxynitride.

[0064] As can be seen from the above, the metal electrode, such as the aluminum electrode, on the back of the photovoltaic cell provided by the exemplary embodiment of the utility model is partially arranged in the doped polysilicon layer, the barrier is completely embedded in the doped polysilicon layer, and the barrier is arranged between the metal electrode and the third surface of the doped polysilicon layer, which can effectively eliminate the damage of the aluminum paste to the doped polysilicon layer and the N-type silicon substrate during the preparation process of the aluminum electrode, thereby replacing the silver electrode to reduce costs and ensure that the aluminum electrode has good electrical contact performance with the doped polysilicon layer. Furthermore, the back passivation contact structure of the photovoltaic cell provided by the exemplary embodiment of the utility model is simple, easy to implement through existing processes, and suitable for mass production.

[0065] An exemplary embodiment of the present utility model further provides a photovoltaic cell assembly, comprising the above-mentioned photovoltaic cell.

[0066] Compared with the prior art, the advantages of the photovoltaic cell assembly of the exemplary embodiment of the utility model are the same as those of the photovoltaic cell, which will not be described in detail here.

[0067] Those skilled in the art should understand that the above embodiments are only for the purpose of clearly illustrating the present invention, and are not intended to limit the scope of the present invention. For those skilled in the art, other changes or modifications may be made based on the above disclosure, and these changes or modifications are still within the scope of the present invention.

Claims

1. A photovoltaic cell, characterized in that: It comprises a silicon substrate, a tunneling oxide layer, a doped polysilicon layer, at least one metal electrode and at least one blocking portion, wherein the tunneling oxide layer and the doped polysilicon layer are distributed in a direction away from the silicon substrate; The barrier portion has a first surface facing away from the silicon substrate, and the orthographic projection of the metal electrode on the first surface of the corresponding barrier portion is located within the first surface of the corresponding barrier portion; The barrier portion is embedded in the doped polysilicon layer, the barrier portion further has a second surface opposite to the first surface, the doped polysilicon layer has a third surface facing the silicon substrate, and a preset distance exists between the second surface of the barrier portion and the third surface of the doped polysilicon layer; The total area of ​​the orthographic projection of the blocking portion on the third surface is smaller than the area of ​​the third surface; The metal electrode is located on one side of the first surface of the corresponding barrier portion, and a portion of the metal electrode is embedded in the doped polysilicon layer.

2. The photovoltaic cell according to claim 1, characterized in that: The preset spacing is 10 nm to 80 nm.

3. The photovoltaic cell according to claim 1, characterized in that: The total area of ​​the orthographic projection of the blocking portion on the third surface is 5% to 99.8% of the area of ​​the third surface.

4. The photovoltaic cell according to claim 1, characterized in that: The barrier portion is made of silicon dioxide or doped silicon dioxide.

5. The photovoltaic cell according to claim 4, characterized in that: The doped silicon dioxide is phosphorus-doped silicon dioxide; and / or, The silicon substrate is an N-type silicon substrate; and / or, The doped polysilicon layer is an n+ doped polysilicon layer.

6. The photovoltaic cell according to any one of claims 1 to 5, characterized in that: The doped polysilicon layer further has a fourth surface opposite to the third surface, and the second surface of the blocking portion and the fourth surface of the doped polysilicon layer have the preset distance therebetween.

7. The photovoltaic cell according to claim 6, characterized in that: The photovoltaic cell further includes a passivation anti-reflection layer disposed on one side of the fourth surface of the doped polysilicon layer.

8. The photovoltaic cell according to any one of claims 1 to 5, characterized in that: The number of the metal electrodes and the blocking parts are both multiple, the multiple blocking parts are distributed at intervals, and each of the blocking parts corresponds to one of the multiple metal electrodes; or, The number of the metal electrodes is plural, the number of the blocking portion is one, and the blocking portion has a connecting portion for the doped polysilicon layer to penetrate.

9. The photovoltaic cell according to claim 8, characterized in that: The metal electrode includes one or more of an aluminum electrode, a silver electrode or a silver-aluminum electrode.

10. A photovoltaic cell assembly, characterized in that: A photovoltaic cell comprising any one of claims 1 to 9.

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