Silicon substrate, solar cell, cell module, and photovoltaic system

Abstract

The present disclosure is suitable for the technical field of solar cells, and provides a silicon substrate, a solar cell, a cell module, and a photovoltaic system. The silicon substrate is simultaneously doped with P-type doping elements and N-type doping elements, the P-type doping elements include at least one of boron, aluminum, gallium, indium and thallium, and the N-type doping elements include at least one of phosphorus, arsenic, antimony, and bismuth. The sum of the doping concentrations of the P-type doping elements and the sum of the doping concentrations of the N-type doping elements are both greater than 1012atoms / cm3, the absolute value of the difference between the sum of the doping concentrations of the P-type doping elements and the sum of the doping concentrations of the N-type doping elements is less than 1014atoms / cm3, and the resistivity of the silicon substrate after thermal donor elimination treatment is greater than 50 ohm·cm. In this way, by simultaneously doping the P-type doping elements and the N-type doping elements having doping concentrations each exceeding 1012atoms / cm3, and controlling the absolute value of the concentration difference between the two types of doping elements to be less than 1014atoms / cm3, compensation doping of the silicon substrate is performed, such that a solar cell can have improved efficiency while using the high-resistivity silicon substrate.

Description

Silicon substrate, solar cell piece, cell assembly and photovoltaic system

[0001] Cross-reference to related applications

[0002] The present disclosure claims priority to the Chinese patent application No. 202410628188.8, filed on May 20, 2024, and entitled “Silicon substrate, solar cell piece, cell assembly and photovoltaic system”, the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of solar cell, and in particular to a silicon substrate, a solar cell piece, a cell assembly and a photovoltaic system. BACKGROUND

[0004] At present, in order to obtain a silicon substrate for manufacturing a solar cell piece, phosphorus, boron and other group III or group V doping elements are usually added in the process of forming a silicon rod. In the related art, in order to reduce the resistance loss to ensure the efficiency of the cell piece, an inherent cognition is formed in the field of solar technology that the resistivity of the silicon substrate is designed to be in a reasonable range with a small value and a small fluctuation, for example, in order to ensure the performance of the cell piece, the resistivity of the silicon substrate can be controlled in a small range of 1-3 ohm.cm or 0.4-1.1 ohm.cm, so as to effectively control the resistance loss to ensure the efficiency.

[0005] However, such inherent cognition limits the further development of technology, and at the same time, the use of such technical solutions has limited improvement in the efficiency of the cell piece, therefore, how to further improve the conversion efficiency of the cell piece has become a technical problem for technical personnel to study. SUMMARY

[0006] The present disclosure provides a silicon substrate, a solar cell piece, a cell assembly and a photovoltaic system, which aims to solve the technical problem of how to further improve the conversion efficiency of the cell piece in the prior art.

[0007] The present disclosure is implemented in this way, the silicon substrate of the embodiment of the present disclosure is used for a solar cell piece, the silicon substrate is simultaneously doped with a P-type doping element and an N-type doping element, the P-type doping element is at least one of boron, aluminum, gallium, indium and thallium, and the N-type doping element is at least one of phosphorus, arsenic, antimony and bismuth;

[0008] The sum of the doping concentrations of the P-type doping elements and the sum of the doping concentrations of the N-type doping elements are both greater than 10 12 atoms / cm 3 The absolute value of the difference between the sum of the doping concentrations of the P-type doping elements and the sum of the doping concentrations of the N-type doping elements is less than 1014 atoms / cm 3 , and the silicon substrate has a resistivity greater than 50 ohm.cm after a thermal donor elimination treatment.

[0009] In some embodiments, the sum of the doping concentrations of the P-type doping elements and the sum of the doping concentrations of the N-type doping elements are both greater than 10 14 atoms / cm 3 .

[0010] In some embodiments, the sum of the doping concentrations of the P-type doping elements and the sum of the doping concentrations of the N-type doping elements are both greater than 10 15 atoms / cm 3 .

[0011] In some embodiments, the absolute value of the difference between the sum of the doping concentrations of the P-type doping elements and the sum of the doping concentrations of the N-type doping elements is less than 5*10 13 atoms / cm 3 .

[0012] In some embodiments, the silicon substrate has a resistivity greater than 100 ohm.cm after a thermal donor elimination treatment.

[0013] In some embodiments, the silicon substrate has a resistivity greater than 200 ohm.cm after a thermal donor elimination treatment.

[0014] In some embodiments, the silicon substrate has a resistivity greater than 500 ohm.cm after a thermal donor elimination treatment.

[0015] In some embodiments, the silicon substrate has a resistivity greater than 1000 ohm.cm after a thermal donor elimination treatment.

[0016] In some embodiments, the silicon substrate has a resistivity greater than 5000 ohm.cm after a thermal donor elimination treatment.

[0017] In some embodiments, the silicon substrate has a thickness of 30-300 um.

[0018] In some embodiments, the silicon substrate is a single crystal silicon substrate.

[0019] The present disclosure also provides a solar cell, which is a back contact solar cell, the solar cell comprising:

[0020] The silicon substrate of any of the above, the back surface of the silicon substrate having a plurality of first regions and a plurality of second regions, the plurality of first regions and the plurality of second regions being arranged alternately and spacedly in sequence;

[0021] a first passivation contact structure stacked on the first region;

[0022] a second passivation contact structure stacked on the second region, a polarity of the second passivation contact structure being different from a polarity of the first passivation contact structure; and

[0023] a backside passivation film layer stacked on the first passivation contact structure and the second passivation contact structure.

[0024] In some embodiments, the first passivation contact structure comprises a first tunneling layer and a first polarity doped layer stacked on the first tunneling layer, the first polarity doped layer comprising at least one of doped polysilicon, doped amorphous silicon, and doped microcrystalline silicon.

[0025] the second passivation contact structure comprises a second tunneling layer and a second polarity doped layer stacked on the second tunneling layer, the second polarity doped layer comprising at least one of doped polysilicon, doped amorphous silicon, and doped microcrystalline silicon, the second polarity doped layer being opposite in polarity to the first polarity doped layer.

[0026] In some embodiments, the first region and the second region have a trench therebetween, the first passivation contact structure and the second passivation contact structure being isolated by the trench, the trench being free of a doped layer formed by doping with a group III element or a group V element; or

[0027] a dielectric film or an intrinsic silicon film layer is provided between the first region and the second region, the first region and the second region being isolated from each other by the dielectric film or the intrinsic silicon film layer.

[0028] In some embodiments, the front surface of the silicon substrate is free of a front surface field formed by doping, or the front surface of the silicon substrate has a front surface field with a surface doping concentration less than 5*10 18 atoms / cm 3 .

[0029] The present disclosure also provides a solar cell piece, the solar cell piece being a bifacial contact cell, the solar cell piece comprising:

[0030] The silicon substrate of any one of the above, the silicon substrate having opposite first and second surfaces;

[0031] a third passivation contact structure stacked on the first surface; and

[0032] a fourth passivation contact structure stacked on the second surface

[0033] In some embodiments, the third passivation contact structure includes a third tunneling layer and a third polarity doped layer stacked on the third tunneling layer, the third polarity doped layer including at least one of doped polysilicon, doped amorphous silicon, and doped microcrystalline silicon.

[0034] The fourth passivation contact structure includes a fourth tunneling layer and a fourth polarity doped layer stacked on the fourth tunneling layer, the fourth polarity doped layer including at least one of doped polysilicon, doped amorphous silicon, and doped microcrystalline silicon, and the fourth polarity doped layer is opposite in polarity to the third polarity doped layer.

[0035] The present disclosure also provides a battery assembly including the solar cell piece of any one of the above.

[0036] The present disclosure also provides a photovoltaic system including the battery assembly of the above.

[0037] In the silicon substrate, the solar cell piece, the battery assembly, and the photovoltaic system of the embodiments of the present disclosure, two different types of doped elements, P-type and N-type, are doped in the silicon substrate 10 respectively, by controlling the doping concentration of the P-type doped element and the N-type doped element and the difference between the doping concentrations of the two to be less than 10 14 atoms / cm 3The silicon substrate can have a resistivity greater than 50 ohm.cm after eliminating the thermal donors, and the back surface passivation can be achieved by using the structure design of the first passivation contact structure, the second passivation contact structure and the back passivation film layer in the back contact solar cell, and the third passivation contact structure and the fourth passivation contact structure are used to passivate the first surface and the second surface respectively in the bifacial contact cell. In this way, the silicon substrate 10 is compensated by doping P-type and N-type doping elements at the same time, and the concentration difference between the two is controlled, so that the resistivity of the silicon substrate 10 is greater than 50 ohm.cm after eliminating the thermal donors. The silicon substrate of the present disclosure is applied to the back contact solar cell using the surface passivation technology of the first passivation contact structure, the second passivation contact structure and the back passivation film layer, or to the bifacial contact cell using the third passivation contact structure and the fourth passivation contact structure. The surface recombination of the back surface of the back contact solar cell and the surface recombination of the bifacial contact cell can be greatly reduced, and the surface recombination lifetime of the back contact solar cell and the bifacial contact cell can be higher than the bulk lifetime, so that the effective lifetime of the whole solar cell is dominated by the bulk region. In this way, the concentration of non-equilibrium carriers in the bulk region transmission channel can be kept at a high level, so as to reduce the resistance loss caused by the low concentration of local non-equilibrium carriers, and to ensure the conversion efficiency of the solar cell. That is to say, in the present disclosure, the silicon substrate is doped by using two different polarity doping elements at the same time, and the doping concentration and the difference of the doping concentration are controlled, so that the solar cell can also improve the efficiency of the solar cell while using high resistivity silicon substrate, which breaks the existing inherent cognition.

[0038] Additional aspects and advantages of the present disclosure will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0039] FIG. 1 is a schematic diagram of a module of a photovoltaic system according to an embodiment of the present disclosure;

[0040] FIG. 2 is a schematic diagram of a module of a cell assembly according to an embodiment of the present disclosure;

[0041] FIG. 3 is a schematic diagram of a cross-sectional structure of a back contact solar cell according to an embodiment of the present disclosure;

[0042] FIG. 4 is a schematic diagram of a cross-sectional structure of a bifacial contact cell according to an embodiment of the present disclosure;

[0043] FIG. 5 is another schematic diagram of a cross-sectional structure of a back contact solar cell according to an embodiment of the present disclosure;

[0044] FIG. 6 is a graph of the relationship between the resistivity of a silicon substrate and the efficiency loss of a battery in the prior art;

[0045] FIG. 7 is a graph of the relationship between the bulk resistance loss, the bulk Rutherford recombination loss, and the resistivity of a silicon substrate of a PERC battery in the prior art;

[0046] FIG. 8 is a graph of the relationship between the conversion efficiency and the resistivity of a silicon substrate of a PERC battery in the prior art;

[0047] FIG. 9 is a graph of the relationship between the bulk resistance loss, the bulk Rutherford recombination loss, and the resistivity of a silicon substrate of a back contact solar cell and a double-sided contact cell according to embodiments of the present disclosure;

[0048] FIG. 10 is a graph of the relationship between the carrier concentration and the resistivity of a silicon substrate of a back contact solar cell and a double-sided contact cell according to embodiments of the present disclosure;

[0049] FIG. 11 is a graph of the relationship between the resistivity of a silicon substrate and the conversion efficiency of a back contact solar cell and a double-sided contact cell according to embodiments of the present disclosure;

[0050] FIG. 12 is a graph of the relationship between the resistivity of a silicon substrate and the maximum power point current of a back contact solar cell and a double-sided contact cell according to embodiments of the present disclosure;

[0051] FIG. 13 is a graph of the relationship between the concentration of non-equilibrium carriers and the SRH minority carrier lifetime of a back contact solar cell and a double-sided contact cell according to embodiments of the present disclosure at different resistivities. DETAILED DESCRIPTION

[0052] In order to make the objectives, technical solutions and advantages of the present disclosure clearer, the present disclosure will be further described in detail below with reference to the accompanying drawings and embodiments. The examples of the embodiments are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present disclosure and cannot be understood as a limitation of the present disclosure. In addition, it should be understood that the specific embodiments described herein are only used to explain the present disclosure and do not limit the present disclosure.

[0053] In the description of the present disclosure, it should be understood that the terms "upper", "lower", "back", "front", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present disclosure.

[0054] In the present disclosure, unless specifically defined and limited otherwise, a first feature "on" or "under" a second feature can include the first and second features being directly in contact with each other, or can include the first and second features not being directly in contact with each other but being in contact with each other through another feature between them. Also, the first feature "over", "above" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in horizontal level than the second feature. The first feature "under", "below" and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in horizontal level than the second feature.

[0055] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present disclosure. For the purpose of simplification of the present disclosure, the components and arrangements of the specific examples are described. Of course, they are merely examples and are presented to provide an exemplary disclosure. The purpose is not to limit the present disclosure. In addition, the present disclosure can repeatedly refer to reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity, and does not itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, the present disclosure provides various specific examples of processes and materials, but those of ordinary skill in the art can realize the application of other processes and / or the use of other materials.

[0056] Referring to FIG. 1, a photovoltaic system 1000 in embodiments of the present disclosure can include a battery assembly 200 in embodiments of the present disclosure.

[0057] Referring to FIG. 2, the battery assembly 200 in embodiments of the present disclosure can include a plurality of solar cell pieces 100 in embodiments of the present disclosure. Specifically, the solar cell piece 100 in embodiments of the present disclosure can be a back contact solar cell or a double-sided contact cell.

[0058] The plurality of solar cell pieces 100 in the battery assembly 200 can be sequentially connected in series to form a cell string, and each cell string can be connected in series, in parallel, or in a combination of series and parallel to realize the current output in parallel, for example, the connection between each cell piece can be realized by welding the solder strip, and the connection between each cell string can be realized by the bus bar.

[0059] Referring to FIG. 3, in some embodiments, the solar cell piece 100 in embodiments of the present disclosure can be a back contact solar cell, in which case the solar cell piece 100 can include a silicon substrate 10, a first passivation contact structure 20, a second passivation contact structure 30, and a back passivation film layer 40 in embodiments of the present disclosure.

[0060] Referring to FIG. 4, in some embodiments, the solar cell 100 in the embodiments of the present disclosure can also be a dual-sided contact cell, in which case the solar cell 100 can include the silicon substrate 10, a third passivation structure 301 and a fourth passivation contact structure 302 in the embodiments of the present disclosure, the silicon substrate 10 has opposite first and second surfaces 101 and 102, which can be the front and back surfaces of the silicon substrate 10, respectively.

[0061] In the silicon substrate 10 in the embodiments of the present disclosure, both P-type doping elements and N-type doping elements are doped, the P-type doping elements are at least one of boron, aluminum, gallium, indium and thallium, and the N-type doping elements are at least one of phosphorus, arsenic, antimony and bismuth.

[0062] In the silicon substrate 10 in the embodiments of the present disclosure, both P-type doping elements and N-type doping elements are doped, the P-type doping elements are at least one of boron, aluminum, gallium, indium and thallium, and the N-type doping elements are at least one of phosphorus, arsenic, antimony and bismuth. 12 atoms / cm 3 The absolute value of the difference between the sum of the doping concentrations of the P-type doping elements and the sum of the doping concentrations of the N-type doping elements is less than 10 14 atoms / cm 3 The resistivity of the silicon substrate 10 after the elimination of thermal donors treatment is greater than 50 ohm.cm.

[0063] It should be noted that in the present disclosure, the "sum of the doping concentrations of the P-type doping elements" refers to the sum of the doping concentrations of all the P-type doping elements doped in the silicon substrate 10. That is to say, if only one of boron, aluminum, gallium, indium and thallium is doped in the silicon substrate 10, the sum of the doping concentrations of the P-type doping elements represents the doping concentration of this element, and if two or more of these elements are doped in the silicon substrate 10, the sum of the doping concentrations of the P-type doping elements represents the sum of the doping concentrations of each P-type doping element.

[0064] Similarly, the "sum of the doping concentrations of the N-type doping elements" refers to the sum of the doping concentrations of all the N-type doping elements doped in the silicon substrate 10. That is to say, if only one of phosphorus, arsenic, antimony and bismuth is doped in the silicon substrate 10, the sum of the doping concentrations of the N-type doping elements represents the doping concentration of this element, and if two or more of these elements are doped in the silicon substrate 10, the sum of the doping concentrations of the N-type doping elements represents the sum of the doping concentrations of each P-type doping element. In the following, if there is the same or similar description, it can be referred to the above processing.

[0065] As shown in FIG. 3, in the back contact solar cell, the back surface 11 of the silicon substrate 10 can have a plurality of first regions 111 and a plurality of second regions 112, which are alternately and spacedly arranged in sequence. The first passivation contact structure 20 is stacked on the first regions 111, and the second passivation contact structure 30 is stacked on the second regions 112, the polarity of the second passivation contact structure 30 being different from that of the first passivation contact structure 20, one of which is P-type and the other is N-type. The back passivation film layer 40 is stacked on the first passivation contact structure 20 and the second passivation contact structure 30, and specifically, the back passivation film layer 40 can cover the entire back surface 11 of the silicon substrate 10.

[0066] Of course, it can be understood that in the present disclosure, the back contact solar cell can also include a front passivation film (not shown in the figure) disposed on the front surface 12 of the silicon substrate 10, which can achieve effective passivation of the front surface.

[0067] Referring to FIG. 4, in the double-sided contact cell, the third passivation contact structure 301 is stacked on the first surface 101, and the fourth passivation contact structure 302 is stacked on the second surface 102. Specifically, the polarity of the third passivation structure 301 is different from that of the fourth passivation contact structure 302, one of which is P-type and the other is N-type.

[0068] In the silicon substrate 10, the solar cell 100, the cell assembly 200 and the photovoltaic system 1000 of the embodiments of the present disclosure, the silicon substrate 10 is respectively doped with two different types of doping elements of P-type and N-type, and by controlling the sum of the doping concentrations of the P-type doping elements and the sum of the doping concentrations of the N-type doping elements to be greater than 10 12 atoms / cm 3 , and controlling the absolute value of the difference between the doping concentrations to be less than 10 14 atoms / cm 3 , the resistivity of the silicon substrate 10 after eliminating the thermal donors can be greater than 50 ohm.cm. In the back contact solar cell, the structure design with the first passivation contact structure 20, the second passivation contact structure 30 and the back passivation film layer 40 is adopted to achieve the passivation of the back surface, and in the double-sided contact cell, the third passivation contact structure 301 and the fourth passivation contact structure 302 are adopted to passivate the first surface 101 and the second surface 102, respectively.

[0069] In this way, by adopting the doping concentrations greater than 10 12 atoms / cm 3doped with P-type and N-type doping elements simultaneously, and the concentration difference between the doping concentrations of the two is controlled to perform a compensating doping on the silicon substrate 10 (i.e., the absolute value of the difference between the doping concentrations of the two is controlled to be less than 10 14 atoms / cm 3 , so that the resistivity of the silicon substrate 10 after eliminating the thermal donors is greater than 50 ohm.cm. Meanwhile, when the silicon substrate 10 of the present disclosure is applied to a back contact solar cell using the surface passivation technology of the first passivation contact structure 20, the second passivation contact structure 30 and the back passivation film layer 40, or to a bifacial contact cell using the third passivation contact structure 301 and the fourth passivation contact structure 302, the surface recombination of the back surface 11 of the back contact solar cell and the surface recombination of the bifacial contact cell can be greatly reduced, so that the surface recombination lifetime of the back contact solar cell and the bifacial contact cell can reach the bulk lifetime or even be higher than the bulk lifetime, thereby making the effective lifetime of the whole cell sheet dominated by the bulk region. In this way, the concentration of the non-equilibrium carriers at each part of the bulk region transmission channel can be kept at a relatively high level, thereby reducing the greater resistance loss caused by the too low local non-equilibrium carrier concentration, and further ensuring the conversion efficiency of the solar cell sheet 100. That is to say, in the present disclosure, by simultaneously doping the silicon substrate 10 with two different polarity doping elements and controlling the doping concentrations of the two and the difference between the doping concentrations of the two, the solar cell sheet 100 can realize the function of improving the efficiency of the solar cell sheet 100 while using a high resistivity silicon substrate 10, which breaks the existing inherent cognition.

[0070] Specifically, in the present disclosure, the silicon substrate 10 is preferably a single crystal silicon substrate. Of course, in some embodiments, it can also be a polycrystalline silicon substrate, which is not particularly limited here.

[0071] In addition, it is not difficult to understand that, in the present disclosure, in the silicon substrate 10, if the sum of the doping concentrations of the P-type doping elements is greater than the sum of the doping concentrations of the N-type doping elements, the silicon substrate 10 exhibits the characteristics of a P-type silicon substrate, and if the sum of the doping concentrations of the P-type doping elements is less than the sum of the doping concentrations of the N-type doping elements, the silicon substrate 10 exhibits the characteristics of an N-type silicon substrate.

[0072] It should be noted that, in the present disclosure, the absolute value of the difference between the sum of the doping concentrations of the P-type doping elements and the sum of the doping concentrations of the N-type doping elements is less than 10 14 atoms / cm 3 , which means that the absolute value of the concentration difference between the two is greater than 0 and less than 10 14 atoms / cm 3 .

[0073] In some embodiments, in the silicon substrate 10, the sum of the doping concentration of the P-type doping element and the sum of the doping concentration of the N-type doping element can preferably both be greater than 10 14 atoms / cm 3 . Preferably, the sum of the doping concentration of the P-type doping element and the sum of the doping concentration of the N-type doping element can both be greater than 10 15 atoms / cm 3 .

[0074] Thus, by adjusting the sum of the doping concentration of the P-type doping element and the sum of the doping concentration of the N-type doping element, the absolute value of the difference between the two can be made to be less than 10 14 atoms / cm 3 , thereby improving the resistivity of the silicon substrate 10 after elimination of the thermal donors.

[0075] Preferably, in some embodiments, in the silicon substrate 10, the absolute value of the difference between the sum of the doping concentration of the P-type doping element and the sum of the doping concentration of the N-type doping element can preferably be less than 5*10 13 atoms / cm 3 . For example, the absolute value of the difference can be 10 13 atoms / cm 3 , 5*10 12 atoms / cm 3 , 10 12 atoms / cm 3 , 5*10 11 atoms / cm 3 , and so on, without limitation.

[0076] In particular, the inventors of the present disclosure have found through research and verification that by optimizing the absolute value of the difference between the sum of the doping concentration of the P-type doping element and the sum of the doping concentration of the N-type doping element in the silicon substrate 10 to be 5*10 13 atoms / cm 3 , the resistivity of the silicon substrate 10 after elimination of the thermal donors can be optimized to have a higher resistivity and to improve the conversion efficiency.

[0077] In some embodiments, the resistivity of the silicon substrate 10 after the elimination of the thermal donors treatment can be greater than 100 ohm.cm. Further, in some embodiments, the resistivity of the silicon substrate 10 after the elimination of the thermal donors treatment can be greater than 200 ohm.cm.

[0078] Still further, in some embodiments, the resistivity of the silicon substrate 10 after the elimination of the thermal donors treatment can be greater than 500 ohm.cm or greater than 1000 ohm.cm or even greater than 5000 ohm.cm.

[0079] Thus, in some embodiments, the sum of the bulk resistance efficiency loss and the bulk recombination efficiency loss can be reduced, and the conversion efficiency can be improved.

[0080] In some embodiments, the thickness of the silicon substrate 10 can be 30 um-300 um. In this way, the concentration of the photo-generated carriers can be avoided to be too low due to the too small thickness of the silicon substrate 10, and the cost of the solar cell can be avoided to be too high due to the too large thickness of the silicon substrate 10.

[0081] In particular, the thickness of the silicon substrate 10 can be, for example, 30 um, 40 um, 50 um, 60 um, 70 um, 80 um, 90 um, 100 um, 150 um, 200 um, 250 um, 300 um, or any value between 30 um and 300 um, without limitation in particular.

[0082] Referring to FIG. 3, in some embodiments, in the back contact solar cell, the first passivated contact structure 20 can include a first tunneling layer 21 and a first polarity doped layer 22 stacked on the first tunneling layer 21, and the first polarity doped layer 22 can include at least one of doped poly-silicon, doped amorphous silicon, and doped microcrystalline silicon.

[0083] Referring to FIG. 3 and FIG. 5, the second passivated contact structure 30 includes a second tunneling layer 31 and a second polarity doped layer 32 stacked on the second tunneling layer 31, and the second polarity doped layer 32 can include at least one of doped poly-silicon, doped amorphous silicon, and doped microcrystalline silicon, and the polarity of the second polarity doped layer 32 is opposite to that of the first polarity doped layer 22. For example, when the first polarity doped layer 22 is a P-type doped layer, the second polarity doped layer 32 can be an N-type doped layer, and when the first polarity doped layer 22 is an N-type doped layer, the second polarity doped layer 32 can be a P-type doped layer.

[0084] In this way, in the back contact solar cell, the first passivated contact structure 20 and the second passivated contact structure 30 adopt the above-mentioned structure design, which can greatly reduce the back surface recombination of the back contact solar cell, so that the surface recombination characteristic lifetime can reach or be higher than the bulk lifetime, and thus the effective lifetime of the back contact solar cell is dominated by the bulk lifetime.

[0085] In particular, in such embodiments, the first tunneling layer 21 and the second tunneling layer 31 can be a thin film oxide layer or a thin film intrinsic silicon layer, without limitation in particular.

[0086] In some embodiments, in the back contact solar cell, the front surface 12 of the silicon substrate 10 does not have a front surface field, or the front surface 12 of the silicon substrate 10 can have a surface doping concentration less than 5*10 18 atoms / cm 3The front surface field can be formed. In this way, the recombination of the front surface 12 of the back contact solar cell can be greatly reduced, and the effective lifetime of the back contact solar cell is dominated by the bulk lifetime.

[0087] Referring to FIG. 5, in some embodiments, the back contact solar cell has a trench 13 between the first region 111 and the second region 112, the first passivated contact structure 20 and the second passivated contact structure 30 are separated by the trench 13, and the trench 13 does not have a doped layer formed by doping with a group III element or a group V element. In this way, the edge recombination of the surface can be reduced.

[0088] Specifically, as shown in FIG. 5, the back passivation film layer 40 covers the first passivated contact structure 20, the second passivated contact structure 30, and the trench 13, that is, the back passivation film layer 40 covers the first passivated contact structure 20, the second passivated contact structure 30, and the region between the first region 111 and the second region 112.

[0089] Of course, in some embodiments, a dielectric film or an intrinsic silicon film layer can also be provided between the first region 111 and the second region 112, and the first region 111 and the second region 112 can be separated from each other by the dielectric film or the intrinsic silicon film layer to reduce edge recombination, which is not limited in particular. Specifically, the dielectric film can include a silicon oxide film, a silicon nitride film, or the like.

[0090] Referring to FIG. 4, in some embodiments, the third passivated contact structure 301 of the double-sided contact solar cell can include a third tunneling layer 3011 and a third polarity doped layer 3012 stacked on the third tunneling layer 3011, and the third polarity doped layer 3012 can include at least one of doped polysilicon, doped amorphous silicon, and doped microcrystalline silicon.

[0091] Referring to FIG. 4, the fourth passivated contact structure 302 includes a fourth tunneling layer 3021 and a fourth polarity doped layer 3022 stacked on the fourth tunneling layer 3021, and the fourth polarity doped layer 3022 can include at least one of doped polysilicon, doped amorphous silicon, and doped microcrystalline silicon. The fourth polarity doped layer 3022 is opposite in polarity to the third polarity doped layer 3012. For example, when the third polarity doped layer 3012 is a P-type doped layer, the fourth polarity doped layer 3022 can be an N-type doped layer, and when the third polarity doped layer 3012 is an N-type doped layer, the fourth polarity doped layer 3022 can be a P-type doped layer.

[0092] In this way, the third passivated contact structure 301 and the fourth passivated contact structure 302 are designed as described above, which can greatly reduce the front surface recombination and the back surface recombination of the double-sided contact solar cell, and the surface recombination characteristic lifetime can reach or be higher than the bulk lifetime, so that the effective lifetime of the double-sided contact solar cell is dominated by the bulk lifetime.

[0093] Specifically, the third tunneling layer 3011 and the fourth tunneling layer 3021 can also be a thin film oxide layer or a thin film intrinsic silicon layer, which is not particularly limited here. Of course, it can also be understood that in the double-sided contact battery, other passivation film layers, such as a silicon nitride film layer, etc., can also be stacked on the third passivation contact structure 301 and the fourth passivation contact structure 302, which is not particularly limited here.

[0094] In some embodiments, when the silicon substrate 10 and the back contact solar cell or the double-sided contact battery are made, phosphorus gettering or surface defect gettering or other effective gettering methods can be used to reduce the body impurities of the silicon substrate, and at the same time, a high-efficiency cleaning process is used to effectively remove the surface impurities, for example, an ozone cleaning process, so as to control the defects in the silicon substrate 10 at a low level.

[0095] Hereinafter, the specific causes of the present disclosure and the technical effects that can be achieved by the present disclosure are described:

[0096] In the development process of photovoltaic technology, before 2015, the P-type full Al back field battery is the mainstream of the scale production of crystalline silicon solar cells, which uses boron-doped polysilicon or silicon wafer as the substrate. In order to ensure the performance of the battery, the resistivity range is 1-3 ohm.cm, the main reason is that:

[0097] 1. Too low resistivity (i.e. too high boron doping concentration) will cause a significant decrease in bulk minority carrier lifetime, resulting in a rapid decrease in the effective collection probability of minority carriers. At the same time, too high boron doping concentration will cause the B-O recombination pair concentration to be too high under the working environment (solar irradiation), resulting in a high light-induced degradation effect.

[0098] 2. Too high resistivity will cause too high resistance loss of current transmission in the silicon substrate.

[0099] After 2015, the market share of P-type monocrystalline PERC battery rapidly increased and gradually occupied the mainstream. At the initial stage of PERC scale production, the silicon substrate followed the silicon substrate specification of the full Al back cell, i.e. boron-doped P-type, with a resistivity range of 1-3 ohm.cm. However, the technical personnel soon found the limitations of this silicon substrate specification:

[0100] 1. The structure of the back local contact of the PERC cell leads to a significant increase in the loss caused by the bulk resistance. With a resistivity of 1-3 ohm.cm, the resistance loss is too large.

[0101] 2. The bulk lifetime of the boron-doped silicon substrate is affected by the B-O recombination pair. As the resistivity decreases, the minority carrier lifetime decreases significantly, resulting in too large recombination loss.

[0102] Until around 2017, the crystalline silicon industry found a new way: mass production using Ga-doped low resistivity P-type silicon substrate, Ga-doping solves the influence of B-O complex on the minority carrier lifetime, so that the minority carrier lifetime of low resistivity silicon substrate is greatly improved. As long as the resistivity does not remain too low to cause significant increase of Auger recombination, the resistivity and recombination loss are nearly irrelevant factors.

[0103] At this point, the industry has an inherent understanding that lower resistivity can achieve higher conversion efficiency, and the resistivity of mass-produced silicon substrate is adjusted to 0.4-1.1 ohm.cm.

[0104] During 2015-2021, the efficiency of mass-produced PERC cells increased from 20.5% to 23.0%, and the cost per kilowatt-hour of photovoltaic power decreased rapidly, but the efficiency has approached the theoretical performance of mass production, and further efficiency improvement and cost reduction have reached a bottleneck. During the gradual maturation of PERC mass production, technicians have been looking for the next generation of technology, during which multiple technologies have formed fierce competition, and finally three cells stand out: phosphorus-doped N-type Topcon, phosphorus-doped N-type HJT, and gallium-doped P-type HPBC. The cell conversion efficiency is >23%, and all have the potential to further lead the cost reduction per kilowatt-hour after PERC.

[0105] As can be seen from the above, in the field of photovoltaic technology, in order to ensure the efficiency of the cell, there is an inherent understanding that 1) the resistivity of the silicon substrate is as small as possible; 2) the upper and lower limits of the resistivity are set.

[0106] The specific reasons for this understanding are as follows:

[0107] First, the efficiency loss caused by the resistivity of the silicon substrate

[0108] The power loss caused by the resistivity of the silicon substrate is approximately estimated according to the current at the maximum power point, wherein the J mpp point of the multicrystalline silicon cell, Topcon cell, HJT cell and PERC cell is about: 34.3 mA / cm 2 , 39.7 mA / cm 2 , 37.3 mA / cm 2 , 39.36 mA / cm 2 , assuming the thickness of the silicon substrate is 150um, the body resistivity loss caused by the silicon substrate with different resistivity in the dark state is calculated, as shown in FIG. 6, which is a graph of the relationship between the resistivity of the silicon substrate of different cell pieces (resistivity in the dark state) and the efficiency loss in the prior art;

[0109] As can be seen from FIG. 6, as the silicon substrate resistivity rises, the efficiency loss caused by the silicon substrate resistance continues to rise, and PERC is the most sensitive, which is also the reason why the PERC cell resistivity selection is smaller than other cells. Among them, the full Al back cell, Topcon, HJT cell is close to 0.05% conversion efficiency loss at ~2.5 ohm.cm, and close to 0.1% conversion efficiency loss at ~5 ohm.cm.

[0110] According to the current 1 yuan / W component price, and the 0.007 yuan / W premium income brought by the per W power improvement, the conversion efficiency loss of 0.05% and 0.1% will bring the component income loss of 10 million and 20 million yuan per GW respectively, and the profit loss caused by the efficiency loss has a great influence on the profit of the component business, which may even affect the profit and loss of the enterprise.

[0111] Second, the upper and lower limits of the silicon substrate resistivity specification;

[0112] As shown in FIG. 7, FIG. 7 is a simulation result diagram of the relationship between the bulk resistance loss and the bulk Auger recombination loss of the PERC cell in the prior art and the resistivity of the silicon substrate;

[0113] As can be seen from FIG. 7, the bulk resistivity loss caused by the bulk resistivity is approximately a linear function, and the loss increases as the resistivity increases; the Auger recombination is related to the square of the carrier concentration, and the bulk Auger recombination loss rapidly rises as the resistivity decreases, and the sum of the two presents a concave curve, which is the source of the upper and lower limits of the resistivity specification. As can be seen from FIG. 7, the minimum value of the sum of the bulk resistivity loss and the bulk Auger recombination loss appears at 0.4-0.6 ohm.cm.

[0114] In addition, please refer to FIG. 8, which is a simulation result of the relationship between the conversion efficiency of the PERC cell in the prior art and the resistivity of the silicon substrate;

[0115] As can be seen from FIG. 8, the peak value of the conversion efficiency of the cell appears at the silicon substrate resistivity of about 0.4-0.6 ohm.cm, and the conversion efficiency rapidly decreases as the resistivity rises or falls, but the decrease in the conversion efficiency caused by the decrease in the resistivity is more significant, and the determining factor is the relationship between the silicon substrate resistivity and the resistance loss and the Auger recombination loss.

[0116] When the resistivity is <0.3 ohm.cm or >1.5 ohm.cm, >0.1% efficiency reduction occurs, considering the efficiency loss caused by the decrease in the resistivity is more rapid, and considering the product reliability related problems, the minimum resistivity is generally set to 0.4 ohm.cm and the upper limit of the resistivity can be set to 1.1 ohm.cm under the consideration of the silicon substrate cost.

[0117] However, after the inventors of the present disclosure conducted in-depth research and verification, it was found that:

[0118] 1. The bulk resistivity of a silicon substrate under light is related to the free carrier concentration, and the doping of the silicon substrate affects the carrier concentration and in turn the bulk resistivity of the silicon substrate under light, while the free carrier concentration is related to the doping concentration and the non-equilibrium carrier concentration;

[0119] 2. During the operation of a solar cell, non-equilibrium carriers are generated under light, which will affect the actual bulk resistivity (i.e. the bulk resistivity under light);

[0120] 3. In the case of higher bulk resistivity (dark-state resistivity), the bulk lifetime is higher, and under light, when the recombination / photo-generation reaches equilibrium, the non-equilibrium carrier concentration is higher; that is, the higher the bulk lifetime, the higher the non-equilibrium carrier concentration, and the bulk resistivity under light will be lower;

[0121] 4. The non-equilibrium carrier concentration has a strict physical correspondence with recombination and cell voltage, and the lower the recombination, the higher the cell voltage, and the non-equilibrium carrier concentration also increases;

[0122] Therefore, if the non-equilibrium carrier concentration reaches the same order of magnitude as the doping concentration of the doping elements of the silicon substrate or even higher, and the increase in the non-equilibrium carrier concentration caused by the increase in the bulk resistivity (dark-state resistivity) of the silicon substrate can significantly reduce the bulk resistivity (i.e. the resistivity under light) of the silicon substrate under light, thereby reducing the bulk resistivity efficiency loss, and the bulk resistivity efficiency loss caused by the increase in the resistivity (dark-state resistivity) of the silicon substrate is less than the bulk resistivity efficiency loss caused by the use of low-resistivity, high-doped silicon substrates in the prior art, that is, when the resistivity (dark-state resistivity) of the silicon substrate increases, the concentration of non-equilibrium carriers increases significantly, which will actually reduce the resistance loss under light. At this time, the sum of the resistance efficiency loss and the Auger recombination efficiency loss (i.e. the overall efficiency loss) decreases monotonically with the increase of the resistivity.

[0123] In order to achieve this technical purpose, the inventors of the present disclosure have found that:

[0124] The back contact solar cell structure is adopted, and the first passivation contact structure 20, the second passivation contact structure 30 and the back passivation film layer 40 are adopted on the back surface 11 of the back contact solar cell, no additional surface doping is performed on the front surface 12 of the back contact solar cell (that is, no front surface field is formed) or a sufficiently low surface doping is adopted (that is, a front surface field with a low doping concentration is formed); or a double-sided contact cell structure is adopted, and the third passivation contact structure 301 and the fourth passivation contact structure 302 are respectively adopted on the two surfaces of the double-sided contact cell. In this way, the recombination of the front / back surface of the solar cell sheet 100 and the double-sided contact cell can be greatly reduced, the characteristic lifetime of the surface recombination can reach or be higher than the bulk lifetime, and the effective lifetime of the cell is dominated by the bulk lifetime.

[0125] At the same time, by adopting such a cell structure, the non-equilibrium carrier concentration in each part of the bulk transport channel of the cell during operation can be ensured at a high level, so as to reduce or avoid the loss of a large resistance caused by too low local non-equilibrium carrier concentration.

[0126] That is to say, the inventors of the present disclosure found through research and verification that by designing the above-mentioned adaptive cell structure, the contradiction between the efficiency of the cell and the resistivity of the silicon substrate 10 can be solved, the above-mentioned inherent cognition is broken, and the P-type doping element and the N-type doping element with a doping concentration greater than 10 12 atoms / cm 3 are simultaneously doped, and the absolute value of the difference between the doping concentrations of the two doping elements is controlled to be less than 10 14 atoms / cm 3 , so that the resistivity of the silicon substrate 10 is greater than 50 ohm.cm, and the conversion efficiency of the solar cell sheet 100 can be improved in the case of high resistivity. That is to say, the inventors of the present disclosure found through research and verification that by adopting the technical solutions of the present disclosure, a higher resistivity can be achieved by controlling the doping concentrations of the two doping elements with different polarities to be greater than 10 12 atoms / cm 3 , and the absolute value of the difference between the two concentrations is controlled to be less than 10 14 atoms / cm 3 , and the conversion efficiency of the solar cell sheet 100 can be improved while the resistivity is high, which breaks the existing inherent cognition.

[0127] Specifically, the test simulation results of the back contact solar cell and the double-sided contact cell of the present disclosure adopting the silicon substrate 10 of the present disclosure are shown in FIGS. 9, 10 and 11.

[0128] Figure 9 is a graph showing the relationship between the bulk resistance loss, the bulk recombination loss, and the resistivity of the silicon substrate (the resistivity in the dark state, i.e., the "silicon wafer resistivity" in the graph) of the back contact solar cell and the bifacial contact cell of the present disclosure using the silicon substrate 10 of the present disclosure.

[0129] As can be seen from Figure 9, by using the passivated contact technology of the back contact solar cell and the bifacial contact cell, the overall efficiency loss caused by the sum of the bulk resistance loss and the bulk recombination loss monotonously decreases with the increase of the resistivity of the silicon substrate 10, thus breaking through the above-mentioned contradiction, i.e., with the increase of the resistivity of the silicon substrate 10, the efficiency loss of the back contact solar cell and the bifacial contact cell as a whole will decrease and eventually converge.

[0130] Figure 10 is a graph showing the relationship between the carrier concentration and the resistivity of the silicon substrate of the back contact solar cell and the bifacial contact cell of the present disclosure using the silicon substrate 10 of the present disclosure. The bulk doping concentration refers to the absolute value of the difference between the doping concentration of the P-type doping element and the doping concentration of the N-type doping element.

[0131] As can be seen from Figure 10, when the silicon substrate resistivity > 1.3 ohm.cm, the non-equilibrium carrier concentration starts to be greater than the bulk doping concentration when the cell is working under light. Eventually, the increase of the non-equilibrium carrier concentration caused by the increase of the bulk resistivity can cover the resistivity change caused by the decrease of the bulk doping concentration. That is, the increase of the non-equilibrium carrier concentration caused by the increase of the bulk resistivity (the resistivity in the dark state) of the silicon substrate can greatly reduce the efficiency loss and thus cover the efficiency loss caused by the decrease of the doping concentration. Meanwhile, as can be seen from the comparison between Figure 10 and Figure 8, compared with the technical solution in the prior art, the technical solution of the present disclosure can greatly improve the conversion efficiency of the solar cell wafer.

[0132] Figure 11 is a graph showing the relationship between the resistivity of the silicon substrate and the conversion efficiency of the cell of the back contact solar cell and the bifacial contact cell of the present disclosure using the silicon substrate 10 of the present disclosure.

[0133] As can be seen from Figure 11, by using the silicon substrate 10 of the present disclosure and applying it in the solar cell wafer 100 having the first passivated contact structure 20, the second passivated contact structure 30, and the back passivated film layer 40 or in the bifacial contact cell having the third passivated contact structure 301 and the fourth passivated contact structure 302, the conversion efficiency of the cell monotonously increases with the increase of the resistivity of the silicon substrate 10 and eventually converges.

[0134] In summary, in the present disclosure, the solar cell wafer 100 using the silicon substrate 10 in the embodiment of the present disclosure can effectively reduce the efficiency loss to improve the conversion efficiency of the cell, and break the existing inherent cognition.

[0135] In addition, the cell using the silicon substrate 10 of the present disclosure also has the following effects:

[0136] 1. Component mismatch is reduced

[0137] As shown in FIG. 12, FIG. 12 is a graph of the relationship between the resistivity of the silicon substrate of the back contact solar cell and the bifacial contact cell in the embodiment of the present disclosure and the maximum power point current.

[0138] As can be seen from FIG. 12, as the resistivity rises, the maximum power point current rises and gradually stabilizes. When the cell is used to make a component, the cell is in a series state, and the final current needs to be consistent. If J mpp When the difference is large, there must be a mismatch problem between the cell wafers, which causes the performance of the cell to be unable to fully play, and causes the CTM to be reduced. Therefore, by properly adjusting the cell structure and technology, high-resistivity silicon substrates (i.e. the silicon substrate 10 in the present disclosure) can be used for production, which will bring an improvement in the CTM of the component.

[0139] 2. Ability to resist non-ideal factors is improved, and power generation is improved

[0140] As shown in FIG. 13, FIG. 13 is a graph of the relationship between the concentration of non-equilibrium carriers of the solar cell wafer 100 and the bifacial contact cell in the embodiment of the present disclosure and the SRH minority carrier lifetime, wherein the abscissa is the concentration of non-equilibrium carriers, and the ordinate is the SRH minority carrier lifetime.

[0141] As can be seen from FIG. 13, the performance of the lifetime introduced by defects with a larger minority carrier capture cross-section under different resistivities is as follows: when the resistivity rises, the lifetime introduced by defects with a larger minority carrier capture cross-section under low injection shows obvious advantages, which means that the efficiency loss caused by silicon substrate cutting, surface scratches, metal ions, etc. will be inhibited to some extent, and the performance of the product will be improved. At the same time, because the lifetime under low injection is increased, better low radiation performance will be brought, the power generation of a single watt component will be improved, and the reduction of the degree of electricity cost will be led.

[0142] 3. Economic value of allowing the use of high-resistivity silicon substrate production

[0143] 1) Cell efficiency benefit: the resistivity is increased to > 50 ohm.cm, the average conversion efficiency is increased by at least 0.05%, and the cost reduction and product premium benefit is about 0.01 yuan / W

[0144] 2) Other benefits: The benefits brought by the reduction of component mismatch and the sensitivity reduction of process low injection life influencing factors vary according to the actual technical level, and the cost reduction and product premium benefits are calculated as 0.1% of the equivalent average efficiency improvement, which is about 0.02 yuan / W.

[0145] In summary, the technical solution of the present disclosure is expected to bring a benefit of 0.041 yuan / W. In 2022, the production capacity of each domestic photovoltaic manufacturer is 85GW, 65GW, 65GW, and 50GW, respectively, and the corresponding net profit in 2022 is 148, 29.3, 36.8, and 55.3 million yuan. If the technical effect of the present disclosure is adopted, it can generate 34.85, 26.65, 26.65, and 20.5 million yuan, respectively, which is equivalent to an increase of 23.5%, 91.0%, 72.4%, and 37.1% in net profit, respectively, and has significant economic value.

[0146] In the description of the present disclosure, the description of the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present disclosure. In the present disclosure, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0147] In addition, the above only describes the preferred embodiments of the present disclosure and does not limit the present disclosure. Any modification, equivalent replacement and improvement made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A silicon substrate, characterized by, The silicon substrate is used for a solar cell piece, the silicon substrate is simultaneously doped with a P-type doping element and an N-type doping element, the P-type doping element is at least one of boron, aluminum, gallium, indium and thallium, and the N-type doping element is at least one of phosphorus, arsenic, antimony and bismuth. The sum of the doping concentrations of the P-type doping elements and the sum of the doping concentrations of the N-type doping elements are both greater than 10 12 atoms / cm 3 The absolute value of the difference between the sum of the doping concentrations of the P-type doping elements and the sum of the doping concentrations of the N-type doping elements is less than 10 14 atoms / cm 3 The resistivity of the silicon substrate after the elimination of thermal donors treatment is greater than 50 ohm.cm.

2. The silicon substrate of claim 1, wherein The sum of the doping concentrations of the P-type doping elements and the sum of the doping concentrations of the N-type doping elements are both greater than 10 14 atoms / cm 3 .

3. The silicon substrate of claim 2, wherein The sum of the doping concentrations of the P-type doping elements and the sum of the doping concentrations of the N-type doping elements are both greater than 10 15 atoms / cm 3 .

4. The silicon substrate of claim 1, wherein The absolute value of the difference between the sum of the doping concentrations of the P-type doping elements and the sum of the doping concentrations of the N-type doping elements is less than 5*10 13 atoms / cm 3 .

5. The silicon substrate of claim 1, wherein The resistivity of the silicon substrate after the elimination of thermal donor treatment is greater than 100 ohm.cm.

6. The silicon substrate of claim 4, wherein The resistivity of the silicon substrate after the elimination of thermal donor treatment is greater than 200 ohm.cm.

7. The silicon substrate of claim 6, wherein The resistivity of the silicon substrate after the elimination of thermal donor treatment is greater than 500 ohm.cm.

8. The silicon substrate of claim 7, wherein The resistivity of the silicon substrate after the elimination of thermal donor treatment is greater than 1000 ohm.cm.

9. The silicon substrate of claim 8, wherein, The resistivity of the silicon substrate after the elimination of thermal donor treatment is greater than 5000 ohm.cm.

10. The silicon substrate of claim 1, wherein The thickness of the silicon substrate is 30 um-300 um.

11. The silicon substrate of claim 1, wherein The silicon substrate is a single crystal silicon substrate.

12. A solar cell, characterized by, The solar cell piece is a back contact solar cell, and the solar cell piece comprises: The silicon substrate according to any one of claims 1-11, a back surface of the silicon substrate has a plurality of first regions and second regions, the plurality of first regions and the plurality of second regions are alternately and sequentially arranged; A first passivation contact structure is stacked on the first region; A second passivation contact structure is stacked on the second region, and a polarity of the second passivation contact structure is different from a polarity of the first passivation contact structure; and A back surface passivation film layer is stacked on the first passivation contact structure and the second passivation contact structure.

13. The solar cell of claim 12, wherein, The first passivation contact structure comprises a first tunneling layer and a first polarity doping layer stacked on the first tunneling layer, and the first polarity doping layer comprises at least one of doped polysilicon, doped amorphous silicon and doped microcrystalline silicon. The second passivation contact structure comprises a second tunneling layer and a second polarity doping layer stacked on the second tunneling layer, and the second polarity doping layer comprises at least one of doped polysilicon, doped amorphous silicon and doped microcrystalline silicon, and a polarity of the second polarity doping layer is opposite to a polarity of the first polarity doping layer.

14. The solar cell of claim 13, wherein, The first region and the second region have a groove therebetween, the first passivation contact structure and the second passivation contact structure are isolated by the groove, and the groove is not provided with a doping layer formed by doping of a group III element or a group V element. Or The first region and the second region are provided with a dielectric film or an intrinsic silicon film layer, and the first region and the second region are isolated from each other by the dielectric film or the intrinsic silicon film layer.

15. The solar cell of claim 12, wherein, The front side of the silicon substrate is free of a doped front surface field, or the front side of the silicon substrate has a front surface field with a surface doping concentration of less than 5*10 18 atoms / cm 3 .

16. A solar cell, characterized by, The solar cell piece is a double-sided contact cell, and the solar cell piece comprises: The silicon substrate according to any one of claims 1-11, the silicon substrate has opposite first and second surfaces; A third passivation contact structure is stacked on the first surface; and A fourth passivation contact structure is stacked on the second surface.

17. The solar cell of claim 16, wherein, The third passivation contact structure comprises a third tunneling layer and a third polarity doping layer stacked on the third tunneling layer, and the third polarity doping layer comprises at least one of doped polysilicon, doped amorphous silicon and doped microcrystalline silicon. The fourth passivation contact structure includes a fourth tunneling layer and a fourth polarity doped layer stacked on the fourth tunneling layer, the fourth polarity doped layer including at least one of doped polysilicon, doped amorphous silicon, and doped microcrystalline silicon, and the fourth polarity doped layer being opposite in polarity to the third polarity doped layer.

18. A battery assembly characterized by, A solar cell including the solar cell of any one of claims 12-17.

19. A photovoltaic system characterized by, A battery assembly including the battery assembly of claim 18.

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