Topcon solar cell and preparation method therefor, photovoltaic module

Abstract

This application relates to the field of photovoltaic technology, and discloses a TOPCon solar cell, its fabrication method, and a photovoltaic module. It includes: a first doped layer disposed on the front side of the TOPCon solar cell; a second doped layer disposed on the back side of the TOPCon solar cell; a composite channel layer disposed on at least one side section of the TOPCon solar cell, the side section being perpendicular to a first direction, the first direction being the extension direction of the front side of the TOPCon solar cell; the composite channel layer including a plurality of leakage channels spaced apart along a second direction, the leakage channels connecting the first doped layer and the second doped layer, the second direction being the extension direction of the side section. The TOPCon solar cell proposed in this application has high carrier mobility and low hot spot effect power loss.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, specifically to TOPCon solar cells and their fabrication methods, and photovoltaic modules. Background Technology

[0002] Hot spots are a common fault in the actual operation of photovoltaic (PV) modules. They refer to situations where some solar cells in a PV module become "mismatched cells" due to shading, performance degradation, or other reasons. These cells are reverse-biased by other normally illuminated solar cells, leading to concentrated power dissipation and high temperatures (up to 100℃~200℃), seriously threatening the lifespan of the PV module and the safety of the PV system. Improving hot spot performance can enhance the efficiency, safety, and lifespan of PV modules while reducing total lifecycle costs. Through collaborative optimization at the design, manufacturing, and operation and maintenance levels, hot spot risks can be significantly reduced, improving the overall economic efficiency and reliability of the PV system.

[0003] It should be noted that the above statements are only used to provide background information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0004] In a first aspect, this application proposes a TOPCon solar cell, comprising: a first doped layer disposed on the front side of the TOPCon solar cell; a second doped layer disposed on the back side of the TOPCon solar cell; and a composite channel layer disposed on at least one side section of the TOPCon solar cell, the side section being perpendicular to a first direction, the first direction being the extension direction of the front side of the TOPCon solar cell; the composite channel layer including a plurality of leakage channels spaced apart along a second direction, the leakage channels connecting the first doped layer and the second doped layer, the second direction being the extension direction of the side section. In the TOPCon solar cell proposed in this application, the leakage channels in the composite channel layer can connect the first doped layer and the second doped layer on the front side (the side facing sunlight) and the back side of the TOPCon solar cell, forming a bypass channel through which charge carriers can pass with low resistance. Therefore, even if part of the surface of the TOPCon solar cell is shaded, making photoelectric conversion difficult and causing reverse bias power consumption, the leakage channels can effectively reduce the series resistance of a photovoltaic module composed of multiple TOPCon solar cells, thereby reducing current mismatch losses caused by hot spot effects. Furthermore, the reduced volume of individual TOPCon solar cells after being cut shortens the current transport path of the combined photovoltaic modules. Combined with the effect of leakage current channels, this significantly improves the adaptability of TOPCon solar cells to complex lighting environments. Therefore, the TOPCon solar cells proposed in this application exhibit high carrier mobility, low hotspot effect power loss, and low thermal aging.

[0005] In some embodiments, at least one of the following conditions is met: the ratio of the total area of ​​the leakage channels to the area of ​​the cross-sectional area of ​​the TOPCon solar cell containing the leakage channels is 0.05% to 25%; the area of ​​the leakage channels is 0.0025 mm². 2 ~0.07mm 2 The shape of the leakage channel includes at least one of the following: rectangular, square, trapezoidal, polygonal, curved, and irregular polygonal. When the aforementioned conditions are met, the arrangement of the leakage channel facilitates a relatively uniform distribution of multiple leakage channels across the side section of the TOPCon solar cell, resulting in a moderate reverse saturation current. This allows for a better balance between leakage loss and the efficiency and effectiveness of the TOPCon solar cell in resisting hot spots, thereby improving the power performance of photovoltaic modules composed of TOPCon solar cells.

[0006] In some embodiments, the leakage channel includes a first amorphous silicon layer and a doped amorphous silicon layer, the first amorphous silicon layer being disposed on the side section, and the doped amorphous silicon layer being disposed on the side of the first amorphous silicon layer away from the silicon substrate, the doping concentration of the doped amorphous silicon layer being 1×10⁻⁶. 18 ~5×10 21 The first amorphous silicon layer in the leakage channel is disposed on the side section, which helps to improve the surface unevenness caused by the dicing on the side section and passivates the composite defects caused by the cutting, thus having a better field passivation effect. When the doped amorphous silicon layer in the leakage channel meets the aforementioned doping concentration, it can have good conductivity, which is beneficial as a carrier transport channel and plays a better role in current dispersion and transport.

[0007] In some embodiments, the thickness of the first amorphous silicon layer is 1 nm to 10 nm; and / or, the thickness of the doped amorphous silicon layer is 5 nm to 100 nm. When the thickness of the first amorphous silicon layer is within the aforementioned range, the recombination loss of charge carriers on the side surface of the TOPCon solar cell can be significantly reduced. When the thickness of the doped amorphous silicon layer is within the aforementioned range, a more stable charge carrier transport path can be formed, improving the effect of resisting hot spots.

[0008] In some embodiments, the recombination channel layer further includes a faceted passivation layer disposed on the side of the leakage channel away from the silicon substrate. The faceted passivation layer includes a second amorphous silicon layer and a modification layer, the modification layer being disposed on the side of the second amorphous silicon layer away from the leakage channel. This improves the passivation effect on edge damage in TOPCon solar cells, suppresses carrier recombination, and enhances the photoelectric conversion efficiency of TOPCon solar cells.

[0009] In some embodiments, the thickness of the second amorphous silicon layer is 1 nm to 10 nm; and / or, the thickness of the modification layer is 5 nm to 100 nm. When the aforementioned thickness range is met, the film density of the passivation layer is better, and the film defects are fewer. As a result, the dangling bonds on the side face can be saturated more fully, which is beneficial to reducing carrier recombination and optical refraction loss.

[0010] In some embodiments, the method further includes a protective layer disposed on the side of the composite channel layer away from the silicon substrate, the protective layer comprising silicon nitride, and the thickness of the protective layer being 20 nm to 80 nm. Thus, the protective layer can effectively isolate the external environment, reduce the erosion of TOPCon solar cells by air and moisture in the environment, and improve the stability and lifespan of structures such as the composite channel layer on the side-section.

[0011] In a second aspect, this application proposes a method for preparing the TOPCon solar cell, comprising: cutting a TOPCon solar cell wafer to obtain a solar cell wafer, the solar cell wafer including at least one side section; performing a mask deposition process on the at least one side section to form a patterned deposition layer; sequentially introducing a first gas and a second mixed gas to perform a first hot-wire chemical vapor deposition process on the side section containing the patterned deposition layer to form a leakage channel on the side section; wherein the first gas includes SiH4, and the second mixed gas includes SiH4, H2, and PH3.

[0012] The method proposed in this application utilizes mask deposition to prepare patterned deposition layers. The perforated structure of the mask controls the distribution and shape of leakage channels on the side-section of the solar cell slice, thereby creating multiple leakage channels on the solar cell slice that can form interlayer connections. Hot-filament chemical vapor deposition is employed, relying on the thermal radiation and pyrolysis of the high-temperature filament to activate the reactive gases. This method helps to reduce damage to the already formed precision structures (especially passivation interfaces) on the TOPCon solar cell when preparing structures such as leakage channels on the side-section. Therefore, it is beneficial to prepare effective leakage channels while protecting the inherent high performance of the TOPCon solar cell, improving the hot spot effect of the TOPCon solar cell, and thus enhancing the photoelectric conversion efficiency of the TOPCon solar cell and the photovoltaic modules it comprises.

[0013] In some embodiments, after forming the leakage channel, the process further includes: sequentially introducing a first gas and a third mixed gas to perform a second hot-wire chemical vapor deposition treatment on the side section containing the leakage channel to obtain a passivation layer, wherein the passivation layer comprises a second amorphous silicon layer and a modification layer; wherein the third mixed gas comprises SiH4 and H2, and the volume ratio of SiH4 to H2 is 1:(1~10). By using the aforementioned combination and ratio of mixed gases to prepare the passivation layer through hot-wire chemical vapor deposition, Si-H bonds can be deposited to passivate the dangling bonds on the side section. This is beneficial for suppressing carrier recombination and improving carrier transport effects.

[0014] In some embodiments, the method further includes: introducing a fourth mixed gas to perform a third hot-wire chemical vapor deposition treatment on the cross-sectional passivation layer to obtain a protective layer, wherein the fourth mixed gas includes SiH4 and NH3. This facilitates the preparation of a protective layer with a dense film structure and good oxygen and water barrier properties.

[0015] In a third aspect, this application proposes a photovoltaic module including the TOPCon solar cell proposed in this application. The photovoltaic module proposed in this application includes a TOPCon solar cell with a leakage current channel in its side section, exhibiting good resistance to hot spot effects, adaptability to different lighting conditions, and high operating power. Attached Figure Description

[0016] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the process for preparing the composite channel layer in one embodiment of this application; Figure 2 This is a schematic diagram of the structure of a photovoltaic module in one embodiment of this application; Figure 3 This is a schematic diagram of the side cross-section structure of a TOPCon solar cell in one embodiment of this application.

[0017] Explanation of reference numerals in the attached figures: Side cut 100; first amorphous silicon layer 110; doped amorphous silicon layer 120; second amorphous silicon layer 130; modification layer 140; protective layer 150; mask 200; photovoltaic module 300. Detailed Implementation

[0018] The embodiments of this application are described in detail below, with examples of these embodiments shown in the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0019] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0020] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are open-ended expressions, meaning they include what is specified in this application but do not exclude other aspects.

[0021] In the description of this application, all figures disclosed herein, whether or not the words "approximately" or "about" are used, are approximate values. Each figure may vary by less than 10% or by a difference that is considered reasonable by one of the art, such as 1%, 2%, 3%, 4%, or 5%.

[0022] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0023] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0024] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0025] To mitigate the hot spot effect of TOPCon solar cells, a bypass diode is connected in parallel for every 10-20 TOPCon solar cells in the photovoltaic module to create a bypass channel. In this structure, the bypass diode can transmit reverse current, providing some anti-hot spot effect. However, the process of setting up the bypass diode is complex, and its current conduction effect is limited, which cannot meet the need to suppress the hot spot effect of photovoltaic modules under complex lighting conditions.

[0026] In a first aspect, this application proposes a TOPCon solar cell, comprising: a first doped layer disposed on the front side of the TOPCon solar cell; a second doped layer disposed on the back side of the TOPCon solar cell; a composite channel layer disposed on at least one side section of the TOPCon solar cell, the side section being perpendicular to a first direction, the first direction being the extension direction of the front side of the TOPCon solar cell; the composite channel layer including a plurality of leakage channels spaced apart along a second direction, the leakage channels connecting the first doped layer and the second doped layer, the second direction being the extension direction of the side section.

[0027] TOPCon solar cells include side cuts formed by slicing TOPCon cells using half-cell technology, as referenced. Figure 1 The side section 100 extends in a second direction, and a composite channel layer is disposed on the side section 100. The composite channel layer includes multiple leakage channels spaced apart along the second direction. (Reference) Figure 2 The first and second doped layers extend in the first direction, and the side cut surface 100 is perpendicular to the first direction. The leakage channel in the composite channel layer connects the first and second doped layers on the front (sunlight-facing side) and back of the TOPCon solar cell, forming a bypass path for carriers to pass through with low resistance. Therefore, even if part of the TOPCon solar cell surface is shaded, making photoelectric conversion difficult and causing reverse bias power loss, the leakage channel effectively reduces the series resistance of the photovoltaic module composed of multiple TOPCon solar cells, thereby reducing current mismatch losses caused by hot spot effects. Furthermore, the reduced volume of individual TOPCon solar cells after cutting shortens the current transmission path of the combined photovoltaic module, which, combined with the leakage channel, significantly improves the adaptability of TOPCon solar cells to complex lighting environments. Therefore, the TOPCon solar cell proposed in this application exhibits high carrier mobility, low hot spot effect power loss, and low thermal aging.

[0028] In some embodiments, at least one of the following conditions is met: the ratio of the total area of ​​the leakage channels to the area of ​​the cross-sectional area of ​​the TOPCon solar cell containing the leakage channels is 0.05% to 25%; the area of ​​the leakage channels is 0.0025 mm². 2 ~0.07mm 2The shape of the leakage channel includes at least one of the following: rectangular, square, trapezoidal, polygonal, curved, and irregular polygonal. When the aforementioned conditions are met, the arrangement of the leakage channel facilitates a relatively uniform distribution of multiple leakage channels across the side section of the TOPCon solar cell, resulting in a moderate reverse saturation current. This allows for a better balance between leakage loss and the efficiency and effectiveness of the TOPCon solar cell in resisting hot spots, thereby improving the power performance of photovoltaic modules composed of TOPCon solar cells.

[0029] In some embodiments, the leakage channel includes a first amorphous silicon layer and a doped amorphous silicon layer, the first amorphous silicon layer being disposed on the side section, and the doped amorphous silicon layer being disposed on the side of the first amorphous silicon layer away from the silicon substrate, the doping concentration of the doped amorphous silicon layer being 1×10⁻⁶. 18 ~5×10 21 The first amorphous silicon layer in the leakage channel is disposed on the side section, which helps to improve the surface unevenness caused by the dicing on the side section and passivates the composite defects caused by the cutting, thus having a better field passivation effect. When the doped amorphous silicon layer in the leakage channel meets the aforementioned doping concentration, it can have good conductivity, which is beneficial as a carrier transport channel and plays a better role in current dispersion and transport.

[0030] In some embodiments, the thickness of the first amorphous silicon layer is 1 nm to 10 nm; and / or, the thickness of the doped amorphous silicon layer is 5 nm to 100 nm. When the thickness of the first amorphous silicon layer is within the aforementioned range, the recombination loss of charge carriers on the side surface of the TOPCon solar cell can be significantly reduced. When the thickness of the doped amorphous silicon layer is within the aforementioned range, a more stable charge carrier transport path can be formed, improving the effect of resisting hot spots.

[0031] In some embodiments, the composite channel layer further includes: a faceted passivation layer disposed on the side of the leakage channel away from the silicon substrate, the faceted passivation layer comprising a second amorphous silicon layer and a modification layer, the modification layer being disposed on the side of the second amorphous silicon layer away from the leakage channel. Reference Figure 3 The second amorphous silicon layer 130 and the modification layer 140 in the passivation layer are disposed on the side cut surface 100. The modification layer 140 includes an α-Si layer, which can sufficiently passivate the side cut surface 100. This improves the passivation effect on the edge damage of the TOPCon solar cell, suppresses carrier recombination, and enhances the photoelectric conversion efficiency of the TOPCon solar cell.

[0032] In some embodiments, the thickness of the second amorphous silicon layer is 1 nm to 10 nm; and / or, the thickness of the modification layer is 5 nm to 100 nm. When the aforementioned thickness range is met, the film density of the passivation layer is better, and the film defects are fewer. As a result, the dangling bonds on the side face can be saturated more fully, which is beneficial to reducing carrier recombination and optical refraction loss.

[0033] In some embodiments, the method further includes: a protective layer disposed on the side of the composite channel layer away from the silicon substrate, the protective layer comprising silicon nitride, and the thickness of the protective layer being 20 nm to 80 nm. (Reference) Figure 3 The protective layer 150 is disposed on the outer side of the side section 100. During the fabrication of the protective layer, the heat generated during silicon nitride deposition can anneal the composite channel layer, strengthen the interfacial bonding, and synergistically improve passivation performance and stability. In addition, the protective layer can effectively isolate the external environment, reduce the erosion of TOPCon solar cells by air and moisture in the environment, and improve the stability and working life of structures such as the composite channel layer on the side section.

[0034] In a second aspect, this application proposes a method for preparing the TOPCon solar cell, comprising: cutting a TOPCon solar cell wafer to obtain a solar cell wafer, the solar cell wafer including at least one side section; performing a mask deposition process on the at least one side section to form a patterned deposition layer; sequentially introducing a first gas and a second mixed gas to perform a first hot-wire chemical vapor deposition process on the side section containing the patterned deposition layer to form a leakage channel on the side section; wherein the first gas includes SiH4, and the second mixed gas includes SiH4, H2, and PH3.

[0035] The method proposed in this application utilizes mask deposition to prepare patterned deposition layers, as referenced... Figure 1 The location and shape of the leakage channels on the side section 100 of the solar cell wafer are controlled by the perforated structure of the mask 200, so as to fabricate multiple leakage channels on the solar cell wafer that can form interlayer connections. (Reference) Figure 3The mask's perforated structure divides the side-section into a mask area and a non-mask area. A leakage channel (including a first amorphous silicon layer 110 and a doped amorphous silicon layer 120) is deposited in the non-mask area. This allows the fabricated leakage channel to act as a bypass diode in the photovoltaic module when the TOPCon solar cell is shaded, effectively reducing overheating caused by hot spot effects. The use of hot-filament chemical vapor deposition, relying on the thermal radiation and pyrolysis of the high-temperature filament to activate the reactive gas, helps minimize the impact on the already formed precision structures (especially the passivation interface) on the TOPCon solar cell when fabricating structures such as the leakage channel on the side-section. Therefore, it is beneficial to fabricate an effective leakage channel while protecting the inherent high performance of the TOPCon solar cell, improving the hot spot effect, and thus enhancing the photoelectric conversion efficiency of the TOPCon solar cell and its photovoltaic module.

[0036] In some embodiments, after forming the leakage channel, the process further includes: sequentially introducing a first gas and a third mixed gas to perform a second hot-wire chemical vapor deposition treatment on the side section containing the leakage channel to obtain a passivation layer. The passivation layer includes a second amorphous silicon layer and a modification layer (including an α-Si layer). The third mixed gas includes SiH4 and H2, with a volume ratio of SiH4 to H2 of 1:(1~10). The passivation layer is prepared using hot-wire chemical vapor deposition with the aforementioned combination and proportion of mixed gases. The second amorphous silicon layer prepared with the silane-rich composition of the first gas has a dense amorphous silicon structure and fewer defects. The modification layer prepared with higher hydrogen dilution and lower silane content in the third mixed gas has a higher hydrogen content and better film conductivity. The Si-H bonds contained therein have a better passivation effect on the dangling bonds on the side section. This is beneficial for suppressing carrier recombination and improving carrier transport effects.

[0037] As an example, the fabrication of leakage channels via hot-filament chemical vapor deposition includes: The first amorphous silicon layer is prepared with a thickness of 1 nm to 10 nm, a temperature of 70 °C to 250 °C, a pressure of 0.1 Pa to 3 Pa, and SiH4 is used as the first gas with a flow rate of 20 sccm to 400 sccm.

[0038] Preparation of a doped amorphous silicon layer: thickness 5nm~100nm, temperature 70℃~250℃, pressure 0.1Pa~3Pa, second mixed gas including SiH4, H2 and PH3, SiH4 to H2 volume ratio 1:(1~10), SiH4 and H2 flow rates 20sccm~400sccm, PH3 flow rate 20sccm~400sccm; doping concentration of the doped modification layer is 1×10 18 ~5×1021 .

[0039] The mask is removed, and a passivation layer is prepared on the cross-section, including: Fabrication of the second amorphous silicon layer: The thickness is 1 nm to 10 nm, the substrate temperature is 70 °C to 250 °C, the pressure is 0.1 Pa to 3 Pa, and the first gas used is SiH4 with a flow rate of 20 sccm to 400 sccm.

[0040] Preparation of the modification layer: The overall thickness is 5nm~100nm, the substrate temperature is 70℃~250℃, the reaction pressure is 0.1Pa~3Pa, the third mixed gas includes SiH4 and H2, the volume ratio of SiH4:H2 is 1:(1~10), and the flow rate is 20sccm~400sccm.

[0041] It also includes the preparation of a protective layer, which comprises silicon nitride, with a thickness of 20 nm to 80 nm and a refractive index N ranging from 1.6 to 2.3. A fourth mixed gas, comprising SiH4 and NH3, is used, with a SiH4 to NH3 ratio of 1:(1 to 8). The substrate temperature is 70 °C to 250 °C, the reaction pressure is 0.1 Pa to 3 Pa, the SiH4 flow rate is 20 sccm to 400 sccm, and the deposition time is 15 s to 300 s.

[0042] In some embodiments, the method further includes: introducing a fourth mixed gas to perform a third hot-wire chemical vapor deposition treatment on the cross-sectional passivation layer to obtain a protective layer, wherein the fourth mixed gas includes SiH4 and NH3. This facilitates the preparation of a protective layer with a dense film structure and good oxygen and water barrier properties.

[0043] In a third aspect, this application proposes a photovoltaic module including the TOPCon solar cell proposed in this application. The photovoltaic module proposed in this application includes a TOPCon solar cell with a leakage current channel in its side section, exhibiting good resistance to hot spot effects, adaptability to different lighting conditions, and high operating power.

[0044] The following specific embodiments illustrate the solution of this application. It should be noted that these embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0045] Example 1 TOPCon cells are sliced ​​along the central cutting line to obtain solar cell slices. The cut edge of the solar cell slice is the side cut surface. The solar cell slices are stacked so that the side cut surfaces are flush and then packaged.

[0046] Mask deposition process: The mask is intermittently perforated, with the perforated areas being non-mask areas, forming a patterned deposition layer; the solid areas are mask areas, serving as protected zones to prevent deposition; the area of ​​a single leakage channel is 0.012 mm². 2 The total area ratio of leakage current channels is 0.05%.

[0047] Leakage channels are prepared by hot-wire chemical vapor deposition, including: The first amorphous silicon layer was prepared with a thickness of 4±0.5 nm, at a temperature of 210±30℃ and a pressure of 0.3±0.2 Pa. The first gas used was SiH4 with a flow rate of 200±50 sccm.

[0048] Preparation of a doped amorphous silicon layer: thickness 40±15 nm, temperature 210±30℃, pressure 0.3±0.2 Pa, the second mixed gas includes SiH4, H2 and PH3, the volume ratio of SiH4 to H2 is 1:3, the flow rates of SiH4 and H2 are 200±10 sccm, and the flow rate of PH3 is 50±40 sccm; the doping concentration of the doped modification layer is 3×10 20 .

[0049] The mask is removed, and a passivation layer is prepared on the cross-section, including: The second amorphous silicon layer was prepared with a thickness of 4±0.5 nm, a substrate temperature of 210±30℃, a pressure of 0.3±0.2 Pa, and SiH4 as the first gas with a flow rate of 200±50 sccm.

[0050] Preparation of the modification layer: The overall thickness is 40±15nm, the substrate temperature is 210±30℃, the reaction pressure is 0.3±0.2Pa, and the third mixed gas includes SiH4 and H2, with a volume ratio of SiH4 to H2 of 1:3 and a flow rate of 200±10sccm for SiH4 and H2.

[0051] It also includes the preparation of a protective layer comprising silicon nitride, with a thickness of 35±5 nm and a refractive index N ranging from 2.00±0.1. A fourth mixed gas comprising SiH4 and NH3 is used, with a SiH4 to NH3 ratio of 1:4. The substrate temperature is 210±30℃, the pressure is 0.3±0.2 Pa, the SiH4 flow rate is 100±30 sccm, and the deposition time is 50±20 s.

[0052] The differences between the other embodiments and Embodiment 1, and the corresponding test results are shown in Table 1.

[0053] Table 1

[0054] Test method: 1. Reverse saturation current test Test standard document number IEC 63202-1 / 2 / 3 / 4 2. Component power gain test and hot spot temperature test Test standard document numbers: IEC 61215 / 1 / 2, IEC 61730-1 / 2 In the description of this application, it should be understood that the terms "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0055] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. "First feature" and "second feature" may include one or more of the indicated feature.

[0056] In the description of this application, "multiple" means two or more.

[0057] In the description of this application, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or the first and second features being in contact through another feature between them.

[0058] In the description of this application, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicate that the first feature is at a higher horizontal level than the second feature.

[0059] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0060] In this application, the order in which the steps are written does not imply a strict execution order and does not limit the implementation process. The specific execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps in this application can be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0061] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A TOPCon solar cell, characterized in that, include: A first doped layer is disposed on the front side of the TOPCon solar cell; A second doped layer is disposed on the back side of the TOPCon solar cell; A composite channel layer is disposed on at least one side section of the TOPCon solar cell, the side section being perpendicular to a first direction, the first direction being the extension direction of the front side of the TOPCon solar cell; The composite channel layer includes a plurality of leakage channels spaced apart along a second direction, the leakage channels connecting the first doped layer and the second doped layer, the second direction being the extension direction of the side section.

2. The TOPCon solar cell according to claim 1, characterized in that, At least one of the following conditions must be met: The ratio of the total area of ​​the leakage channels to the area of ​​the cross-section of the TOPCon solar cell containing the leakage channels is 0.05% to 25%. The area of ​​the leakage current channel is 0.0025 mm². 2 ~0.07mm 2 ; The shape of the leakage current channel includes at least one of the following: rectangle, square, trapezoid, polygonal, curved, and irregular polygon.

3. The TOPCon solar cell according to claim 1, characterized in that, The leakage channel includes a first amorphous silicon layer and a doped amorphous silicon layer. The first amorphous silicon layer is disposed on the side section, and the doped amorphous silicon layer is disposed on the side of the first amorphous silicon layer away from the silicon substrate. The doping concentration of the doped amorphous silicon layer is 1×10⁻⁶. 18 ~5×10 21 .

4. The TOPCon solar cell according to claim 3, characterized in that, The thickness of the first amorphous silicon layer is 1 nm to 10 nm; and / or, The thickness of the doped amorphous silicon layer is 5 nm to 100 nm.

5. The TOPCon solar cell according to any one of claims 1 to 4, characterized in that, The composite channel layer further includes: A faceted passivation layer is disposed on the side of the leakage channel away from the silicon substrate. The faceted passivation layer includes a second amorphous silicon layer and a modification layer, wherein the modification layer is disposed on the side of the second amorphous silicon layer away from the leakage channel.

6. The TOPCon solar cell according to claim 5, characterized in that, The thickness of the second amorphous silicon layer is 1 nm to 10 nm; and / or, The thickness of the modified layer is 5nm to 100nm.

7. The TOPCon solar cell according to any one of claims 1 to 4, characterized in that, Also includes: A protective layer is disposed on the side of the composite channel layer away from the silicon substrate, the protective layer comprising silicon nitride, and the thickness of the protective layer being 20 nm to 80 nm.

8. A method for preparing a TOPCon solar cell according to any one of claims 1 to 7, characterized in that, include: TOPCon solar cells are cut to obtain solar cell cut sheets, the solar cell cut sheets including at least one side cut surface; At least one of the said side sections is subjected to mask deposition to form a patterned deposition layer; A first gas and a second mixed gas are sequentially introduced to perform a first hot-wire chemical vapor deposition process on the side section containing the patterned deposition layer, so as to form a leakage channel on the side section. The first gas includes SiH4, and the second mixed gas includes SiH4, H2, and PH3.

9. The method according to claim 8, characterized in that, After forming the leakage current path, it also includes: A first gas and a third mixed gas are sequentially introduced to perform a second hot-wire chemical vapor deposition process on the side section containing the leakage channel to obtain a cross-section passivation layer, the cross-section passivation layer comprising a second amorphous silicon layer and a modification layer; The third mixed gas comprises SiH4 and H2, wherein the volume ratio of SiH4 to H2 is 1:(1~10); and / or A fourth mixed gas is introduced to perform a third hot-wire chemical vapor deposition process on the passivation layer of the cross section to obtain a protective layer, wherein the fourth mixed gas includes SiH4 and NH3.

10. A photovoltaic module, characterized in that, Includes the TOPCon solar cell as described in any one of claims 1 to 7.

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