Manufacturing method of solar cell, solar cell and photovoltaic module

Abstract

The invention relates to the photovoltaic field, and provides a manufacturing method of a solar cell, the solar cell and a photovoltaic module, and the manufacturing method of the solar cell comprises the steps: providing a substrate which comprises a first region and a second region which are alternately arranged; forming a doped conductive layer, wherein the doped conductive layer covers the first region and the second region; pre-heating treatment is carried out, the pre-heating treatment at least heats the doped conductive layer in the second area to a preset temperature, and the temperature of the second area is kept at the preset temperature before the laser treatment is carried out; laser processing is carried out, and in the laser processing, a scanning area formed by laser beams is adopted to move along a preset scanning path so as to irradiate the doped conductive layer located in the second area; and performing film opening treatment to remove the doped conductive layer in the second region. The reliability of the formed solar cell can be improved.

Description

Technical Field

[0001] The present disclosure relates to the field of photovoltaics, and particularly to a method for manufacturing a solar cell, a solar cell, and a photovoltaic module. Background Art

[0002] A solar cell is a thin photovoltaic semiconductor sheet that directly generates electricity using sunlight, also known as a "solar chip" or "photovoltaic cell". As long as it is illuminated by light with a certain illumination intensity, it can instantaneously output a voltage and generate a current in the case of a circuit. In physics, it is called solar photovoltaics (abbreviated as PV), or simply PV for short.

[0003] The production process of solar cells is divided into silicon wafer inspection, surface texturing and cleaning, diffusion junction formation, laser removal of silicon glass, etching steps, deposition of an antireflection film, screen printing, rapid sintering, etc.

[0004] Currently, during the formation of solar cells, the laser power is usually high, which can affect the substrate performance. Summary of the Invention

[0005] Embodiments of the present disclosure provide a method for manufacturing a solar cell, a solar cell, and a photovoltaic module, which can at least improve the reliability of the formed solar cell.

[0006] According to some embodiments of the present disclosure, on the one hand, an embodiment of the present disclosure provides a method for manufacturing a solar cell, including: providing a substrate, the substrate including alternately arranged first regions and second regions; forming a doped conductive layer, the doped conductive layer covering the first regions and the second regions; performing a preheating treatment, the preheating treatment heating at least the doped conductive layer of the second regions to a preset temperature, and before performing a laser treatment, the temperature of the second regions is maintained at the preset temperature; performing the laser treatment, in the laser treatment, a scanning region formed by a laser beam moves along a preset scanning path to irradiate the doped conductive layer located in the second regions; performing a film opening treatment, the film opening treatment removing the doped conductive layer located in the second regions.

[0007] In some embodiments, heating at least the second regions to the preset temperature includes: heating the substrate as a whole.

[0008] In some embodiments, the preset temperature of the preheating treatment is 50°C to 200°C, and the heating duration is 10s to 100s.

[0009] In some embodiments, the solar cell is a back-contact cell, the first region and the second region are alternately arranged on the back surface of the back-contact cell, and the laser treatment includes: the preheating treatment is carried out synchronously with the irradiation of the laser beam. When the laser beam irradiates the nth second region, the preheating treatment heats the (n + 1)th second region.

[0010] In some embodiments, the manufacturing method further includes: during the laser treatment, it further includes: obtaining the surface temperature of the doped conductive layer irradiated by the laser treatment, and adjusting the heating temperature of each part of the second region by the preheating treatment according to the surface temperature of the doped conductive layer.

[0011] In some embodiments, during the laser treatment, it further includes: detecting the surface temperature of the doped conductive layer irradiated by the laser treatment, and adjusting the laser power, scanning speed or spot overlap rate of the laser treatment.

[0012] In some embodiments, during the adjustment of the laser treatment, the spot overlap rate is controlled to be 30% - 70%.

[0013] In some embodiments, before forming the doped conductive layer, it further includes: forming a protective layer, the protective layer is located in the second region, and the protective layer is removed during the opening film treatment.

[0014] In some embodiments, the process parameters of the laser treatment include: the laser power is 20W - 40W, the laser scanning speed is 50000mm / s - 80000mm / s, and the laser frequency is 500Khz - 800Khz.

[0015] In some embodiments, the opening film treatment includes: a first etching process, the first etching process uses a first etching reagent to etch the doped conductive layer; a second etching process, the second etching process uses a second etching reagent to etch the doped conductive layer and part of the substrate.

[0016] In some embodiments, the process parameters of the first etching process include: the first etching reagent is an alkaline reagent, and the concentration of the alkaline reagent is 2% - 5%, and / or, the process parameters of the second etching process include: the process temperature is 60°C - 80°C, the process time is 100s - 300s, the second etching reagent is an alkaline reagent added with an additive, and the concentration of the alkaline reagent is 3% - 7%.

[0017] According to some embodiments of the present disclosure, on the other hand, an embodiment of the present disclosure further provides a solar cell, formed by the manufacturing method of the solar cell as described above, including: a substrate, the substrate includes an alternately arranged first region and a second region; a doped conductive layer, the doped conductive layer is located on the surface of the first region.

[0018] In some embodiments, the morphology of the second region is in the shape of a pyramid base, and the average size of the opening of the pyramid base shape is 8 μm to 20 μm, and the height is less than 0.5 μm.

[0019] According to some embodiments of the present disclosure, on the other hand, an embodiment of the present disclosure further provides a photovoltaic module, including: a battery string, the battery string includes: a plurality of solar cells formed by the manufacturing method of the solar cell as described above, or, a plurality of solar cells as described above; a welding strip, the welding strip is electrically connected to at least two of the solar cells to serially connect adjacent solar cells.

[0020] The technical solution provided by the embodiment of the present disclosure has at least the following advantages: Before laser treatment, preheating treatment is first performed to keep the second region at a preset temperature, so that the energy required for laser treatment to reach the melting temperature threshold of the doped conductive layer can be reduced, thereby reducing the power of laser treatment. Moreover, since the preheating treatment will make the temperature of the second region uniform, improving the uniformity of laser treatment and die opening treatment, and can also reduce the damage of laser treatment to the solar cell, thereby improving the reliability of the formed solar cell. Description of the Drawings

[0021] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplary illustrations do not limit the embodiments unless otherwise stated. The figures in the drawings do not constitute a proportional limitation; in order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or in the traditional technology, the drawings required to be used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0022] Figure 1 It is a flowchart of a manufacturing method of a solar cell provided by an embodiment of the present disclosure; Figures 2 to 3 It is a schematic structural diagram corresponding to each step of a manufacturing method of a solar cell provided by an embodiment of the present disclosure; Figures 4 to 5 It is a schematic structural diagram corresponding to each step of a manufacturing method of a solar cell provided by another embodiment of the present disclosure; Figure 6A schematic structural diagram of a photovoltaic module provided by another embodiment of the present disclosure; Figure 7 A cross-sectional view of a photovoltaic module provided by another embodiment of the present disclosure.

[0023] Description of reference numerals: 100, substrate; 101, doped conductive layer; 102, emitter; 103, tunneling layer; 104, front passivation layer; 105, back passivation layer; 106, glass layer; 107, front electrode; 108, back electrode.

[0024] 200, substrate; 201, doped conductive layer; 202, second doped conductive layer; 204, front passivation layer; 205, back passivation layer; 206, glass layer; 207, first electrode; 208, second electrode.

[0025] 40, solar cell; 41, encapsulant film; 42, cover plate; 43, solder ribbon. Detailed implementation manners

[0026] In the related art, laser treatment is directly used to irradiate the doped conductive layer. Using the principle of photo-thermal coupling, the laser treatment provides sufficient energy to be converted into heat to heat the surface of the doped conductive layer, so that its surface reaches a thermally molten and damaged state, resulting in an accelerated treatment speed of this area in the subsequent film opening treatment. Based on this, the treatment speed in the subsequent film opening treatment is different from that of the area not treated by laser, so as to complete the removal of the doped conductive layer in the second area while retaining the doped conductive layer in the first area. However, directly through laser treatment, due to the energy distribution characteristics of the laser treatment spot, the energy in the spot overlap area is too high, and the substrate is severely amorphous, which hinders the subsequent film opening treatment. Moreover, dense small tower bases will appear on the substrate surface, affecting carrier transport, reducing FF, and the problems of small tower bases and film opening treatment residues simultaneously affect the growth of the film layer in the subsequent passivation process, resulting in negative effects such as a decrease in Voc.

[0027] Moreover, due to the energy distribution characteristics (Gaussian distribution) of the laser during the laser treatment process, the energy will be concentrated in the central area of the spot, the energy gradient in the surrounding area decreases, and there is also a secondary laser effect in the spot overlap area, etc. To a great extent, the heat distribution is uneven after the actual laser action, and various poor morphologies are formed after film opening, reducing FF and Voc, resulting in the improvement of the photoelectric conversion efficiency of the solar cell being less than expected.

[0028] The technical solutions provided by the embodiments of the present disclosure have at least the following advantages: Before the laser treatment, a preheating treatment is first performed to keep the second region at a preset temperature, so that the energy required for the laser treatment to reach the melting temperature threshold of the doped conductive layer can be reduced, thereby reducing the power of the laser treatment. Moreover, since the preheating treatment will make the temperature of the second region uniform, improving the uniformity of the laser treatment and the mold opening treatment, and reducing the damage of the laser treatment to the solar cell, thus improving the reliability of the formed solar cell.

[0029] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "a plurality of" is more than two, unless otherwise clearly and specifically defined.

[0030] Referring to "embodiments" herein means that the specific features, structures or characteristics described in connection with the embodiments may be included in at least one embodiment of the present disclosure. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

[0031] In the description of the embodiments of the present disclosure, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may mean: there is A, there is both A and B, and there is B. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0032] In the description of the embodiments of the present disclosure, the term "a plurality of" refers to more than two (including two). Similarly, "a plurality of groups" refers to more than two groups (including two groups), and "a plurality of pieces" refers to more than two pieces (including two pieces).

[0033] In the description of the embodiments of the present disclosure, technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the embodiments of the present disclosure.

[0034] In the description of the embodiments of the present disclosure, unless otherwise clearly defined and limited, technical terms such as "installation", "connection", "connection", "fixation" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific situations.

[0035] In the corresponding drawings of the embodiments of the present disclosure, for better understanding and convenience of description, the thickness and area of the layers are enlarged. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component can be "directly" on the surface of the other component, or there can be a third component between the two components. On the contrary, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on a partial edge of the entire surface.

[0036] In the description of the embodiments of the present disclosure, when a certain component "includes" another component, unless otherwise specified, other components are not excluded, and other components may further be included. In addition, when a component such as a layer, film, region, or plate is referred to as "on / at" another component, it can be "directly on" the other component (that is, on the surface of the other component and there is no other component between them), or there can be another component between them. In addition, when a layer, film, region, plate, etc. component is "directly located on" another component, or when a layer, film, region, plate, etc. component is located on the surface of another component, it means that there is no other component located between them.

[0037] The terms used in the description of the various embodiments herein are only for describing specific embodiments and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is also intended to include the plural form, unless the context clearly indicates otherwise. Among them, the component includes components such as layers, films, regions, or plates.

[0038] The following will elaborate on the embodiments of the present disclosure in conjunction with the drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present disclosure, many technical details are presented for the reader to better understand the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed by the present disclosure can still be implemented.

[0039] Reference Figures 1 to 3 , where Figure 1 is a flowchart of a solar cell provided by an embodiment of the present disclosure; Figure 2 is a schematic structural diagram of a laser treatment provided by an embodiment of the present disclosure; Figure 3 is a schematic structural diagram of a solar cell formed after a film opening treatment provided by an embodiment of the present disclosure.

[0040] In some embodiments, the method for manufacturing a solar cell may include: S10: providing a substrate 100, the substrate 100 including an alternately arranged first region and second region.

[0041] The method for manufacturing a solar cell may further include: S11: forming a doped conductive layer 101, the doped conductive layer 101 covering the first region and the second region.

[0042] The method for manufacturing a solar cell may further include: S12: performing a preheating treatment, the preheating treatment heating at least the doped conductive layer 101 in the second region to a preset temperature, and the temperature in the second region remaining at the preset temperature before the laser treatment.

[0043] The method for manufacturing a solar cell may further include: S13: performing a laser treatment, in the laser treatment, a scanning region formed by laser beams moving along a preset scanning path to irradiate the doped conductive layer 101 located in the second region.

[0044] The method for manufacturing a solar cell may further include: S14: performing a film opening treatment, the film opening treatment removing the doped conductive layer 101 located in the second region.

[0045] The technical solution provided by the embodiment of the present disclosure has at least the following advantages: before the laser treatment, a preheating treatment is first performed to keep the second region at the preset temperature, so that the energy required for the laser treatment to reach the melting temperature threshold of the doped conductive layer 101 can be reduced, thereby reducing the power of the laser treatment, and since the preheating treatment will make the temperature in the second region uniform, improving the uniformity of the laser treatment and the film opening treatment, and can also reduce the damage of the laser treatment to the solar cell, thereby improving the reliability of the formed solar cell.

[0046] In some embodiments, the formed solar cell is a TOPcon cell, and the formed doped conductive layer 101 may be a front emitter 102 or a back doped layer. Taking the formed doped conductive layer 101 as the back doped layer as an example, the first region of the substrate 100 is a metal region, and the second region is a non-metal region, where the metal region is the region where the back electrode 108 is subsequently formed, and the non-metal region is the region misaligned with the back electrode 108.

[0047] It should be noted that the area where the back electrode 108 is formed here refers to the area of the orthographic projection of the back electrode 108 on the surface of the substrate 100 after the back electrode 108 is formed. The area misaligned with the back electrode 108 refers to the area on the surface of the substrate 100 where there is no orthographic projection of the back electrode 108 after the back electrode 108 is formed.

[0048] After forming the doped conductive layer 101, through pre-heat treatment, laser treatment, and film opening treatment, selective doping can be formed on the back surface, so that the doped conductive layer 101 can be controlled to be formed only in the area where the electrode is formed, thereby reducing the problem of carrier recombination in the doped conductive layer 101, and further improving the reliability of the formed TOPCON battery.

[0049] Similarly, if the doped conductive layer 101 is the front emitter 102, the first region of the substrate 100 is the metal region, and the second region is the non-metal region. Among them, the metal region is the region where the front electrode 107 is subsequently formed, and the non-metal region is the region misaligned with the front electrode 107. By using pre-heat treatment, laser treatment, and film opening treatment, a selective emitter can be formed on the front surface, thereby improving the reliability of the TOPCON battery. The corresponding description can refer to the description when the doped conductive layer 101 formed is used as an example of the doped layer on the back surface above, and will not be elaborated here.

[0050] Continuing to take the formed doped conductive layer 101 as an example of the doped layer on the back surface, in some embodiments, after providing the substrate 100, an emitter 102 can also be formed on the front surface of the substrate 100, and a tunneling layer 103 can be formed on the back surface of the substrate 100, and then the doped conductive layer 101 is formed.

[0051] In some embodiments, the method of forming the front emitter 102 may include: by performing a diffusion process on the substrate 100, diffusing some doping elements into the substrate 100 to convert part of the substrate 100 into the emitter 102.

[0052] The process of forming the tunneling layer 103 can directly form the tunneling layer 103 on the back surface of the substrate 100 through a deposition process. The deposition process can include any one of atomic layer deposition or chemical vapor deposition.

[0053] The method of forming the doped conductive layer 101 may include: forming an intrinsic polysilicon layer on the surface of the tunneling layer 103 by using a deposition process. For example, an intrinsic polysilicon layer can be formed by using an atomic layer deposition process. Then, a doping process is performed on the intrinsic polysilicon layer to dope doping elements into the intrinsic polysilicon layer to form the doped conductive layer 101.

[0054] The material of the doped conductive layer 101 can also be at least one of amorphous silicon or silicon carbide.

[0055] In some embodiments, during the doping process of the intrinsic polysilicon layer, a glass layer 106 is also formed on the surface of the doped conductive layer 101. The preheating treatment, laser treatment, and film opening treatment also process the glass layer 106. The preheating treatment and laser treatment are used to make the glass layer 106 more porous, thereby increasing the etching rate of the film opening treatment on the laser-treated glass layer 106, and thus completing the selective etching of the doped conductive layer 101.

[0056] In some embodiments, at least the second region is heated to a preset temperature, including: heating the substrate 100 as a whole. Heating the substrate 100 as a whole can reduce the process difficulty of the preheating treatment and the alignment difficulty, so that during the formation process, it is only necessary to place the solar cell on the heating platform without additional alignment.

[0057] In some embodiments, heating the second region can also be local heating of the second region. For example, the second region can be directly heated by directly irradiating the second region with a heating beam.

[0058] In some embodiments, the preset temperature of the preheating treatment is 50°C to 200°C, such as 50°C, 70°C, 90°C, 100°C, 130°C, 160°C, 180°C, or 200°C, etc., and the heating duration is 10s to 100s, such as 10s, 20s, 30s, 40s, 50s, 60s, 70s, 80s, 90s, or 100s. If the preset temperature of the preheating treatment is less than 50°C, the performance of reducing the laser treatment power is weak. If the preset temperature of the preheating treatment is greater than 200°C, it will cause too high a heating temperature, which may damage the substrate of the doped conductive layer 101 by laser treatment and may affect the reliability of the formed solar cell.

[0059] In some embodiments, the process parameters of the laser treatment include: the laser power is 20W to 40W, such as 20W, 25W, 28W, 30W, 35W, 38W, or 40W, etc., the laser scanning speed is 50000mm / s to 80000mm / s, such as 50000mm / s, 55000mm / s, 60000mm / s, 65000mm / s, 70000mm / s, 75000mm / s, or 80000mm / s, etc., and the laser frequency is 500Khz to 800Khz, such as 500Khz, 550Khz, 600Khz, 650Khz, 700Khz, 750Khz, or 800Khz, etc.

[0060] For the laser power, if the laser power is less than 20W, it may lead to poor laser processing effects. For example, if the laser processing irradiates the glass layer 106, it may lead to poor ability to change the porosity of the glass layer 106. If the laser power is greater than 40W, it may cause damage to the solar cell.

[0061] For the laser scanning speed and laser frequency, the laser scanning speed and laser frequency will affect the time and effect of laser processing, and will affect the cost and performance of the solar cell. If the laser scanning speed and laser frequency are too high, it will affect the effect of laser processing, and the laser scanning has been completed before the porosity of the glass layer 106 has been fully changed. If the laser scanning speed and laser frequency are too low, it will lead to too long laser processing time and affect the manufacturing cost of the solar cell.

[0062] In some embodiments, the laser processing can use infrared laser, green light, ultraviolet laser, etc. By using laser processing to damage the glass layer 106, subsequent laser processing and film opening processing can produce differential corrosion to complete selective etching.

[0063] In some embodiments, during the laser processing, it further includes: detecting the surface temperature of the doped conductive layer 101 irradiated by the laser processing, and adjusting the laser power, scanning speed or spot overlap rate of the laser processing. In other words, that is, adjusting the laser processing according to the surface temperature while performing the laser processing. By adjusting the laser processing, the damage caused by the laser processing to the solar cell can be reduced.

[0064] For example, in the scanning path of the laser processing, measure the surface temperature of the doped conductive layer 101. When it is detected that the surface temperature of the doped conductive layer 101 is abnormally uneven, the laser power, scanning speed or spot overlap rate of different laser beams can be adjusted to improve the uneven situation of the surface temperature of the doped conductive layer 101.

[0065] For the laser processing, the laser processing usually scans the surface of the doped conductive layer 101 through multiple laser beams. Therefore, the uneven situation of the surface temperature of the doped conductive layer 101 can be improved by locally adjusting different laser beams.

[0066] For the spot overlap rate, the overlapped part of the spots is often the part with relatively high energy in the laser processing. Adjusting the spot overlap rate can make the processing of the doped conductive layer 101 by the laser processing relatively uniform.

[0067] In some embodiments, during the process of adjusting the laser treatment, the spot overlap rate is controlled to be 30% - 70%, such as 30%, 40%, 50%, 60% or 70%, etc. For laser treatment, although the spot overlap rate can be controlled to be 0, a spot overlap rate of 0 will result in a slower laser treatment process. Moreover, for laser treatment, the spot is usually circular. Setting the spot overlap rate to 0 will cause residues in the laser treatment, and some film layers will not be irradiated by the laser, which will affect the complete etching of the second doped conductive layer 101 when removing the second doped conductive layer 101 later. Therefore, it is necessary to control the spot to have a certain overlap rate. However, if the spot overlap rate is too high, the energy in the overlapping part will be superimposed and accumulated, which will damage the formed solar cell. Therefore, controlling the spot overlap rate to be 30% - 70% can take into account both the improvement of the reliability of the solar cell and the efficiency and performance of the solar cell.

[0068] In an embodiment of the present disclosure, by performing a preheating treatment before the laser treatment, the initial temperature of the doped conductive layer 101 covering the second region is set to a preset temperature, thereby reducing the power of the laser treatment, improving the uniformity of heat distribution during the laser treatment, reducing the residues of the doped conductive layer 101 removed by the die-opening treatment, and at the same time, the energy in the overlapping part of the spots will not cause the amorphous phenomenon of the doped conductive layer 101, thus avoiding affecting the subsequent film-opening treatment, further reducing the problem of residues of the doped conductive layer 101, improving the performance of the formed solar cell, increasing the photoelectric conversion efficiency by 0.01% - 0.03%, reducing the thermal damage caused by the laser treatment, and reducing recombination; moreover, through the preheating treatment, the laser treatment can also reach the target temperature in a short time, improving the processing speed of the laser treatment, correspondingly increasing the production capacity of the batch production of solar cells, and enhancing the product competitiveness.

[0069] In some embodiments, the film-opening treatment may include: a first etching process that uses a first etching reagent to etch the doped conductive layer 101; a second etching process that uses a second etching reagent to etch the doped conductive layer 101 and a part of the substrate 100. The first etching process is used to remove the damage on the surface of the doped conductive layer 101, and the second etching process is used to completely remove the doped conductive layer 101 and planarize the surface of the substrate 100 to facilitate the uniformity of the subsequent film layer formation.

[0070] In some embodiments, a glass layer 106 is also formed during the formation of the doped conductive layer 101, and the first etching process is also used to etch the glass layer 106 and a part of the doped conductive layer 101.

[0071] In some embodiments, the process parameters of the first etching process include: the first etching reagent is an alkaline reagent, and the concentration of the alkaline reagent is 2% - 5%, for example, 2%, 3%, 4% or 5%, and / or the process parameters of the second etching process include: the process temperature is 60°C - 80°C, for example, 60°C, 65°C, 70°C, 75°C or 80°C, the process time is 100s - 300s, for example, 100s, 150s, 200s, 250s, 270s or 300s, etc., and the second etching reagent is an alkaline reagent added with an additive, and the concentration of the alkaline reagent is 3% - 7%.

[0072] For the first etching process, affected by the laser treatment, the surface of the doped conductive layer 101 is more easily etched. Therefore, an alkaline reagent with a concentration of 2% - 5% can be used to complete the etching. For the second etching process, it is necessary to ensure that the doped conductive layer 101 is completely removed. Moreover, in order to improve the flatness of the surface of the substrate 100 after etching, an additive is added, so as to facilitate the formation of a flatter surface of the substrate 100, thereby improving the reliability of the formed solar cell.

[0073] In the embodiments of the present disclosure, due to the reduction of the power of the laser treatment, the depth of the thermal damage to the surface of the substrate 100 can be reduced, which can be reduced from 3μm - 5μm thickness of the substrate 100 damage to 1μm - 2μm. It can reduce the recombination of carriers, improve the lateral transport effect of carriers, and also reduce the depth of the substrate 100 removed by the second etching process, and reduce the generation of fragments during the formation of the solar cell.

[0074] In some embodiments, before forming the doped conductive layer 101, it further includes: forming a protective layer. The protective layer is located in the second region, and the protective layer is removed during the opening film process. By forming the protective layer, the damage to the substrate 100 caused by the laser treatment can be reduced. Moreover, removing the protective layer during the opening film process can also avoid affecting the formation of subsequent film layers, thereby further improving the performance of the solar cell.

[0075] In some embodiments, after completing the opening film process, it may further include: forming a back passivation layer 105 and a front passivation layer 104. The back passivation layer 105 covers the surface of the doped conductive layer 101 and also covers the surface of the substrate 100. The front passivation layer 104 covers the surface of the emitter 102.

[0076] After forming the back passivation layer 105 and the front passivation layer 104, a front electrode 107 and a back electrode 108 are further formed. The front electrode 107 is electrically connected to the emitter 102, and the back electrode 108 is electrically connected to the doped conductive layer 101.

[0077] Similarly, if the formed doped conductive layer 101 is the front emitter 102, after pre-heat treatment, laser treatment, and film opening treatment, the tunneling layer 103, doped conductive layer 101, front passivation layer 104, and back passivation layer 105 are formed. For the same or corresponding parts, reference can be made to the above content, which will not be elaborated below.

[0078] Another embodiment of the present disclosure further provides a method for manufacturing a solar cell. Different from the above embodiment, the solar cell formed in this embodiment is a back-contact solar cell. Hereinafter, the method for manufacturing the solar cell provided by another embodiment of the present disclosure will be described with reference to the accompanying drawings. It should be noted that for the same or corresponding parts as those in the above embodiment, reference can be made to the above embodiment, which will not be elaborated below.

[0079] Reference Figure 4 and Figure 5 , Figure 4 is a schematic structural diagram of laser treatment provided by another embodiment of the present disclosure; Figure 5 is a schematic structural diagram after film opening treatment provided by another embodiment of the present disclosure.

[0080] The solar cell is a back-contact solar cell. The formed doped conductive layer 201 is doped with elements of the first doping type. The first region of the substrate 200 is the region where the doped conductive layer 201 needs to be retained, and the second region is the region where the second doped conductive layer 202 with elements of the second doping type needs to be formed.

[0081] In some embodiments, the process of forming the doped conductive layer 201 may include: forming a semiconductor layer, and then doping the semiconductor layer to form the doped conductive layer 201.

[0082] During the doping process, a glass layer 206 is also formed on the surface of the doped conductive layer 201. The laser treatment can treat the glass layer 206 whose orthographic projection is located in the second region.

[0083] In some embodiments, the first region and the second region are alternately arranged on the back surface of the back-contact cell. The laser treatment includes: the pre-heat treatment is carried out synchronously with the irradiation of the laser beam. When the laser beam irradiates the nth second region, the pre-heat treatment heats the (n + 1)th second region.

[0084] In other words, the pre-heat treatment can be carried out simultaneously with the laser treatment, thereby reducing the process steps of the method for manufacturing the solar cell and reducing the cost of the solar cell.

[0085] Moreover, for laser processing, since the laser processing speed is relatively fast, during the preheating process, the next area to be processed by laser will be heated. And due to the fast laser processing speed, the temperature of the next area will not drop before the laser processing of the current area is completed. Therefore, the effect of laser processing will not be affected.

[0086] In some embodiments, the method for manufacturing a solar cell further includes: during the laser processing, it also includes: obtaining the surface temperature of the doped conductive layer 201 irradiated by the laser processing, and adjusting the heating temperature of each part of the second area during the preheating process according to the surface temperature of the doped conductive layer 201.

[0087] In other words, adjust the heating effect of the preheating process on the (n + 1)-th second area according to the effect of laser processing on the n-th second area, so as to adjust the local temperature at different positions according to the laser processing, thereby further improving the uniformity of the laser processing on each position.

[0088] For example, the surface temperature of the doped conductive layer 201 at the position of the overlapping area of the laser processing spots is relatively high. Then, during the preheating process, the local heating temperature can be controlled to decrease, so that the uniformity of the laser processing can be improved, and the reliability of the formed solar cell can be enhanced.

[0089] In some embodiments, after the film opening process is completed, it may further include: forming a second doped conductive layer 202 in the second area. After forming the second doped conductive layer 202, a back passivation layer 205 and a front passivation layer 204 may be formed. The back passivation layer 205 covers the surfaces of the doped conductive layer 201 and the second doped conductive layer 202.

[0090] After forming the back passivation layer 205 and the front passivation layer 204, a first electrode 207 and a second electrode 208 are further formed. The first electrode 207 is electrically connected to the doped conductive layer 201, and the second electrode 208 is electrically connected to the second doped conductive layer 202.

[0091] An embodiment of the present disclosure also provides a solar cell, which can be formed by the above method for manufacturing a solar cell. It should be noted that the same or corresponding parts can refer to the above embodiments, and will not be described in detail below.

[0092] In some embodiments, the solar cell may include: a substrate, and the substrate includes alternately arranged first areas and second areas.

[0093] The solar cell may include: a doped conductive layer, and the doped conductive layer is located on the surface of the first area.

[0094] In some embodiments, the topography of the second region is in the shape of the base of a pyramid, and the average size of the opening of the pyramid base topography is 8 μm to 20 μm, and the height is less than 0.5 μm. By controlling the average size of the opening of the pyramid base topography to be 8 μm to 20 μm and the height to be less than 0.5 μm, the flatness and uniformity of the back substrate can be improved, thereby improving the performance of the solar cell.

[0095] The average size here may refer to the length or the width.

[0096] An embodiment of the present disclosure further provides a photovoltaic module, which may include a plurality of solar cells formed by the manufacturing method of the solar cells in the above embodiments, or a plurality of solar cells in the above embodiments. Hereinafter, a photovoltaic module provided by an embodiment of the present disclosure will be described with reference to the drawings. It should be noted that the same or corresponding parts as above may refer to the above embodiments, and will not be described in detail hereinafter.

[0097] Reference Figure 6 and Figure 7 , wherein, Figure 6 is a partial perspective view of a photovoltaic module provided by an embodiment of the present disclosure, Figure 7 is Figure 6 a partial cross-sectional view along the first section direction BB1.

[0098] In some embodiments, the photovoltaic module includes: a battery string, and the battery string includes: a plurality of solar cells 40 formed by the formation method of the solar cells 40 in some or all of the above embodiments, or a plurality of the above solar cells; a welding strip 43, and the welding strip 43 is electrically connected to at least two solar cells 40 to serially connect adjacent solar cells 40.

[0099] The photovoltaic module further includes: an encapsulation film 41, and the encapsulation film 41 is used to cover the surface of the battery string.

[0100] The photovoltaic module further includes: a cover plate 42, and the cover plate 42 is used to cover the surface of the encapsulation film 41 away from the battery string.

[0101] In some embodiments, the encapsulation film 41 includes a first encapsulation layer and a second encapsulation layer. The first encapsulation layer covers one of the front or back surfaces of the solar cell, and the second encapsulation layer covers the other of the front or back surfaces of the solar cell. Specifically, at least one of the first encapsulation layer or the second encapsulation layer may be an organic encapsulation film such as a polyvinyl butyral (PVB) film, an ethylene-vinyl acetate copolymer (EVA) film, a polyethylene octene copolymer elastomer (POE) film, or a polyethylene terephthalate (PET) film. Alternatively, at least one of the first encapsulation layer or the second encapsulation layer may also be a film such as an EP film, an EPE film, or a PVP film. Among them, the EP film refers to a co-extruded film composed of an EVA film and a POE film stacked, the EPE film refers to a co-extruded film formed by sequentially stacking an EVA film + a POE film + an EVA film, and the PVP film refers to a co-extruded film formed by stacking a POE film + an EVA film + a POE film. The method of preparing the co-extruded film can be to extrude one or more raw materials onto another film that has already been made during the film processing, or to bond different types of films that have already been made together.

[0102] In some cases, there is a demarcation line between the first encapsulation layer and the second encapsulation layer before lamination. After the lamination process, there will no longer be the concept of the first encapsulation layer and the second encapsulation layer in the formed photovoltaic module, that is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 41.

[0103] In some embodiments, the cover plate 42 can be a cover plate with a light-transmitting function such as a glass cover plate or a plastic cover plate. Specifically, the surface of the cover plate 42 facing the encapsulation film 41 can be an uneven surface or a suede surface including a plurality of convex structures, so as to increase the utilization rate of incident light. The cover plate 42 includes a first cover plate and a second cover plate. The first cover plate is opposite to the first encapsulation layer, and the second cover plate is opposite to the second encapsulation layer.

[0104] It should be noted that the battery string in the embodiments of the present disclosure is formed by connecting a plurality of back-contact batteries in series. If the solar cell is of other types, the structure of the photovoltaic module can be adjusted accordingly.

[0105] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing the present disclosure. In actual applications, various changes can be made in form and details without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, the protection scope of the embodiments of the present disclosure should be determined by the scope defined by the claims.

Claims

1. A method for manufacturing a solar cell, characterized in that: include: Providing a substrate, the substrate comprising first regions and second regions arranged alternately; forming a doped conductive layer, wherein the doped conductive layer covers the first region and the second region; Performing a preheating process, wherein the preheating process heats at least the doped conductive layer in the second region to a preset temperature, and before the laser treatment is performed, the temperature of the second region is maintained at the preset temperature; Performing the laser processing, wherein a scanning area formed by a laser beam moves along a preset scanning path to irradiate the doped conductive layer located in the second area; A film opening process is performed to remove the doped conductive layer located in the second region.

2. The method for manufacturing a solar cell according to claim 1, characterized in that: The step of heating at least the second zone to a preset temperature includes: heating the substrate as a whole.

3. The method for manufacturing a solar cell according to claim 1 or 2, characterized in that: The preset temperature of the preheating treatment is 50° C. to 200° C., and the heating time is 10s to 100s.

4. The method for manufacturing a solar cell according to claim 1, characterized in that: The solar cell is a back contact cell, the first area and the second area are alternately arranged on the back side of the back contact cell, and the laser processing includes: The preheating process is performed synchronously with the irradiation of the laser beam. When the laser beam irradiates the nth second region, the preheating process heats the n+1th second region.

5. The method for manufacturing a solar cell according to claim 4, characterized in that: The manufacturing method further includes: during the laser processing, obtaining the surface temperature of the doped conductive layer irradiated by the laser processing, and adjusting the heating temperature of each part of the second region by the pre-heating processing according to the surface temperature of the doped conductive layer.

6. The method for manufacturing a solar cell according to claim 1 or 4, characterized in that: The laser processing also includes: detecting the surface temperature of the doped conductive layer irradiated by the laser processing, and adjusting the laser power, scanning speed or spot overlap rate of the laser processing.

7. The method for manufacturing a solar cell according to claim 6, characterized in that: During the adjustment of the laser treatment, the spot overlap rate is controlled to be 30% to 70%.

8. The method for manufacturing a solar cell according to claim 1, characterized in that: Before forming the doped conductive layer, the method further includes: forming a protective layer, wherein the protective layer is located in the second area, and the protective layer is removed during the film opening process.

9. The method for manufacturing a solar cell according to claim 1, characterized in that: The process parameters of the laser treatment include: laser power of 20W~40W, laser scanning speed of 50000mm / s~80000mm / s, and laser frequency of 500Khz~800Khz.

10. The method for manufacturing a solar cell according to claim 1, characterized in that: Film opening process includes: A first etching process, wherein the first etching process uses a first etching agent to etch the doped conductive layer; A second etching process, wherein the second etching process uses a second etching agent to etch the doped conductive layer and a portion of the substrate.

11. The method for manufacturing a solar cell according to claim 10, characterized in that: The process parameters of the first etching process include: the first etching reagent is an alkaline reagent, and the concentration of the alkaline reagent is 2%~5%, and / or the process parameters of the second etching process include: the process temperature is 60℃~80℃, the process time is 100s~300s, the second etching reagent is an alkaline reagent with an additive, and the concentration of the alkaline reagent is 3%~7%.

12. A solar cell, characterized in that: The method for manufacturing a solar cell according to any one of claims 1 to 11, characterized in that it comprises: A substrate, the substrate comprising first regions and second regions arranged alternately; A doped conductive layer is located on a surface of the first region.

13. The solar cell according to claim 12, characterized in that: include: The second zone has a pyramid base morphology, and the average size of the opening of the pyramid base morphology is 8 μm to 20 μm, and the height is less than 0.5 μm.

14. A photovoltaic module, characterized in that: include: A battery string, the battery string comprising: a plurality of solar cells formed by the method for manufacturing a solar cell according to any one of claims 1 to 11, or a plurality of solar cells according to any one of claims 12 to 13; a welding ribbon, the welding ribbon being electrically connected to at least two of the solar cells to connect adjacent solar cells in series; A packaging film, the packaging film is used to cover the surface of the battery string; A cover plate is used to cover the surface of the packaging film away from the battery string.

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