Photovoltaic cell preparation method and photovoltaic cell

Abstract

The invention discloses a photovoltaic cell preparation method and a photovoltaic cell. The photovoltaic cell preparation method comprises the following steps: providing a silicon substrate with antireflection films on both sides; metalizing at least one surface of the silicon substrate to obtain a photovoltaic cell; wherein the metallization treatment on at least one surface of the silicon substrate comprises the following steps: providing a substrate, and forming a groove, a photosensitive film layer and / or a mask layer on the substrate; filling mixed slurry in the groove, wherein the mixed slurry comprises conductive slurry and a photosensitizer; or sequentially filling the photosensitizer and the conductive slurry in the groove; and aligning the substrate with the silicon substrate, irradiating one side, far away from the silicon substrate, of the groove by laser, and enabling the conductive slurry to generate a grid line on the silicon substrate to obtain the photovoltaic cell. According to the invention, the interface characteristics between the conductive slurry and the substrate are optimized, so that the energy window of laser transfer printing is easier to control and adjust, and the efficiency and quality of laser transfer printing are improved.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and more specifically, to a method for preparing a photovoltaic cell and a photovoltaic cell. Background Art

[0002] Photovoltaic cells, also known as solar cells, are photoelectric semiconductor sheets that use sunlight to generate electricity directly. Under certain illumination conditions, photovoltaic cells can output voltage and generate current. The structure of photovoltaic cells includes electrodes, which are usually obtained by metallization. Metallization treatment includes but is not limited to screen printing, post-sintering, laser transfer, etc. Among them, laser transfer technology can achieve high-precision and high-efficiency electrode patterning.

[0003] Since the interface characteristics between the slurry and the transfer substrate are difficult to control, laser transfer technology has problems such as unstable laser energy window during the transfer process, which affects the transfer efficiency and transfer quality. Therefore, it is a technical problem that needs to be solved urgently in this field. Summary of the invention

[0004] In view of this, the present invention provides a method for preparing a photovoltaic cell, which is used to optimize the interface characteristics between the conductive paste and the substrate, make the energy window of laser transfer easier to control and adjust, and improve the efficiency and quality of laser transfer.

[0005] In a first aspect, the present application provides a method for preparing a photovoltaic cell, comprising the following steps:

[0006] Providing a silicon substrate with anti-reflection films on both sides;

[0007] Performing metallization treatment on at least one side of the silicon substrate to obtain a photovoltaic cell;

[0008] The metallization treatment of at least one side of the silicon substrate comprises:

[0009] A substrate is provided, wherein a groove is formed on the substrate, and the groove penetrates a portion of the substrate along the thickness direction of the substrate; in addition, a photosensitive film layer and / or a mask layer is provided on the substrate, wherein the photosensitive film layer is located in the groove, and the mask layer is located on at least one side of the substrate, and along the thickness direction of the substrate, the orthographic projection of the mask layer does not overlap with the orthographic projection of the groove;

[0010] Filling the groove with a mixed slurry, wherein the mixed slurry includes a conductive slurry and a photosensitive agent; or, filling the groove with a photosensitive agent and a conductive slurry in sequence;

[0011] The substrate is aligned with the silicon base, and a laser is used to irradiate the groove away from the side of the silicon base, so that the conductive paste generates grid lines on the silicon base to obtain a photovoltaic cell.

[0012] Optionally, the mass percentage of the photosensitizer in the mixed slurry is in the range of 0.1%-5%.

[0013] Optionally, the photosensitizer includes a photopolymer, a photodye, a photoinorganic material, a photochromic material, a photoexpanding agent, a photocrosslinking material or a photogasification material.

[0014] Optionally, the conductive paste includes conductive powder, glass powder and an organic vehicle.

[0015] Optionally, the scanning rate of the laser is 100 mm / s-50000 mm / s, and the laser power is 10 W-200 W.

[0016] Optionally, along the thickness direction of the substrate, the cross-sectional shape of the groove is rectangular, trapezoidal or fan-shaped.

[0017] Optionally, the grooves include main gate grooves and sub-gate grooves, the main gate grooves extend along a first direction and are arranged along a second direction, the first direction is the side length direction of the silicon substrate, the second direction intersects with the first direction, and the sub-gate grooves extend along the second direction and are arranged along the first direction.

[0018] Optionally, the width of the main gate groove along the second direction ranges from 45 μm to 200 μm, and the width of the sub-gate groove along the first direction ranges from 8 μm to 30 μm.

[0019] Optionally, the method for preparing a silicon substrate with anti-reflection films on both sides includes texturing, first diffusion, laser, second diffusion, etching, growth of a protective layer, doping, cleaning, passivation and coating in sequence.

[0020] In a second aspect, the present application provides a photovoltaic cell, which is prepared by any of the photovoltaic cell preparation methods described above.

[0021] Compared with the prior art, the photovoltaic cell preparation method and photovoltaic cell provided by the present invention achieve at least the following beneficial effects:

[0022] The photovoltaic cell preparation method and photovoltaic cell provided by the present invention increase the application of photosensitizer in the photovoltaic cell preparation method. The addition of photosensitizer can improve the photosensitivity of the conductive paste, making it more susceptible to laser energy regulation. By adding photosensitizer to the conductive paste or adding photosensitizer to the interface between the conductive paste and the substrate, the interface characteristics between the conductive paste and the substrate are optimized, the energy window of laser transfer is broadened, the energy window of laser transfer is easier to control and regulate, and the stability and consistency of laser transfer are improved. At the same time, by adjusting the type and concentration of the photosensitizer, the transfer process can be controlled. Precise control can improve the efficiency and quality of laser transfer; a photosensitive film layer is arranged on the substrate, and the photosensitive film layer can enhance the photosensitivity shedding ability of the conductive paste on the substrate; a mask layer is arranged on the substrate, and the mask layer can effectively shield the laser from irradiating the area outside the groove on the substrate, thereby reducing laser overflow and mis-engraving damage to the battery cell; both the photosensitive film layer and the mask layer can optimize the energy control and slurry stability in the laser transfer process, improve the accuracy and consistency of the transfer process, and reduce the influence of laser energy on the transfer result. The photovoltaic cell preparation method can improve production efficiency and save costs while ensuring high-quality transfer.

[0023] Of course, any product implementing the present invention does not necessarily need to achieve all of the technical effects described above at the same time.

[0024] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0026] Figure 1 It is a flow chart of a method for preparing a photovoltaic cell provided by the present invention;

[0027] Figure 2 It is a flow chart of metallizing at least one side of a silicon substrate provided by the present invention;

[0028] Figure 3 yes Figure 2 A flowchart of an optional implementation method of metallizing at least one side of a silicon substrate;

[0029] Figure 4 is a cross-sectional view of a substrate provided by the present invention;

[0030] Figure 5 is a cross-sectional view of another substrate provided by the present invention;

[0031] Figure 6It is a bottom view of a substrate provided by the present invention;

[0032] Figure 7 This is a flow chart of preparing a silicon substrate with anti-reflection films on both sides provided by the present invention;

[0033] Figure 8 yes Figure 7 A flow chart of an optional implementation method for preparing a silicon substrate with anti-reflection films on both sides;

[0034] Fig. 9 It is a structural schematic diagram of a photovoltaic cell provided by the present invention. DETAILED DESCRIPTION

[0035] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0036] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0037] Technologies, methods, and devices known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and devices should be considered as part of the specification.

[0038] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0039] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0040] Reference Figure 1-Figure 3 , Figure 1 It is a flow chart of a method for preparing a photovoltaic cell provided by the present invention; Figure 2 It is a flow chart of metallizing at least one side of a silicon substrate provided by the present invention;

[0041] Figure 3 yes Figure 2 A flowchart of an optional implementation method of metallizing at least one side of a silicon substrate. This embodiment provides a method for preparing a photovoltaic cell, comprising the following steps:

[0042] S1: Provide a silicon substrate 00' with anti-reflection films on both sides (not shown in the figure).

[0043] Specifically, refer to Figure 1 As shown, the main function of the anti-reflection film is to reduce the loss of reflected light, improve the light absorption rate of the photovoltaic cell and the photovoltaic power generation efficiency. How to prepare the silicon substrate 00' with anti-reflection films on both sides will be described in the following embodiments.

[0044] S2: performing metallization treatment on at least one side of the silicon substrate 00 ′ to obtain the photovoltaic cell 00 .

[0045] Specifically, continue to refer to Figure 1 As shown, at least one side of the silicon substrate 00' is metallized in order to form a grid line (also called a metal electrode) on at least one side of the silicon substrate 00'. The silicon substrate 00' is a thin sheet structure, including two oppositely arranged sides. Therefore, only one side of the silicon substrate 00' can be metallized, or both sides of the silicon substrate 00' can be metallized, which is not limited here; the main function of the grid line is to collect and transmit the photogenerated electrons and holes (carriers) generated by the photovoltaic cell 00 under light conditions, and transmit the carriers to the external circuit of the photovoltaic cell 00, thereby generating electrical energy and realizing solar energy conversion; the grid line includes a main grid and a sub-grid (also called a fine grid). According to the structure of the grid line, the photovoltaic cell 00 can be divided into a multi-main grid cell and a main grid-free cell, etc. The grid line structure of the multi-main grid cell includes a main grid and a sub-grid, and the grid line structure of the main grid-free cell only includes a sub-grid.

[0046] The metallization treatment of at least one side of the silicon substrate 00' includes:

[0047] S2-1: Provide a substrate 1, on which a groove 11 is formed, and the groove 11 partially penetrates the substrate 1 along the thickness direction X of the substrate 1; in addition, a photosensitive film layer 12 and / or a mask layer 13 are also provided on the substrate 1, the photosensitive film layer 12 is located in the groove 11, and the mask layer 13 is located on at least one side of the substrate 1, and along the thickness direction X of the substrate 1, the orthographic projection of the mask layer 13 does not overlap with the orthographic projection of the groove 11.

[0048] Specifically, combined Figure 2-Figure 3 As shown, in the laser transfer technology, the substrate 1 (or transfer substrate) is a structure for containing the slurry. The shape of the substrate 1 is consistent with the shape of the silicon substrate 00', and the areas of the two are comparable. The substrate 1 and the silicon substrate 00' are placed parallel to each other. The laser irradiates the substrate 1, and the slurry on the substrate 1 can be transferred to the silicon substrate 00'. The slurry on the silicon substrate 00' is solidified to finally form the gate line.

[0049] Reference Figure 3As shown in (a), a groove 11 is provided on the substrate 1, and the groove 11 penetrates part of the substrate 1 along the thickness direction X of the substrate 1. The groove 11 is used to contain the slurry. The arrangement of the groove 11 on the substrate 1 corresponds to the arrangement of the gate line on the silicon substrate 00'. The material of the substrate 1 can be epoxy resin, which is a high molecular polymer with a molecular formula of (C 11 H 12 O3)n, is a general term for a class of polymers containing more than two epoxy groups in the molecule, is a condensation product of epichlorohydrin and bisphenol A or polyol, and is a thermosetting resin; the substrate 1 can also be called a mask, and the mask can be a metal mask, a semiconductor mask, an oxide mask, a polymer mask or a photoresist mask, etc. The metal mask is made of metals such as gold, silver or aluminum, has high absorptivity and high temperature resistance, and can withstand high-power laser irradiation; the semiconductor mask is made of semiconductor materials such as silicon or gallium arsenide, and can select the light absorption wavelength as needed, which is very useful in laser applications of specific wavelengths; the oxide mask is made of oxide materials such as silicon dioxide or titanium oxide, and has good corrosion resistance and selectivity to light wavelength; the polymer mask is made of polymer materials such as polyimide or polyethylene, which is cheap and easy to process, but has low absorptivity and high temperature resistance; the photoresist mask is made of photosensitive resin, has high resolution, and can produce fine patterns.

[0050] Reference Figure 3 (a)- Figure 3 As shown in (c), a photosensitive film layer 12 is also provided on the substrate 1, and the photosensitive film layer 12 is located in the groove 11, and the groove 11 is used to accommodate the slurry (not marked in the figure). The photosensitive film layer 12 can be located between the groove 11 and the slurry. The photosensitive film layer 12 has good photosensitivity and chemical stability. The photosensitive film layer 12 makes the interface between the slurry and the groove 11 more susceptible to light and reduces the adhesion between the slurry and the substrate 1. When irradiated with laser, the photosensitive film layer 12 can absorb laser energy to make the slurry fall off onto the silicon base 00', thereby enhancing the photosensitivity and printing stability of the slurry on the substrate 1, and improving the quality of laser transfer; the photosensitive film layer 12 can be coated on the substrate 1 by spin coating, spray coating, etc. The photosensitive film layer 12 can be coated on the substrate 1 for a long time (such a substrate 1 can be used for many times without the photosensitive film layer 12 disappearing), or it can be coated on the substrate 1 for a short time (such a substrate 1 can be used once or twice before the photosensitive film layer 12 disappears), which is not specifically limited here.

[0051] Continue to refer to Figure 3 (a)- Figure 3As shown in (c), a mask layer 13 is also provided on the substrate 1, and the mask layer 13 is located on at least one side of the substrate 1, for example: the mask layer 13 is only located on the side of the substrate 1 close to the silicon base 00', or the mask layer 13 is only located on the side of the substrate 1 away from the silicon base 00', or the mask layer 13 is located on both sides of the substrate 1, which is not specifically limited here; along the thickness direction X of the substrate 1, the orthographic projection of the mask layer 13 does not overlap with the orthographic projection of the groove 11, and this is set to ensure that the mask layer 13 does not affect the absorption of laser energy by the slurry in the groove 11 while shielding the laser from irradiating the area outside the groove 11, thereby improving the energy window (also called process window) of laser transfer and the quality of laser transfer. The material of the mask layer 13 can be a photochromic material, and the photochromic material includes spirocyclic ninhydrin compounds, such as: spirocyclic ninhydrin (C 13 H 10 O4), 1,3,3-trimethylspiroinhydrinhydrin (C 16 H 14 O4) or 6-nitrospiroinhydrinhydrin (C 13 H9N3O6), etc.; the mask layer 13 can be coated on the substrate 1 by spin coating, spray coating, etc. The mask layer 13 can be coated on the substrate 1 for a long time (such a substrate 1 can be used for many times without the mask layer 13 disappearing), or it can be coated on the substrate 1 for a short time (such a substrate 1 can be used once or twice before the mask layer 13 disappears), which is not specifically limited here.

[0052] Continue to refer to Figure 3 As shown, the substrate 1 provided in this embodiment is provided with a photosensitive film layer 12 and a mask layer 13 at the same time, the photosensitive film layer 12 is located in the groove 11, and the mask layer 13 is located on both sides of the substrate 1; in an optional other embodiment, the substrate 1 may be provided with only a photosensitive film layer 12, the photosensitive film layer 12 is located in the groove 11, and the mask layer 13 is not provided on the substrate 1; in an optional other embodiment, the substrate 1 may be provided with only a mask layer 13, the mask layer 13 is located on both sides of the substrate 1, and the photosensitive film layer 12 is not provided on the substrate 1; in an optional other embodiment, In another optional embodiment, only a mask layer 13 may be provided on the substrate 1, and the mask layer 13 is only located on the side of the substrate 1 close to the silicon base 00', and no photosensitive film layer 12 is provided on the substrate 1; in another optional embodiment, only a mask layer 13 may be provided on the substrate 1, and the mask layer 13 is only located on the side of the substrate 1 away from the silicon base 00', and no photosensitive film layer 12 is provided on the substrate 1; the arrangement of the photosensitive film layer 12 and the mask layer 13 on the substrate 1 can be adaptively adjusted according to actual conditions, and no specific limitation is made here.

[0053] S2-2: Filling the groove 11 with a mixed slurry, wherein the mixed slurry includes a conductive slurry and a photosensitive agent; or, filling the groove 11 with a photosensitive agent and a conductive slurry in sequence.

[0054] Specifically, combined Figure 2-Figure 3 As shown, the groove 11 is used to contain the slurry. After the laser irradiates the substrate 1, the slurry on the substrate 1 is transferred to the silicon substrate 00'. The slurry on the silicon substrate 00' is solidified to finally form the gate line 01. The process of filling the slurry in the groove 11 is a prior art in the art and will not be described here. Regarding the selection of the slurry, there are at least the following two situations:

[0055] The first type is that the slurry is a mixed slurry, which includes a conductive slurry and a photosensitive agent. The components of the conductive slurry, the material of the photosensitive agent, etc. will be described in the following embodiments; after laser irradiation, the conductive slurry and the photosensitive agent are transferred to the silicon substrate 00' together, and the photosensitive agent can quickly produce volume changes, viscosity changes or gasification and decomposition effects, so as to cause the conductive slurry to solidify in the desired area or chemically combine with the surface of the silicon substrate 00', thereby realizing the transfer or solidification of the gate line 01 pattern, and the photosensitive agent eventually evaporates. By doping the photosensitive agent in the conductive slurry, the laser energy window can be accurately controlled and adjusted to achieve a stable and high-quality laser transfer effect.

[0056] It should be noted that:

[0057] (1) The conductive paste and the photosensitive agent can be uniformly mixed using a mixer or a three-roll mill.

[0058] (2) The method for determining whether the conductive paste and the photosensitive agent are uniformly mixed is as follows:

[0059] First, uniformity check: apply a small amount of the mixture on a glass slide to observe whether its color and texture are consistent, and whether there is obvious stratification or particle aggregation;

[0060] Second, measure the particle size distribution: Use a laser particle size analyzer to measure the particle size distribution of the particles in the mixture to ensure that the photosensitive agent particles are evenly dispersed in the conductive paste without obvious agglomeration;

[0061] Third, centrifugation test: The stratification of the mixture is determined by centrifugation. Evenly mixed conductive paste and photosensitive agent will not show obvious stratification after centrifugation.

[0062] The second method is to fill the groove 11 with photosensitive agent and conductive paste in turn, and the coating equipment or process can be selected to accurately control the coating amount; the materials of the photosensitive agent and conductive paste are the same as those in the mixed paste and will not be repeated here; after laser irradiation, a stable interface is formed between the photosensitive agent and the conductive paste, and the photosensitive agent expands rapidly or produces other responses, prompting the conductive paste to solidify in the required area or chemically combine with the surface of the silicon substrate 00', thereby realizing the transfer or solidification of the gate line 01 pattern, and the photosensitive agent eventually evaporates. By filling the groove 11 with photosensitive agent and conductive paste in turn, the laser energy window can be accurately controlled and adjusted, thereby improving the stability and consistency of the transfer, and achieving a stable and high-quality laser transfer effect.

[0063] S2 - 3 : Align the substrate 1 with the silicon base 00 ′, and irradiate the groove 11 with laser away from the side of the silicon base 00 ′, so that the conductive paste generates a gate line 01 ′ on the silicon base 00 ′, thereby obtaining a photovoltaic cell 00 .

[0064] Specifically, combined Figure 2-Figure 3 As shown, the substrate 1 is aligned with the silicon substrate 00'. Along the thickness direction X of the substrate 1, there is a certain distance between the substrate 1 and the silicon substrate 00'. A laser is used to emit laser, and the laser irradiates the groove 11 away from the side of the silicon substrate 00'. The conductive paste absorbs the laser energy and vaporizes. The conductive paste is released onto the silicon substrate 00', and finally a grid line 01 is generated on the silicon substrate 00' to obtain a photovoltaic cell 00, wherein the laser that can be selected includes but is not limited to a fiber laser, a solid laser or a carbon dioxide laser, etc.; compared with the prior art, the photovoltaic cell preparation method provided in this embodiment improves the laser transfer method and is applicable to all types of photovoltaic cells.

[0065] Table 1: Transfer results of existing technology and improved scheme

[0066]

[0067] Note: In the prior art, the photosensitive film layer 12 and the mask layer 13 are not provided on the substrate 1, and only the conductive paste is transferred into the gate lines; in the improved scheme, the photosensitive film layer 12 and the mask layer 13 are provided on the substrate 1, and the mixed paste is transferred into the gate lines.

[0068] It can be seen from the results in Table 1 that, compared with the photovoltaic cell preparation method in the prior art, the photovoltaic cell preparation method provided in this embodiment has greatly improved average transfer efficiency and average pattern edge clarity, and greatly reduced problems such as scattering and diffusion loss, edge diffusion and erroneous transfer. At the same time, the amount of residual slurry is also reduced significantly, indicating that the photovoltaic cell preparation method provided in this embodiment makes the energy window of laser transfer easier to control and adjust, improves the stability and consistency of laser transfer, can achieve precise control of the laser transfer process, improves the efficiency and quality of laser transfer, and ensures high-quality transfer while saving costs.

[0069] Compared with the prior art, the photovoltaic cell preparation method provided in this embodiment achieves at least the following beneficial effects:

[0070] The photovoltaic cell preparation method provided in this embodiment adds the application of photosensitive agent. The addition of photosensitive agent can improve the photosensitivity of the conductive paste, making it more susceptible to laser energy regulation. By adding photosensitive agent to the conductive paste or adding photosensitive agent to the interface between the conductive paste and the substrate, the interface characteristics between the conductive paste and the substrate are optimized, the energy window of laser transfer is broadened, the energy window of laser transfer is easier to control and adjust, and the stability and consistency of laser transfer are improved. At the same time, by adjusting the type and concentration of the photosensitive agent, the transfer process can be accurately controlled, which improves The efficiency and quality of high laser transfer are improved; a photosensitive film layer is arranged on the substrate, the photosensitive film layer can enhance the photosensitivity shedding ability of the conductive paste on the substrate, a mask layer is arranged on the substrate, the mask layer can effectively shield the laser from irradiating the area outside the groove on the substrate, reduce laser overflow and mis-engraving damage to the battery cell, the photosensitive film layer and the mask layer can both optimize the energy control and paste stability during the laser transfer process, improve the accuracy and consistency of the transfer process, and reduce the influence of laser energy on the transfer result. The photovoltaic cell preparation method can improve production efficiency and save costs while ensuring high-quality transfer.

[0071] In an optional embodiment, the mass percentage of the photosensitizer in the mixed slurry is in the range of 0.1%-5%.

[0072] Specifically, continue to refer to Figure 3As shown, this embodiment explains that the photosensitive agent has a certain mass percentage in the mixed slurry to achieve the transfer or curing of the grid line pattern. The mass percentage range of the photosensitive agent in the mixed slurry can be 0.1%-3%, such as the mass percentage of the photosensitive agent in the mixed slurry can be 0.1%, 0.85%, 1.2%, 2.5% or 3%, etc., or, the mass percentage range of the photosensitive agent in the mixed slurry can also be 3.5%-5%, such as the mass percentage of the photosensitive agent in the mixed slurry can be 3.5%, 3.9%, 4%, 4.3%, 4.6% or 5%, etc., thereby avoiding the situation that the photosensitive agent cannot produce enough photochemical reaction to achieve the expected volume change, viscosity change or gasification decomposition when the mass percentage of the photosensitive agent in the mixed slurry is too small, resulting in the photosensitivity shedding effect of the conductive slurry after laser irradiation is not obvious, and it can also avoid the problems of reduced performance of the conductive slurry, increased cost, excessive photosensitivity reaction, etc. when the mass percentage of the photosensitive agent in the mixed slurry is too large. Therefore, in this embodiment, the mass percentage range of the photosensitive agent in the mixed slurry is set to 0.1%-5%, which can avoid the problems of the conductive slurry performance degradation, cost increase, excessive photosensitivity reaction, etc. while avoiding the insignificant photosensitivity shedding effect of the conductive slurry; wherein, the conductive slurry performance degradation means that a high concentration of photosensitive agent may change the rheological properties and mechanical properties of the conductive slurry, resulting in the conductive slurry being difficult to control during the laser transfer process, affecting the final transfer quality; photosensitive agent is usually a high-cost chemical, and too high an addition ratio will significantly increase production costs and reduce economic benefits; excessive photosensitivity reaction means that excessive photosensitive agent causes the conductive slurry to decompose or expand excessively under laser irradiation, resulting in diffusion or irregularity of the pattern edge, affecting the transfer accuracy.

[0073] In an optional embodiment, the photosensitizer includes a photopolymer, a photodye, a photoinorganic material, a photochromic material, a photoexpanding agent, a photocrosslinking material, or a photogasification material.

[0074] Specifically, continue to refer to Figure 3 As shown, photopolymers are a class of light-sensitive polymers whose structure and properties will change significantly under the action of light; photopolymers may include: poly(N,N-dimethylacrylamide) (PDMAAm), poly(vinylpyridine) (P4VP), methacrylate (CH2=C(CH3)COOCH3), ethyl acrylate (CH2=C(CH2CH3)COOCH2CH3) or butyl acrylate (CH2=C(CH2CH2CH3)COOCH2CH2CH3), etc.

[0075] Photochromic dyes are a class of materials that can change color when stimulated by a light source; photochromic dyes may include: acridine orange (C 17 H 14ClN2O), acridinium yellow (C 17 H 12 N2O), acridine red (C 17 H 11 N3O2), phenothiazine (C 12 H9NS), methylene blue (C 16 H 18 ClN3S) or thiophenothiazine (C 12 H9NS2) etc.

[0076] Photoinduced inorganic materials are materials that use inorganic materials as luminescent matrices. After being irradiated by a light source, such materials can absorb energy and undergo electronic transitions, thereby exhibiting certain luminescent properties. Photoinduced inorganic materials may include silver halides, oxides, or spiropyran materials, wherein silver halides include silver chloride (AgCl), silver bromide (AgBr), or silver iodide (AgI), etc., oxides include titanium dioxide (TiO2), or zinc oxide (ZnO), etc., and spiropyran materials include 5-chloro-1,3-dihydro-3-phenyl-2H-spiro[3,3]cyclopenta[1,2-b]pyran (C 17 H 14 ClNO), 1,3-dihydro-1,3,3-trimethyl-2H-spiro[3,3]cyclopenta[1,2-b]pyran (C 16 H 16 NO) or 1,3-dihydro-3-(4-methylphenyl)-2H-spiro[3,3]cyclopenta[1,2-b]pyran (C 18 H 18 NO) etc.

[0077] Photochromic materials are materials that can change color after being stimulated by a light source. Photochromic materials may include: spirocyclic ninhydrin (C 13 H 10 O4), 1,3,3-trimethylspiroinhydrinhydrin (C 16 H 14 O4), 6-nitrospiroinhydrinhydrin (C 13 H9N3O6), 5-chloro-1,3-dihydro-3-phenyl-2H-spiro[3,3]cyclopenta[1,2-b]pyran (C 17 H 14 ClNO), 1,3-dihydro-1,3,3-trimethyl-2H-spiro[3,3]cyclopenta[1,2-b]pyran (C 16 H 16 NO) or 1,3-dihydro-3-(4-methylphenyl)-2H-spiro[3,3]cyclopenta[1,2-b]pyran (C 18 H 18 NO) etc.

[0078] A photoexpanding agent is a material that expands in volume through a physical and chemical reaction under the action of light. The photoexpanding agent can expand rapidly under laser irradiation, resulting in a decrease in the interfacial tension of the slurry and promoting the shedding of the slurry. The photoexpanding agent may include polyacrylates and polyvinyl alcohols. Among them, polyacrylate photoexpanding agents have an extremely fast expansion rate and can expand rapidly to several times their original size within a few nanoseconds. The differences in the molecular structure and molecular weight of this type of photoexpanding agent may affect its expansion rate and degree; polyvinyl alcohol photoexpanding agents have rapid expansion characteristics and can expand rapidly to several times their original size within a few microseconds. This type of photoexpanding agent usually has a higher sensitivity and a faster response speed to lasers.

[0079] Photocrosslinking material is a polymer material that can trigger a crosslinking reaction through light energy. After absorbing light energy, the polymer itself or the linear polymer and the small molecule crosslinking agent can undergo a crosslinking reaction to form a network structure; the photocrosslinking material may include: polyethylene glycol diacrylate (PEGDA), poly (N, N-dimethylacrylamide) (PDMAAm) or poly (vinyl pyridine) (P4VP) and the like.

[0080] Photogasification material is a material that causes volume expansion through physical and chemical reactions under the action of light. Photogasification material can include aromatic nitro compounds and azo compounds. Aromatic nitro compounds include: nitrobenzene (C6H5NO2), o-nitrotoluene (C7H7NO2) or p-nitrotoluene (C7H7NO2), etc. Azo compounds include azobenzene (C6H5N=NC6H5), 4-methylazobenzene (C7H7N=NC7H7) or 4-ethylazobenzene (C8H9N=NC8H9), etc.

[0081] In an optional embodiment, the conductive paste includes conductive powder, glass powder and an organic vehicle.

[0082] Specifically, continue to refer to Figure 3 As shown, the conductive powder includes metal powder, which plays a conductive function. The sintering quality of the conductive powder directly affects the output of the collected current. The conductive powder can be silver powder; the glass powder not only has a high-temperature bonding effect, but also serves as a flux for the sintering of the conductive powder and a medium for forming a silver-silicon ohmic contact; the organic carrier has a cohesive effect, which can help the transfer of the conductive paste and avoid the collapse or flow of the conductive paste, thereby effectively controlling the thinning ability of the grid line and enhancing the printing quality of the conductive paste; the conductive paste is a prior art in the field and will not be described here.

[0083] In an optional embodiment, the scanning rate of the laser is 100 mm / s-50000 mm / s, and the laser power is 10 W-200 W.

[0084] Specifically, continue to refer to Figure 3 As shown, this embodiment explains that the laser has a certain scanning rate to realize the laser transfer technology. The scanning rate of the laser can be 100mm / s-50000mm / s, such as the scanning rate of the laser can be 100mm / s, 2000mm / s, 8000mm / s, 12000mm / s, 25000mm / s, 36000mm / s, 44000mm / s or 50000mm / s, etc., so as to avoid the problem that when the laser scanning rate is too low, the slurry absorbs too much laser energy and solidifies before being transferred to the silicon substrate 00', and when the laser scanning rate is too high, the slurry absorbs insufficient laser energy and cannot be transferred to the silicon substrate 00'. Therefore, this embodiment sets the scanning rate of the laser to 100mm / s-50000mm / s, which can avoid the slurry from solidifying before being transferred to the silicon substrate 00' and avoid the problem that the slurry cannot be transferred to the silicon substrate 00'.

[0085] This embodiment explains that the laser has a certain power to realize the laser transfer technology, and the laser power can be 10W-200W, such as the laser power can be 10W, 35W, 50W, 75W, 100W, 130W, 165W, 180W or 200W, so as to avoid the failure of the transfer due to the inability to transfer the slurry to the silicon substrate 00' when the laser power is too small, and to avoid the damage of the structure of the silicon substrate 00' due to the laser damage when the laser power is too large. Therefore, this embodiment sets the laser power to 10W-200W, which can avoid the failure of the transfer due to the inability to transfer the slurry to the silicon substrate 00' and avoid the damage of the structure of the silicon substrate 00' due to the laser damage.

[0086] Figure 4 is a cross-sectional view of a substrate provided by the present invention; Figure 5 It is a cross-sectional view of another substrate provided by the present invention. In an optional embodiment, along the thickness direction X of the substrate 1, the cross-sectional shape of the groove 11 is rectangular, trapezoidal or fan-shaped.

[0087] Specifically, refer to Figure 3 As shown, along the thickness direction X of the substrate 1, the cross-sectional shape of the groove 11 can be a rectangle, referring to Figure 4 As shown, along the thickness direction X of the substrate 1, the cross-sectional shape of the groove 11 can be a trapezoid, referring to Figure 5 As shown, along the thickness direction X of the substrate 1, the cross-sectional shape of the groove 11 can be fan-shaped. As long as the groove 11 can accommodate the slurry, the slurry can be transferred to the silicon substrate 00' after laser irradiation. The cross-sectional shape of the groove 11 along the thickness direction X of the substrate 1 can be adaptively adjusted according to actual conditions and is not specifically limited here.

[0088] Figure 6It is a bottom view of a substrate provided by the present invention. In an optional embodiment, the groove 11 includes a main gate groove 111 and a secondary gate groove 112, the main gate groove 111 extends along a first direction Y and is arranged along a second direction Z, the first direction Y is the side length direction of the silicon substrate 00', the second direction Z intersects with the first direction Y, and the secondary gate groove 112 extends along the second direction Z and is arranged along the first direction Y.

[0089] Specifically, combined Figure 3 , Figure 6 As shown, since the arrangement of the grooves 11 on the substrate 1 corresponds to the arrangement of the grid lines 01 on the photovoltaic cell 00, the structure of the grooves 11 depends on the structure of the photovoltaic cell 00 finally formed. When the photovoltaic cell 00 finally formed is a multi-main grid cell, the grooves 11 include a main grid groove 111 and a secondary grid groove 112. The main grid groove 111 extends along a first direction Y and is arranged along a second direction Z. The first direction Y is the side length direction of the silicon substrate 00', and the second direction Z intersects with the first direction Y. Optionally, the second direction Z is perpendicular to the first direction Y, and the secondary grid groove 112 extends along the second direction Z and is arranged along the first direction Y. When the photovoltaic cell 00 finally formed is a main grid-free cell, the grooves 11 may only include the secondary grid groove 112, which is not specifically limited here.

[0090] In an alternative embodiment, in combination Figure 3 , Figure 6 As shown, the width of the main gate groove 111 along the second direction Z is in the range of 45 μm-200 μm, and the width of the sub-gate groove 112 along the first direction Y is in the range of 8 μm-30 μm.

[0091] Specifically, this embodiment explains that the main gate groove 111 has a certain width along the second direction Z to form a main gate on the silicon substrate 00'. For example, the width of the main gate groove 111 along the second direction Z can be 45μm, 75μm, 100μm, 125μm, 150μm, 175μm or 200μm, etc., so as to avoid the situation where the width of the main gate groove 111 is too small and the slurry is difficult to fill into the main gate groove 111, resulting in incomplete transfer or defects. At the same time, the laser spot may completely cover the main gate groove 111, resulting in overexposure or ablation of the slurry. It can also avoid the situation where the laser cannot completely cover the main gate groove 111 when the width of the main gate groove 111 is too large, resulting in unprocessed areas during the transfer process, affecting the integrity and quality of the formed main gate, and at the same time causing more material waste and increased production costs. Therefore, in this embodiment, the width range of the main gate groove 111 along the second direction Z is set to 45μm-200μm, which can avoid incomplete or defective transfer, overexposure or ablation of the slurry while avoiding the problems of affecting the integrity and quality of the formed main gate, material waste and increased production costs.

[0092] This embodiment explains that the auxiliary gate groove 112 has a certain width along the first direction Y to form an auxiliary gate on the silicon substrate 00'. For example, the width of the auxiliary gate groove 112 along the first direction Y can be 8μm, 15μm, 20μm, 22μm, 25μm, 27μm or 30μm, etc., so as to avoid the situation that the slurry is difficult to fill into the auxiliary gate groove 112 when the width of the auxiliary gate groove 112 is too small, resulting in incomplete transfer or defects, and the laser spot may completely cover the auxiliary gate groove 112, resulting in overexposure or ablation of the slurry. It can also avoid the situation that the laser cannot completely cover the auxiliary gate groove 112 when the width of the auxiliary gate groove 112 is too large, resulting in unprocessed areas in the transfer process, affecting the integrity and quality of the formed main gate, and causing more material waste and increased production costs. Therefore, in this embodiment, the width range of the auxiliary gate groove 112 along the first direction Y is set to 8μm-30μm, which can avoid incomplete or defective transfer, overexposure or ablation of the slurry while avoiding the problems of affecting the integrity and quality of the formed main gate, material waste and increased production costs.

[0093] In an alternative embodiment, continue to refer to Figure 3 As shown, the depth of the groove 11 along the thickness direction X of the substrate 1 ranges from 8 μm to 20 μm.

[0094] This embodiment explains that the groove 11 has a certain depth along the thickness direction X of the substrate 1 to accommodate the slurry, such as the depth of the groove 11 along the thickness direction X of the substrate 1 can be 8μm, 10μm, 12μm, 14μm, 16μm, 18μm or 20μm, etc., so that the slurry can be prevented from falling off from the substrate 1 before laser irradiation when the depth of the groove 11 is too shallow, and the generated gate line 01 is easy to collapse, and the slurry can be prevented from not falling off from the substrate 1 when the depth of the groove 11 is too deep. Therefore, this embodiment sets the depth range of the groove 11 along the thickness direction X of the substrate 1 to 8μm-20μm, which can prevent the slurry from falling off from the substrate 1 before laser irradiation, and the generated gate line 01 is easy to collapse, while avoiding the problem of the slurry not being able to fall off from the substrate 1.

[0095] Figure 7 This is a flow chart of preparing a silicon substrate with anti-reflection films on both sides provided by the present invention; Figure 8 yes Figure 7 A flowchart of an optional implementation method of preparing a silicon substrate with anti-reflection films on both sides. In an optional embodiment, the preparation method of a silicon substrate 00' with anti-reflection films on both sides includes texturing, first diffusion, laser, second diffusion, etching, growth of a protective layer, doping, cleaning, passivation and coating.

[0096] S0-1: Velveting.

[0097] Combination Figure 7 , Figure 8 As shown in (A), the texturing method can be to soak the silicon wafer 000 in an alkaline liquid in a tank-type device. The silicon wafer 000 is a thin sheet structure, including a front side 001 and a back side 002 arranged oppositely. After the texturing, a velvet surface is formed on both the front side 001 and the back side 002 (not shown in the figure). The silicon wafer 000 after the texturing can be referred to as FIG. Figure 8 As shown in (A), the purpose of texturing is to remove pollution and cut the damaged layer, forming a rough texture surface to increase the silicon wafer 000's absorption of sunlight and reduce reflectivity.

[0098] S0-2: First diffusion.

[0099] Combination Figure 7 , Figure 8 (A)- Figure 8 As shown in (B), the first diffusion method can be to diffuse in a diffusion furnace using boron trichloride (BCl3) as a diffusion source, so that a borosilicate glass layer 010 is formed on the front side 001 and the back side 002 at the same time, and the process parameters include: a flow range of boron trichloride (BCl3) of 200sccm-350sccm, a flow range of nitrogen (N2) of 2000sccm-3000sccm, a flow range of oxygen (O2) of 600sccm-1000sccm, a temperature range of 860°C-960°C, and a time of 1400s;

[0100] If the flow rate of BCl3 is less than 200sccm, the borosilicate glass layer 010 cannot be formed. If the flow rate of BCl3 is greater than 350sccm, the cost is wasted. Therefore, setting the flow rate range of BCl3 to 200sccm-350sccm can not only avoid the problem of being unable to form the borosilicate glass layer 010, but also avoid the problem of wasting costs. Specifically, the flow rate of BCl3 can be 200sccm, 240sccm, 280sccm, 320sccm or 350sccm. If N2 If the flow rate of N2 is less than 2000sccm, the source pressure is insufficient. If the flow rate of N2 is greater than 3000sccm, the boron trichloride gas is thin and the reaction is not sufficient. Therefore, setting the flow range of N2 to 2000sccm-3000sccm can not only avoid the problem of insufficient source pressure, but also avoid the problem of thin boron trichloride gas and insufficient reaction. Specifically, the flow rate of N2 can be 2000sccm, 2200sccm, 2400sccm, 2600sccm, 2800sccm m or 3000sccm; if the flow rate of O2 is less than 600sccm, the oxygen as the reaction gas is thin and the reaction is not sufficient. If the flow rate of O2 is greater than 1000sccm, excessive borosilicate glass is easily generated. Therefore, setting the flow rate range of O2 to 600sccm-1000sccm can not only avoid the problem of thin oxygen and insufficient reaction, but also avoid the problem of excessive borosilicate glass generation; specifically, the flow rate of O2 can be 600sccm, 700sccm, 800sccm, 900sccm or 1000sccm; if the temperature is less than 860°C, the reaction temperature is too low and the reaction is not sufficient; if the temperature is greater than 960°C, excessive borosilicate glass is easily generated; therefore, setting the temperature range to 860°C-960°C can not only avoid the problem of too low reaction temperature and insufficient reaction, but also avoid the generation of excessive borosilicate glass; specifically, the temperature can be 860°C, 880°C, 900°C, 920°C, 940°C or 960°C; the structure of the silicon wafer after forming the borosilicate glass layer is as shown in FIG. Figure 8 As shown in (B).

[0101] S0-3: Laser.

[0102] Combination Figure 7 , Figure 8 (B)- Figure 8 As shown in (C), the laser method can be to use a laser device to irradiate the borosilicate glass layer 010 on a portion of the front surface 001, so that the boron atoms in the borosilicate glass layer 010 diffuse into the silicon wafer 000 to form a P++ heavily doped layer 021. The process parameters include: laser power of 55W, laser speed of 15000mm / s, laser frequency of 55kHz, and laser wavelength of 850nm; refer to Figure 8 (B)- Figure 8 As shown in (C), the borosilicate glass layer 010 irradiated by the laser is region A, and the portion of the silicon wafer 000 corresponding to region A forms a P++ heavily doped layer 021 .

[0103] S0-4: Second spread.

[0104] Combination Figure 7 , Figure 8 (B)- Figure 8 As shown in (D), the second diffusion method can be to use a diffusion furnace to perform high-temperature oxidation advancement by passing oxygen, so that some boron atoms in the borosilicate glass layer 010 diffuse into the silicon wafer 000 to form a P+ doped layer 022.

[0105] The process parameters include: the flow range of O2 is 10000sccm-28000sccm, the flow range of N2 is 10000sccm-15000sccm, the advancement temperature is 1000℃, and the time is 3500s; if the flow rate of O2 is less than 10000sccm, the P+ doping layer 022 cannot be formed, and if the flow rate of O2 is greater than 28000sccm, the cost is wasted. Therefore, setting the flow range of O2 to 10000sccm-28000sccm can not only avoid the problem of being unable to form the P+ doping layer 022, but also avoid the problem of wasting costs; specifically, the flow rate of O2 can be 10000sccm, 15000sccm, 100 00sccm, 250000sccm or 28000sccm; if the flow rate of N2 is less than 10000sccm, the generated pn junction is too shallow, and if the flow rate of N2 is greater than 15000sccm, the generated pn junction is too deep, affecting the power generation quality. Therefore, setting the flow rate range of N2 to 10000sccm-15000sccm can not only avoid the problem of the generated pn junction being too shallow, but also avoid the problem of the generated pn junction being too deep and affecting the power generation quality. Specifically, the flow rate of N2 can be 10000sccm, 11000sccm, 12000sccm, 13000sccm, 14000sccm or 15000sccm; refer to Figure 8 (B)- Figure 8 As shown in (D), the borosilicate glass layer 010 that is not irradiated by the laser is area B, and the portion of the silicon wafer 000 corresponding to area B forms a P+ doped layer 022. Along the thickness direction X' of the silicon wafer 000, the depth of the P+ doped layer 022 is less than the depth of the P++ heavily doped layer 021.

[0106] S0-5: Etching.

[0107] Combination Figure 7 , Figure 8 (D)- Figure 8 As shown in (E), the etching method can be to first etch the back side 002 on a chain etcher to remove the borosilicate glass layer 010 on the back side 002, and then polish the back side 002 in a tank device to remove the velvet on the back side 002; etching is a prior art in the art, and the structure of the silicon wafer 000 after etching is as shown in Figure 8 As shown in (E).

[0108] S0-6: Growth protection layer.

[0109] Combination Figure 7 , Figure 8 (E)- Figure 8 (F), comprising the following steps:

[0110] S0-6-1: growing a tunnel oxide layer 030 on the back side 002.

[0111] The method is to grow a tunnel oxide layer 030 by high temperature oxidation, the tunnel oxide layer 030 may be a silicon dioxide (SiO2) layer, and the process parameters include: the flow rate of O2 is in the range of 30000sccm-38000sccm, the temperature is in the range of 580°C-620°C, and the thickness of the tunnel oxide layer 030 is in the range of 1nm-2nm;

[0112] Among them, if the flow rate of O2 is less than 30000sccm, the tunneling oxide layer 030 cannot be formed. If the flow rate of O2 is greater than 38000sccm, the formed tunneling oxide layer 030 is too thick, which affects the tunneling effect of carriers. Therefore, setting the flow range of O2 to 30000sccm-38000sccm can not only form the tunneling oxide layer 030 normally, but also avoid the problem that the formed tunneling oxide layer 030 is too thick and affects the tunneling effect of carriers; specifically, the flow rate of O2 can be 30000sccm, 32000sccm, 34000sccm, 36000sccm or 38000sccm; if the temperature is less than 580℃, the reaction rate is too slow and time is wasted. If the temperature is greater than 620℃, the growth rate of the tunneling oxide layer 030 is too fast and difficult to control. Therefore, the temperature range is set to 580℃-620℃, not only can avoid the problem of too slow reaction rate and waste of time, but also can avoid the problem of too fast growth rate and difficult control of tunneling oxide layer 030; specifically, the temperature can be 580℃, 590℃, 600℃, 610℃ or 620℃; if the thickness of tunneling oxide layer 030 is less than 1nm, tunneling oxide layer 030 is too thin, which affects the passivation effect of photovoltaic cell; if tunneling oxide layer 030 is greater than 2nm, tunneling oxide layer 030 is too thick, which affects the tunneling effect of carriers. Therefore, setting the thickness range of tunneling oxide layer 030 to 1nm-2nm can not only avoid affecting the passivation effect of photovoltaic cell, but also avoid affecting the tunneling effect of carriers; specifically, the thickness of tunneling oxide layer 030 can be 1nm, 1.2nm, 1.4nm, 1.6nm, 1.8nm or 2nm.

[0113] S0-6-2: An intrinsic amorphous silicon layer 040 is grown on both the front side 001 and the back side 002.

[0114] The method is to deposit the intrinsic amorphous silicon layer 040 by thermal decomposition, and the process parameters include: the flow range of silicon tetrahydride (SiH4, also known as silane) is 1300sccm-1700sccm, the temperature range is 590℃-610℃, and the thickness range of the intrinsic amorphous silicon layer 040 is 30nm-150nm;

[0115] Among them, if the flow rate of SiH4 is less than 1300sccm, a suitable intrinsic amorphous silicon layer 040 cannot be formed, and if the flow rate of SiH4 is greater than 1700sccm, the cost is wasted. Therefore, setting the flow rate range of SiH4 to 1300sccm-1700sccm can not only avoid the problem of being unable to form a suitable intrinsic amorphous silicon layer 040, but also avoid the problem of wasting costs; specifically, the flow rate of SiH4 can be 1300sccm, 1400sccm, 1500sccm, 1600sccm or 1700sccm; if the temperature is less than 590°C, the reaction rate is too slow and time is wasted. If the temperature is greater than 610°C, the growth rate of the intrinsic amorphous silicon layer 040 is too fast and difficult to control. Therefore, setting the temperature range to 590°C-610°C can not only avoid the problem of too slow reaction rate and time waste, but also avoid the problem of intrinsic amorphous silicon layer 040 The problem of too fast growth rate and difficulty in control; specifically, the temperature can be 590°C, 595°C, 600°C, 605°C or 610°C; if the thickness of the intrinsic amorphous silicon layer 040 is less than 30nm, it will lead to greater difficulty in subsequent doping and increased difficulty in metallization matching; if the thickness of the intrinsic amorphous silicon layer 040 is greater than 150nm, the amorphous silicon layer 040 absorbs light seriously, affecting the photoelectric conversion efficiency of the photovoltaic cell. Therefore, setting the thickness range of the intrinsic amorphous silicon layer 040 to 30nm-150nm can not only avoid the problem of greater difficulty in subsequent doping and increased difficulty in metallization matching, but also avoid the problem of serious light absorption of the amorphous silicon layer 040, affecting the photoelectric conversion efficiency of the photovoltaic cell; specifically, the thickness of the intrinsic amorphous silicon layer 040 can be 30nm, 60nm, 90nm, 120nm or 150nm; the structure of the silicon wafer 000 after growing the intrinsic amorphous silicon layer 040 is as follows Figure 8 As shown in (F).

[0116] S0-7: Doping.

[0117] Combination Figure 7 , Figure 8 (F)- Figure 8 (G) as shown, comprising the following steps:

[0118] S0-7-1: transforming the intrinsic amorphous silicon layer 040 into a polycrystalline silicon layer 050.

[0119] The method is to transform the intrinsic amorphous silicon layer 040 into the polycrystalline silicon layer 050 in a diffusion furnace, and the process parameters include: the flow range of N2 is 500sccm-2000sccm, the flow range of O2 is 600sccm-3000sccm, and the temperature range is 800℃-920℃; the functions of the polycrystalline silicon layer 050 include: serving as an emission layer to further enhance the transport of photogenerated carriers, thereby improving the performance of photovoltaic cells in terms of fill factor, short-circuit current and open-circuit voltage.

[0120] S0-7-2: A phosphosilicate glass layer 060 is grown on both the front side 001 and the back side 002 .

[0121] The method is to use phosphorus oxychloride (POCl3) as a diffusion source to diffuse in a diffusion furnace to grow a phosphosilicate glass layer 060. The process parameters include: the doping concentration of POCl3 is 1.0×10 20 atoms / cm 3 -5.0×10 20 atoms / cm 3 The structure of the silicon wafer 000 after the growth of the phosphorus silicon glass layer 060 is as follows Figure 8 As shown in (G).

[0122] S0-8: Cleaning.

[0123] Combination Figure 7 , Figure 8 (G)- Figure 8 (H), comprising the following steps:

[0124] S0-8-1: Etch the front side 001 to remove the phosphosilicate glass layer 060 on the front side 001.

[0125] The method is to etch the front surface 001 in a chain etching machine, and the process parameters include: a hydrogen fluoride (HF) solution with a volume concentration of 20%-40%, and a conveyor belt speed of 4m / min.

[0126] S0-8-2: Etch the silicon wafer 000 to remove the polysilicon layer 050 on the front side 001.

[0127] The method is to use flowing liquid medicine to soak and rinse the silicon wafer 000 in the tank equipment. The process parameters include: potassium hydroxide (KOH) solution with a volume concentration of 4%-8%, an additive volume of 5L, a temperature range of 50℃-65℃, a time of 300s, and a volume ratio of potassium hydroxide (KOH) to additive of 96:1.

[0128] S0-8-3: Etch the silicon wafer 000 to remove the borosilicate glass layer 010 on the front side 001 and remove the phosphosilicate glass layer 060 on the back side 002.

[0129] The method is to immerse the silicon wafer 000 in a tank-type device, and the process parameters include: a hydrogen fluoride (HF) solution with a volume concentration of 35%-40%; wherein, if the volume concentration of the hydrogen fluoride (HF) solution is less than 35%, it is insufficient to completely remove the borosilicate glass layer 010 on the front side 001 and the phosphosilicate glass layer 060 on the back side 002; if the volume concentration of the hydrogen fluoride (HF) solution is greater than 40%, it is easy to damage the silicon wafer 000. Therefore, setting the volume concentration range of the hydrogen fluoride (HF) solution to 35%-40% can not only avoid the problem of being unable to completely remove the borosilicate glass layer 010 on the front side 001 and the phosphosilicate glass layer 060 on the back side 002, but also avoid the problem of damaging the silicon wafer 000; specifically, the volume concentration of the HF solution can be 35%, 36%, 37%, 38%, 39% or 40%.

[0130] S0-8-4: Wash the etched silicon wafer 000 with water.

[0131] The method is to soak and rinse the silicon wafer 000 with flowing deionized water to prevent the residual liquid attached to the silicon wafer 000 in the previous process from affecting the normal progress of the next process.

[0132] S0-8-5: Acid wash the silicon wafer 000 after water washing.

[0133] The method comprises the following steps: using flowing liquid medicine to soak and rinse the silicon wafer 000 in the tank-type equipment, and the process parameters include: a hydrogen fluoride (HF) solution with a volume concentration of 10% and a hydrochloric acid (HCl) solution with a volume concentration of 7%.

[0134] S0-8-6: Slowly pull the pickled silicon wafer 000.

[0135] The method is to lift the flower basket carrying the silicon wafer 000 from the water washing tank at a relatively slow speed, so that the liquid attached to the silicon wafer 000 flows out without any residue, thereby ensuring that there is no watermark on the surface of the silicon wafer.

[0136] S0-8-7: Dry the silicon wafer 000 after slow pulling.

[0137] The method is to dry the silicon wafer in a drying furnace. The process parameters include: temperature of 80°C and time of 600s. The structure of the silicon wafer 000 after drying is as follows: Figure 8 As shown in (H).

[0138] S0-9: Passivation.

[0139] Combination Figure 7 , Figure 8 (H)- Figure 8As shown in (I), the passivation method can be to deposit an aluminum oxide layer 070 on the front surface 001 by using a thermal atomic deposition (ALD) method, and the process parameters include: a temperature of 260° C. and a deposition thickness of 4 nm; the functions of the aluminum oxide layer 070 include fixing negative charges, eliminating parasitic capacitance effects, and improving passivation effects; the structure of the silicon wafer 000 after passivation is as shown in FIG. Figure 8 As shown in (I).

[0140] S0-10: Coating.

[0141] Combination Figure 7 , Figure 8 (I)- Figure 8 As shown in (J), the coating method may be to form an anti-reflection layer 080 (also called anti-reflection film) on both the front side 001 and the back side 002 by plasma chemical vapor deposition (PECVD). The film layer may be made of silicon nitride. The process parameters include: a volume ratio of ammonia (NH3) to silicon tetrahydride (SiH4, also called silane) of 4:1-10:1, a temperature range of 480°C-550°C, and a pressure of 210Pa. The functions of the anti-reflection layer 080 include: reducing light reflection, increasing light absorption, passivating the surface and body of the silicon wafer 000, improving the short-circuit current and open-circuit voltage of the photovoltaic cell, and improving the conversion efficiency of the photovoltaic cell. The structure of the silicon wafer 000 after coating is as shown in FIG. Figure 8 As shown in (J).

[0142] It should be noted that the above describes a method for preparing a silicon substrate with anti-reflection films on both sides. In other embodiments, the method for preparing a silicon substrate with anti-reflection films on both sides can be adaptively adjusted according to actual conditions and will not be repeated here.

[0143] Fig. 9 This embodiment also provides a photovoltaic cell, which is prepared by any of the above-mentioned photovoltaic cell preparation methods.

[0144] Specifically, refer to Fig. 9As shown, the photovoltaic cell 100 provided in this embodiment is prepared by any of the above-mentioned photovoltaic cell preparation methods, and has the following structure: the photovoltaic cell 100 includes a first area 110 and a second area 120 arranged alternately along the thickness direction Y' perpendicular to the silicon wafer 000. Along the thickness direction X' of the silicon wafer 000, based on the silicon wafer 000, the front first area 110 includes a P+ doped layer 022, an aluminum oxide layer 070 and an anti-reflection layer 080 from the inside to the outside, the back first area 110 includes a tunneling oxide layer 030, a polysilicon layer 050 and an anti-reflection layer 080 from the inside to the outside, the front second area 120 includes a P++ doped layer 021 and an electrode 90 from the inside to the outside, and the back second area 120 includes a tunneling oxide layer 030, a polysilicon layer 050 and an electrode 90; this embodiment provides a photovoltaic cell 100 prepared by any of the above-mentioned photovoltaic cell preparation methods. In other embodiments, the structure of the photovoltaic cell can be adaptively adjusted according to actual conditions, which will not be repeated here.

[0145] It can be seen from the above embodiments that the photovoltaic cell preparation method and photovoltaic cell provided by the present invention achieve at least the following beneficial effects:

[0146] The photovoltaic cell preparation method and photovoltaic cell provided by the present invention increase the application of photosensitizer in the photovoltaic cell preparation method. The addition of photosensitizer can improve the photosensitivity of the conductive paste, making it more susceptible to laser energy regulation. By adding photosensitizer to the conductive paste or adding photosensitizer to the interface between the conductive paste and the substrate, the interface characteristics between the conductive paste and the substrate are optimized, the energy window of laser transfer is broadened, the energy window of laser transfer is easier to control and regulate, and the stability and consistency of laser transfer are improved. At the same time, by adjusting the type and concentration of the photosensitizer, the transfer process can be controlled. Precise control can improve the efficiency and quality of laser transfer; a photosensitive film layer is arranged on the substrate, and the photosensitive film layer can enhance the photosensitivity shedding ability of the conductive paste on the substrate; a mask layer is arranged on the substrate, and the mask layer can effectively shield the laser from irradiating the area outside the groove on the substrate, thereby reducing laser overflow and mis-engraving damage to the battery cell; both the photosensitive film layer and the mask layer can optimize the energy control and slurry stability in the laser transfer process, improve the accuracy and consistency of the transfer process, and reduce the influence of laser energy on the transfer result. The photovoltaic cell preparation method can improve production efficiency and save costs while ensuring high-quality transfer.

[0147] Although some specific embodiments of the present invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A method for preparing a photovoltaic cell, characterized in that: The following steps are involved: Providing a silicon substrate with anti-reflection films on both sides; Performing metallization treatment on at least one side of the silicon substrate to obtain a photovoltaic cell; Wherein, the metallization treatment of at least one side of the silicon substrate comprises: A substrate is provided, wherein a groove is formed on the substrate, and the groove penetrates a portion of the substrate along the thickness direction of the substrate; in addition, a photosensitive film layer and / or a mask layer is further provided on the substrate, wherein the photosensitive film layer is located in the groove, and the mask layer is located on at least one side of the substrate, and along the thickness direction of the substrate, the orthographic projection of the mask layer does not overlap with the orthographic projection of the groove; Filling the groove with a mixed slurry, wherein the mixed slurry includes a conductive slurry and a photosensitive agent; or, filling the groove with the photosensitive agent and the conductive slurry in sequence; The substrate is aligned with the silicon base, and a laser is irradiated on the side of the groove away from the silicon base, so that the conductive paste generates a grid line on the silicon base to obtain the photovoltaic cell.

2. The method for preparing a photovoltaic cell according to claim 1, characterized in that: The mass percentage of the photosensitizer in the mixed slurry is in the range of 0.1%-5%.

3. The method for preparing a photovoltaic cell according to claim 1, characterized in that: The photosensitizer includes a photopolymer, a photodye, a photoinorganic material, a photochromic material, a photoexpanding agent, a photocrosslinking material or a photogasification material.

4. The method for preparing a photovoltaic cell according to claim 1, characterized in that: The conductive paste comprises conductive powder, glass powder and an organic carrier.

5. The method for preparing a photovoltaic cell according to claim 1, characterized in that: The scanning rate of the laser is 100 mm / s-50000 mm / s, and the laser power is 10 W-200 W.

6. The method for preparing a photovoltaic cell according to claim 1, characterized in that: Along the thickness direction of the substrate, the cross-sectional shape of the groove is rectangular, trapezoidal or fan-shaped.

7. The method for preparing a photovoltaic cell according to claim 1, characterized in that: The grooves include main gate grooves and auxiliary gate grooves, the main gate grooves extend along a first direction and are arranged along a second direction, the first direction is the side length direction of the silicon substrate, the second direction intersects with the first direction, and the auxiliary gate grooves extend along the second direction and are arranged along the first direction.

8. The method for preparing a photovoltaic cell according to claim 7, characterized in that: The width of the main gate groove along the second direction ranges from 45 μm to 200 μm, and the width of the sub-gate groove along the first direction ranges from 8 μm to 30 μm.

9. The method for preparing a photovoltaic cell according to claim 1, characterized in that: The method for preparing the silicon substrate with anti-reflection films on both sides comprises texturing, first diffusion, laser, second diffusion, etching, growth of protective layer, doping, cleaning, passivation and coating in sequence.

10. A photovoltaic cell, characterized in that: The photovoltaic cell is prepared by the photovoltaic cell preparation method according to any one of claims 1 to 9.

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