Solar cell, method of manufacture and photovoltaic module

Abstract

This invention discloses a solar cell, its fabrication method, and a photovoltaic module. The solar cell includes: a silicon substrate having a first surface and a second surface disposed opposite to each other; a passivation contact structure disposed on the second surface of the silicon substrate; a first dielectric layer disposed on the surface of the passivation contact structure, including a plurality of metal regions and non-metal regions spaced apart along a first direction, the metal regions and non-metal regions extending along a second direction perpendicular to the first direction, the metal regions forming at least one opening penetrating the first dielectric layer along the thickness direction; a composite film layer disposed at the opening and in contact with the passivation contact structure; and a first electrode located within the metal region and in contact with the composite film layer. The solar cell, fabrication method, and photovoltaic module of this invention can ensure the photoelectric conversion efficiency and long-term stability of the TOPCon cell.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, specifically relating to a solar cell, its preparation method, and a photovoltaic module. Background Technology

[0002] TOPCon cells (tunneling oxide passivated contact cells) have become a core technology direction for the industrial upgrading and cost reduction of photovoltaic cells due to their high open-circuit voltage, high conversion efficiency, and excellent stability. Their back side features a composite passivation structure composed of an ultrathin silicon oxide layer and a heavily doped polycrystalline silicon layer, which significantly reduces interfacial recombination and achieves efficient selective carrier transport. To enable this passivation structure to perform its actual power generation function, electrode conduction must be achieved through metal electrodes to ensure efficient collection of photogenerated carriers.

[0003] Currently, the mainstream technology in the industry uses screen printing silver paste to prepare the back metal electrode. However, silver, as a precious metal, not only has high raw material costs but also experiences volatile market prices. Data shows that back silver paste consumption accounts for more than 60% of the total silver consumption in TOPCon batteries, directly leading to persistently high battery manufacturing costs. This has become a key bottleneck restricting the large-scale popularization of TOPCon batteries and hindering the achievement of the "cost reduction and efficiency improvement" strategic goal. Therefore, developing a back electrode preparation technology that uses inexpensive metals to replace silver paste while simultaneously meeting the requirements of battery performance and large-scale production is a technical challenge that the photovoltaic industry urgently needs to overcome.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a solar cell, a preparation method, and a photovoltaic module that can ensure the photoelectric conversion efficiency and long-term stability of TOPCon cells.

[0006] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0007] A solar cell, comprising:

[0008] A silicon substrate having a first surface and a second surface disposed opposite to each other;

[0009] A passivated contact structure is disposed on the second surface of the silicon substrate;

[0010] A first dielectric layer is disposed on the surface of the passivated contact structure. The first dielectric layer includes a plurality of metal regions and non-metal regions spaced apart along a first direction. The metal regions and the non-metal regions extend along a second direction, which is perpendicular to the first direction. The metal regions are formed with at least one opening that penetrates the first dielectric layer along the thickness direction.

[0011] A composite film layer is disposed at the opening and in contact with the passivation contact structure;

[0012] The first electrode is located in the metal region and is in contact with the composite film layer.

[0013] In one or more embodiments of the present invention, the opening extends along a second direction, and / or the openings are spaced apart along the second direction.

[0014] In one or more embodiments of the present invention, the opening includes at least one of a circular opening, a square opening, a rectangular opening, and a strip-shaped opening, wherein,

[0015] The diameter of the circular opening is 20μm-200μm;

[0016] The side length of the square opening is 20μm-200μm;

[0017] The width of the rectangular opening is 20μm-100μm, and the length is 1mm-5mm;

[0018] The width of the elongated opening is 20μm-100μm, and its length is less than or equal to the length of the first electrode in the second direction.

[0019] In one or more embodiments of the present invention, the linewidth of the first electrode is smaller than the maximum diameter of the circular opening, and / or the linewidth of the first electrode is smaller than the maximum side length of the square opening.

[0020] In one or more embodiments of the present invention, the material of the first electrode is selected from non-precious metal materials, including one or more of copper, aluminum, nickel, cobalt, iron, zinc, and tin; and / or,

[0021] The first electrode has a linewidth of 20μm-150μm, a thickness of 5μm-50μm, and an adhesion force greater than or equal to 4N / cm. 2 .

[0022] In one or more embodiments of the present invention, the composite film layer includes a transition layer and a conductive layer sequentially stacked in a direction away from the passivation contact structure;

[0023] The transition layer and the conductive layer are made of different materials, and / or the thickness of the conductive layer is greater than the thickness of the transition layer.

[0024] In one or more embodiments of the present invention, the material of the transition layer is selected from non-precious metal materials, including one or more of titanium, zinc, magnesium, nickel, aluminum, and copper; and / or,

[0025] The thickness of the transition layer is 5nm-20nm; and / or,

[0026] The conductive layer is made of non-precious metals, including one or more of nickel, aluminum, titanium, zinc, copper, and magnesium; and / or,

[0027] The thickness of the conductive layer is 50nm-200nm; and / or,

[0028] The adhesion of the composite film layer is greater than or equal to 5 N / cm. 2 Sheet resistance is less than or equal to 5 mΩ / sq.

[0029] In one or more embodiments of the present invention, an alloy layer is formed on the side of the passivated contact structure located at the opening that is away from the silicon substrate;

[0030] The thickness of the alloy layer is less than the thickness of the composite film layer, and / or the alloy layer includes one of titanium silicon alloy, zinc silicon alloy, magnesium silicon alloy, nickel silicon alloy, aluminum silicon alloy or copper silicon alloy, and / or the thickness of the alloy layer is 10nm-30nm.

[0031] In one or more embodiments of the present invention, the solar cell further includes:

[0032] An emitter layer is disposed on the first surface;

[0033] A second dielectric layer is disposed on the emitter layer; and,

[0034] The second electrode is disposed on the second dielectric layer and is in contact with the emitter layer.

[0035] A method for preparing a solar cell, comprising:

[0036] A silicon substrate is provided, the silicon substrate having a first surface and a second surface disposed opposite to each other;

[0037] A passivated contact structure is prepared on the second surface of the silicon substrate;

[0038] A first dielectric layer is prepared on the passivated contact structure. The first dielectric layer includes a plurality of metal regions and non-metal regions spaced apart along a first direction. The metal regions and the non-metal regions extend along a second direction, which is perpendicular to the first direction.

[0039] The first dielectric layer is patterned to form at least one opening penetrating the first dielectric layer along the thickness direction in the metal region.

[0040] Prepare a composite film layer located at the opening;

[0041] A first electrode is fabricated in the metal region, and the first electrode is in contact with the composite film layer.

[0042] In one or more embodiments of the present invention, a laser process is used to pattern the first dielectric layer by synergistically controlling the laser wavelength, pulse width, pulse energy, and scanning speed; wherein...

[0043] The laser wavelength range is 355nm-1064nm;

[0044] The pulse width range is 10 ps-100 ns;

[0045] The pulse energy range is 0.1 mJ-1 mJ;

[0046] The scanning speed range is 100mm / s-500mm / s.

[0047] In one or more embodiments of the present invention, preparing a composite film layer located at the opening includes:

[0048] A composite film layer is deposited, the composite film layer covering the first dielectric layer and the passivation contact structure of the opening;

[0049] Prepare a mask layer, wherein the mask layer covers only the composite film layer of the opening;

[0050] Remove the composite film layer on the first dielectric layer;

[0051] Remove the mask layer from the opening;

[0052] Annealing treatment.

[0053] In one or more embodiments of the present invention, the preparation of the mask layer includes:

[0054] A mask layer is printed on the composite film layer of the opening;

[0055] The mask layer is dried in stages.

[0056] In one or more embodiments of the present invention, the mask layer is made of an acid-sensitive material; and / or,

[0057] The first drying step is at a temperature of 80℃-100℃ and a drying time of 10-15 minutes. The second drying step is at a temperature of 120℃-150℃ and a drying time of 5-8 minutes.

[0058] In one or more embodiments of the present invention, an acidic stripping solution is used for stripping to remove the mask layer within the opening; wherein...

[0059] The acidic stripping solution includes a 5%-10% hydrochloric acid aqueous solution, the stripping temperature is 25℃-35℃, and the stripping time is 1min-3min.

[0060] In one or more embodiments of the present invention, a wet etching method is used to remove the composite film layer on the first dielectric layer; wherein...

[0061] The wet etching solution is an alkaline composite etching solution containing sodium hydroxide, sodium carbonate and an etching inhibitor. The concentration of sodium hydroxide is 50g / L-80g / L, the concentration of sodium carbonate is 20g / L-40g / L, the concentration of etching inhibitor is 5g / L-10g / L, the etching temperature is 40℃-60℃, and the etching time is 3min-8min.

[0062] In one or more embodiments of the present invention, in the annealing step, the annealing atmosphere is a nitrogen protective atmosphere with a nitrogen purity ≥99.99%, the annealing temperature is 300℃-450℃, the heating rate is 5℃ / min-10℃ / min, the holding time is 30min-60min, the cooling rate is 3℃ / min-5℃ / min, and the sheet resistance of the composite film is reduced by 10%-20% after annealing.

[0063] In one or more embodiments of the present invention, after annealing, an alloy layer is formed on the side of the passivated contact structure of the opening facing away from the silicon substrate.

[0064] In one or more embodiments of the present invention, the preparation of the first electrode includes:

[0065] Print the first electrode;

[0066] The first electrode is dried; wherein,

[0067] The drying temperature is 150℃-180℃, and the drying time is 15min-20min. After drying, the adhesion of the first electrode is ≥4N / cm. 2 .

[0068] In one or more embodiments of the present invention, the method for preparing the solar cell further includes:

[0069] An emitter layer is prepared on the first surface;

[0070] A second dielectric layer is prepared on the emitter layer;

[0071] A second electrode is prepared on the second dielectric layer to contact the emitter layer.

[0072] A photovoltaic module includes the solar cell described above or a solar cell prepared by the method described above.

[0073] Compared with existing technologies, the solar cell, preparation method and photovoltaic module of the present invention improve the carrier collection efficiency, enhance the interfacial bonding and conductivity and reduce the manufacturing cost by optimizing the design of the laser-opened film pattern and combining the composite film layer and electrode design. This improves the photoelectric conversion efficiency and structural stability of the cell and achieves cost reduction and efficiency improvement.

[0074] The solar cell, its fabrication method, and its photovoltaic module of the present invention, through graphically optimized laser parameter control, ensure the opening depth while avoiding damage to the back passivation contact structure, effectively protecting the passivation contact structure, thereby improving the open-circuit voltage and fill factor, and ultimately improving the photoelectric conversion efficiency of the cell. Attached Figure Description

[0075] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0076] Figure 1 This is a schematic diagram of the structure of a solar cell in one embodiment of the present invention;

[0077] Figure 2 for Figure 1 A magnified schematic diagram of the partial structure at point A in the middle;

[0078] Figure 3 This is a schematic diagram of the open-film pattern of the solar cell in this invention;

[0079] Figures 4a-4f This is a schematic diagram of the fabrication process steps of the solar cell in this invention;

[0080] Figure 5 This is a partial structural schematic diagram of a solar cell according to another embodiment of the present invention;

[0081] Figure 6 This is a partial structural schematic diagram of a solar cell in another embodiment of the present invention. Detailed Implementation

[0082] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0083] In this invention, unless otherwise expressly specified and limited, the disclosed "range" is defined in the form of a lower limit and / or an upper limit. A given range is defined by selecting a lower limit and / or an upper limit, which defines the boundary of the particular range. Ranges defined in this way may include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form an unspecified range, and any lower limit can be combined with other lower limits to form an unspecified range. Similarly, any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower limit or upper limit and can be combined with any other point or single value or with other lower limits or upper limits to form an unspecified range.

[0084] In this invention, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0085] This invention discloses a solar cell, comprising:

[0086] A silicon substrate having a first surface and a second surface disposed opposite to each other;

[0087] A passivated contact structure is disposed on the second surface of a silicon substrate;

[0088] A first dielectric layer is disposed on the surface of a passivation contact structure. The first dielectric layer includes a plurality of metal regions and non-metal regions spaced apart along a first direction. The metal regions and the non-metal regions extend along a second direction, which is perpendicular to the first direction. The metal regions are formed with at least one opening penetrating the first dielectric layer along the thickness direction.

[0089] A composite film layer is disposed at the opening and in contact with the passivation contact structure;

[0090] The first electrode is located in the metal region and is in contact with the composite film.

[0091] This invention also discloses a method for preparing a solar cell, comprising:

[0092] Providing a silicon substrate, wherein the silicon substrate has a first surface and a second surface disposed opposite to each other;

[0093] Preparing a passivated contact structure on the second surface of the silicon substrate;

[0094] Preparing a first dielectric layer on the passivated contact structure, wherein the first dielectric layer comprises a plurality of metal regions and non-metal regions spaced apart along a first direction, the metal regions and the non-metal regions extend along a second direction, and the second direction is perpendicular to the first direction;

[0095] Patterning the first dielectric layer to form at least one opening penetrating the first dielectric layer along a thickness direction in the metal region;

[0096] Preparing a composite film layer located in the opening;

[0097] Preparing a first electrode in the metal region, and the first electrode is in contact with the composite film layer.

[0098] Specifically, in this preparation method, a laser process is used, and the first dielectric layer is patterned by cooperatively regulating laser wavelength, pulse width, pulse energy and scanning speed; wherein the laser wavelength ranges from 355nm to 1064nm; the pulse width ranges from 10ps to 100ns; the pulse energy ranges from 0.1mJ to 1mJ; and the scanning speed ranges from 100mm / s to 500mm / s.

[0099] The invention also discloses a photovoltaic module, comprising the solar cell described above, or comprising a solar cell prepared by the preparation method of the solar cell described above.

[0100] The invention improves the carrier collection efficiency, enhances the interface bonding force and conductive performance, reduces the manufacturing cost, improves the photoelectric conversion efficiency and structural stability of the battery, and realizes cost reduction and efficiency improvement through the optimized design of the laser opening pattern combined with the design of the composite film layer and the electrode.

[0101] Through the regulation of laser parameters optimized by patterning, the invention avoids damaging the back passivated contact structure while ensuring the opening depth, effectively protects the passivated contact structure, thereby improving the open-circuit voltage and fill factor, and finally achieving the improvement of the photoelectric conversion efficiency of the battery.

[0102] The present invention will be further described below with reference to the accompanying drawings.

[0103] Refer Figure 1 is a schematic structural view of the solar cell of the present invention, the solar cell is a TOPCon cell comprising a silicon substrate 10, in combination with Figure 4aAs shown, the silicon substrate 10 includes a oppositely disposed first surface S1 and a second surface S2, the first surface S1 is the front surface of the silicon substrate 10 (i.e., the light-receiving surface), and the second surface S2 is the back surface of the silicon substrate 10 (i.e., the back-light surface). The silicon substrate 10 of the present invention is preferably an N-type silicon substrate.

[0104] Referring Figure 1 As shown, in the present invention, a passivation contact structure 12 is provided on the second surface S2 of the silicon substrate 10. Specifically, the passivation contact structure 12 includes a tunneling layer and a doped layer stacked in sequence. The tunneling layer is in contact with the second surface S2 of the silicon substrate 10, and can provide a good interface passivation effect. Wherein, the tunneling layer is silicon oxide (SiO X ) layer, silicon oxynitride (SiO X N Y ) one or a combination of two of the layers, preferably a silicon oxide layer. The doping type of the doped layer is the same as that of the silicon substrate 10. The doped layer can provide field passivation effect, improve contact and reduce resistance.

[0105] Referring Figure 1 and in combination with Figure 3 As shown, in the present invention, a first dielectric layer is provided on the surface of the passivation contact structure 12. The surface of the first dielectric layer includes a plurality of metal regions S distributed at intervals along a first direction (the Figure 3 y-direction as shown) and non-metallic regions between adjacent metal regions S, both the metal regions S and the non-metallic regions extend along a second direction (the Figure 3 x-direction as shown), and the second direction is perpendicular to the first direction. Each metal region S is formed with at least one opening 20 penetrating the first dielectric layer in the thickness direction.

[0106] In an exemplary embodiment, each metal region S is provided with an opening 20 continuously extending along the second direction (the Figure 3 x-direction as shown) (as shown in Figure 3 by d). The openings 20 in the plurality of metal regions S are arranged in an array in the first direction (the Figure 3 y-direction as shown).

[0107] Wherein, the opening 20 continuously extending along the second direction comprises an elongated opening. The width of the elongated opening is 20 μm-100 μm, for example, it can be 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, etc., or it can be a range composed of any of the above values. The length of the elongated opening is less than or equal to the length of the first electrode 51.

[0108] In another exemplary embodiment, each metal region S is provided with a plurality of openings 20 distributed at intervals in the second direction (the Figure 3 x-direction as shown) (as shown in Figure 3(As shown in a, b, and c). That is, all openings 20 present a discrete point distribution on the surface of the passivated contact structure. When multiple openings 20 in each metal region S are arranged in a straight line with equal spacing, multiple metal regions S are arranged in a straight line with equal spacing, and the openings 20 corresponding to adjacent metal regions S are arranged in a straight line with equal spacing in the first direction, all openings 20 present an array of point distribution on the surface of the passivated contact structure.

[0109] The plurality of openings 20 spaced apart along the second direction include at least one of circular openings, square openings, and rectangular openings. The diameter of the circular opening is 20μm-200μm, for example, 20μm, 50μm, 100μm, 150μm, 200μm, etc., or any range of the above values. The side length of the square opening is 20μm-200μm, for example, 20μm, 50μm, 100μm, 150μm, 200μm, etc., or any range of the above values. The width of the rectangular opening is 20μm-100μm, for example, 20μm, 30μm, 40μm, 50μm, etc., or any range of the above values, and the length is 1mm-5mm, for example, 1mm, 3mm, 5mm, etc., or any range of the above values.

[0110] In the above technical solution, by limiting the distribution of the openings 20 to discrete point distribution, the carrier recombination loss of the subsequent composite film layer, electrode and tunneling passivation structure can be significantly suppressed, thereby improving the open circuit voltage (Voc), improving the fill factor (FF), maximizing the light absorption efficiency and improving the battery conversion efficiency.

[0111] In another exemplary embodiment, a portion of the metal region S is provided with a second direction ( Figure 3 The elongated opening extends continuously in the x-direction (as shown), and the remaining metal region S has multiple openings in the second direction (as shown). Figure 3 (as shown in the x-direction) Circular, square, or rectangular openings spaced apart (e.g.) Figure 3 (As shown in e). The combination and distribution of openings with different shapes can also suppress carrier recombination losses in subsequent composite films, electrodes and tunneling passivation structures, thereby increasing the open-circuit voltage (Voc) and fill factor (FF), and improving light absorption efficiency and cell conversion efficiency.

[0112] In this invention, the first dielectric layer includes a first passivation layer 21 and a first antireflection layer 31. The first passivation layer 21 can provide excellent field passivation and chemical passivation effects, and the first antireflection layer 31 can reduce reflectivity and increase light utilization.

[0113] Illustratively, the first passivation layer 21 is an aluminum oxide passivation layer. The first anti-reflection layer 31 can be a laminated film formed by any one or more of silicon nitride layer, silicon oxynitride layer and silicon oxide layer, preferably a silicon nitride layer. Silicon nitride has inactive chemical properties, strong acid and alkali corrosion resistance, which can reduce the sensitivity of the cell to the environment.

[0114] Referring Figure 1 and in combination with Figure 2 , according to the present invention, a composite film layer in contact with the passivation contact structure 12 is arranged in the opening 20 of the first dielectric layer. The composite film layer comprises a transition layer 41 and a conductive layer 42 stacked sequentially. The transition layer 41 is used for improving the binding force between the composite film layer and the first dielectric layer as well as the passivation contact structure. The conductive layer 42 is used for ensuring the conductivity of the electrode.

[0115] The thickness of the conductive layer 42 is greater than that of the transition layer 41. The thickness of the transition layer 41 is 5 nm to 20 nm, for example, it can be 5 nm, 10 nm, 15 nm, 20 nm, etc., or can be a range formed by any of the above values. The thickness of the conductive layer 42 is 50 nm to 200 nm, for example, it can be 50 nm, 100 nm, 150 nm, 200 nm, etc., or can be a range formed by any of the above values.

[0116] The materials of both the transition layer 41 and the conductive layer 42 are selected from non-noble metal materials. The non-noble metal materials can comprise one or more of titanium, zinc, magnesium, nickel, aluminum and copper.

[0117] It should be noted that different materials should be selected for the transition layer 41 and the conductive layer 42 in the composite film layer. That is, the composite film layer can adopt combinations such as titanium-nickel, zinc-aluminum, magnesium-copper, etc. The adhesive force of the composite film layer is greater than or equal to 5N / cm 2 , and the sheet resistance is less than or equal to 5mΩ / sq. After the composite film layer is prepared and the solar cell is annealed, an alloy layer (not shown) is formed on the side of the passivation contact structure in the opening 20 facing away from the silicon substrate 10, and the metal material in the alloy layer is the same as the metal material of the transition layer 41 in the composite film layer. The alloy layer can comprise one of titanium-silicon alloy, zinc-silicon alloy, magnesium-silicon alloy, nickel-silicon alloy, aluminum-silicon alloy or copper-silicon alloy. The thickness of the alloy layer is less than that of the composite film layer, and the thickness of the alloy layer is 10 nm to 30 nm, for example, it can be 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, etc., or can be a range formed by any of the above values.

[0118] According to the present invention, a first electrode 51 is arranged in each metal region S of the first dielectric layer. The first electrode 51 is in contact with the composite film layer in the opening 20. When the opening 20 on the first dielectric layer is presented as shown in Figure 3When the patterns shown as a, b, c and e in

[0119] in an embodiment, as Figure 2 shown, the line width W of the first electrode 51 is equal to the maximum dimension R of the opening 20. It should be noted that the line width W of the first electrode 51 is generally the width of the contact portion between the first electrode 51 and the surface of the solar cell.

[0120] in another embodiment, as Figure 5 shown, when the opening 20 is selected from circular openings and / or square openings, the line width W of the first electrode 51 is smaller than the maximum dimension R of the opening 20. It should be noted that the line width W of the first electrode 51 is generally the width of the contact portion between the first electrode 51 and the surface of the solar cell.

[0121] in yet another embodiment, as Figure 6 shown, when the opening 20 is selected from rectangular openings and / or elongated openings, the maximum line width W of the first electrode 51 is larger than the maximum dimension R of the opening 20. It should be noted that the line width W of the first electrode 51 is generally the width of the contact portion between the first electrode 51 and the surface of the solar cell.

[0122] The line width W of the first electrode 51 is 20μm-150μm, for example, it can be 20μm, 30μm, 50μm, 70μm, 100μm, 120μm, 150μm, etc., or can be a range composed of any of the above values. The thickness H of the first electrode 51 is 5μm-50μm, for example, it can be 5μm, 7μm, 10μm, 20μm, 40μm, 50μm, etc., or can be a range composed of any of the above values. The adhesive force of the first electrode 51 is greater than or equal to 4N / cm 2 . The material of the first electrode 51 is selected from non-noble metal materials, including one or more of copper, aluminum, nickel, cobalt, iron, zinc and tin.

[0123] The present invention, through optimal design of the laser film opening pattern, combined with the composite film layer and electrode design, improves carrier collection efficiency, enhances interfacial bonding force and conductive performance, reduces manufacturing cost, improves the photoelectric conversion efficiency and structural stability of the battery, and achieves cost reduction and efficiency improvement.

[0124] referring to Figure 1 shown, the emitter layer 11 is formed at the first surface S1 of the silicon substrate 10 of the present invention through a diffusion process or a PECVD (plasma enhanced chemical vapor deposition) process. Illustratively, the emitter layer 11 of the present invention is a P-type doped layer (that is, P+ emitter), which is formed under the first surface S1 of the silicon substrate (that is, inside the silicon substrate) through a boron doping process.

[0125] In the present invention, a second dielectric layer is disposed on the first surface S1 of the silicon substrate 10 and on the surface of the emitter layer 11. The second dielectric layer may comprise a second anti-reflection layer 32 and / or a second passivation layer. The second anti-reflection layer 32 can reduce reflectivity and increase light utilization rate. The second anti-reflection layer 32 may be a laminated film formed by any one or more of a silicon nitride layer, a silicon oxynitride layer, and a silicon oxide layer, and is preferably a silicon nitride layer. The second passivation layer is an aluminum oxide passivation layer, which can provide excellent field passivation and chemical passivation effects.

[0126] The second electrode 52 of the present invention is located on the first surface S1 of the silicon substrate 10 and is in contact with the emitter layer 11. The material of the second electrode 52 may be selected from conventional silver paste.

[0127] It can be understood that, in the solar cell of the present embodiment, the backlight surface may further comprise a plurality of main electrodes perpendicularly distributed with the first electrode 51 (not shown in the figures), and the light-receiving surface may also comprise a plurality of main electrodes perpendicularly distributed with the second electrode 52 (not shown in the figures). The material of the main electrodes may be selected from conventional silver paste.

[0128] The preparation method of the solar cell of the present invention specifically comprises the following steps:

[0129] 1. Providing a battery preform.

[0130] Reference Figure 4a as shown, the battery preform comprises a silicon substrate 10, the silicon substrate 10 comprises a first surface S1 and a second surface S2 disposed opposite to each other, the first surface S1 is the front side (i.e., the light-receiving surface) of the silicon substrate 10, and the second surface S2 is the back side (i.e., the backlight surface) of the silicon substrate 10. The silicon substrate 10 of the present invention is an N-type silicon substrate.

[0131] A P-type doped emitter layer 11 is formed at the first surface S1 of the silicon substrate 10 by a boron diffusion process. Specifically, diffusion may be performed in a high-temperature furnace tube by a deposition propulsion method using a boron source (e.g., BCl3 or BBr3, etc.).

[0132] It can be understood that before the boron diffusion step, single-sided or double-sided texturing may also be performed on the first surface S1 and the second surface S2 of the silicon substrate 10. After the boron diffusion step, backside polishing treatment may also be performed on the silicon substrate 10. Since the texturing process and the polishing process are not the innovations of the present invention, the present application will not elaborate on them in detail herein.

[0133] A second dielectric layer is formed at the first surface S1 of the silicon substrate 10 by an ALD (Atomic Layer Deposition) process. Wherein, the second dielectric layer may comprise a second anti-reflection layer 32 and / or a second passivation layer. The second anti-reflection layer 32 can reduce reflectivity and increase the utilization rate of light. The second anti-reflection layer 32 may be a laminated film formed by any one or more of a silicon nitride layer, a silicon oxynitride layer and a silicon oxide layer, and is preferably a silicon nitride layer. The second passivation layer is an aluminum oxide passivation layer, which can provide excellent field passivation and chemical passivation effects.

[0134] A tunneling layer and a doped layer stacked in sequence are prepared on the second surface S2 of the silicon substrate 10 by a PECVD process to form a passivated contact structure 12. The tunneling layer is in contact with the second surface S2 of the silicon substrate 10, and can provide good interface passivation effect. Wherein, the tunneling layer is silicon oxide (SiO X ) layer, silicon oxynitride (SiO X N Y ) layer, a combination of one or both of them, preferably a silicon oxide layer. The doping type of the doped layer is the same as that of the silicon substrate 10. The doped layer can provide a field passivation effect, improve contact and reduce resistance at the same time.

[0135] A first dielectric layer is formed at the second surface S2 of the silicon substrate 10 by an ALD (Atomic Layer Deposition) process. Wherein, the first dielectric layer comprises a first passivation layer 21 and a first anti-reflection layer 31. The first passivation layer 21 can provide excellent field passivation and chemical passivation effects, and the first anti-reflection layer 31 can reduce reflectivity and increase the utilization rate of light. The first passivation layer 21 is an aluminum oxide passivation layer. The first anti-reflection layer 31 may be a laminated film formed by any one or more of a silicon nitride layer, a silicon oxynitride layer and a silicon oxide layer, and is preferably a silicon nitride layer. Silicon nitride has inactive chemical properties and strong acid and alkali corrosion resistance, which can reduce the sensitivity of the battery to the environment.

[0136] 2. Laser film opening

[0137] Ref. Figure 4bAs shown, a laser process is used to pattern the first dielectric layer by synergistically controlling the laser wavelength, pulse width, pulse energy and scanning speed, forming multiple openings 20. The laser wavelength range is 355nm-1064nm, for example, 355nm, 450nm, 670nm, 890nm, 1064nm, or any combination of these values; the pulse width range is 10ps-100ns, for example, 10ps, 50ps, 100ps, 1000ps, 1ns, 10ns, 50ns, 100ns, or any combination of these values; the pulse energy range is 0.1mJ-1mJ, for example, 0.1mJ, 0.3mJ, 0.5mJ, 0.7mJ, 1mJ, or any combination of these values; the scanning speed range is 100mm / s-500mm / s, for example, 100mm / s, 200mm / s, 300mm / s, 400mm / s, 500mm / s, or any combination of these values.

[0138] For example, a specific combination of laser wavelength 355nm, pulse width 50ps, pulse energy 0.5mJ, and scanning speed 300mm / s is selected to achieve precise removal of the first dielectric layer while avoiding damage to the passivated contact structure.

[0139] refer to Figure 3 As shown, the laser-engraved pattern can be one or more of the following combinations: array of dots (a), line segments (b), or continuously extending lines (d); and patterns (c) and (e). Dot patterns can be circular or square, with a diameter or side length of 20μm-200μm; line segment patterns can be rectangular, with a width of 20μm-100μm and a length of 1mm-5mm; continuously extending line patterns can be elongated strips, with a width of 20μm-100μm and a length consistent with the length of the electrode to be fabricated subsequently. The engraving size error is controlled within ±5μm to ensure precise positioning for subsequent coating and electrode fabrication.

[0140] In existing technologies, laser delamination processes often use a single laser parameter to remove the passivation layer (dielectric layer). This can easily lead to problems such as insufficient delamination depth, resulting in poor contact between the subsequent coating and the substrate (a silicon substrate with passivation contact structure), or excessive delamination damaging the passivation contact structure. These issues can impair the battery's carrier collection efficiency, causing a decrease in the battery's open-circuit voltage and fill factor, and affecting the battery's photoelectric conversion efficiency.

[0141] In the present invention, the pattern for laser film opening is optimally designed. By adjusting parameters such as the shape, size and arrangement of the film opening pattern, the film opening region is better matched with the lateral transport path of carriers, which shortens the transmission distance of photo-generated carriers reaching the electrodes, reduces the lateral resistance loss. Meanwhile, in combination with the patterned and optimized laser parameter adjustment, through the cooperative adjustment of multiple parameters, the first dielectric layer is accurately removed while ensuring the film opening depth, so as to avoid damaging the passivation contact structure and effectively protect the passivation contact structure, thereby increasing the open-circuit voltage and fill factor, and ultimately achieving the improvement of the photoelectric conversion efficiency of the battery.

[0142] 3. Preparation of composite film layer

[0143] Reference Figure 4c As shown, a composite film layer comprising a transition layer 41 and a conductive layer 42 is formed by physical vapor deposition (PVD) on the second surface S2 of the silicon substrate 10 after laser film opening. The composite film layer covers the first dielectric layer and the passivation contact structure 12 in the opening.

[0144] Wherein, the material of the transition layer 41 is selected from non-noble metal materials, comprising one or more of titanium, zinc, magnesium, nickel, aluminum and copper, with a thickness of 5nm-20nm, for example, 5nm, 10nm, 15nm, 20nm, etc., or a range composed of any of the above values, which is used to improve the binding force between the composite film layer and the first dielectric layer and the passivation contact structure. The material of the conductive layer 42 is selected from non-noble metal materials, comprising one or more of nickel, aluminum, titanium, zinc, copper, aluminum and magnesium, with a thickness of 50nm-200nm, for example, 50nm, 100nm, 150nm, 200nm, etc., or a range composed of any of the above values, which is used to ensure the conductive performance of the subsequently prepared electrodes.

[0145] Existing PVD coating mostly adopts a single metal layer structure, which has poor interface compatibility with the battery substrate and subsequent electrodes, and is prone to film layer falling off or peeling.

[0146] In the present invention, the composite film layer is adopted, the transition layer improves the binding strength between the composite film layer and the first dielectric layer and the passivation contact structure, the conductive layer provides an excellent conductive path, reduces the contact resistance, and ensures the conductive performance of the subsequently prepared electrodes. The two layer structures cooperate with each other, so that a strong binding interface is formed between the composite film layer and the battery substrate as well as the subsequently printed electrodes, which effectively avoids the falling off and cracking of the coating layer and the peeling of the electrodes, and improves the structural stability and long-term service life of the battery.

[0147] 4. Removing the composite film layer on the surface of the first dielectric layer

[0148] Reference Figure 4dAs shown, a mask layer 60 is printed on the surface of the composite film layer, wherein the mask layer 60 only covers the laser film opening region, that is, only covers the composite film layer located in the opening 20. The mask layer 60 is made of acid-intolerant ink material, preferably an alkali-resistant and acid-intolerant ink such as epoxy resin-based acid-strippable ink is used as the material of the mask layer. The printing thickness is controlled at 10μm-30μm, and the printing accuracy error is ≤3μm, so as to ensure that the mask layer accurately covers the laser film opening region and does not block the non-film opening region.

[0149] Step-by-step drying treatment is performed on the mask layer 60, wherein the drying temperature of the first step is 80°C-100°C, for example, it can be 80°C, 90°C, 100°C, etc., or it can be a range composed of any of the above values; the drying time of the first step is 10min-15min, for example, it can be 10min, 12min, 14min, 15min, etc., or it can be a range composed of any of the above values. The drying temperature of the second step is 120°C-150°C, for example, it can be 120°C, 130°C, 140°C, 150°C, etc., or it can be a range composed of any of the above values; the drying time of the second step is 5min-8min, for example, it can be 5min, 6min, 7min, 8min, etc., or it can be a range composed of any of the above values.

[0150] By defining the printing thickness of the mask layer 60 and adopting the step-by-step drying process, a unique mask preparation solution can be formed. After drying, the hardness of the mask layer 60 is ≥2H, and there are no defects such as air bubbles and cracks.

[0151] Reference Figure 4e As shown, wet etching is performed on the composite film layer in the non-laser film opening region. The composite film layer on the surface of the first dielectric layer is removed through an alkaline wet etching process. Wherein, the wet etching solution is an alkaline composite etching solution comprising sodium hydroxide, sodium carbonate and a corrosion inhibitor, which is composed of sodium hydroxide with a concentration of 50g / L-80g / L, sodium carbonate with a concentration of 20g / L-40g / L, a corrosion inhibitor with a concentration of 5g / L-10g / L and deionized water. The etching temperature is controlled at 40°C-60°C, and the etching time is controlled at 3min-8min, so as to ensure that the composite film layer in the non-film opening region is completely etched and removed, and the mask layer 60 and the composite film layer under the mask layer 60 are not damaged.

[0152] Reference Figure 4f As shown, after etching is completed, an acidic stripping solution (hydrochloric acid with a volume concentration of 5%-10%) is used for stripping, the stripping temperature is 25°C-35°C, and the time is 1min-3min, and no mask layer remains after stripping.

[0153] 5. Annealing

[0154] The annealed process with nitrogen protection atmosphere combined with segmented temperature rising and falling is used to perform annealing treatment on the above demolded structure. Wherein, the annealing atmosphere is a nitrogen protection atmosphere with nitrogen purity ≥99.99%, the annealing temperature is controlled at 300°C-450°C, the heating rate is 5°C / min-10°C / min, the holding time is 30min-60min, and the cooling rate is 3°C / min-5°C / min, and the performance index that the sheet resistance of the composite film layer is reduced by 10%-20% after annealing is controlled, so as to eliminate process stress, improve the binding force between the composite film layer and the substrate, and optimize the conductive performance of the composite film layer.

[0155] It should be noted that after annealing treatment, an alloy layer (not shown) is formed on the side of the passivation contact structure 12 in the opening, which side faces away from the silicon substrate 10, and the metal material in the alloy layer is the same as the metal material of the transition layer in the composite film layer. The alloy layer may comprise one of titanium-silicon alloy, zinc-silicon alloy, magnesium-silicon alloy, nickel-silicon alloy, aluminum-silicon alloy or copper-silicon alloy. The thickness of the alloy layer is 10nm-30nm, for example, it can be 10nm, 15nm, 20nm, 25nm, 30nm, etc., or it can be a range composed of any of the above values.

[0156] 6. Printing electrode

[0157] Refer to Figure 1 As shown, the main grid on the back side (second surface) of the battery (not shown), the first back electrode 51, the main grid on the front side (first surface) (not shown) and the second front electrode 52 are printed sequentially. Conventional silver paste is selected for the front main grid, the back main grid and the front second electrode, and the first back electrode is made of non-noble metal materials, such as copper, aluminum, nickel, cobalt, iron, zinc, tin or other inexpensive metals. The line width of the first back electrode is controlled to be 20μm-150μm, for example, it can be 20μm, 30μm, 50μm, 70μm, 100μm, 120μm, 150μm, etc., or can be a range composed of any of the above values; the thickness of the first back electrode is controlled to be 5μm-50μm, for example, it can be 5μm, 7μm, 10μm, 20μm, 40μm, 50μm, etc., or can be a range composed of any of the above values.

[0158] After printing, drying treatment is carried out, the drying temperature is 150°C-180°C, and the time is 15min-20min. A single temperature drying mode is adopted, and meanwhile the adhesion of the first electrode after drying is controlled to be ≥4N / cm 2 , and the performance indicators of no defects such as broken wires and burrs are met, so as to improve process stability.

[0159] In the present invention, inexpensive metals are used instead of silver paste to prepare the first back electrode, which reduces the use of silver paste and effectively reduces the production cost of the battery.

[0160] Example 1:

[0161] The battery preform includes an N-type silicon substrate; a P+ emitter layer formed on the first surface of the silicon substrate; and a front-side SiN electrode located on the surface of the P+ emitter layer. X Layer; passivation contact structure formed on the second surface of the silicon substrate, with AlO2 located on the surface of the passivation contact structure. X Layers and located in AlO X SiN on the back side of the layer surface X layer.

[0162] Backside SiN X Layer-by-layer laser ablation. A multi-parameter coordinated control mode is employed, combining a 1064nm laser wavelength, an 80ns pulse width, 0.8mJ laser energy, and a 400mm / s scanning speed to create a continuously extending line pattern. Figure 3 (d) The linewidth is 60μm, and the film opening size error is controlled within ±5μm, accurately removing SiN. X Layer to avoid damaging the underlying passivated contact structure.

[0163] PVD coating is applied after laser delamination. A composite film structure consisting of a transition layer and a conductive layer is adopted. The transition layer is made of zinc with a thickness of 15 nm; the conductive layer is made of aluminum with a thickness of 180 nm. The composite film is a zinc-aluminum combination, with an overall adhesion of 5.5 N / cm² and a sheet resistance of 4.2 mΩ / sq.

[0164] A mask layer was printed after PVD coating. An epoxy resin-based acid-removable ink was selected as the mask layer material, with a printing thickness of 25 μm and a printing accuracy error of 3 μm, covering only the laser-opened area. The drying process employed a step-by-step drying method: the first step was at 85℃ for 14 minutes; the second step was at 140℃ for 7 minutes. After drying, the mask layer had a hardness of 2H and was free of defects such as bubbles and cracks.

[0165] After printing the mask layer, wet etching was performed. The wet etching solution used a composite alkaline formula, consisting of 75 g / L sodium hydroxide, 35 g / L sodium carbonate, 9 g / L etching inhibitor, and deionized water. The etching temperature was controlled at 55℃, and the etching time was 6 min. After etching, a 10% (v / v) hydrochloric acid stripping solution was used to strip the mask at 32℃ for 2.5 min, leaving no mask residue after stripping.

[0166] Wet etching was followed by annealing. The annealing atmosphere was 99.99% pure nitrogen, the annealing temperature was controlled at 420℃, the heating rate was 9℃ / min, the holding time was 50min, and the cooling rate was 4.5℃ / min. After annealing, the sheet resistance of the composite film decreased by 18%, effectively improving the adhesion between the composite film and the substrate and the conductivity.

[0167] After annealing, the back main grid, back first electrode, front main grid, and front second electrode were printed sequentially. The back first electrode was printed using Al paste with a linewidth of 120 μm and a thickness of 40 μm. The front main grid, back main grid, and front second electrode were printed using conventional silver paste. After drying at 170°C for 16 min, the electrode adhesion was 4.2 N / cm². 2 It is free from defects such as broken lines and burrs.

[0168] Example 2:

[0169] The battery preform includes an N-type silicon substrate; a P+ emitter layer formed on the first surface of the silicon substrate; and a front-side SiN electrode located on the surface of the P+ emitter layer. X Layer; passivation contact structure formed on the second surface of the silicon substrate, with AlO2 located on the surface of the passivation contact structure. X Layers and located in AlO X SiN on the back side of the layer surface X layer.

[0170] Backside SiN X Layer-by-layer laser ablation. A multi-parameter coordinated control mode is employed, combining a 355nm laser wavelength, a 50ps pulse width, a 0.5mJ laser energy, and a 300mm / s scanning speed. The ablation pattern is a point-line composite pattern. Figure 3 (c) Wherein, the point diameter is 100μm, the center distance between adjacent points is 1mm; the line width is 100μm, the length is 800μm, the spacing between adjacent line segments is 1mm, the film opening size error is controlled within ±5μm, and SiN is accurately removed. X This layer avoids damaging the underlying passivated contact structure and also avoids incomplete etching.

[0171] PVD coating is applied after laser delamination. A composite film structure consisting of a transition layer and a conductive layer is adopted. The transition layer is made of aluminum with a thickness of 10 nm; the conductive layer is made of copper with a thickness of 150 nm. The composite film is an aluminum-copper combination, with an overall adhesion of 6 N / cm² and a sheet resistance of 4.0 mΩ / sq.

[0172] A mask layer was printed after PVD coating. An epoxy resin-based acid-removable ink was selected as the mask layer material, with a printing thickness of 25 μm and a printing accuracy error of 3 μm, covering only the laser-opened area. The drying process employed a step-by-step drying method: the first step was at 85℃ for 14 minutes; the second step was at 140℃ for 7 minutes. After drying, the mask layer had a hardness of 2H and was free of defects such as bubbles and cracks.

[0173] After printing the mask layer, wet etching was performed. The wet etching solution used a composite alkaline formula, consisting of 75 g / L sodium hydroxide, 35 g / L sodium carbonate, 9 g / L etching inhibitor, and deionized water. The etching temperature was controlled at 55℃, and the etching time was 6 min. After etching, a 10% (v / v) hydrochloric acid stripping solution was used to strip the mask at 32℃ for 2.5 min, leaving no mask residue after stripping.

[0174] Wet etching was followed by annealing. The annealing atmosphere was 99.99% pure nitrogen, the annealing temperature was controlled at 420℃, the heating rate was 9℃ / min, the holding time was 50min, and the cooling rate was 4.5℃ / min. After annealing, the sheet resistance of the composite film decreased by 18%, effectively improving the adhesion between the composite film and the substrate and the conductivity.

[0175] After annealing, the back main grid, back first electrode, front main grid, and front second electrode were printed sequentially. The back first electrode was printed using Al paste with a linewidth of 120 μm and a thickness of 40 μm. The front main grid, back main grid, and front second electrode were printed using conventional silver paste. After drying at 170°C for 16 min, the electrode adhesion was 4.2 N / cm². 2 It is free from defects such as broken lines and burrs.

[0176] Example 3:

[0177] The only difference between this embodiment and Embodiment 2 is that, in this embodiment, the film-opening pattern uses an array of dot patterns. Figure 3 (a) Wherein, the dot diameter is 150 μm, the center-to-center distance between adjacent dots is 1 mm, and the film opening size error is controlled within ±5 μm, precisely removing SiN. X This layer avoids damaging the underlying passivated contact structure and also avoids incomplete etching.

[0178] Example 4:

[0179] The only difference between this embodiment and Embodiment 2 is that, in this embodiment, the film-opening pattern adopts an array of line segment patterns. Figure 3 (b) The line segment has a linewidth of 150 μm and a length of 600 μm, with a spacing of 1 mm between adjacent segments. The film opening size error is controlled within ±5 μm, precisely removing SiN. X This layer avoids damaging the underlying passivated contact structure and also avoids incomplete etching.

[0180] Compared with existing technologies, the solar cell, fabrication method, and photovoltaic module of this invention organically integrate optimized patterned film opening, composite film layer, and inexpensive metal electrode fabrication. Patterned film opening provides a highly efficient and low-damage conductive window, composite film layer ensures interfacial adhesion and conductivity, and inexpensive metal electrode fabrication replaces expensive silver paste to achieve electrode conduction. These three elements work together to significantly reduce the amount of silver paste used on the back side, saving raw material costs. Furthermore, by optimizing the carrier collection path and interfacial contact performance, the photoelectric conversion efficiency of the cell is maintained or even improved. This reduces manufacturing costs while ensuring the power generation performance and long-term reliability of the cell, meeting the cost reduction and efficiency improvement requirements for large-scale photovoltaic applications.

[0181] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0182] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A solar cell, characterized in that, include: A silicon substrate having a first surface and a second surface disposed opposite to each other; A passivated contact structure is disposed on the second surface of the silicon substrate; A first dielectric layer is disposed on the surface of the passivated contact structure. The first dielectric layer includes a plurality of metal regions and non-metal regions spaced apart along a first direction. The metal regions and the non-metal regions extend along a second direction, which is perpendicular to the first direction. The metal regions are formed with at least one opening that penetrates the first dielectric layer along the thickness direction. A composite film layer is disposed at the opening and in contact with the passivation contact structure; The first electrode is located in the metal region and is in contact with the composite film layer.

2. The solar cell according to claim 1, characterized in that, The opening extends along the second direction, and / or the openings are spaced apart along the second direction.

3. The solar cell according to claim 2, characterized in that, The opening includes at least one of a circular opening, a square opening, a rectangular opening, and a long strip opening, wherein: The diameter of the circular opening is 20μm-200μm; The side length of the square opening is 20μm-200μm; The width of the rectangular opening is 20μm-100μm, and the length is 1mm-5mm; The width of the elongated opening is 20μm-100μm, and its length is less than or equal to the length of the first electrode in the second direction.

4. The solar cell according to claim 3, characterized in that, The linewidth of the first electrode is smaller than the maximum diameter of the circular opening, and / or the linewidth of the first electrode is smaller than the maximum side length of the square opening.

5. The solar cell according to claim 4, characterized in that, The material of the first electrode is selected from non-precious metal materials, including one or more of copper, aluminum, nickel, cobalt, iron, zinc, and tin; and / or, The first electrode has a linewidth of 20μm-150μm, a thickness of 5μm-50μm, and an adhesion force greater than or equal to 4N / cm. 2 .

6. The solar cell according to claim 1, characterized in that, The composite film layer includes a transition layer and a conductive layer stacked sequentially in the direction away from the passivation contact structure; The transition layer and the conductive layer are made of different materials, and / or the thickness of the conductive layer is greater than the thickness of the transition layer.

7. The solar cell according to claim 6, characterized in that, The transition layer is made of non-precious metals, including one or more of titanium, zinc, magnesium, nickel, aluminum, and copper; and / or, The thickness of the transition layer is 5nm-20nm; and / or, The conductive layer is made of non-precious metals, including one or more of titanium, zinc, magnesium, nickel, aluminum, and copper; and / or, The thickness of the conductive layer is 50nm-200nm; and / or, The adhesion of the composite film layer is greater than or equal to 5 N / cm. 2 Sheet resistance is less than or equal to 5 mΩ / sq.

8. The solar cell according to claim 1, characterized in that, An alloy layer is formed on the side of the passivated contact structure located at the opening that faces away from the silicon substrate; The thickness of the alloy layer is less than the thickness of the composite film layer, and / or the thickness of the alloy layer is 10nm-30nm, and / or the alloy layer includes one of titanium silicon alloy, zinc silicon alloy, magnesium silicon alloy, nickel silicon alloy, aluminum silicon alloy or copper silicon alloy.

9. The solar cell according to claim 1, characterized in that, Also includes: An emitter layer is disposed on the first surface; A second dielectric layer is disposed on the emitter layer; and, The second electrode is disposed on the second dielectric layer and is in contact with the emitter layer.

10. A method for preparing a solar cell, characterized in that, include: A silicon substrate is provided, the silicon substrate having a first surface and a second surface disposed opposite to each other; A passivated contact structure is prepared on the second surface of the silicon substrate; A first dielectric layer is prepared on the passivated contact structure. The first dielectric layer includes a plurality of metal regions and non-metal regions spaced apart along a first direction. The metal regions and the non-metal regions extend along a second direction, which is perpendicular to the first direction. The first dielectric layer is patterned to form at least one opening penetrating the first dielectric layer along the thickness direction in the metal region. Prepare a composite film layer located at the opening; A first electrode is fabricated in the metal region, and the first electrode is in contact with the composite film layer.

11. The method for preparing a solar cell according to claim 10, characterized in that, Using laser technology, the first dielectric layer is patterned by synergistically controlling the laser wavelength, pulse width, pulse energy, and scanning speed; wherein: The laser wavelength range is 355nm-1064nm; The pulse width range is 10 ps-100 ns; The pulse energy range is 0.1 mJ-1 mJ; The scanning speed range is 100mm / s-500mm / s.

12. The method for preparing a solar cell according to claim 10, characterized in that, Preparing a composite film layer located at the opening includes: A composite film layer is deposited, the composite film layer covering the first dielectric layer and the passivation contact structure of the opening; Prepare a mask layer, wherein the mask layer covers only the composite film layer of the opening; Remove the composite film layer on the first dielectric layer; Remove the mask layer from the opening; Annealing treatment.

13. The method for preparing a solar cell according to claim 12, characterized in that, Fabrication of the mask layer includes: A mask layer is printed on the composite film layer of the opening; The mask layer is dried in stages.

14. The method for preparing a solar cell according to claim 13, characterized in that, The mask layer is made of a non-acid-resistant material; and / or, The first drying step is at a temperature of 80℃-100℃ and a drying time of 10-15 minutes. The second drying step is at a temperature of 120℃-150℃ and a drying time of 5-8 minutes.

15. The method for preparing a solar cell according to claim 12, characterized in that, An acidic stripping solution is used to remove the mask layer from the opening; wherein, The acidic stripping solution includes a 5%-10% hydrochloric acid aqueous solution, the stripping temperature is 25℃-35℃, and the stripping time is 1min-3min.

16. The method for preparing a solar cell according to claim 12, characterized in that, The composite film layer on the first dielectric layer is removed using a wet etching method; wherein... The wet etching solution is an alkaline composite etching solution containing sodium hydroxide, sodium carbonate and an etching inhibitor. The concentration of sodium hydroxide is 50g / L-80g / L, the concentration of sodium carbonate is 20g / L-40g / L, the concentration of etching inhibitor is 5g / L-10g / L, the etching temperature is 40℃-60℃, and the etching time is 3min-8min.

17. The method for preparing a solar cell according to claim 12, characterized in that, In the annealing process, the annealing atmosphere is a nitrogen protective atmosphere with a nitrogen purity of ≥99.99%. The annealing temperature is 300℃-450℃, the heating rate is 5℃ / min-10℃ / min, the holding time is 30min-60min, and the cooling rate is 3℃ / min-5℃ / min. After annealing, the sheet resistance of the composite film layer is reduced by 10%-20%.

18. The method for preparing a solar cell according to claim 12, characterized in that, After annealing, an alloy layer is formed on the side of the passivated contact structure of the opening that is away from the silicon substrate.

19. The method for preparing a solar cell according to claim 10, characterized in that, The preparation of the first electrode includes: Print the first electrode; The first electrode is dried; wherein, The drying temperature is 150℃-180℃, and the drying time is 15min-20min. After drying, the adhesion of the first electrode is ≥4N / cm. 2 .

20. The method for preparing a solar cell according to claim 10, characterized in that, Also includes: An emitter layer is prepared on the first surface; A second dielectric layer is prepared on the emitter layer; A second electrode is prepared on the second dielectric layer to contact the emitter layer.

21. A photovoltaic module, characterized in that, The solar cell includes those prepared by any one of the solar cells as described in any one of claims 1-9 or by any one of the solar cell preparation methods as described in any one of claims 10-20.

Images