Electrode grid line preparation method and photovoltaic cell

Abstract

The invention discloses an electrode grid line preparation method and a photovoltaic cell, and relates to the technical field of photovoltaic cells. The preparation method of the electrode grid line comprises the following steps: S1, providing a polymer layer which is prepared by adopting a double-roller casting method and is used as a transfer printing substrate; s2, coating the forming side of the polymer layer with conductive slurry which at least can fill the grooves in the polymer layer, and removing redundant conductive slurry on the surface of the polymer layer; s3, a base material is provided, the side, provided with the conductive slurry, of the polymer layer is attached to the base material, and the conductive slurry is transferred to the base material in a transfer printing mode with preset technological parameters; s4, removing the polymer layer; s5, sintering the conductive slurry on the base material to form an electrode grid line; the detail precision and the resolution ratio of the electrode grid line are improved, finer pattern preparation is achieved, the electrode grid line with the width of 3-15 microns, the height of 6-25 microns and the height-width ratio of 100%-300% can be prepared, and the overall performance and the photoelectric conversion efficiency of a photovoltaic cell can be improved; the technological process is simplified and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic cells, and particularly to a method for preparing electrode grid lines and a photovoltaic cell. Background Art

[0002] With the increasing global demand for renewable energy, the photovoltaic industry is developing rapidly and is faced with the important tasks of improving energy efficiency and reducing costs. As a key component of a photovoltaic cell, the quality of the electrode grid lines directly affects the photoelectric conversion efficiency and overall performance of the cell.

[0003] The main function of the electrode grid lines is to collect and export the current generated by the photovoltaic cell. Common electrode grid line printing technologies mainly include: screen printing, inkjet printing, offset printing, flexible printing, etc. The most commonly used technology in the manufacturing process of photovoltaic cells is screen printing. This technology prints a conductive paste (such as silver paste) onto the surface of the photovoltaic cell through a screen to form an electrode pattern, thereby achieving the collection and conduction of electrical energy.

[0004] Currently, the screen printing technology has mature processes and widespread equipment; it is applicable to photovoltaic cells of different sizes and types; and this technology is relatively simple with low production costs, suitable for large-scale industrial production, and is currently the most widely used solar cell electrode printing technology.

[0005] However, screen printing is difficult to achieve very fine patterns and high-resolution printing. The prepared electrode line width is too wide, which not only reduces the light absorption effect but also increases the amount of silver paste used; at the same time, it has high requirements for the printing environment and requires good cleanliness; in addition, screen printing is a relatively slow production process and cannot meet the needs of large-scale production, affecting production efficiency. For the above problems that have emerged, no effective solutions have been proposed yet. Summary of the Invention

[0006] Object of the Invention: To provide a method for preparing electrode grid lines and a photovoltaic cell to at least solve one of the problems existing in the above prior art.

[0007] Technical Solution: A method for preparing electrode grid lines includes the following steps:

[0008] S1. Provide a polymer layer prepared by a twin-roll casting method and used as a transfer substrate.

[0009] S2. Coat a conductive paste on the forming side of the polymer layer that can at least fill the grooves thereon, and remove the excess conductive paste on the surface of the polymer layer so that the surfaces of the grooves and the conductive paste are in the same plane.

[0010] S3. Provide a substrate, bond the side of the polymer layer with the conductive paste to the substrate, assist with an ultraviolet lamp, and transfer the conductive paste to the substrate by a transfer method with preset process parameters. Among them, the transfer is carried out by roll pressing, and the process parameters of the transfer are: the pressure is 1-20 MPa, the temperature is 80-250 °C, and the time is 3-30 s. During the roll pressing process, the ultraviolet lamp is directed at the bonding area, and the time is consistent with the transfer time.

[0011] S4. Remove the polymer layer so that the conductive paste remains on the substrate.

[0012] S5. Sinter the conductive paste on the substrate to form electrode grid lines.

[0013] Preferably, S1. Provide a polymer layer prepared by a double-roll casting method and used as a transfer substrate, including:

[0014] Extrude molten polymer between two parallel rotating rollers, and there are protrusions preset on the surface of one of the rollers. The protrusions roll-press the required groove shape on one side surface of the polymer to form a polymer layer and use it as a transfer substrate.

[0015] Preferably, extrude molten polymer between two parallel rotating rollers, and there are protrusions preset on the surface of one of the rollers. The protrusions roll-press the required groove shape on one side surface of the polymer to form a polymer layer and use it as a transfer substrate, including:

[0016] By presetting the process parameters of the roller processing, when the molten polymer reaches the axis of the pattern roller, the pattern roller presses out grooves on the polymer. After passing through this area, temperature cooling is carried out in sequence, and the polymer layer is solidified.

[0017] Preferably, extrude molten polymer between two parallel rotating rollers, and there are protrusions preset on the surface of one of the rollers. The protrusions roll-press the required groove shape on one side surface of the polymer to form a polymer layer and use it as a transfer substrate, and further include:

[0018] First pass the extruded polymer through the first double-roll pressing to control the thickness of the polymer film, and then pass it through the second double-roll pressing to press out the required groove shape.

[0019] Preferably, the thickness of the polymer layer is 15-50 μm.

[0020] Preferably, S1. Provide a polymer layer, including:

[0021] Prepare a polymer layer with a thickness of 35-85 μm by using the double-roll casting method.

[0022] Preferably, S2, applying a conductive paste capable of filling the grooves on the forming side of the polymer layer and removing the excess conductive paste on the surface of the polymer layer so that the surfaces of the grooves and the conductive paste are on the same plane, includes:

[0023] Using an inclined plate extrusion coating method to evenly apply the conductive paste on the formed polymer layer, so that the conductive paste completely fills the grooves, and scraping off the excess conductive paste to ensure that the conductive paste is completely filled and evenly distributed without deformation.

[0024] Preferably, S3, providing a substrate and laminating the side of the polymer layer with the conductive paste to the substrate, includes:

[0025] At a preset temperature, while closely laminating the conductive paste to the surface of the substrate by applying pressure and irradiating with a directional ultraviolet lamp, curing the conductive paste; and within the preset temperature, pressure, and ultraviolet irradiation range, the macroscopic morphology of the conductive paste transferred onto the substrate does not change.

[0026] Wherein, the substrate is one of a crystalline silicon wafer, glass, perovskite, metal, or polymer substrate.

[0027] Preferably, S4, removing the polymer layer so that the conductive paste remains on the substrate, includes:

[0028] After lifting off the polymer layer, leaving the successfully transferred conductive paste pattern to form the basic structure of the photovoltaic electrode grid line.

[0029] Preferably, S5, sintering the conductive paste on the substrate to form electrode grid lines with a preset aspect ratio, includes:

[0030] Putting the silicon wafer with the transferred conductive paste into a heating furnace to cure or sinter the conductive paste; for high-temperature paste, the sintering temperature is 500 - 800 °C to ensure that the conductive paste is completely sintered and forms a tight connection with the silicon wafer to generate electrode grid lines with a preset aspect ratio, and the low-temperature paste is cured at 200 - 300 °C.

[0031] Preferably, the conductive paste is one of silver paste, aluminum paste, copper paste, silver-coated copper paste, chromium paste, tin paste, indium paste, nickel paste, titanium paste, tantalum paste, or silver-coated nickel.

[0032] Preferably, the polymer layer is one of polyimide, polylactic acid, polyethylene terephthalate, polyamide, polycarbonate, polyvinyl chloride, polytetrafluoroethylene, or polyvinylidene fluoride.

[0033] Preferably, the shape of the groove is one of an isosceles triangle, isosceles trapezoid, ellipse, hexagon, right trapezoid, or rectangle.

[0034] Preferably, the width of the electrode grid line is 3 - 15 μm, the height is 6 - 25 μm, and the aspect ratio is 100% - 300%.

[0035] To achieve the above object, according to another aspect of the present application, a photovoltaic cell is also provided.

[0036] The photovoltaic cell according to the present application includes the prepared electrode grid lines.

[0037] Beneficial effects: In the embodiment of the present application, the method of transferring and preparing the electrode grid lines is adopted. Through S1, providing a polymer layer prepared by a double-roll casting method and used as a transfer substrate; S2, coating a conductive paste on the forming side of the polymer layer that can at least fill the grooves thereon, and removing the excess conductive paste on the surface of the polymer layer so that the surfaces of the grooves and the conductive paste are on the same plane; S3, providing a substrate, attaching the side of the polymer layer with the conductive paste to the substrate, assisted by an ultraviolet lamp, and through a transfer method with preset process parameters, transferring the conductive paste to the substrate; wherein, the transfer is carried out by roll pressing, and the process parameters of the transfer are: the pressure is 1 - 20 MPa, the temperature is 80 - 250 °C, and the time is 3 - 30 s; during the roll pressing process, the ultraviolet lamp is directed to irradiate at the pressing joint, and the time is consistent with the transfer time; S4, removing the polymer layer so that the conductive paste remains on the substrate; S5, sintering the conductive paste on the substrate to form the electrode grid lines, achieving the purpose of preparing the electrode grid lines, thereby realizing the technical effects of saving process time, simplifying the process flow, the substrate film having good flexibility and being easy to detach, and further solving the problems that screen printing is difficult to achieve very fine patterns and high-resolution printing, the prepared electrode line width is too wide, which not only reduces the light absorption effect but also increases the silver paste consumption; at the same time, it has high requirements for the printing environment and requires good cleanliness; in addition, screen printing is a relatively slow production process and cannot meet the needs of large-scale production, affecting production efficiency. Description of the Drawings

[0038] Figure 1 is a schematic structural flow chart of the method for preparing the electrode grid lines of the present invention;

[0039] Figure 2 is a three-dimensional structural schematic diagram of the roller of the method for preparing the electrode grid lines of the present invention;

[0040] Figure 3 is a front view of the roller of the method for preparing the electrode grid lines of the present invention; and

[0041] Figure 4 is a schematic flow chart of the method for preparing the electrode grid lines of the present invention.

[0042] The reference numerals are as follows:

[0043] 1, roller

[0044] 2. Polymer layer;

[0045] 3. Groove;

[0046] 4. Conductive paste;

[0047] 5. Substrate;

[0048] 6. Electrode grid line. Detailed implementation manners

[0049] In order to enable those skilled in the art to better understand the solutions of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0050] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so as to implement the embodiments of this application described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units does not necessarily need to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0051] In addition, the terms "installed", "set up", "provided with", "connected", "connected to", "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there can be internal communication between two devices, components or parts. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will detail this application with reference to the drawings and in combination with the embodiments.

[0053] As Figures 1-4 shown, this application relates to a method for preparing an electrode grid line and a photovoltaic cell. As Figure 1 and 4 shown, the method for preparing an electrode grid line includes the following steps:

[0054] S1. Provide a polymer layer 2 prepared by a twin-roll casting method and used as a transfer substrate;

[0055] It can ensure good transfer effect, thus providing guarantee for the normal realization of subsequent processes.

[0056] As Figures 2-3 shown, according to an embodiment of the present invention, preferably, S1. Provide a polymer layer prepared by a twin-roll casting method and used as a transfer substrate, including:

[0057] Extrude molten polymer between two parallel rotating rollers, and there are protrusions preset on the surface of one of the rollers. The protrusions roll and form a required groove shape on one side surface of the polymer to form a polymer layer as a transfer substrate;

[0058] It can achieve good roll-forming effect, thus obtaining a polymer layer with the required shape.

[0059] Certainly, the polymer can be synthetic resin.

[0060] Specifically, in the twin-roll casting method, the molten polymer (such as PET) is uniformly heated and mixed in a die or a batching tank, and then extruded and formed through two parallel cooling rollers. The polymer forms a film between the rollers, and after cooling and shaping, it detaches from the rollers to form a film with uniform thickness. The thickness of the film can be regulated in various ways, mainly including the following key factors: roller spacing, roller speed, material flow rate, temperature, and roller surface state. The production line can stably prepare 20 - 100 μm PET film through the above adjustments.

[0061] The Tg of PET is usually between 80°C and 85°C, and this temperature range is an important index determining the performance and application of PET in high-temperature environments; when it is lower than this temperature, PET shows brittleness and rigidity; while when it is higher than this temperature, the material becomes more ductile and malleable.

[0062] The melt processing temperature of PET is usually between 250°C and 270°C. At this stage, PET needs to be heated to the molten state for extrusion, injection molding, etc.; too high temperature may cause decomposition or degradation at this stage, so it needs to be carefully controlled.

[0063] To improve the internal stress of PET products, annealing treatment is usually carried out after molding. The annealing temperature is generally set between 85°C and 120°C, and the treatment time depends on specific conditions to improve the stability and toughness of the material.

[0064] First, PET resin (polyethylene terephthalate) needs to be pretreated in a dryer to remove residual moisture, reduce the risk of hydrolysis, and improve the stability of melt extrusion.

[0065] It should be noted that the following process parameters can be adopted, including but not limited to:

[0066] The dried PET particles enter a twin-screw extruder, and the temperatures of each zone of the extruder are set as follows:

[0067] Temperature of the feeding zone: 150 - 180 °C, ensuring that the PET particles are evenly heated and stably conveyed;

[0068] Temperature of the compression zone: 200 - 240 °C, gradually plasticizing the PET particles and improving fluidity;

[0069] Temperature of the metering zone: 230 - 270 °C, ensuring that the molten PET has good uniformity and viscosity control.

[0070] The molten PET resin enters a twin-roll casting system through an extrusion die, and the parameters during the casting process are as follows:

[0071] Roll temperature: 30 - 80 °C, adjusting the cooling rate by controlling the roll temperature to reduce internal stress;

[0072] Roll spacing: 0.1 - 0.5 mm, ensuring that the molten PET is evenly spread and formed;

[0073] Cooling water temperature: 15 - 25 °C, assisting in cooling and solidifying to improve the dimensional stability of the film material.

[0074] During the casting process, a micro-nano structure etching roll is used for forming. One side of the roll surface has a convex structure with a size of 5 - 50 μm, which is used to form the required groove morphology on the PET film.

[0075] (Optional) The cast PET film is subjected to unidirectional stretching, and the stretching ratio is controlled within 1.5 - 3.0 to further improve the mechanical strength and surface flatness of the film material.

[0076] Subsequently, the photovoltaic conductive paste is evenly coated on the groove surface of the PET film by the inclined plate extrusion coating method. The main components of the conductive paste are silver powder, organic carrier, and glass powder. After the paste is filled, a scraper or a precision roller is used to ensure uniform filling in the grooves, avoiding air bubbles or voids.

[0077] Next, the groove surface of the PET film is covered on the surface of the photovoltaic silicon wafer (monocrystalline silicon or polycrystalline silicon), and a preset uniform pressure is applied to ensure that the conductive paste is closely attached to the silicon wafer, improving the subsequent transfer accuracy.

[0078] Since the photovoltaic conductive paste contains a photocurable polymer, it undergoes a curing reaction after being irradiated with ultraviolet light, improving the initial mechanical strength. Subsequently, the PET film is lifted to achieve the successful transfer of the conductive paste.

[0079] Finally, the transferred silver paste needs to be sintered at high temperature, the organic components volatilize, the glass powder acts as a flux, and the silver particles are sintered to form highly conductive electrode grid lines.

[0080] Throughout the process, the PET film remains smooth and undamaged, and can be recycled 10 - 30 times after cleaning and drying, improving the material utilization rate and reducing the production cost.

[0081] It should be noted that before preparing the polymer layer, the PET resin is first dried by a dryer to remove residual moisture, then melt-extruded by a twin-screw extruder, and then the extruded plasticized PET is made into a film by a double-roll casting method. In this application, the smooth PET film can be recycled.

[0082] According to an embodiment of the present invention, preferably, by extruding a molten polymer between two parallel rotating rollers, and a protrusion is preset on the surface of one of the rollers, the protrusion rolls on one side surface of the polymer to form a polymer layer with a required groove shape, and serves as a transfer substrate, including:

[0083] By presetting the process parameters of the rollers, when the molten polymer reaches the axis of the pattern roller, the pattern roller presses out grooves on the polymer, and after passing through this area, temperature cooling is carried out in sequence, and the polymer layer is solidified.

[0084] Specifically, by controlling the roller temperature, when the molten PET resin reaches the axis of the pattern roller, the temperature is 150 - 180 °C at this time, and the pattern roller can easily press out grooves on the PET. After passing through this area, the temperature is cooled, and the PET film is solidified.

[0085] According to an embodiment of the present invention, preferably, by extruding a molten polymer between two parallel rotating rollers, and a protrusion is preset on the surface of one of the rollers, the protrusion rolls on one side surface of the polymer to form a polymer layer with a required groove shape, and serves as a transfer substrate, further including:

[0086] The extruded polymer is first passed through the first double-roll rolling to control the thickness of the polymer film, and then passed through the second double-roll rolling to press out the required groove shape.

[0087] It can achieve the effect of facilitating the regulation of the thickness of the PET film, so as to flexibly meet the requirements of various use environments.

[0088] According to an embodiment of the present invention, preferably, the thickness of the polymer layer 2 is 15 - 50 μm. Preferably, the thickness of the polymer layer is 15 - 30 μm.

[0089] S2. Coating a conductive paste 4 on the forming side of the polymer layer 2 that can at least fill the grooves 3 thereon, and removing the excess conductive paste 4 on the surface of the polymer layer 2, so that the surfaces of the grooves 3 and the conductive paste 4 are on the same plane;

[0090] It can achieve a good coating effect of the conductive paste 4 and make it evenly distributed on the polymer layer.

[0091] According to an embodiment of the present invention, preferably, in S2, a conductive paste 4 that can at least fill the grooves 3 thereon is coated on the forming side of the polymer layer 2, and the excess conductive paste 4 on the surface of the polymer layer 2 is removed so that the surfaces of the grooves 3 and the conductive paste 4 are on the same plane, including:

[0092] Using the inclined plate extrusion coating method to evenly apply the conductive paste on the polymer layer that has been precision embossed, it can ensure that the conductive paste is tightly filled in the grooves of the polymer layer. At the same time, the excess conductive paste on the surface is scraped off, thereby ensuring that the conductive paste is completely filled and evenly distributed without deformation.

[0093] It should be known that one of the main components of the photovoltaic conductive paste is a binder (phenolic resin, epoxy resin, etc.), and its function is to form a stable bond between the particles of the conductive paste and between the particles and the silicon wafer.

[0094] S3. Provide a substrate 5, bond the side of the polymer layer 2 with the conductive paste 4 to the substrate 5, assist with an ultraviolet lamp, and through a transfer method with preset process parameters, transfer the conductive paste to the substrate; wherein, the transfer is carried out by roll pressing, and the process parameters of the transfer are: the pressure is 1 - 20 MPa, the temperature is 80 - 25 °C, and the time is 3 - 30 s; during the roll pressing process, the ultraviolet lamp is directed to irradiate at the bonding place, and the time is consistent with the transfer time;

[0095] According to an embodiment of the present invention, more preferably, in S3, bonding the side of the polymer layer 2 with the conductive paste 4 to the substrate 5 includes:

[0096] At a preset temperature, while tightly bonding the conductive paste to the surface of the substrate by applying pressure and directed ultraviolet lamp irradiation, cure the conductive paste; and within the range of the temperature, pressure, and ultraviolet irradiation, the macroscopic morphology of the conductive paste 4 transferred to the substrate 5 does not change; wherein, the substrate 5 is one of a crystalline silicon wafer, glass, metal, or polymer substrate.

[0097] By applying a uniform pressure to the side of the polymer layer without the conductive paste coated and heating and drying it, due to the adhesiveness of the conductive paste to the silicon wafer, the conductive paste can be transferred onto the silicon wafer, and the conductive paste can be tightly bonded to the silicon wafer, thereby ensuring a good transfer effect and further ensuring the stability of the structure of the conductive paste.

[0098] S4. Remove the polymer layer 2 so that the transferred conductive paste remains on the substrate 5;

[0099] According to an embodiment of the present invention, preferably, in S4, removing the polymer layer 2 so that the conductive paste 4 remains on the substrate 5 includes:

[0100] After removing the polymer layer, the successfully transferred conductive paste pattern is left behind, forming the basic structure of the photovoltaic electrode grid line.

[0101] It can achieve the effect of facilitating the removal and separation of the polymer layer, so as to completely retain the conductive paste pattern on the silicon wafer.

[0102] S5. Sinter the conductive paste 4 on the substrate 5 to form the electrode grid line 6.

[0103] According to an embodiment of the present invention, preferably, S5. Sinter the conductive paste 4 on the substrate 5 to form an electrode grid line 6 with a preset aspect ratio, including:

[0104] Put the silicon wafer after transferring the conductive paste 4 into a heating furnace, and perform curing or sintering treatment on the conductive paste 4; for high-temperature paste, the sintering temperature is 500 - 800 °C to ensure that the conductive paste is completely sintered and forms a tight connection with the silicon wafer, generating an electrode grid line 6 with a preset aspect ratio, and the low-temperature paste is cured at 200 - 300 °C.

[0105] After the conductive paste is sintered at high temperature, it can form a conductive paste electrode grid line 6 with the required depth and width. Preferably, the size of the conductive paste electrode grid line is 10 μm deep and 5 μm wide.

[0106] According to an embodiment of the present invention, preferably, the conductive paste 4 is one of silver paste, aluminum paste, copper paste, silver-coated copper paste, chromium paste, tin paste, indium paste, nickel paste, titanium paste, tantalum paste or silver-coated nickel. It can be understood that the above materials all have good electrical conductivity, can achieve the effect of multiple materials available for selection, so as to achieve the effect of flexible use, and further achieve the effect of improving market competitiveness. In this application, more preferably, the conductive paste 4 is silver paste.

[0107] Preferably, in this application, a photo-curable conductive paste is used. Different from traditional silver paste, its components are special photosensitive resin and photoinitiator. The photosensitive resin has the property of curing at a specific wavelength; common types include acrylic resins and epoxy resins. The photo-curable resin provides a matrix to support silver particles and forms a firm polymer network after curing. The photoinitiator will release free radicals or ions under light irradiation, thereby initiating the polymerization reaction of the resin. The selection and dosage of the photoinitiator directly affect the curing speed and efficiency. The photosensitive resin can be composed of one or more of acrylic resin, epoxy resin, phenolic resin, polyurethane resin mixed in a certain proportion. The photoinitiator includes styrene photoinitiator, benzophenone type, allyl photoinitiator.

[0108] It should be noted that in thin film applications, silica usually exists in an amorphous form, especially when deposited under low temperature conditions. This amorphous structure has no long-range order but has short-range ordered SiO tetrahedrons. It exhibits a relatively low refractive index in optical devices. Due to the lack of grain boundaries, amorphous silica layers usually have good insulation properties and high dielectric strength. High-quality silica layers have extremely low surface roughness. The characteristics of this coating provide the prerequisite for the cured conductive paste to be peeled off from the PET film.

[0109] In this application, through the precisely engraved roller bump shape, the size and shape of the PET transfer electrode grid lines are controlled, and the ohmic loss of the electrode grid lines is reduced. The triangular prism-shaped silver paste grid lines have better conductive efficiency than the cuboid-shaped silver paste grid lines, and more light incident on the triangular side can be refracted into the solar panel and be fully utilized. The light-curable conductive paste and the recyclable PET film greatly reduce the production cost. This method has a simple process, and the materials and equipment involved are economical, environmentally friendly, and have low process costs.

[0110] From the above description, it can be seen that this application has achieved the following technical effects:

[0111] In the embodiment of this application, the method of transferring to prepare electrode grid lines is adopted. Through S1, providing a polymer layer prepared by a double-roller casting method and used as a transfer substrate; S2, coating a conductive paste on the forming side of the polymer layer that can at least fill the grooves thereon, and removing the excess conductive paste on the surface of the polymer layer so that the surfaces of the grooves and the conductive paste are on the same plane; S3, providing a substrate, attaching the side of the polymer layer with the conductive paste to the substrate, assisted by an ultraviolet lamp, and through a transfer method with preset process parameters, transferring the conductive paste to the substrate; wherein, the transfer is carried out by roll pressing, and the process parameters of the transfer are: the pressure is 1 - 20 MPa, the temperature is 80 - 25 °C, and the time is 3 - 30 s; during the roll pressing process, the ultraviolet lamp is directed at the bonding area, and the time is consistent with the transfer time; S4, removing the polymer layer so that the conductive paste remains on the substrate; S5, sintering the conductive paste on the substrate to form electrode grid lines, achieving the purpose of preparing electrode grid lines, thus realizing the technical effects of saving process time, simplifying the process flow, the substrate film having good flexibility and being easy to detach, and further solving the problems that screen printing is difficult to achieve very fine patterns and high-resolution printing, the prepared electrode line width is too wide, which not only reduces the light absorption effect but also increases the silver paste consumption; at the same time, it has high requirements for the printing environment and needs good cleanliness; in addition, screen printing is a relatively slow production process and cannot meet the requirements of large-scale production, affecting production efficiency.

[0112] According to an embodiment of the present invention, preferably, the polymer layer is one of polyimide, polylactic acid, polyethylene terephthalate, polyamide, polycarbonate, polyvinyl chloride, polytetrafluoroethylene or polyvinylidene fluoride. It can be understood that the base layer provides mechanical support for the entire structure and enables it to withstand the stress and deformation during the processing. The base layer can endow the material with specific stiffness, strength and durability; at the same time, with a variety of base materials available for selection, the effects of flexible selection and easy use can be achieved, thereby improving the practicality.

[0113] According to an embodiment of the present invention, preferably, the shape of the groove is one of an isosceles triangle, an isosceles trapezoid, an ellipse, a hexagon, a right trapezoid or a rectangle.

[0114] By designing the convex part of the mold and the shape of the groove to be a complementary structure, it is possible to ensure precise docking and imprinting effects during the mold forming process, thereby achieving a high-precision transfer effect and improving the quality of the electrode grid lines of the final product.

[0115] Specifically, the shape of the mold can be selected from the following geometric structures:

[0116] Isosceles triangle: Suitable for scenarios where concentrated force transmission is required, and can form a sharp and clear transfer effect at the edge of the electrode grid line.

[0117] Isosceles trapezoid: It has a larger bottom width and a narrower top structure, suitable for applications that require electrode grid lines with a gradually changing width, and ensures uniform filling during the transfer process.

[0118] Ellipse: It can provide a smooth edge transition effect, suitable for electrode designs that require more uniform current distribution, reducing resistance and local stress concentration.

[0119] Hexagon: It has a stable structure and good density distribution effect, suitable for electrode grid line designs that require improved transfer accuracy and stability.

[0120] Right trapezoid: Suitable for photovoltaic electrode designs that require uniform grid line width and neat edges, ensuring the accuracy of current distribution.

[0121] Rectangle: A classic and common design, suitable for the transfer of standardized electrode grid lines, providing the largest contact area to improve the current conduction efficiency.

[0122] It should be noted that the shape and size of the protrusion correspond to the electrode grid line, and in actual operation, the size and shape of the electrode grid line to be transferred are controlled to reduce the ohmic loss of the electrode grid line; the longitudinal cross-sectional shape of the protrusion includes but is not limited to: one of a triangle, a trapezoid, a rectangle, a rhombus, a semicircle, and a polygon; in this embodiment, preferably, the longitudinal cross-sectional shape of the protrusion is a triangle or a trapezoid. The longitudinal cross-sectional design of a triangle or a trapezoid helps to change the incident and refraction path of light, can better capture and guide light, can effectively reduce the reflection loss of light, so that more light is absorbed by the semiconductor material and converted into electrical energy, thereby improving the photoelectric conversion efficiency.

[0123] According to an embodiment of the present invention, preferably, the electrode grid lines have a width of 3-15 μm, a height of 6-25 μm, and an aspect ratio of 100%-300%.

[0124] By setting the electrode grid lines within the above range, the following beneficial effects are achieved:

[0125] Reduce the shading area and improve the photoelectric conversion efficiency: Since the grid line width is reduced to 3-15μm, compared with traditional processes (such as screen printing, usually with a width of ≥30μm), the illuminated area it occupies is greatly reduced, thereby increasing the light absorption rate of the solar cell and improving the photoelectric conversion efficiency.

[0126] Reduce line resistance and improve conductivity: The 6-25μm height design increases the gate line cross-sectional area, reducing the width while ensuring sufficient conductivity, thereby reducing the resistance per unit length, reducing power loss, and improving current carrying capacity.

[0127] Improve aspect ratio and enhance mechanical stability: An aspect ratio of 100%-300% gives the grid lines a more three-dimensional structure. Compared with low aspect ratio designs, it can better reduce the resistance in the current transmission path, while improving the mechanical strength of the electrode to avoid breakage or deformation caused by stress or environmental factors.

[0128] Optimize the electron collection path and reduce the series resistance: As the height increases, the electron transmission path is shortened, which helps to reduce the carrier recombination loss, improve the electron collection efficiency, reduce the series resistance (Rs), and thus improve the fill factor (FF) of the device.

[0129] Compatible with high-precision manufacturing processes and improving mass production feasibility: Grid lines in this size range are suitable for high-precision manufacturing technologies such as electrospinning, electrochemical deposition, and laser direct writing. Compared with traditional screen printing methods, they can achieve more uniform and finer patterned structures, improving production consistency.

[0130] Applicable to new photovoltaic cell technologies: This design can be applied to advanced solar cells such as HJT (heterojunction), TOPCon, BC, perovskite / silicon tandem, etc., to improve their overall conversion efficiency and meet the needs of the high-end photovoltaic market.

[0131] Overall, electrode grid lines with a width of 3-15 μm and an aspect ratio of 100%-300% not only reduce shading losses, but also improve conductivity, mechanical stability, and electron collection efficiency, making them an important design trend for high-performance photovoltaic devices.

[0132] This application also relates to a photovoltaic cell including the electrode grid lines prepared as above. The photovoltaic electrode grid lines prepared in this embodiment can be applied to photovoltaic cells. The basic principle and the technical effects produced are the same as those of the above embodiments. For the parts not mentioned in this embodiment, please refer to the corresponding content above.

[0133] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A method for preparing an electrode grid line, characterized in that, It includes the following steps: S1. Provide a polymer layer prepared by a double-roll casting method and used as a transfer substrate; S2. Coat a conductive paste on the forming side of the polymer layer, which can at least fill the grooves thereon, and remove the excess conductive paste on the surface of the polymer layer so that the surfaces of the grooves and the conductive paste are on the same plane; S3. Provide a substrate, bond the side of the polymer layer with the conductive paste to the substrate, assist with an ultraviolet lamp, and transfer the conductive paste to the substrate by a transfer method with preset process parameters; wherein, the transfer is carried out by roll pressing, and the process parameters of the transfer are: the pressure is 1-20 MPa, the temperature is 80-250 °C, and the time is 3-30 s; during the roll pressing process, the ultraviolet lamp is directed to irradiate at the bonding place, and the time is consistent with the transfer time; S4. Remove the polymer layer so that the conductive paste remains on the substrate; S5. Sinter the conductive paste on the substrate to form electrode grid lines.

2. The method for preparing an electrode grid line according to claim 1, wherein S1. Provide a polymer layer prepared by a double-roll casting method and used as a transfer substrate, including: Extrude molten polymer between two parallel rotating rollers, and there are protrusions preset on the surface of one of the rollers. The protrusions roll-press the required groove shape on one side surface of the polymer to form a polymer layer, which is used as a transfer substrate.

3. The method for preparing an electrode gate line according to claim 1, wherein Extrude molten polymer between two parallel rotating rollers, and there are protrusions preset on the surface of one of the rollers. The protrusions roll-press the required groove shape on one side surface of the polymer to form a polymer layer, which is used as a transfer substrate, including: By presetting the process parameters of the roller processing, when the molten polymer reaches the axis of the pattern roller, the pattern roller presses out grooves on the polymer. After passing through this area, temperature cooling is carried out in sequence, and the polymer layer is solidified.

4. The method for preparing an electrode grid line according to claim 1, wherein, Extrude molten polymer between two parallel rotating rollers, and there are protrusions preset on the surface of one of the rollers. The protrusions roll-press the required groove shape on one side surface of the polymer to form a polymer layer, which is used as a transfer substrate, and further includes: The extruded polymer is first roll-pressed by the first double-roll to control the thickness of the polymer film, and then roll-pressed by the second double-roll to press out the required groove shape.

5. The method for preparing an electrode grid line according to claim 1, wherein The thickness of the polymer layer is 15-50 μm.

6. The method for preparing the electrode grid line according to claim 1, wherein S1. Provide a polymer layer, including: Prepare a polymer layer with a thickness of 35-85 μm by using the double-roll casting method.

7. The method for preparing the electrode grid line according to claim 1, wherein S2. Coat a conductive paste on the forming side of the polymer layer, which can fill the grooves thereon, and remove the excess conductive paste on the surface of the polymer layer so that the surfaces of the grooves and the conductive paste are on the same plane, including: Use the inclined plate extrusion coating method to evenly apply the conductive paste on the formed polymer layer, so that the conductive paste completely fills the grooves, and scrape off the excess conductive paste to ensure that the conductive paste is filled completely and evenly distributed without deformation.

8. The method for preparing an electrode grid line according to claim 1, wherein S3. Provide a substrate, bond the side of the polymer layer with the conductive paste to the substrate, including: At a preset temperature, while closely bonding the conductive paste to the surface of the substrate by applying pressure and directional ultraviolet lamp irradiation, cure the conductive paste; and within the preset temperature, pressure, and ultraviolet irradiation range, the macroscopic morphology of the conductive paste transferred to the substrate does not change; Among them, the substrate is one of a crystalline silicon wafer, glass, perovskite, metal, or polymer substrate.

9. The method for preparing an electrode grid line according to claim 1, wherein S4. Remove the polymer layer so that the conductive paste remains on the substrate, including: After lifting off the polymer layer, the successfully transferred conductive paste pattern is left behind to form the basic structure of the photovoltaic electrode grid line.

10. The method for preparing an electrode grid line according to claim 1, wherein S5. Sinter the conductive paste on the substrate to form electrode grid lines with a preset aspect ratio, including: Put the silicon wafer with the transferred conductive paste into a heating furnace for curing or sintering treatment of the conductive paste; for high-temperature paste, the sintering temperature is 500 - 800 °C to ensure complete sintering of the conductive paste and a tight connection with the silicon wafer to generate electrode grid lines with a preset aspect ratio, and the low-temperature paste is cured at 200 - 300 °C.

11. The method for preparing an electrode gate line according to claim 1, wherein The conductive paste is one of silver paste, aluminum paste, copper paste, silver-coated copper paste, chromium paste, tin paste, indium paste, nickel paste, titanium paste, tantalum paste or silver-coated nickel.

12. The method for preparing an electrode grid line according to claim 1, wherein The polymer layer is one of polyimide, polylactic acid, polyethylene terephthalate, polyamide, polycarbonate, polyvinyl chloride, polytetrafluoroethylene or polyvinylidene fluoride.

13. The method for preparing an electrode grid line according to claim 1, wherein The shape of the groove is one of isosceles triangle, isosceles trapezoid, ellipse, hexagon, right trapezoid or rectangle.

14. The method for preparing the electrode grid line according to claim 1, wherein The width of the electrode grid line is 3 - 15 μm, the height is 6 - 25 μm, and the aspect ratio is 100% - 300%.

15. A photovoltaic cell, characterized in that, Including the electrode grid lines prepared by the preparation method according to any one of claims 1 to 14.

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