Solar cell grid line preparation method and solar cell

Abstract

The invention relates to a high-precision and high-resolution solar cell grid line preparation method. According to the method, a direct photoetching technology is adopted, accurate exposure is carried out on a photosensitive adhesive layer through a high-precision designed shading mask, and a patterned opening which is completely consistent with the layout of a grid line on the surface of a solar cell is formed. And then, accurately filling conductive slurry into the opening by using a coating or ink-jet printing technology, removing redundant slurry through mechanical scraping or chemical cleaning, and forming a stable grid line structure with excellent conductivity after high-efficiency grid line forming technical treatment such as drying and laser irradiation or high-temperature heat treatment. According to the scheme, the detail precision and the resolution ratio of the electrode grid line are improved, finer pattern preparation is achieved, the accuracy of the size of the grid line is ensured by accurately controlling the thickness of the photosensitive adhesive layer and the width of the patterning opening, and the overall performance and the photoelectric conversion efficiency of the solar cell can be improved. According to the preparation method, the technological process is simplified, and the production efficiency is improved.

Description

Technical Field

[0001] The present application relates to the field of solar energy technology, and in particular to a method for preparing a solar cell grid line and a solar cell. Background Art

[0002] With the implementation of "dual carbon", the construction of a new power system is advancing rapidly. Among them, the photovoltaic industry, as the core force in the field of new energy, has ushered in an unprecedented period of development opportunities. The technological progress of solar cells is directly related to the performance and efficiency of the entire system. At present, the industrialized production model dominated by single-crystal silicon solar cells has been firmly established and has occupied a dominant position in the market, with its output accounting for more than 90%. In the performance optimization path of solar cells, the electrode grid wire is a key component, and its design and preparation process are crucial to improving the photoelectric conversion efficiency. Silver paste has become the first choice for current electrode grid wire materials due to its excellent conductivity and chemical stability, and is widely used in the manufacture of photovoltaic cells.

[0003] The widespread use of silver paste has effectively promoted the improvement of photovoltaic cell performance, but the limitations of traditional screen printing technology in the preparation of electrode grid lines have become increasingly prominent. Although the technology is mature and the equipment is popular, its limited accuracy, high waste generation, high cost, and production efficiency that cannot meet the needs of large-scale production have become bottlenecks restricting the further development of the photovoltaic industry. To solve these problems, it is particularly important to explore more efficient and accurate electrode grid line preparation technology. Summary of the invention

[0004] The purpose of the present application is to provide a method for preparing a solar cell grid line, which can accurately control the width and shape of the electrode grid line and reduce the loss of the electrode grid line. The method specifically includes: forming a photosensitive resin layer on a substrate; Forming a patterned opening on the photosensitive resin layer, wherein the patterned opening corresponds to a gate line position; Filling the patterned openings of the photosensitive adhesive layer with a conductive paste, and removing excess conductive paste on the photosensitive adhesive layer; The conductive paste is converted into solar cell grid lines.

[0005] In one of the embodiments, the photosensitive resin layer is exposed to ultraviolet light through a light-shielding mask to form the patterned opening.

[0006] In one embodiment, the patterned opening is formed by laser scanning.

[0007] In one of the embodiments, after the patterned openings are filled or the conductive paste is dried, a step of removing the photosensitive adhesive layer using an etching solution is also included.

[0008] In one embodiment, the method further includes heating the conductive paste to 120-180° C. and drying the conductive paste.

[0009] In one embodiment, the width of the gate line is less than 10 μm.

[0010] In one of the embodiments, the thickness of the photosensitive resin layer is in the range of 5-20 μm, the width of the patterned opening is in the range of 1-20 μm, the width of the patterned opening is less than or equal to 10 μm, preferably, the width of the patterned opening is less than or equal to 8 μm, preferably, the width of the patterned opening is less than or equal to 6 μm, preferably, the width of the patterned opening is less than or equal to 5 μm, preferably, the width of the patterned opening is less than or equal to 4 μm, preferably, the width of the patterned opening is less than or equal to 3 μm, preferably, the width of the patterned opening is less than or equal to 2 μm.

[0011] In one embodiment, two different types of conductive pastes are formed in the patterned openings, and the conductive paste directly in contact with the substrate includes a dopant component.

[0012] In one embodiment, the conductive paste is converted into solar cell grid lines by sintering the conductive paste using a laser irradiation method.

[0013] In addition, the present application also provides a solar cell, which uses the aforementioned solar cell grid line preparation method to manufacture surface grid lines.

[0014] Compared with the prior art, the present application has the following beneficial effects: the solar cell grid line preparation method proposed in the present application, by adopting photolithography technology to replace traditional screen printing, successfully realizes the high-precision preparation of electrode grid lines with a width of 5μm to 10μm, and the depth and width of the patterned openings accurately correspond to the thickness and width requirements of the surface grid lines, greatly improving the detail accuracy and resolution of the electrode grid lines. By accurately controlling the patterned openings on the photosensitive adhesive layer, it is ensured that the conductive paste is only filled in the necessary area, effectively avoiding the waste of silver paste caused by insufficient precision in the traditional screen printing process. At the same time, the process design of multiple coating and scraping of the conductive paste further improves the filling integrity of the silver paste. The precisely controlled electrode grid line width and shape not only reduces the light blocking, but also optimizes the current collection and conduction path, thereby improving the light absorption efficiency and photoelectric conversion efficiency of photovoltaic cells. In addition, the introduction of dopants in the conductive paste that is in direct contact with the substrate may further improve the interface contact characteristics between the electrode and the silicon wafer and reduce the contact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic flow chart of the steps of the method for preparing a solar cell grid line in an embodiment of the present application; Figure 2 It is a schematic diagram of the structures of each step of the method for preparing a solar cell grid line in an embodiment of the present application.

[0016] Description of reference numerals: 100, substrate; 200, photosensitive adhesive layer; 300, conductive paste; 400, gate line. DETAILED DESCRIPTION

[0017] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It is to be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some structures related to the present application are shown in the accompanying drawings, rather than all structures. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0018] The terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0019] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0020] The continuous innovation of solar cell technology has promoted the upgrading of photovoltaic materials, structural design and preparation process. Among them, the electrode grid line is a key component of solar cells, and the optimization of its preparation process plays a vital role in improving the photoelectric conversion efficiency of the battery. Although the traditional screen printing technology is mature and the equipment is popular, it has gradually revealed its limitations in terms of accuracy, material utilization and production efficiency. Next, the specific scheme, technical features, implementation steps and technical effects of the solar cell grid line preparation technology of this application will be introduced in detail. Please refer to Figure 1 to Figure 2A method for preparing a solar cell grid line in a preferred embodiment of the present application improves the detail accuracy and resolution of the electrode grid line through direct photolithography, realizes finer patterns, improves printing resolution, and reduces production costs. The method for preparing a solar cell grid line specifically includes forming a photosensitive adhesive layer 200 on a substrate 100, forming a patterned opening on the photosensitive adhesive layer 200, wherein the patterned opening corresponds to the grid line position, filling the patterned opening of the photosensitive adhesive layer with a conductive paste 300, and removing excess conductive paste on the photosensitive adhesive layer to convert the conductive paste 300 into a solar cell grid line 400.

[0021] The method of removing the excess conductive paste on the photosensitive adhesive layer 200 is to scrape it off, so that the patterned opening can be completely filled with the conductive paste, and the upper surface of the conductive paste in the patterned opening can be flush with the upper surface of the photosensitive adhesive layer 200. The size of the solar cell grid line can be completely controlled by the size of the patterned opening designed in advance. And because the photosensitive adhesive layer and the formation of the patterned opening can accurately control the size, the grid line size at each position can be accurately controlled, so that the performance of the prepared batch of solar cells can be more concentrated, reducing the difference in subsequent grading.

[0022] Before converting the conductive paste 300 into a gate, the step of removing the photosensitive resin layer 200 may be included, and the step of drying the conductive paste 300 may be further included. There is no strict order limit between these two steps, but in the preferred technical solution, the conductive paste 300 is dried on the basis of the photosensitive resin layer 200, so that the size of the conductive paste 300 can be strictly controlled under the limiting effect of the photosensitive resin layer 200.

[0023] The specific implementation method may be as follows: a photosensitive resin layer 200 is formed on a substrate 100, and the photosensitive resin layer 200 is exposed and developed through a light shielding mask to form a photosensitive resin layer 200 with a patterned opening, wherein the patterned opening corresponds to the surface grid line position, and the depth and width of the patterned opening correspond to the thickness and width of the surface grid line. On the photosensitive resin layer 200 with the patterned opening, a conductive paste 300 is coated and the excess conductive paste 300 on the photosensitive resin layer 200 is scraped off, the conductive paste 300 is dried, the photosensitive resin layer 200 is removed, and the conductive paste 300 is converted into a solar cell grid line. The substrate 100 may be a solar cell sheet that has been prepared with structures such as diffusion, passivation layer, and anti-reflection layer, or a cell sheet in an intermediate step. Those skilled in the art may form grid lines in corresponding steps as needed, and this application does not impose too many restrictions on this.

[0024] In the step of forming the patterned opening, the photosensitive resin layer can be exposed to ultraviolet light and developed through a light-shielding mask to form the patterned opening, or the patterned opening can be formed by laser scanning. Through the light-shielding mask or laser scanning, the patterned opening can be accurately positioned and the relevant dimensions can be controlled, so that the position of the patterned opening is accurate and the size is controllable, and the position and amount of the conductive paste filled in the patterned opening can be formed at a specific position according to the design requirements, thereby achieving stable control of the gate line.

[0025] In the above two methods of forming the patterned openings of the present application, it is also possible to design gate lines with gradually changing sizes. Since the gate lines collect current on the surface, the gate lines at different positions will affect the current collection efficiency. In the existing improvement scheme, the gate lines at positions far away from the bus bars will have reduced gate line widths. However, when screen printing is currently used, the size is difficult to control accurately and usually cannot meet the design requirements. When the technical solution of the present application is used, the relevant gate line sizes can be accurately and stably controlled to meet the design requirements of size changes. Compared with screen printing, it has a very large improvement in process stability and size controllability.

[0026] A photosensitive adhesive layer 200 with a thickness precisely controlled within the range of 8-20 μm is uniformly deposited on the substrate 100 by coating technology, so that the photosensitive adhesive layer 200 has good photosensitivity and excellent flatness and adhesion to ensure the smooth progress of subsequent processes. Subsequently, the photosensitive adhesive layer 200 is accurately exposed using a high-precision designed light-shielding mask (replaceable mask). In this process, the pattern on the light-shielding mask accurately corresponds to the layout of the grid lines on the surface of the solar cell. Through the selective irradiation of ultraviolet light (UV), the photosensitive adhesive layer 200 undergoes chemical changes in specific areas, forming patterned openings that are completely consistent with the shape of the grid lines 400. The depth and width of these openings directly determine the thickness and width of the final solar cell grid lines, thereby achieving precise control of the grid line 400 structure. Next, on the photosensitive adhesive layer 200 with patterned openings, a coating machine or inkjet printing technology is used to uniformly and accurately fill each opening with the conductive paste 300. At the same time, the excess conductive paste 300 on the photosensitive adhesive layer 200 is carefully removed by mechanical scraping or chemical cleaning, ensuring that the conductive paste 300 is only retained at the preset gate line 400 position, thereby avoiding material waste. Afterwards, the substrate 100 coated with the conductive paste 300 is placed in a drying device, and the solvent in the conductive paste 300 is volatilized by appropriate temperature and time control to achieve a preliminary drying effect. The conductive paste is heated to 120-180° C. to dry the conductive paste. Finally, the conductive paste 300 is sintered by a sintering technology such as laser irradiation or high-temperature heat treatment. For example, by providing a stable heat source, the organic matter in the conductive paste 300 is completely decomposed, and the metal particles are fused with each other, further improving the conductivity and stability of the gate line 400.

[0027] Generally, the whole high temperature heating method can be used for processing. In this method, the conductive paste can be sintered at a high temperature, and the temperature range is between 300-800°C, preferably 650-700°C. This method is a very mature paste sintering method. For example, silver paste is used, and the silver paste is subjected to high temperature to form a complete, continuous, high-resolution silver grid line.

[0028] When sintering is performed by laser irradiation, the laser spot is selected between 110%-200% of the grid line width, the wavelength is selected as any value in the range of 500-1100nm, the laser scanning speed is in the range of 5-15mm / s, and in this mode, sintering is performed by laser first, and then the photosensitive adhesive layer 200 is removed. Within the above parameter range, better laser sintering can be achieved. This sintering process belongs to local sintering. With the photosensitive adhesive layer and laser sintering, the impact on other areas outside the grid line can be minimized. In the application scenario of heterojunction solar cells, the impact on the amorphous silicon layer can be avoided. For heterojunction solar cells, it is a better grid line formation solution. For high-temperature heat treatment, it can be selected to heat to 300℃-800℃, and the slurry is sintered by heating to complete the process of converting the slurry into grid lines.

[0029] The preparation of high-resolution electrode grid lines by photolithography silver paste technology mainly depends on the interaction between precise photolithography process control and material properties. First, a layer of photosensitive glue is coated on the crystalline silicon wafer to form a photosensitive glue layer 200. The selection of photosensitive glue should take into account its sensitivity to UV light and etching performance. Then, through UV irradiation, the photosensitive glue undergoes chemical changes in the light-receiving area to form an etchable pattern. The pattern on the mask plays a role in guiding the photolithography, so that the photosensitive glue changes only in the required area. The pattern on the mask corresponds to the position, shape and size of the grid line 400. Then, the photosensitive glue is etched away with an etching solution to form a pattern of the electrode grid line. The etching solution is selected from 1-3wt% Na2CO3 (sodium carbonate), NH4OH (ammonium hydroxide), TMAH (tetramethylammonium hydroxide), NaHCO3 (sodium bicarbonate) or NaOH (sodium hydroxide), and then washed with clean water and dried. In addition, an organic solvent that can dissolve the photosensitive glue can also be used as an etching solution. In addition, the timing of removal can be chosen after the patterned opening is filled or after the conductive paste is dried. A better technical solution is to remove the remaining photosensitive adhesive layer after the conductive paste is dried. Under the action of the patterned opening limiter, the conductive paste can be strictly located at the set position after drying. Specifically, when the conductive paste is silver paste, the silver paste is applied to fill the photosensitive adhesive groove. After drying and high-temperature sintering, the silver paste is tightly combined with the silicon wafer to form a high-quality electrode grid line.

[0030] In addition, in a further preferred technical solution, the photosensitive adhesive is selected to have a material that has very little effect on the light transmittance, that is, the photosensitive adhesive layer 200 absorbs as little or no light as possible when the solar cell is working. In the technical solution of selecting this material, the photosensitive adhesive layer 200 may not be removed and may be retained in the solar cell structure. Of course, in this method, the selected material also needs to be able to withstand the temperature of the conductive paste sintering. In another improved technical solution, the conductive paste is converted into the grid line by sintering, and the selected photosensitive adhesive material is a material that can be removed during the sintering process. By completing the conversion of the conductive paste and the removal of the photosensitive adhesive layer at the same time during sintering, processing steps can be saved. Compared with the screen printing technical route, the steps of using liquids can be minimized, and the complexity of the process will not be greatly increased. In the entire process, only the steps of forming the photosensitive adhesive layer 200 and exposing and developing need to be added, which can be achieved by simple improvements on the original production line. The accuracy and stability of grid line production can be greatly improved through simple improvements.

[0031] This application uses photolithography as a graphic transfer process, providing a high-precision, high-resolution method for the precise and controllable preparation of photovoltaic silver paste electrodes. Through optical lithography, photolithography can accurately transfer complex patterns from a photomask to the surface of a photovoltaic cell, and form a fine electrode structure based on this, thereby improving the photoelectric conversion efficiency and cell performance, and ensuring uniform performance. Compared with screen printing, the method of this application can not only achieve finer line widths and higher pattern resolution, but also effectively reduce material waste, improve production efficiency, and meet the large-scale, high-efficiency production needs of the photovoltaic industry. The technical solution of this application can accurately control the grid line size, thereby avoiding manufacturing differences in various parts during the production process of the cell, reducing the differences between different solar cells, and facilitating the concentration of cell grading.

[0032] In order to further improve the filling effect, the steps of applying and scraping the conductive paste 300 are repeated more than twice. The viscosity, coating speed and coating amount of the conductive paste 300 are controlled to ensure that the paste can smoothly enter and fill each opening. Subsequently, a precision scraper or scraper device is used to scrape off the excess conductive paste 300 on the surface of the photosensitive adhesive layer 200 along a preset path to ensure that only the paste in the opening is retained. During the second (or more) coating, special attention is paid to the weak areas or openings that may exist in the initial filling, and these areas are fully supplemented by adjusting the amount of conductive paste 300 or the coating angle. At the same time, the scraping device is continued to remove the excess paste on the surface to keep the surface of the photosensitive adhesive layer 200 clean and smooth.

[0033] In the process of further optimizing the solar cell grid line preparation process, two different types of conductive pastes 300 are formed through the photosensitive adhesive layer 200, and the conductive paste 300 directly in contact with the substrate 100 includes a dopant component. At the bottom of these openings, that is, the area directly in contact with the substrate 100, a layer of conductive paste 300 containing a specific dopant component is applied. This dopant is usually selected from chemical elements or compounds that have good compatibility with the substrate 100 material (such as silicon) and can effectively improve its conductive properties, consistent with the doping type of the substrate 100. After the conductive paste 300 is dried and preliminarily dried, the dopant will gradually diffuse into the interior of the substrate 100 material during the sintering process, forming a heavily doped area with a higher doping concentration than other areas. This heavily doped area, as a selective emitter, can significantly reduce the contact resistance of the solar cell in this area, improve the current collection efficiency, and will not affect the conversion efficiency due to heavy doping. Next, a layer of conductive paste 300 without dopant or with low dopant content is coated on the conductive paste 300 containing dopant components. This layer of paste mainly plays the role of conductive connection and protection of the heavily doped area under the layer, ensuring the integrity and stability of the structure of the gate line 400. In this way, the selective emitter can be made while the gate line 400 is finely manufactured. At the same time, combined with the precise control of the patterned opening size, the size and distribution of the heavily doped area can also be precisely controlled. At the same time, the gate line and the heavily doped area are automatically aligned without the need for additional alignment steps, simplifying the selective emitter formation steps.

[0034] In the solar cell grid line preparation process, in order to further improve the sintering effect of the conductive paste 300 and ensure the stability and conductive performance of the grid line 400 structure, the conductive paste 300 is sintered by laser irradiation. After the conductive paste 300 is coated and preliminarily dried, the conductive paste 300 is precisely irradiated by high-precision laser equipment. The laser beam has high energy density and good directionality, and can quickly heat the conductive paste 300 to its sintering temperature, thereby inducing a cross-linking reaction or melting and resolidification process of the internal components of the paste, forming a dense grid line 400 structure with excellent conductive performance. During the laser irradiation process, by accurately controlling the laser power, scanning speed, spot size and other parameters, the sintering process of the conductive paste 300 can be finely controlled, which helps to ensure the consistency of the width, thickness and shape of the grid line 400, while reducing problems such as damage to the substrate 100 or loss of the paste due to excessive heating.

[0035] When applying a conductive paste with a dopant, sintering by laser can be more conducive to the doping of the dopant, and a concentration gradient can be formed in the heavily doped area, thereby improving the battery carrier collection performance. Specifically, in this step, the laser wavelength selects a laser in the range of 350-650nm, the laser scanning speed is selected in the range of 2-10mm / s, and the laser spot is selected in the range of 90%-110% of the grid line width. Relative to laser sintering, the laser energy is increased, the scanning speed is reduced, and the laser is more concentrated. Combined with a conductive paste with a dopant, a heavily doped area can be better formed in a local position, thereby forming a selective emitter. In this way, the present application realizes the preparation of the heavily doped area through one step, and at the same time converts the conductive paste into a grid line to complete the grid line production. In addition, combined with the lithography method of the present application, the parameters of each structure under each step and link can be accurately controlled, so that multiple required structural layers can be prepared in fewer steps, and the precise control of related structures can be achieved. In addition, in this step, the process is carried out on the basis of retaining the photosensitive resin layer 200. In order to minimize the heat conduction to the substrate, a heat conductive layer can be further formed on the photosensitive resin layer 200 to conduct the heat generated during the laser processing to both sides. Since a relatively higher temperature is required to achieve local doping, forming a heat conductive layer is a better implementation solution.

[0036] In a further technical solution, during laser sintering, the substrate 100 is placed on a carrier with a temperature lower than 10°C, and a gas with a temperature lower than 10°C is continuously purged on the surface of the substrate 100. In this further solution, the relatively low-temperature carrier and the relatively low-temperature gas purging can keep other areas of the substrate 100 at a relatively low temperature. Combined with the characteristic that the laser can control only local irradiation, the high-temperature area can be limited to a smaller range at the grid line. When this method is specifically applied to heterojunction solar cells, the sintering temperature of the conductive paste can be increased. No low-temperature conductive paste is required, and conventional conductive paste can be used. In other battery structures, the related structures can also be avoided from undergoing a high-temperature step again. The method of the present application is the basis for achieving the above-mentioned technical effects.

[0037] In the refined process of preparing the grid lines of solar cells, in order to further simplify the operating procedures and improve production flexibility and efficiency, the present application can further adopt a replaceable light-shielding mask plate (i.e., mask plate) as an exposure tool, that is, the light-shielding mask is a replaceable mask plate. In the preparation process, it is no longer dependent on a light-shielding mask with a single fixed pattern, but a series of prefabricated replaceable mask plates with different pattern designs are prepared, which can be customized according to the specific needs of the solar cell grid lines, including the layout, width, spacing and other key parameters of the grid lines 400. When it is necessary to prepare solar cells with different grid line 400 structures, it is simply necessary to replace the currently used mask plate with the corresponding design version.

[0038] In the refined process of preparing solar cell grid lines, in order to ensure that the size of each layer of structure is precisely controllable and improve the stability and reliability of the overall process, a step of flattening the photosensitive adhesive layer 200 is added, that is, it also includes flattening the photosensitive adhesive layer 200 to make the thickness of the photosensitive adhesive layer 200 uniform. Physical or chemical methods are used to flatten it. Physical methods may include mechanical polishing, grinding or the use of special flattening tools to remove the raised parts on the surface of the adhesive layer and fill the recessed areas; chemical methods may involve the use of specific chemical solvents or reactants to improve the surface flatness of the adhesive layer by dissolving, crosslinking or polymerization. After the flattening treatment, the thickness of the photosensitive adhesive layer 200 will become more uniform and the surface roughness will be significantly reduced, providing good basic conditions for subsequent process steps. At this time, whether it is the coating of the conductive paste 300 or the exposure and development operation, the size and shape can be more accurately controlled to reduce the errors and defects caused by the unevenness of the substrate 100.

[0039] In the precision process of preparing the grid lines of solar cells, it is crucial to accurately control the thickness of the photosensitive glue layer 200 and the width of the patterned opening. These two parameters directly affect the subsequent filling effect of the conductive paste 300, the dimensional accuracy of the grid lines 400, and the performance of the final battery. The thickness of the photosensitive glue layer 200 is in the range of 5-20μm, the width of the patterned opening is in the range of 1-20μm, and the aspect ratio of the patterned opening is in the range of 1:2 to 3:1. The grid lines are precisely controlled within the above range. The above dimensions can take into account the filling efficiency of the conductive paste 300 and the dimensional accuracy of the grid lines 400. The narrower opening width helps to reduce the parasitic resistance between the grid lines 400 and improve the current collection efficiency of the battery. At the same time, within the width range, it can also ensure that the conductive paste 300 can be fully and evenly filled into the opening to avoid the generation of voids or defects. By accurately controlling the thickness of the photosensitive glue layer 200 and the width of the patterned opening, the dimensional accuracy of the grid lines 400 can be significantly improved. This helps to reduce performance fluctuations and defective product rates caused by dimensional deviations. Through the above method, the width of the grid line formed is in the range of 1-20μm, the width of the patterned opening is less than or equal to 10μm, preferably, the width of the patterned opening is less than or equal to 8μm, preferably, the width of the patterned opening is less than or equal to 6μm, preferably, the width of the patterned opening is less than or equal to 5μm, preferably, the width of the patterned opening is less than or equal to 4μm, preferably, the width of the patterned opening is less than or equal to 3μm, preferably, the width of the patterned opening is less than or equal to 2μm. Through the method of the present application, the width of the solar cell grid line formed can be less than 2μm, while in other embodiments, this accuracy cannot be achieved, and the grid line cannot be stably and controllably manufactured at this accuracy.

[0040] In the complete process of preparing solar cell grid lines, in order to ensure the high efficiency and stability of solar cells, the front side of the substrate is also textured, diffused, and a passivation layer and an anti-reflection layer are deposited before forming the photosensitive adhesive. The light capture capacity of the substrate surface is increased, so that more sunlight can be absorbed and utilized by the battery, thereby improving the photoelectric conversion efficiency, reducing the recombination centers on the substrate surface, reducing the recombination probability of carriers on the surface, and improving the open circuit voltage and fill factor of the battery. The anti-reflection layer reduces the reflection loss of sunlight on the battery surface, improves the light transmittance, and further improves the photoelectric conversion efficiency of the battery.

[0041] In the refinement process of preparing the grid lines of solar cells, in order to ensure that the grid lines 400 can be accurately and efficiently formed on the surface of the substrate, while avoiding adverse effects on the design dimensions such as the thickness of the grid lines 400, after the patterned opening is formed by exposure and development, a step of removing the passivation layer and the anti-reflection layer in the patterned opening is added, that is, it also includes removing the passivation layer and the anti-reflection layer in the patterned opening. The passivation layer and the anti-reflection layer have a positive effect on improving the performance of the battery, but in the area where the grid lines 400 are formed, they may become obstacles for the direct contact between the conductive paste 300 and the substrate, affecting the filling effect of the conductive paste 300 and the conductive performance of the grid lines 400. In addition, if these two layers of materials remain too much in the grid line 400 area, they will also occupy a certain space, resulting in a reduction in the thickness of the grid lines 400 or deformation of the shape, thereby affecting the overall performance of the battery and the accuracy of the design dimensions.

[0042] The relevant technical solutions of the present application are described below through a specific implementation method.

[0043] Apply a 10μm layer of photosensitive glue on the crystalline silicon wafer, place a mask with a gate line pattern on top, and after UV irradiation for 5 minutes, etch the gate line pattern with an etching solution. Apply silver paste on the crystalline silicon wafer with photosensitive glue so that the silver paste fills the grooves tightly. After scraping off the excess silver paste, cover it evenly on the silicon wafer and dry it at 130℃ for 8 minutes. After drying, the adhesion of photovoltaic silver paste to silicon wafer increases, and the silver paste can fit tightly with the silicon wafer. At this time, irradiate the silicon wafer with UV for 5 minutes, and etch the remaining photosensitive glue with a specific etching solution. The etching solution is selected from 1-3wt% Na2CO3, NH4OH, TMAH, NaHCO3 or NaOH, and then wash with clean water and dry to obtain a silver paste with a gate line pattern. After high-temperature sintering, the silver paste forms a silver paste electrode gate line with a width of 5μm and a height of 10μm.

[0044] In addition, the present application also provides a solar cell, which uses the above-mentioned solar cell grid line preparation method to make surface grid lines. The obtained solar cell is used to further form a solar cell module, and the quality consistency of the solar cell product obtained by the method of the present application is more controllable.

[0045] As can be seen from the foregoing, this application proposes an optimized method for preparing solar cell grid lines. This method improves the detail accuracy and resolution of the electrode grid lines through direct photolithography technology, realizes the precise preparation of finer patterns, and effectively reduces production costs. In terms of process optimization, a photosensitive adhesive layer flattening step is also introduced to improve the surface flatness of the adhesive layer through physical or chemical methods to ensure the accuracy of subsequent processes. At the same time, in order to improve the conductive performance, this method also innovatively coats a conductive paste containing a specific dopant component at the bottom of the grid line to form a heavily doped area to enhance the photoelectric conversion efficiency and current collection efficiency.

[0046] In addition, before forming the photosensitive adhesive layer, the present application also includes the pre-treatment steps of texturing, diffusion, deposition of a passivation layer and an anti-reflection layer on the front side of the substrate to further improve the photoelectric conversion efficiency and stability of the battery. The solar cell grid line preparation method of the present application not only realizes high-precision and high-resolution grid line preparation, but also improves the overall performance and production efficiency of the battery through a series of optimization measures, which is of significance to promoting the technological development of the photovoltaic industry.

[0047] The above is only a specific implementation of the present application, and any other improvements made based on the concept of the present application are deemed to be within the protection scope of the present application.

Claims

1. A method for preparing a solar cell grid line, used for preparing a grid line on a solar cell, characterized in that: include: forming a photosensitive resin layer on a substrate; Forming a patterned opening on the photosensitive resin layer, wherein the patterned opening corresponds to a gate line position; Filling the patterned openings of the photosensitive adhesive layer with a conductive paste, and removing excess conductive paste on the photosensitive adhesive layer; The conductive paste is converted into solar cell grid lines.

2. The method for preparing a solar cell grid line according to claim 1, characterized in that: The photosensitive resin layer is exposed to ultraviolet light and developed through a light-shielding mask to form the patterned opening.

3. The method for preparing a solar cell grid line according to claim 1, characterized in that: The patterned opening is formed by laser scanning.

4. The method for preparing a solar cell grid line according to claim 2, characterized in that: After the patterned openings are filled or the conductive paste is dried, the method further includes removing the photosensitive adhesive layer using an etching solution.

5. The method for preparing a solar cell grid line according to claim 1, characterized in that: The method also includes heating the conductive paste to 120-180° C. and drying the conductive paste.

6. The method for preparing a solar cell grid line according to claim 1, characterized in that: The width of the gate line is less than 10 μm.

7. The method for preparing a solar cell grid line according to claim 6, characterized in that: The thickness of the photosensitive adhesive layer is in the range of 5-20 μm, and the width of the patterned opening is in the range of 1-20 μm.

8. The method for preparing a solar cell grid line according to claim 1, characterized in that: Two different types of conductive pastes are formed in the patterned openings, and the conductive paste directly contacting the substrate includes a dopant component.

9. The method for preparing a solar cell grid line according to claim 8, characterized in that: The method of converting the conductive paste into solar cell grid lines is to sinter the conductive paste by laser irradiation.

10. A solar cell, characterized in that: The surface grid lines are prepared by using the solar cell grid line preparation method as described in any one of claims 1 to 9.

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