Preparation method of solar cell, solar cell and photovoltaic module
Through microwave treatment and preheating treatment combined with ultraviolet radiation treatment, the problem of uneven curing inside the slurry is solved, and the cell efficiency and electrical performance of solar cells are improved.
Patent Information
- Application Number
- CN202510451790.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-10
- Publication Date
- 2025-08-01
AI Technical Summary
In the existing solar cell preparation process, the slurry drying method causes the slurry shell to cure but the inside is not completely cured, affecting the volatility of organic matter, and the residual organic matter causes the electrode to break or poor contact, reducing battery efficiency.
The conductive paste is dried by microwave treatment, combined with preheating treatment and ultraviolet radiation treatment to ensure that the slurry is uniformly cured and avoid organic matter residues.
It improves the curing consistency of conductive paste, reduces the electrode contact resistance and line resistance, improves the filling factor and open circuit voltage, and improves the battery efficiency.
Smart Images
Figure CN120417528A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the technical field of solar cells, and specifically relates to a method for preparing a solar cell, a solar cell, and a photovoltaic module. Background Art
[0002] The grid electrode of a solar cell is a key structure on the cell surface that collects photocurrent. It is typically produced through screen printing of a slurry, followed by drying and sintering. The purpose of drying is to remove organic solvents and tar from the slurry, allowing it to solidify into a film that adheres tightly to the silicon wafer surface.
[0003] In the existing solar cell preparation process, the slurry drying method is surface heating. Heat is transferred from the outside of the slurry to its inside. The outside and inside of the slurry cure at different speeds. It is easy for the outer shell of the slurry to cure but the inside is not completely cured, which affects the volatilization effect of the organic matter inside the slurry. The residual organic matter will decompose during the subsequent high-temperature sintering to produce bubbles or pollution, resulting in electrode breakage or poor contact, affecting the battery efficiency. Summary of the Invention
[0004] The purpose of the present application is to provide a method for preparing solar cells, solar cells and photovoltaic modules, so as to solve the technical problem that the slurry drying method in the prior art is prone to the phenomenon that the outer shell of the slurry is cured but the inside is not completely cured, which affects the volatilization effect of the organic matter in the conductive slurry, and the residual organic matter will affect the efficiency of the cell.
[0005] In order to achieve the above objectives, the present application provides a first aspect of a method for preparing a solar cell, comprising:
[0006] Providing a cell, wherein a conductive paste is formed on the light-receiving surface and / or the backlight surface of the cell;
[0007] The conductive paste on the cell is subjected to microwave treatment to solidify the conductive paste.
[0008] In one or more embodiments, during the microwave treatment, the wavelength of the microwave is 0.1 m to 1 m.
[0009] In one or more embodiments, the power of the microwave is 500W to 1500W.
[0010] In one or more embodiments, the microwave treatment time is less than or equal to 30 s.
[0011] In one or more embodiments, the microwave treatment is performed in an air atmosphere or an inert atmosphere.
[0012] In one or more embodiments, before the step of subjecting the conductive paste on the cell to microwave treatment, the following steps are further included:
[0013] Preheating the cell on which the conductive paste is formed.
[0014] In one or more embodiments, the heating method for the preheating treatment is one or a combination of more of resistance heating, infrared heating, and electromagnetic heating.
[0015] In one or more embodiments, the preheating temperature for the preheating treatment is 100°C to 400°C, and the preheating time is less than or equal to 150 s.
[0016] In one or more embodiments, the time of the preheating treatment is longer than the time of the microwave treatment.
[0017] In one or more embodiments, after the step of subjecting the conductive paste on the cell to microwave treatment, the following steps are further included:
[0018] Performing ultraviolet light irradiation treatment on the conductive paste on the cell.
[0019] In one or more embodiments, in the ultraviolet light irradiation treatment, the wavelength of the ultraviolet light is 315 nm to 400 nm.
[0020] In one or more embodiments, the treatment time of the ultraviolet light irradiation treatment is less than or equal to 5 s.
[0021] To achieve the above object, a second aspect of the present application provides a method for manufacturing a solar cell, including:
[0022] Performing one or more metalization processes on the cell, forming a conductive paste on the light-receiving surface and / or the backlight surface of the cell in each of the metalization processes, and curing the conductive paste;
[0023] Wherein, in at least one of the metalization processes, the above-mentioned preparation method according to any one of the embodiments is used to cure the conductive paste.
[0024] In one or more embodiments, in each of the metalization processes, the above-mentioned preparation method according to any one of the embodiments is used to cure the conductive paste.
[0025] In one or more embodiments, three metalization processes are performed on the cell, forming a conductive paste on the light-receiving surface and / or the backlight surface of the cell in each of the metalization processes, and curing the conductive paste.
[0026] Among them, each time the metal chemical process is carried out, the conductive paste is cured by using the preparation method described in any of the above embodiments.
[0027] In one or more embodiments, after all the metal chemical processes are completed, the conductive paste on the battery chip is sintered.
[0028] To achieve the above object, a third aspect of the present application provides a solar cell, which is prepared by using the preparation method described in any of the above embodiments.
[0029] To achieve the above object, a fourth aspect of the present application provides a photovoltaic module, including the solar cell described in any of the above embodiments.
[0030] Different from the prior art, the beneficial effects of the present application are:
[0031] In the present application, the conductive paste is dried by microwave treatment, which can effectively avoid the residue of organic substances, thereby avoiding the generation of bubbles or contamination in the subsequent sintering process, resulting in electrode fracture or poor contact. It can effectively optimize the contact resistance and line resistance of the grid electrode, which is beneficial to improving the fill factor and open circuit voltage, and enhancing the efficiency of the battery chip. Description of the Drawings
[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0033] ]] Figure 1 It is a schematic flowchart of an embodiment of the preparation method of the solar cell of the present application;
[0034] Figure 2 It is a schematic flowchart of another embodiment of the preparation method of the solar cell of the present application;
[0035] Figure 3 It is a schematic flowchart of yet another embodiment of the preparation method of the solar cell of the present application;
[0036] Figure 4 It is an SEM image of the grid electrode of the battery chip in Embodiment 1 of the present application;
[0037] Figure 5 It is an SEM image of the grid electrode of the battery chip in Comparative Example 1 of the present application;
[0038] Figure 6 It is a data graph of the photoelectric conversion efficiency of the battery chips in Embodiment 1 and Comparative Example 1;
[0039] Figure 7 is a graph showing the fill factor FF data of the battery cells of Example 1 and Comparative Example 1 of the present application;
[0040] Figure 8 1 is a box plot of the contact resistance Rc of the front grid line electrodes of the battery cells of Example 1 and Comparative Example 1;
[0041] Figure 9 It is a data graph of the total series resistance Rs of the battery cells of Example 1 and Comparative Example 1 of the present application. DETAILED DESCRIPTION
[0042] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.
[0043] The gate electrodes on the battery cell are generally prepared through screen printing, drying and sintering processes. The purpose of drying is to remove the organic solvents and tar in the gate slurry, so that the slurry solidifies into a film and tightly adheres to the surface of the silicon wafer; the purpose of sintering is to establish ohmic contact between the metal particles and the silicon substrate at high temperature, reduce the contact resistance between the electrode and the silicon wafer, and optimize the carrier collection efficiency.
[0044] At present, the drying method of gate paste is surface heating. Heat is transferred from the outside of the paste to its inside, resulting in different curing speeds of the outside and inside of the conductive paste. It is easy for the outer shell of the conductive paste to cure but the inside is not completely cured, which affects the volatilization effect of the organic matter inside the conductive paste. The residual organic matter will decompose and produce bubbles or pollution during subsequent high-temperature sintering, causing electrode breakage or poor contact, affecting battery efficiency.
[0045] To solve the above problems, the applicant has developed a new method for preparing solar cells. This method dries the slurry by microwave treatment, ensuring a consistent curing rate across the slurry, thereby effectively avoiding organic residues and improving cell efficiency.
[0046] Specifically, see Figure 1 , Figure 1 It is a schematic flow chart of an embodiment of a method for preparing a solar cell of the present application.
[0047] like Figure 1 As shown, the preparation method comprises:
[0048] S100. Provide a solar cell, on which a conductive paste is formed on the light-receiving surface and / or the backlight surface.
[0049] First, the preparation method of this embodiment is applied to a solar cell with a conductive paste printed on its surface. Among them, the conductive paste can be printed on the light-receiving surface of the solar cell, or on the backlight surface of the solar cell, or printed on both surfaces at the same time.
[0050] The solar cell can be any solar cell that needs to arrange grid electrodes or back fields in the art. Exemplarily, the solar cell can be an aluminum back surface field (BSF) cell, a passivated emitter and rear cell (PERC) cell, a heterojunction with intrinsic thin layer (HJT) cell, a tunnel oxide passivated contact (TOPCon) cell, a back contact (BC) cell, etc., and all can implement this embodiment.
[0051] The conductive paste can be any metal paste commonly used in the art, such as conductive silver paste, etc. The conductive paste can be arranged in a grid or mesh pattern on the surface of the solar cell, or evenly arranged on the surface of the solar cell, so as to form grid electrodes or back fields for collecting photo-generated current after subsequent drying and sintering processes.
[0052] S200. Perform microwave treatment on the conductive paste on the solar cell to cure the conductive paste.
[0053] In this embodiment, the microwave treatment method is used to cure the conductive paste. Since microwave treatment is volume heating and does not require a heat transfer medium, the inside and outside of the conductive paste can be heated simultaneously, which helps the volatilization of moisture and organic matter, and also avoids the situation where the outer surface of the paste is dried but the inside is not dried, thus effectively avoiding the residue of organic matter, helping to reduce the resistance, and improving the fill factor and cell efficiency.
[0054] In one embodiment, the microwave wavelength of the microwave treatment can be 0.1 m to 1 m. Correspondingly, the frequency of the microwave can be 300 MHz to 3 GHz.
[0055] More specifically, the microwave frequency can be 433 MHz, 915 MHz or 2450 MHz.
[0056] In one embodiment, the treatment time of the microwave treatment can be less than or equal to 30 s. More preferably, the treatment time of the microwave treatment can be 15 s to 3 os.
[0057] In one embodiment, the power of the microwave can be 500 W to 1500 W. More preferably, the power of the microwave can be 900 W.
[0058] It should be understood that parameters such as microwave frequency, treatment time, and conductive paste thickness are interrelated. High-frequency microwaves heat quickly but penetrate shallowly, making them suitable for thin layers. Low-frequency microwaves, on the other hand, have strong penetration but slow heating, making them suitable for thicker materials. In practice, the microwave frequency and treatment time can be adjusted based on process parameters such as the thickness of the conductive paste to ensure complete curing of the paste, thus achieving the desired effect of this embodiment.
[0059] Microwave treatment has no strict requirements on the atmosphere of the conductive paste. In one embodiment, microwave treatment can be carried out in an air atmosphere; but in another embodiment, in order to suppress the generation of arcs, microwave treatment can also be carried out in an inert atmosphere, for example, in a nitrogen atmosphere, and both can achieve the effects of this embodiment.
[0060] In one embodiment, the method of performing microwave treatment on the conductive paste on the cell may be: transferring the cell through an irradiation area of a microwave generating mechanism to complete the microwave treatment.
[0061] The microwave generating mechanism may be any element capable of generating microwave energy, such as a transistor-type microwave generator, a microwave photon generator, a solid-state microwave generator, etc., all of which can achieve the effects of this embodiment.
[0062] Based on the above method, the overall processing efficiency can be improved and it is more suitable for industrial assembly lines.
[0063] Furthermore, in order to ensure a uniform curing effect across the cell, the cell may be transported at a uniform speed through the irradiation area of the microwave generating mechanism.
[0064] Of course, in another embodiment, the cell may be kept in a stationary state for microwave treatment, which can also achieve the effect of this embodiment.
[0065] In a specific implementation, the microwave generating mechanism can be encapsulated in a sealed cavity, and the battery slices can be placed on a roller conveyor passing through the sealed cavity for transportation.
[0066] Furthermore, the roller material of the roller conveyor belt can be ceramic. Ceramics are insulating materials that do not absorb or reflect microwaves, ensuring the uniformity of microwave distribution and reducing the risk of local discharge. At the same time, ceramics are resistant to high temperatures and have chemical stability, making them suitable for high-temperature environments.
[0067] Based on the preparation methods of the above-mentioned embodiments, drying the conductive paste through microwave treatment can effectively avoid organic residue, thereby avoiding the generation of bubbles or contamination in the subsequent sintering process that may lead to electrode breakage or poor contact. It can effectively optimize the contact resistance and line resistance of the gate electrode, which is beneficial to improving the fill factor and open circuit voltage, thereby improving the efficiency of the battery cell.
[0068] In the preparation methods of the above embodiments, a single microwave treatment method is used to dry the conductive paste. However, since the cell includes a multi-layer structure such as a silicon substrate, a passivation layer, and a paste, the dielectric properties of different materials are inconsistent, and the absorption effects of microwaves are inconsistent. Therefore, when using a single microwave treatment, there may be a problem that the temperatures of the silicon substrate and the paste are inconsistent, and due to the difference in the thermal expansion coefficients of the materials, the grid lines may crack and fall off, and due to uneven local temperatures of the silicon wafer, there may be a problem of wafer cracking.
[0069] To solve the above problems, please refer to Figure 2 , Figure 2 which is a schematic flowchart of another embodiment of the preparation method of the solar cell of the present application.
[0070] As Figure 2 shown, the preparation method includes:
[0071] S100': Provide a cell, and a conductive paste is formed on the light-receiving surface and / or the backlight surface of the cell.
[0072] S200': Perform a preheating treatment on the cell on which the conductive paste is formed.
[0073] S300': Perform a microwave treatment on the conductive paste on the cell to cure the conductive paste.
[0074] In this embodiment, after screen printing is completed, the cell also undergoes a preheating treatment before the microwave treatment. The preheating treatment can make the temperatures of the silicon substrate, the conductive paste, the passivation layer and other layer structures of the cell consistent, and then effectively avoid the problems of grid line cracking, falling off and wafer cracking caused by the difference in the thermal expansion coefficients of the materials during the subsequent microwave treatment, and improve the heating uniformity.
[0075] In one embodiment, the temperature of the preheating treatment can be 100-400°C, and the preheating time can be less than or equal to 150 s.
[0076] In one embodiment, in order to ensure sufficient preheating of each layer of the cell, the preheating time can be longer than the microwave treatment time.
[0077] In one embodiment, the preheating treatment can be resistance heating, or infrared heating, or electromagnetic heating, or a combination of the above multiple heating methods, as long as the layer structures of the cell can be heated to the same temperature, and the effects of this embodiment can be achieved.
[0078] It should be understood that the purpose of the preheating treatment in this embodiment is to preheat each layer structure of the battery cell to the same temperature. Therefore, any heating means that can achieve this purpose can achieve the effect of this embodiment, and it is not limited to the heating methods listed above.
[0079] In a specific embodiment, due to the higher thermal efficiency and heating rate of infrared heating, the preheating treatment can specifically adopt infrared heating. By using infrared heating to assist microwave heating, the temperature can be monitored and the temperature curve can be adjusted through the temperature control module, so as to avoid the uneven stress distribution caused by the difference in thermal expansion coefficients between the grid electrode and the silicon substrate.
[0080] In one embodiment, the method for preheating treatment and microwave treatment of the battery cell can be specifically as follows: The battery cell is conveyed through the action area of the preheating mechanism and the irradiation area of the microwave generating mechanism in sequence to complete the preheating treatment and microwave treatment.
[0081] Based on the above method, the overall processing efficiency can be improved, which is more suitable for industrial production lines.
[0082] Furthermore, the battery cell can maintain a uniform motion state and pass through the action area of the preheating mechanism and the irradiation area of the microwave generating mechanism in sequence, so that each part of the battery cell can be quickly subjected to microwave treatment after the preheating treatment is completed, avoiding heat loss, ensuring that the temperatures of each layer are consistent during the subsequent microwave treatment, and at the same time ensuring that the curing effects of each part of the battery cell are consistent.
[0083] Due to the uniform motion of the battery cell, in order to control the preheating time and microwave treatment time of the battery cell, in the conveying direction of the battery cell, the length of the action area of the preheating mechanism can be greater than the length of the irradiation area of the microwave generating mechanism. In specific implementation, the lengths of the action area of the preheating mechanism and the irradiation area of the microwave generating mechanism can be adjusted based on actual requirements to ensure sufficient preheating and microwave treatment of the battery cell.
[0084] In practical applications, the preheating mechanism and the microwave suppressor can be encapsulated in different areas of the same cavity, so as to avoid heat loss of the battery cell before reaching the microwave suppressor from the preheating mechanism. In the above embodiment, the preheating mechanism and the microwave generating mechanism are arranged adjacent to each other, and there may be problems of mutual interference. For example, when the preheating mechanism is an infrared heating device, the infrared heating tube will absorb microwaves, resulting in uneven microwave distribution and low energy utilization rate.
[0085] To solve the above problems, in another embodiment, the method for preheating treatment and microwave treatment of the battery cell can be specifically as follows: The battery cell is conveyed through the action area of the preheating mechanism, the action area of the microwave suppressor, and the irradiation area of the microwave generating mechanism in sequence to complete the preheating treatment and microwave treatment.
[0086] Based on the above solution, before the solar cell wafer that has completed the preheating treatment enters the irradiation area of the microwave generating mechanism, it also passes through the action area of the microwave suppressor, thus effectively avoiding mutual interference between the preheating mechanism and the microwave generating mechanism, ensuring uniform microwave distribution, and improving energy utilization efficiency.
[0087] Of course, in other embodiments, the solar cell wafer can also pass through the action area of the microwave suppressor before entering the action area of the preheating mechanism or after leaving the irradiation area of the microwave generating mechanism, so as to avoid microwave leakage, ensure uniform microwave distribution, and avoid harming the operators.
[0088] Same as Figure 1 the embodiment shown, the conveying method of the solar cell wafer can be to place the solar cell wafer on a roller conveyor belt that sequentially passes through the action area of the preheating mechanism and the irradiation area of the microwave generating mechanism. Among them, the material of the roller can be ceramic.
[0089] Based on the preparation methods of the above embodiments, the preheating treatment assists the microwave treatment in drying the conductive paste. On the one hand, the microwave treatment can ensure the volatilization of moisture and organic matter in each part of the conductive paste, reduce the grid line resistance, and improve the fill factor. On the other hand, the preheating treatment can avoid the problem of inconsistent temperature in each part of the solar cell wafer easily caused by the microwave treatment, and avoid problems such as grid line cracking, shedding, and chipping caused by the difference in the thermal expansion coefficient of the material, and improve the heating uniformity.
[0090] In the above embodiments, the drying operation is carried out by preheating the solar cell wafer first and then performing microwave treatment. In other embodiments, the surface of the conductive paste after microwave treatment can also be repaired. Specifically, please refer to Figure 3 , Figure 3 which is a schematic flow chart of another embodiment of the preparation method of the solar cell of the present application.
[0091] As Figure 3 shown, the preparation method includes:
[0092] S100": Provide a solar cell wafer, and a conductive paste is formed on the light-receiving surface and / or the backlight surface of the solar cell wafer.
[0093] S200": Perform microwave treatment on the conductive paste on the solar cell wafer to cure the conductive paste.
[0094] S300": Perform ultraviolet light irradiation treatment on the conductive paste on the solar cell wafer.
[0095] The surface defects of the conductive paste after drying are the key issues affecting its conductive performance and subsequent applications. In this embodiment, in order to eliminate the surface defects of the conductive paste after drying, the conductive paste after microwave treatment is also subjected to ultraviolet light irradiation treatment.
[0096] Through ultraviolet light injection, the surface defects generated during the curing process of the conductive paste can be activated and repaired, reducing the surface recombination rate, thereby improving the open-circuit voltage.
[0097] In one embodiment, during the ultraviolet light irradiation treatment, the ultraviolet light can be UVA, and the wavelength of the ultraviolet light is 315 nm to 400 nm.
[0098] In one embodiment, the treatment time of the ultraviolet light irradiation treatment can be less than or equal to 5 s.
[0099] It should be understood that the wavelength and time of the ultraviolet light irradiation treatment are associated with parameters such as the thickness of the conductive paste. In other embodiments, based on the actual material and thickness of the conductive paste, the wavelength of the ultraviolet light and the irradiation treatment time can be adjusted according to actual needs, and the effects of this embodiment can also be achieved.
[0100] In specific implementation, the microwave generating mechanism and the ultraviolet light generating mechanism can be sequentially encapsulated in a cavity, and the battery wafers are conveyed through the irradiation areas of the microwave generating mechanism and the ultraviolet light generating mechanism by a conveyor belt to complete the microwave treatment and the ultraviolet light irradiation treatment.
[0101] It should be noted that the above embodiments show two schemes of preheating the battery wafers and then performing microwave treatment, and performing microwave treatment and then ultraviolet light irradiation treatment on the battery wafers. In other embodiments, a scheme of simultaneously using preheating treatment and ultraviolet light irradiation treatment can also be adopted, that is, the battery wafers are sequentially subjected to preheating treatment, microwave treatment and ultraviolet light irradiation treatment, and the effects of this embodiment can also be achieved, which will not be elaborated here.
[0102] It should be noted that the preparation methods of the above embodiments only show one drying process in the solar cell preparation process. In the complete solar cell preparation process, screen printing of the conductive paste needs to be performed multiple times. Therefore, the present application also provides a preparation method of a solar cell, and this preparation method adopts Figures 1 to 3 any of the preparation methods shown in
[0103] Specifically, this preparation method includes:
[0104] Performing one or more metallization processes on the battery wafers, forming a conductive paste on the light-receiving surface and / or the backlight surface of the battery wafers in each of the metallization processes, and curing the conductive paste.
[0105] Among them, each metallization process adopts Figures 1 to 3 any of the methods shown in
[0106] In this preparation method, the battery wafers undergo one or more metallization processes, and microwave treatment is used to cure the conductive paste in each metallization process.
[0107] After all the metallization processes are completed, the conductive paste on the battery wafers can be sintered to complete the preparation of the grid electrodes and the back field of the solar cell.
[0108] Exemplarily, the back grid, the back field, and the front grid of the solar cell can be screen-printed separately in three times, and microwave treatment is performed for drying after each screen-printing. After the last microwave treatment is completed, sintering is carried out to complete the preparation of the grid electrodes and the back field.
[0109] Of course, in other embodiments, a technical solution combining microwave treatment and other conventional drying methods can also be adopted. For example, only 1 metallization process uses microwave treatment to cure the conductive paste, and other metallization processes use common infrared heating treatment, etc., which can also achieve the effects of this embodiment and should all be considered within the protection scope of this application.
[0110] The beneficial effects of the technical solution of this application will be further elaborated in detail below with specific embodiments.
[0111] Example 1:
[0112] A kind of battery wafer is prepared by the following steps:
[0113] The conductive silver paste is printed on the front and back of the battery wafer step by step. After each printing, a drying process is carried out on the conductive silver paste. After the last drying is completed, a sintering process is carried out on the electrode wafer.
[0114] Among them, the drying process is specifically as follows:
[0115] The battery wafer is placed on the conveyor belt and enters a drying furnace equipped with infrared heating tubes, a microwave suppressor, and a microwave generating mechanism arranged in sequence. The battery wafer uniformly passes through the action area of the infrared heating tubes and the irradiation area of the microwave generating mechanism under the action of the conveyor belt. The battery wafer undergoes infrared heating treatment and microwave treatment in sequence to dry the conductive silver paste. Among them, the heating temperature of the infrared heating treatment is 120 °C, the heating time is 120 s, the microwave frequency of the microwave treatment is 2450 MHz, the microwave power is 900 W, and the microwave treatment time is 20 S.
[0116] Example 2: <(
[0117] A kind of battery wafer, the preparation method is basically the same as that of Example 1, the difference is that:
[0118] The heating temperature of the infrared heating treatment is 100 °C, the heating time is 150 s, the microwave frequency of the microwave treatment is 915 MHz, the microwave power is 1500 W, and the microwave treatment time is 15 s.
[0119] Example 3:
[0120] A battery cell, the preparation method is basically the same as that of Example 1, the difference is that:
[0121] The heating temperature of the infrared heating treatment is 400 °C, the heating time is 60 s, the microwave frequency of the microwave treatment is 433 MHz, the microwave power is 500 W, and the microwave treatment time is 30 s.
[0122] Example 4:
[0123] A battery cell, the preparation method is basically the same as that of Example 1, the difference is that:
[0124] In the drying furnace of Example 4, a nitrogen flow equalizing plate is arranged so that the irradiation area of the microwave generating mechanism is in a nitrogen atmosphere.
[0125] Example 5:
[0126] A battery cell is prepared by the following steps:
[0127] Conductive silver paste is printed on the front and back of the battery cell step by step. After each printing, a drying process is carried out on the conductive silver paste. After the last drying is completed, a sintering process is carried out on the electrode plate.
[0128] Among them, the drying process is specifically:
[0129] The battery cell is placed on the conveyor belt and enters a drying furnace equipped with infrared heating tubes and a microwave generating mechanism, so that the battery cell passes through the action area of the infrared heating tubes and the irradiation area of the microwave generating mechanism simultaneously under the action of the conveyor belt, and the battery cell is synchronously subjected to infrared heating treatment and microwave treatment to dry the conductive silver paste. Among them, the heating temperature of the infrared heating treatment is 120 °C, the microwave frequency of the microwave treatment is 2450 MHz, the microwave power is 900 W, and the infrared heating treatment and microwave treatment time is 20 S.
[0130] Comparative Example 1:
[0131] A battery cell, the preparation method is basically the same as that of Example 1, the difference is that:
[0132] The drying process of Comparative Example 1 is specifically:
[0133] Place the battery cells on the conveyor belt and enter the drying furnace equipped with infrared heating tubes, so that the battery cells uniformly pass through the action area of the infrared heating tubes under the action of the conveyor belt. The battery cells are subjected to infrared heating treatment to dry the conductive silver paste. Among them, the heating temperature of the infrared heating treatment is 200-300 °C, the temperature gradient increases, and the total heating time is 17 s.
[0134] Effect Example 1: Characterization Analysis
[0135] Perform characterization analysis on the grid line electrodes of the battery cells prepared in Example 1 and Comparative Example 1 to obtain Figure 4 and Figure 5 , Figure 4 is the SEM image of the grid line electrode of the battery cell in Example 1 of this application, Figure 5 is the SEM image of the grid line electrode of Comparative Example 1 of this application.
[0136] As Figure 5 shown, there are more bubbles inside the grid line electrode of Comparative Example 1, which is likely to cause poor electrode contact. This is mainly due to the incomplete volatilization of the internal organic matter during the drying process of the conductive silver paste in Comparative Example 1, and the residual organic matter decomposes to generate bubbles during the subsequent sintering process.
[0137] As Figure 4 shown, there are no bubbles inside the grid line electrode of the battery cell in Example 1, and the compactness is higher.
[0138] The above data prove that the drying method in Example 1 can effectively avoid the residue of organic matter and ensure the complete curing of the conductive silver paste everywhere.
[0139] Effect Example 2: Electrical Performance Analysis
[0140] Prepare battery cells by the methods of Example 1 and Comparative Example 1 on different dates, and measure and calculate their photoelectric conversion efficiency, that is, the cell efficiency eta, to obtain Figure 6 , Figure 6 is the data graph of the photoelectric conversion efficiency of the battery cells in Example 1 and Comparative Example 1.
[0141] As Figure 6 shown, the photoelectric conversion efficiency of the battery cells in Example 1 is significantly better than that in Comparative Example 1. The average photoelectric conversion efficiency of the battery cells in Example 1 is 26.46%, which is 0.34% higher than that in Comparative Example 1.
[0142] Furthermore, the calculation formula for the cell efficiency of a solar cell is as follows:
[0143]
[0144] In the formula, η is the cell efficiency, P in is the incident light power, V OC is the open circuit voltage, JSC where \(J_{sc}\) is the short - circuit current density and \(FF\) is the fill factor.
[0145] Among them, \(V\) OC *\(J\) SC \(= P\) max and \(P\) max is the maximum output power of the battery. Therefore, the larger the fill factor \(FF\), the higher the battery efficiency.
[0146] Therefore, we prepared cell wafers by using the methods of Example 1 and Comparative Example 1 on different dates, and measured and calculated the fill factor \(FF\) of the cell wafers of Example 1 and Comparative Example 1, and obtained Figure 7 data Figure 7 which is the data graph of the fill factor \(FF\) of the cell wafers of Example 1 and Comparative Example 1 of this application.
[0147] As Figure 7 shown, the fill factor \(FF\) of the cell wafers of Example 1 is significantly higher than that of Comparative Example 1, and the maximum increase in the fill factor \(FF\) of the cell wafers of Example 1 relative to Comparative Example 1 is 0.58%.
[0148] Furthermore, the correlation formula between the fill factor \(FF\) and the total series resistance \(Rs\) of the solar cell is as follows:
[0149]
[0150] Among them, the total series resistance \(Rs\) includes the contact resistance \(Rc\) of the grid - line electrode. Therefore, the smaller the contact resistance \(Rc\) of the grid - line electrode, the larger the fill factor \(FF\).
[0151] Therefore, we prepared cell wafers by using the methods of Example 1 and Comparative Example 1 on different dates, and measured the contact resistance \(Rc\) of the front - side grid - line electrodes, and obtained Figure 8 , Figure 8 which is the box plot of the contact resistance \(Rc\) of the front - side grid - line electrodes of the cell wafers of Example 1 and Comparative Example 1.
[0152] As Figure 8 shown, the contact resistance \(Rc\) of the front - side grid - line electrodes of the cell wafers of Example 1 is significantly lower than that of Comparative Example 1. Among them, the median of the contact resistance \(Rc\) of the front - side grid - line electrodes of the cell wafers of Example 1 is reduced by 34.35% relative to Comparative Example 1.
[0153] Furthermore, we also measured the total series resistance \(Rs\) of the cell wafers of Example 1 and Comparative Example 1, and obtained Figure 9 , Figure 9 which is the data graph of the total series resistance \(Rs\) of the cell wafers of Example 1 and Comparative Example 1 of this application.
[0154] As Figure 9As shown, the total series resistance Rs of the cell in Example 1 is significantly lower than that in Comparative Example 1. The average value of the total series resistance RS of the cell in Example 1 is reduced by 4.17% relative to Comparative Example 1.
[0155] The above data shows that the cell in Example 1 has a higher fill factor FF, a lower grid electrode contact resistance Rc and a lower total series resistance RS compared to Comparative Example 1, and has more excellent cell efficiency.
[0156] Effect Example 3:
[0157] The preparation efficiency and energy consumption of the cells in Example 1 and Comparative Example 1 were calculated, and the results show that:
[0158] The preparation efficiency of the cell in Example 1 is increased by at least 0.09% compared to Comparative Example 1, and the energy consumption is reduced by at least 10%.
[0159] Therefore, the preparation method of the cell in Example 1 has higher efficiency and lower energy consumption. The reason is that: since microwave heating has the advantages of fast start-up speed, directly acting on the object, and not relying on the medium to transfer heat energy, its energy consumption is also significantly lower than that of existing resistance heating, infrared heating and electromagnetic heating, and the heating efficiency is also higher.
[0160] For those skilled in the art, it is obvious that the present application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present application is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claimed rights.
[0161] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard 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 method for preparing a solar cell, characterized in that, Comprising: Providing a solar cell wafer, on which a conductive paste is formed on the light-receiving surface and / or the backlight surface; Performing microwave treatment on the conductive paste on the solar cell wafer to cure the conductive paste.
2. The preparation method according to claim 1, characterized in that, During the microwave treatment, the wavelength of the microwave is 0.1 m to 1 m; and / or, During the microwave treatment, the power of the microwave is 500 W to 1500 W; and / or, The treatment time of the microwave treatment is less than or equal to 30 s.
3. The preparation method according to claim 1, characterized in that, The microwave treatment is carried out in an air atmosphere or an inert atmosphere.
4. The preparation method according to claim 1, characterized in that, Before the step of performing microwave treatment on the conductive paste on the solar cell wafer, it further includes: Performing preheating treatment on the solar cell wafer on which the conductive paste is formed.
5. The preparation method according to claim 4, characterized in that, The heating method of the preheating treatment is one or a combination of more of resistance heating, infrared heating, and electromagnetic heating; and / or, The preheating temperature of the preheating treatment is 100 °C to 400 °C, and the preheating time is less than or equal to 150 s; and / or, The time of the preheating treatment is longer than the time of the microwave treatment.
6. The preparation method according to claim 1, wherein After the step of performing microwave treatment on the conductive paste on the solar cell wafer, it further includes: Performing ultraviolet light irradiation treatment on the conductive paste on the solar cell wafer.
7. The preparation method according to claim 6, characterized in that, During the ultraviolet light irradiation treatment, the wavelength of the ultraviolet light is 315 nm to 400 nm; and / or, The treatment time of the ultraviolet light irradiation treatment is less than or equal to 5 s.
8. A method for preparing a solar cell, characterized in that, Comprising: Performing one or more metallization processes on a solar cell wafer, in each of the metallization processes, forming a conductive paste on the light-receiving surface and / or the backlight surface of the solar cell wafer, and performing curing treatment on the conductive paste; Wherein, in at least one of the metallization processes, the preparation method according to any one of claims 1 to 7 is used to cure the conductive paste.
9. The preparation method according to claim 8, characterized in that, In each of the metallization processes, the preparation method according to any one of claims 1 to 7 is used to cure the conductive paste.
10. The preparation method according to claim 8, wherein Comprising: Performing three metallization processes on a solar cell wafer, in each of the metallization processes, forming a conductive paste on the light-receiving surface and / or the backlight surface of the solar cell wafer, and performing curing treatment on the conductive paste. Wherein, in each of the metallization processes, the preparation method according to any one of claims 1 to 7 is used to cure the conductive paste.
11. According to the preparation method described in claim 8, characterized in that, It further includes: After completing all the metallization processes, performing sintering treatment on the conductive paste on the solar cell wafer.
12. A solar cell, characterized in that, Prepared by using the preparation method according to any one of claims 1 to 7 or the preparation method according to any one of claims 8 to 11.
13. A photovoltaic module, characterized in that, Comprising the solar cell according to claim 12.