Carbon nanotube composite silver paste fine grid partition printing method
By using a carbon nanotube composite silver paste partition printing method, a balance between silver-silicon ohmic contact and passivation layer protection is achieved, reducing the production cost of photovoltaic cells and improving cell performance. This method is applicable to various cell structures such as PERC, TOPCon, and HJT.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 宜宾英发德耀科技有限公司
- Filing Date
- 2026-03-12
- Publication Date
- 2026-06-05
AI Technical Summary
Crystalline silicon photovoltaic cells have high production costs, and there is a significant conflict between silver-silicon contacts and passivation layers. Existing processes struggle to balance cost reduction and performance improvement.
Carbon nanotube-silver composite paste is used for partitioned printing. Conventional silver paste is used for ohmic contact and current conduction, while carbon nanotube-silver composite paste is used for current transmission. This avoids damaging the passivation layer and optimizes the connection method to reduce the amount of silver used.
It reduces the cost of precious metals in photovoltaic cells, improves the photoelectric conversion efficiency of cells, resolves the contradiction between silver-silicon contacts and passivation layers, and is suitable for cell structures with various passivation methods.
Smart Images
Figure CN122161203A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of crystalline silicon photovoltaic cell technology, specifically a method for printing fine grid sections using carbon nanotube composite silver paste. Background Technology
[0002] Currently, crystalline silicon photovoltaic cells generally use silver paste to prepare grid electrodes, relying on the grid lines to collect photogenerated carriers generated inside the cell and conduct them to form current. However, silver is a precious metal with a high price, and the secondary grid of the cell requires a large amount of silver paste. In order to ensure the efficiency of carrier collection, it is difficult to significantly reduce the amount of silver paste used under the current process, resulting in high cell production costs. This has become one of the core bottlenecks restricting the cost reduction and efficiency improvement of photovoltaic cells. Photovoltaic cells are characterized by high manufacturing costs and limited profit margins for industrial scale.
[0003] Furthermore, the contradiction between silver-silicon contact and passivation is quite prominent: the core function of the passivation layer is to suppress carrier recombination, but for silver-silicon to achieve good ohmic contact, the passivation layer must be etched and destroyed to collect carriers. Once the passivation layer is damaged over a large area, surface recombination surges, and the Voc drops significantly, leading to a decline in battery performance. This is even more pronounced in high-efficiency batteries such as TOPCon and HJT, severely limiting their performance release. Base metals cannot effectively replace silver paste: base metals such as copper and aluminum have poor compatibility with silicon wafers, making it difficult to form stable ohmic contacts. They are also prone to oxidation, have low carrier mobility, and increasing the grid line cross-sectional area will increase light-blocking losses. They also have poor compatibility with existing processes, exacerbating the contradiction between contact and passivation, making it impossible to balance cost reduction and performance. Therefore, using pastes made of inexpensive, high-mobility materials to improve traditional screen printing methods has become an urgent and feasible path to overcome industry bottlenecks.
[0004] Based on this, a method for printing fine grid partitions of carbon nanotube composite silver paste is provided, which can eliminate the drawbacks of existing technical solutions. Summary of the Invention
[0005] The purpose of this invention is to provide a method for printing fine grids of carbon nanotube composite silver paste to solve the problems of high battery production cost and prominent contradiction between silver-silicon contact and passivation in the prior art.
[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for partitioned printing of carbon nanotube composite silver paste is applied to the preparation of sub-grid electrodes in crystalline silicon photovoltaic cells. The method uses conventional silver paste and carbon nanotube-silver composite paste to perform partitioned printing in the sub-grid region. The partition printing method specifically includes the following steps: Step S1: Prepare conventional silver paste and carbon nanotube-silver composite paste; Step S2: The sub-busbar region of the crystalline silicon photovoltaic cell is divided into a conventional silver paste printing area and a carbon nanotube-silver composite paste printing area. The conventional silver paste printing area is used to achieve ohmic contact of the silicon wafer and conduct current, while the carbon nanotube-silver composite paste printing area is used for current transmission. Step S3: The two printing areas are printed in two steps using a printing process. First, the conventional silver paste printing area is printed to form a contact structure, and then the carbon nanotube-silver composite paste printing area is printed to form a current transmission structure, so that the two printing areas form an electrically connected sub-gate electrode structure.
[0007] Furthermore, the carbon nanotube-silver composite slurry is composed of the following components by weight: silver content of 75-85 wt%, carbon nanotube content of 1-8 wt%, glass powder content of 0-5 wt%, and organic carrier content of 7-10 wt%, and the carbon nanotube-silver composite slurry is prepared by mixing, grinding, and filtering.
[0008] Furthermore, the two printing areas are connected in a unidirectional splicing or superimposed vertically.
[0009] Furthermore, when the two printing areas are connected in a superimposed manner, the conventional silver paste printing area serves as a seed layer to form an ohmic contact with the silicon wafer, and the carbon nanotube-silver composite paste printing area covers the conventional silver paste seed layer to achieve the current transmission effect.
[0010] Furthermore, the length ratio of the carbon nanotube-silver composite paste printing area to the conventional silver paste printing area is set to 1:1 to 4:1.
[0011] Furthermore, the preparation method of the sub-gate electrode is any one or a combination of single-wire printing, inkjet printing, laser transfer, and mask patterning.
[0012] Furthermore, the front and back main grids and the front sub-grid of the crystalline silicon photovoltaic cell are printed using a conventional one-step silver paste printing operation, while the back sub-grid is printed using the partitioned printing method.
[0013] Furthermore, the crystalline silicon photovoltaic cell is any one of PERC, TOPCon, XBC, HJT cells or perovskite photovoltaic devices.
[0014] Furthermore, the carbon nanotubes are carboxylated modified carbon nanotubes.
[0015] Furthermore, in step S3, a pre-drying and high-temperature sintering operation is performed after printing. The pre-drying temperature is 120~150℃ and the time is 1~5min.
[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for partitioned printing of carbon nanotube-silver composite paste in the sub-grid region. By introducing carbon nanotube-silver composite paste into the sub-grid region, the carbon nanotube-silver composite paste and conventional silver paste are used for partitioned printing in the sub-grid region of the photovoltaic cell. The conventional silver paste printing area achieves silver-silicon ohmic contact and conducts current, while the carbon nanotube-silver composite paste printing area only undertakes the function of current transmission without damaging the passivation layer structure. At the same time, the formulation of carbon nanotube-silver composite paste and the partitioned connection form are optimized to achieve the effect of reducing silver paste usage and improving the photoelectric conversion efficiency of the battery. It is suitable for battery applications with different structures and multiple passivation methods. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the method steps of the present invention.
[0018] Figure 2 This is a schematic diagram of the printing process of the present invention.
[0019] Figure 3 This is a schematic diagram of the structure of the CNTs-Ag hybrid fine gate of the present invention.
[0020] Figure 4 This is a schematic diagram of the Ag seed layer and CNTs-Ag outer electrode structure of the present invention.
[0021] Figure 5 This is a schematic diagram of a standard printing process.
[0022] Figure 6 This is a schematic diagram of a conventional fine grid structure.
[0023] Figure label annotation: N-type silicon wafer 10, SiO x / poly-Si passivated contact layer 20, Si x N y Antireflection layer 30, Ag seed layer 40, CNTs-Ag outer layer 50. [1][2] Detailed Implementation
[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.
[0025] To address the technical problems of high silver consumption and the conflict between silver-silicon contact and passivation layer protection in traditional silver paste printing, this invention proposes a carbon nanotube composite silver paste fine-grid partitioning printing method. This method solves the technical pain points of traditional silver paste printing through functional partitioning and material adaptation. Figures 1-4As shown, this partitioned printing method is applied to the preparation of sub-gate electrodes for crystalline silicon photovoltaic cells. Conventional silver paste and carbon nanotube-silver composite paste are used for partitioned printing in the sub-gate area. Conventional silver paste refers to the standard silver paste used in the field for preparing photovoltaic cell electrodes, which usually contains a high content of silver powder, glass powder and organic carrier. The sub-gate is a fine grid line relative to the main grid. The zone printing method specifically includes the following steps: Step S1: Prepare conventional silver paste and carbon nanotube-silver composite paste; Step S2: The sub-busbar region of the crystalline silicon photovoltaic cell is divided into a conventional silver paste printing area and a carbon nanotube-silver composite paste printing area. The conventional silver paste printing area is used to realize the ohmic contact of the silicon wafer and conduct current, while the carbon nanotube-silver composite paste printing area is used for current transmission. The conventional silver paste printing area and the carbon nanotube-silver composite paste printing area are electrically connected through a predetermined connection method. Step S3: The two printing areas are printed in two steps using a printing process. First, a conventional silver paste printing area is printed to form a contact structure. Then, a carbon nanotube-silver composite paste printing area is printed to form a current transmission structure. Conventional silver paste is used to form the sub-grid segment of the printing area through screen printing. The screen mesh is 400-500 mesh. After printing, pre-drying is performed at a temperature of 120-150℃ for 1-5 minutes to remove volatile components from the organic carrier. Carbon nanotube-silver composite paste is used to form the sub-grid segment through screen printing. This sub-grid segment is unidirectionally spliced or superimposed with the sub-grid segment of the printing area in the first step. The printing parameters are the same as in the first step. After pre-drying, high-temperature sintering is performed. After natural cooling, a complete sub-grid electrode is formed, so that the two printing areas form an electrically connected sub-grid electrode structure. After the sub-grid is printed in sections, the main grid is printed using conventional silver paste. The main grid and the sub-grid form an electrical connection, completing the overall preparation of the battery electrode. Specifically, the carbon nanotube-silver composite slurry is composed of the following components by weight: silver content of 75-85 wt%, carbon nanotube content of 1-8 wt%, glass powder content of 0-5 wt%, and organic carrier content of 7-10 wt%. The carbon nanotube-silver composite slurry is prepared by mixing, grinding, and filtering. The preparation steps of carbon nanotube-silver composite paste are as follows: Carbon nanotubes are modified by carboxylation to improve their dispersibility with silver powder and organic carrier. Spherical nano-silver powder with a particle size of 1~5μm is selected as the silver powder. Low melting point borosilicate glass powder is selected as the glass powder. The organic carrier is a mixture of terpineol, ethyl cellulose and dispersant in a mass ratio of 85:10:5. Ag powder, modified CNTs, glass powder and organic carrier are weighed according to the above component ratio and added to a ball mill to make the components uniformly dispersed. The ground paste is filtered through a filter screen to remove large particle impurities and then degassed for 10~20 minutes to obtain carbon nanotube-silver composite paste that meets the requirements of printing process. Specifically, the connection between the two printing areas is either unidirectional splicing or superimposed. When the connection between the two printing areas is superimposed, the conventional silver paste printing area serves as a seed layer to form an ohmic contact with the silicon wafer, and the carbon nanotube-silver composite paste printing area covers the conventional silver paste seed layer to achieve the current transmission effect. Specifically, the length ratio of the carbon nanotube-silver composite paste printing area to the conventional silver paste printing area is set to 1:1 to 4:1. The component ratio, partition length ratio, and connection form of the CNTs-Ag composite paste can be adjusted according to the battery performance requirements. For example, for high-power batteries, the amount of CNTs added can be increased to 4wt%, and for low-cost batteries, the length ratio of the composite paste to the conventional silver paste can be increased to 3:1. Specifically, the secondary gate electrode can be fabricated using any one or more of the following methods: single-wire printing, inkjet printing, laser transfer, and mask patterning. Specifically, the crystalline silicon photovoltaic cell is any one of PERC, TOPCon, XBC, HJT cells or perovskite photovoltaic devices. The partition printing method of the present invention can be directly adapted to existing photovoltaic cell production equipment such as screen printing, laser transfer printing, and inkjet printing without large-scale production line modification. The equipment adaptation cost is low, and the process parameters can be adjusted according to different cell structures and passivation methods, making it widely applicable. Specifically, the front and back main grids and the front sub-grid of the crystalline silicon photovoltaic cell are printed using a conventional one-step silver paste printing operation, while the back sub-grid is printed using a partitioned printing method. Specifically, in step S3, after printing, pre-drying and high-temperature sintering operations are performed. The pre-drying temperature is 120~150℃ and the time is 1~5min. Specifically, this invention replaces part of the conventional silver paste with a carbon nanotube-silver composite paste, reducing the silver content in the carbon nanotube-silver composite paste to 75-85 wt%. Furthermore, the printing area does not require silver-silicon contact, which can further reduce the cross-sectional area of the grid lines. Since the electron mobility of carbon nanotubes is higher than that of silver, the carbon nanotube-silver composite paste improves the sub-grid current transmission efficiency. At the same time, the partitioned printing avoids contact between the silver paste in the printing area and the passivation layer, resulting in more stable performance over long-term use. Compared with traditional processes, this invention reduces the precious metal cost of photovoltaic cells.
[0026] Regarding the above-mentioned invention, the following will describe it in conjunction with specific embodiments and comparative examples. The partition printing method of the present invention can be applied to PERC, TOPCon, XBC, HJT cells or perovskite photovoltaic devices. The preparation method is screen printing. The present invention uses TOPCon crystalline silicon photovoltaic cells for electrical performance verification.
[0027] Example 1 In this embodiment, as Figures 1-4As shown, a carbon nanotube composite silver paste fine grid partition printing method is applied to the preparation of sub-grid electrodes of crystalline silicon photovoltaic cells. Conventional silver paste (Ag) and carbon nanotube-silver composite paste (CNTs-Ag) are used to perform partition printing in the sub-grid area. The zone printing method specifically includes the following steps: Step S1: Prepare conventional silver paste and carbon nanotube-silver composite paste; Step S2: The sub-busbar region of the crystalline silicon photovoltaic cell is divided into a conventional silver paste printing area and a carbon nanotube-silver composite paste printing area. The conventional silver paste printing area is used to realize the ohmic contact of the silicon wafer and conduct current, while the carbon nanotube-silver composite paste printing area is used for current transmission. Step S3: The two printing areas are printed in two steps using a printing process. First, the conventional silver paste printing area is printed to form a contact structure, and then the carbon nanotube-silver composite paste printing area is printed to form a current transmission structure, so that the two printing areas form an electrically connected sub-gate electrode structure. The length ratio of the carbon nanotube-silver composite paste printing area to the conventional silver paste printing area was set to 1:1, and the carbon nanotube (CNTs) content in the carbon nanotube-silver composite paste was 2wt%.
[0028] Example 2 In this embodiment, as Figures 1-4 As shown, a carbon nanotube composite silver paste fine grid partition printing method is applied to the preparation of sub-grid electrodes of crystalline silicon photovoltaic cells. Conventional silver paste and carbon nanotube-silver composite paste are used to perform partition printing in the sub-grid area. The partition printing method is consistent with the steps and parameters in Example 1, except that the carbon nanotube content in the carbon nanotube-silver composite paste is adjusted to 4wt%.
[0029] Example 3 In this embodiment, as Figures 1-4 As shown, a carbon nanotube composite silver paste fine grid partition printing method is applied to the preparation of sub-grid electrodes of crystalline silicon photovoltaic cells. Conventional silver paste and carbon nanotube-silver composite paste are used to perform partition printing in the sub-grid area. The partition printing method is the same as the steps and parameters in Example 1, except that the carbon nanotube content in the carbon nanotube-silver composite paste is adjusted to 8wt%.
[0030] Example 4 In this embodiment, as Figures 1-4 As shown, a carbon nanotube composite silver paste fine grid partition printing method is applied to the preparation of sub-grid electrodes of crystalline silicon photovoltaic cells. Conventional silver paste and carbon nanotube-silver composite paste are used to perform partition printing in the sub-grid area. The partition printing method is consistent with the steps and parameters in Example 2, except that the length ratio of the carbon nanotube-silver composite paste printing area to the conventional silver paste printing area is adjusted to 2:1.
[0031] Example 5 In this embodiment, as Figures 1-4 As shown, a carbon nanotube composite silver paste fine grid partition printing method is applied to the preparation of sub-grid electrodes of crystalline silicon photovoltaic cells. Conventional silver paste and carbon nanotube-silver composite paste are used for partition printing in the sub-grid area. The partition printing method is consistent with the steps and parameters in Example 2, except that the length ratio of the carbon nanotube-silver composite paste printing area to the conventional silver paste printing area is adjusted to 3:1.
[0032] Example 6 In this embodiment, as Figures 1-4 As shown, a carbon nanotube composite silver paste fine grid partition printing method is applied to the preparation of sub-grid electrodes of crystalline silicon photovoltaic cells. Conventional silver paste and carbon nanotube-silver composite paste are used to perform partition printing in the sub-grid area. The partition printing method is consistent with the steps and parameters in Example 2, except that the length ratio of the carbon nanotube-silver composite paste printing area to the conventional silver paste printing area is adjusted to 4:1.
[0033] Example 7 In this embodiment, as Figures 1-4 As shown, a carbon nanotube composite silver paste fine grid partition printing method is applied to the fabrication of sub-grid electrodes in crystalline silicon photovoltaic cells. Conventional silver paste and carbon nanotube-silver composite paste are used for partition printing in the sub-grid region. The partition printing method is consistent with the steps and parameters in Example 1, except that the connection form of the printed areas is adjusted to be stacked vertically. The conventional silver paste printing area serves as a seed layer to form an ohmic contact with the silicon wafer, and the carbon nanotube-silver composite paste printing area covers the conventional silver paste seed layer to achieve current transmission. The cross-section of the printed pattern is shown in the figure. Figure 4 As shown, the carbon nanotube (CNT) content in the carbon nanotube-silver composite paste is 4 wt%.
[0034] Comparative Example 1 In this comparative example, such as Figure 5 and Figure 6 As shown, this comparative example uses a traditional process, with continuous line printing of conventional silver paste in the sub-gate area in one step. The printing process is as follows: Figure 5 As shown, the fine grid structure is as follows Figure 6 As shown.
[0035] Comparing the above embodiments with the comparative examples: In embodiments 1-6, the connection form of the sub-grid region is unidirectional splicing; in embodiment 7, the connection form of the sub-grid region is vertical stacking; in embodiments 1-3, the length ratio of the two regions in the carbon nanotube-silver composite paste is fixed at 1:1; the CNT content in the carbon nanotube-silver composite paste is adjusted according to the above paste ratio, and the corresponding Ag content is reduced; in embodiments 4-6, the carbon nanotube content in the carbon nanotube-silver composite paste is a fixed value of 4wt%; in comparative example 1, the main grid and sub-grid on the front and back of the battery are printed using traditional processes, and the sub-grid on one side is printed in one step (e.g., ...). Figure 5 As shown), the sub-gate line type is continuous (such as...) Figure 6 As shown), in the above embodiment, the sub-gate area is printed in two steps (as shown). Figure 1 and Figure 2 As shown), sub-grid line splicing or top and bottom overlay (such as...) Figure 3 and Figure 6 (as shown) To further demonstrate the application value of the partitioned printing method in this invention, the TOPCon photovoltaic cells prepared in the examples and comparative examples were subjected to performance tests. The test results are shown in Table 1. Eta is the conversion efficiency, Isc is the short-circuit current, Voc is the open-circuit voltage, FF is the fill factor, and Count is the quantity. Table 1 - Schematic diagram of electrical performance parameters for examples and comparative examples
[0036] According to the table above, to characterize the efficiency gain obtained by the partition printing method in this invention, the efficiency of the battery prepared using the partition printing method in this invention was tested, and the test data were summarized in Table 1. In Examples 1 to 3, the conventional slurry and composite slurry in the sub-grid area were spliced in one direction, and the carbon nanotube content in the carbon nanotube-silver composite slurry was adjusted. By comparing the battery performance parameters with those of Comparative Example 1, it can be concluded that the carbon nanotube-silver composite slurry can improve the short-circuit current and open-circuit voltage. The battery efficiency of Example 2 was improved by 0.05% compared with Comparative Example 1. In Examples 4 to 6, the carbon nanotube content in the carbon nanotube-silver composite slurry was adjusted, and the ratio of the conventional slurry and carbon nanotube-silver composite slurry in the sub-grid area was adjusted to further optimize the sub-grid pattern distribution of the composite slurry and the conventional slurry. In Example 4, both the open-circuit voltage and short-circuit current were improved, and the final battery efficiency was improved by 0.1% compared with Comparative Example 1. In Example 7, the conventional slurry was used as the seed layer, and the sub-grid composite slurry and conventional slurry areas were connected and covered from top to bottom, which improved the short-circuit current compared with Comparative Example 1, and the battery efficiency was 0.03%. To further demonstrate the practical effect of the partitioned printing method in this invention, a visual representation of the partitioned printing method is provided, such as... Figures 1-6 As shown; Figure 2 The following is a flowchart of the photovoltaic cell sub-busbar printing process of the present invention. The two-step partitioned printing process of the present invention is as follows: front main busbar printing → front sub-busbar printing area (conventional silver paste) printing → front sub-busbar printing area (CNTs-Ag composite paste) printing → back main busbar printing → back sub-busbar partitioned printing. The present invention splits the traditional one-step printing of front and back sub-busbars into two-step partitioned printing. The remaining steps are consistent with the traditional process, ensuring process compatibility. Figure 3This is a schematic diagram of the CNTs-Ag hybrid fine grid structure of the photovoltaic cell of the present invention. The diagram shows a linear grid line spliced in sections. The grid line is composed of alternating Ag segments (conventional silver paste printing area) and CNTs-Ag segments (composite paste printing area). The two grid lines are seamlessly spliced to form a complete current transmission path. Only the Ag segment contacts the passivation layer, while the CNTs-Ag segment does not contact the passivation layer, thus achieving local protection of the passivation layer. Figure 4 This diagram shows the cross-sectional structure of the Ag seed layer and the CNTs-Ag outer electrode. Taking the back of a TOPCon cell as an example, it illustrates the cross-section of the sub-gate electrode with a stacked connection. The structure from bottom to top is: N-type silicon wafer 10 → SiO x / poly-Si passivated contact layer 20→Si x N y Antireflection layer 30 → Ag seed layer 40 (conventional silver paste) → CNTs-Ag outer layer 50, N-type silicon wafer 10 is the photovoltaic cell substrate used to generate photogenerated carriers, SiO x / poly-Si passivated contact layer 20, Si x N y The antireflection layer 30 is used to passivate the silicon wafer surface and reduce light reflection. SiO enables selective passage of charge carriers, while poly-Si enhances electron transport and prevents direct contact between silver and the silicon substrate, reducing recombination. The Ag seed layer 40 is prepared using conventional silver paste. The Ag seed layer 40 is only a thin layer with a small amount of silver paste, forming a low-resistance ohmic contact with the silicon wafer to guide photogenerated charge carriers, serving as the contact end for current transmission. The CNTs-Ag outer layer 50 covers the outside of the Ag seed layer and does not contact the passivation layer, achieving full protection of the passivation layer. Only the current guided by the Ag seed layer 40 is transmitted to the main gate, serving as the transmission end for current transmission. At the same time, the high mobility of carbon nanotubes is used to improve the transmission efficiency. Figure 5 The flowchart shows the traditional photovoltaic cell sub-busbar printing process. The conventional one-step silver paste printing process is as follows: front main busbar printing → front sub-busbar one-step printing → back main busbar printing → back sub-busbar one-step printing. Both the front and back sub-busbars are formed into a continuous line through one printing, without partition design. This process uses a large amount of silver paste, and the sub-busbars damage the passivation layer silver silicon contact over a large area, increasing the recombination. Figure 6 This is a schematic diagram of a traditional photovoltaic cell fine grid structure. The traditional fine grid structure consists of continuous, uninterrupted linear grid lines. The entire grid line is made of conventional silver paste. The grid lines disrupt the large-area contact between the silver and silicon in the silicon wafer passivation layer, leading to increased carrier recombination. In summary, this invention achieves functional separation of the contact and transmission ends through the partitioned printing of conventional silver paste and CNTs-Ag composite paste. The conventional silver paste area completes the silver-silicon ohmic contact and carrier extraction, while the CNTs-Ag composite paste area only undertakes the current transmission function without damaging the passivation layer structure. This fundamentally solves the inherent contradiction between silver-silicon contact and passivation. Furthermore, this invention reduces the consumption of precious metal silver by optimizing the CNTs-Ag composite paste formulation and connection method, making it easy to adapt to various battery and device structures such as PERC, TOPCon, HJT, and perovskite, and has good application prospects.
[0037] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A method for printing carbon nanotube composite silver paste in a fine grid pattern, characterized in that, For the fabrication of sub-gate electrodes used in crystalline silicon photovoltaic cells, conventional silver paste and carbon nanotube-silver composite paste are used for partitioned printing in the sub-gate region; The partition printing method specifically includes the following steps: Step S1: Prepare conventional silver paste and carbon nanotube-silver composite paste; Step S2: The sub-busbar region of the crystalline silicon photovoltaic cell is divided into a conventional silver paste printing area and a carbon nanotube-silver composite paste printing area. The conventional silver paste printing area is used to achieve ohmic contact of the silicon wafer and conduct current, while the carbon nanotube-silver composite paste printing area is used for current transmission. Step S3: The two printing areas are printed in two steps using a printing process. First, the conventional silver paste printing area is printed to form a contact structure, and then the carbon nanotube-silver composite paste printing area is printed to form a current transmission structure, so that the two printing areas form an electrically connected sub-gate electrode structure.
2. The method for printing carbon nanotube composite silver paste fine grid partitions according to claim 1, characterized in that, The carbon nanotube-silver composite slurry is composed of the following components by weight: silver content of 75-85 wt%, carbon nanotube content of 1-8 wt%, glass powder content of 0-5 wt%, and organic carrier content of 7-10 wt%. The carbon nanotube-silver composite slurry is prepared by mixing, grinding, and filtering.
3. The method for printing carbon nanotube composite silver paste in a fine grid pattern according to claim 1, characterized in that, The two printing areas are connected either by unidirectional splicing or by overlapping.
4. The method for printing carbon nanotube composite silver paste fine grid partitions according to claim 3, characterized in that, When the two printing areas are connected in a superimposed manner, the conventional silver paste printing area serves as a seed layer to form an ohmic contact with the silicon wafer, and the carbon nanotube-silver composite paste printing area covers the conventional silver paste seed layer to achieve the current transmission effect.
5. The method for printing carbon nanotube composite silver paste fine grid partitions according to claim 1, characterized in that, The length ratio of the carbon nanotube-silver composite paste printing area to the conventional silver paste printing area is set to 1:1 to 4:
1.
6. The method for printing carbon nanotube composite silver paste fine grid partitions according to claim 1, characterized in that, The secondary gate electrode is prepared by any one or a combination of single-wire printing, inkjet printing, laser transfer, and mask patterning.
7. The method for printing carbon nanotube composite silver paste fine grid partitions according to claim 1, characterized in that, The front and back main grids and the front sub-grid of the crystalline silicon photovoltaic cell are printed using a conventional one-step silver paste printing operation, while the back sub-grid is printed using the partitioned printing method.
8. The method for printing carbon nanotube composite silver paste fine grid partitions according to claim 1, characterized in that, The crystalline silicon photovoltaic cell is any one of PERC, TOPCon, XBC, HJT cells or perovskite photovoltaic devices.
9. The method for printing carbon nanotube composite silver paste fine grid partitions according to claim 1, characterized in that, The carbon nanotubes are carboxylated modified carbon nanotubes.
10. The method for printing carbon nanotube composite silver paste fine grid partitions according to claim 1, characterized in that, In step S3, after printing, pre-drying and high-temperature sintering are performed. The pre-drying temperature is 120~150℃ and the time is 1~5min.