Photovoltaic cell double-side-edge coating equipment and coating method

Abstract

The invention discloses photovoltaic cell double-side-edge coating equipment and a coating method. The photovoltaic cell double-side-edge coating equipment comprises a furnace body, wherein a reaction furnace tube is arranged in the furnace body; a gas inlet and a gas extraction opening are respectively formed in two ends of the reaction furnace tube; a carrier with a discharging function is arranged in the reaction furnace tube, the carrier is connected to an external power supply through an electrode stem, and a battery piece is placed in the carrier; and after the power supply is switched on, an alternating electric field is formed between the cutting surface of the battery piece and the carrier, so that the process gas in the reaction furnace tube is ionized to form plasmas, and the edge passivation of the battery piece is realized. The device has the advantages of being compact in structure, convenient to operate, high in reliability and the like, passivation layer coating can be carried out on the edge of a battery piece with a single / double cutting face through optimization design of the reaction cavity and the carrier, a good passivation effect is achieved, passivation film layers such as PECVD deposition silicon nitride, silicon oxide and amorphous silicon can be considered at the same time only by replacing a gas source, and the production cost is reduced. And PEALD deposition of aluminum oxide can also be considered.

Description

Technical Field

[0001] This invention relates to the field of semiconductor fabrication technology, and specifically to a photovoltaic cell double-sided coating equipment and coating method. Background Technology

[0002] The use of half-cell cells for module encapsulation has become mainstream in the photovoltaic industry. Manufacturing modules with half-cell cells offers numerous advantages, such as reduced module current, lower resistance losses, higher module voltage, and increased module output power. As the power requirements for modules increase, three-cell and four-cell cell technologies have emerged based on half-cell technology. Existing multi-slicing technologies mainly fall into two categories: one involves slicing the silicon wafer at the wafer end, with subsequent processes all being half-cell or multi-slice production. This approach, limited by automation and screen printing, has a relatively large impact on production capacity. The other approach involves producing the entire wafer first, followed by laser slicing after cell fabrication, which has a relatively smaller impact on production capacity. However, the second half-cell technology requires slicing the entire cell, which damages the edges, increasing edge recombination and affecting parameters such as open-circuit voltage (Voc) and fill factor (FF), ultimately reducing cell efficiency. Edge passivation technology was developed to address these issues by passivating the cut edges, repairing damage, and restoring the cell's performance.

[0003] Currently, edge passivation technology for half-cell batteries is relatively mature. The mainstream approach in the market is to use ALD (Atomic Layer Deposition) to deposit alumina and passivate the cut surfaces. PECVD and HWCVD (Hot Wire CVD) technologies are also used for edge passivation. The ALD alumina deposition temperature is generally between 150 and 300°C, and the alumina needs annealing to achieve optimal passivation. If the annealing temperature is too low, the passivation effect will be weakened; if the annealing temperature is too high, it will affect other aspects of battery performance. Furthermore, because ALD is an atomic layer deposition technology, deposition is self-limiting, resulting in a relatively slow deposition rate. This leads to a longer ALD process time and higher gas consumption costs compared to PECVD. Although the long process time can be compensated for by increasing the wafer load, prolonged dark annealing (>2 hours) at 150–300°C can also cause other problems. PECVD technology has a shorter process time, lower gas consumption, and slightly better overall operating costs than ALD. However, existing PECVD technologies require consideration of discharge, making the process more complex than ALD. Moreover, most PECVD technology solutions on the market are designed for the edge passivation of half a cell (one cut edge). If the current mainstream technology is adopted, one side needs to be passivated first, and then the cell direction needs to be reversed to passivate the other side. This increases the automation of flipping and lengthens the process time, which will have a certain impact on production capacity, cell efficiency and yield. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that edge passivation technology is difficult to adapt to the requirements of multi-sided passivation of solar cells. The invention provides a photovoltaic cell double-sided coating equipment and coating method that is simple in principle, easy to operate and conducive to improving production capacity.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A photovoltaic cell double-sided coating equipment includes a furnace body with an internal reaction furnace tube; the two ends of the reaction furnace tube are respectively provided with an air inlet and an air outlet; a carrier with a discharge function is provided inside the reaction furnace tube, and the carrier is connected to an external power source through an electrode rod, and the solar cell is placed inside the carrier; when the power is turned on, an alternating electric field is formed between the cut surface of the solar cell and the carrier, which ionizes the process gas inside the reaction furnace tube to form plasma, thereby achieving edge passivation of the solar cell.

[0006] As a further improvement of the present invention, the carrier includes a boat support, a material box, and an outer electrode plate and an inner electrode plate spaced apart. The ends of the outer electrode plate and the inner electrode plate are connected to the electrode rod through conductive blocks, and the potentials of the outer electrode plate and the inner electrode plate are opposite. The material box is placed in the groove formed by the inner electrode plate and the boat support, and the cut surface of the battery cell faces the inner electrode plate and has the same potential as the inner electrode plate. When the power is turned on, an alternating electric field is formed between the cut surface of the battery cell and the outer electrode plate, and between the outer electrode plate and the inner electrode plate.

[0007] As a further improvement of the present invention, the opposite sides of the material box are provided with a through structure, and the inner electrode plate is provided with a plurality of hollow through holes. The battery cells are stacked in the material box, and the cut surface of the battery cells faces the hollow through holes of the inner electrode plate.

[0008] As a further improvement of the present invention, the cut surface of the battery cell is spaced 0-10 mm from the inner electrode plate.

[0009] As a further improvement of the present invention, the outer electrode plate and the inner electrode plate are connected by an insulating ring and a connecting rod.

[0010] As a further improvement of the present invention, the outer electrode plate and the inner electrode plate are spaced 5 to 50 mm apart.

[0011] As a further improvement of the present invention, the bottom of the boat support is provided with multiple positioning frames to fix the position of the material box.

[0012] As a general technical concept, the present invention also provides a coating method based on the above-mentioned photovoltaic cell double-sided coating equipment, comprising the following steps: Step S1: After the solar cells are cut, they are placed horizontally in the material box and stacked into a stack. The cut edge of the solar cell faces the through side of the material box. A cover plate is placed on the top solar cell in the material box to prevent plating around. Then, multiple material boxes are placed on the boat support and the carrier is sent into the reactor tube. Step S2: The temperature of the reactor tube is raised to 120℃~300℃ and evacuated to a vacuum state; Step S3: Introduce hydrogen gas to perform hydrogen plasma pretreatment on the cut surface of the battery cell; Step S4: Deposit an intrinsic hydrogenated amorphous silicon layer or an oxygen-doped amorphous silicon layer as the first passivation layer; Step S5: Deposit an intrinsic amorphous silicon layer or an intrinsic amorphous silicon layer plus a doped amorphous silicon layer as a second passivation layer; Step S6: Introduce hydrogen gas to perform hydrogen plasma pretreatment on the deposited second passivation layer; Step S7: Deposit silicon oxide or silicon nitride as a mask layer; Step S8: Remove the carrier and unload the materials, and test and classify the battery cells.

[0013] As a further improvement of the present invention, in step S4, if an intrinsic hydrogenated amorphous silicon layer is deposited, pure silane is introduced as a reaction gas, the deposition pressure is 30-200 Pa, the radio frequency power is 100-6000 W, and the thickness of the deposited intrinsic hydrogenated amorphous silicon layer is 1-3 nm. If an oxygen-doped amorphous silicon layer is deposited, silane and carbon dioxide or nitrous oxide are introduced as reaction gases. The flow rate ratio of silane to carbon dioxide or nitrous oxide is 1 to 4:1, the deposition pressure is 30 to 200 Pa, the radio frequency power is 100 to 6000 W, and the thickness of the deposited oxygen-doped amorphous silicon layer is 2 to 5 nm.

[0014] As a further improvement of the present invention, in step S5, if an intrinsic amorphous silicon layer is deposited, silane is introduced as a reaction gas and hydrogen is introduced as a dilution gas. The deposition pressure is 30-200 Pa, the flow ratio of silane to hydrogen is 1:2-10, the radio frequency power is 100-5000 W, and the thickness of the deposited intrinsic amorphous silicon layer is 15-100 nm. If depositing intrinsic amorphous silicon plus doped amorphous silicon, first introduce silane as the reactant gas and hydrogen as the dilution gas. The deposition pressure is 30–200 Pa, the flow ratio of silane to hydrogen is 1:2–10, the RF power is 100–5000 W, and the thickness of the deposited intrinsic amorphous silicon layer is 5–20 nm. Then introduce silane, hydrogen, and phosphine. The deposition pressure is 30–200 Pa, the flow ratio of silane to hydrogen is 1:2–10, the flow ratio of silane to phosphine is 1–4:1, the RF power is 100–5000 W, and the thickness of the deposited doped amorphous silicon layer is 5–20 nm. Finally, deposit another layer of intrinsic amorphous silicon on the outer layer with a thickness of 5–60 nm.

[0015] Compared with the prior art, the advantages of the present invention are as follows: The photovoltaic cell double-sided coating equipment and method of the present invention have an air inlet and an air outlet at both ends of the reactor tube. A carrier with discharge function is installed inside the reactor tube, and the carrier is connected to an external power source via electrode rods. The solar cell is placed inside the carrier. When the power is turned on, an alternating electric field is formed between the cut surface of the solar cell and the carrier, causing the process gas inside the reactor tube to ionize and form plasma, thus achieving edge passivation of the solar cell. This invention features a compact structure, convenient operation, and high reliability. By optimizing the design of the reaction chamber and carrier, passivation layer coating can be applied to the edges of single / double-cut solar cells, achieving a good passivation effect, repairing damage, improving edge recombination, and restoring the performance of the solar cell. Furthermore, only the gas source needs to be replaced. It can simultaneously perform PECVD deposition of silicon nitride, silicon oxide, and amorphous silicon passivation films, and can also perform PEALD deposition of alumina, significantly increasing production capacity and reducing costs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram illustrating the structural principle of the photovoltaic cell double-sided coating equipment in a specific embodiment of the present invention; Figure 2 This is a schematic diagram of the structural principle of the vehicle in a specific embodiment of the present invention; Figure 3 This is a schematic diagram of the structural principle of the vehicle with the hidden outer electrode plate in a specific embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the structural principle of the boat support in a specific embodiment of the present invention; Figure 5 This is a schematic diagram illustrating the structural principle of the outer electrode plate in a specific embodiment of the present invention; Figure 6 This is a schematic diagram illustrating the structural principle of the inner electrode plate in a specific embodiment of the present invention; Figure 7 This is a schematic diagram of the process of coating both sides of a photovoltaic cell in a specific embodiment of the present invention.

[0017] Legend: 1. Furnace body; 2. Heating wire; 3. Furnace tube; 4. Gas inlet pipe; 5. Furnace door support; 6. Support rod; 7. Electrode rod; 8. Exhaust port; 9. Carrier; 10. Boat support; 101. Positioning frame; 11. Lower conductive graphite block; 12. Upper conductive graphite block; 13. Outer electrode plate; 131. First connecting plate; 132. Second connecting plate; 14. Inner electrode plate; 141. Third connecting plate; 142. Fourth connecting plate; 15. Material box; 16. Insulating support base; 17. Conductive support base; 18. Insulating ring; 19. Connecting rod. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0019] In the description of this invention, it should be understood that the terms "side", "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more unless otherwise explicitly specified.

[0021] Example 1 like Figure 1 and Figure 2 As shown, the photovoltaic cell double-sided coating equipment of the present invention includes a furnace body 1 with a reactor tube 3 inside, and a heating wire 2 is provided between the furnace body 1 and the reactor tube 3 to heat the reactor tube 3 and maintain the temperature required for the process. The reactor tube 3 is a quartz furnace tube or a stainless steel metal furnace tube. The front end of the reactor tube 3 is provided with an inlet pipe 4 and a furnace door support 5. The inlet pipe 4 is used to transport gas, and the furnace door support 5 cooperates with the furnace door to achieve a seal of the reactor tube 3. The rear end of the reactor tube 3 is provided with an exhaust port 8, which is connected to a vacuum pump through a pipeline to evacuate the reactor tube 3 and maintain stable process pressure. The reactor tube 3 is provided with a support rod 6 inside, which is used to support a carrier 9 with a discharge function. The carrier 9 is connected to an external power source through an electrode rod 7, and the cut solar cells are placed in the carrier 9. When the power is turned on, an alternating electric field is formed between the cut surface of the solar cell and the carrier 9, which ionizes the process gas in the reactor tube 3 to form plasma, thereby achieving edge passivation of the solar cells.

[0022] like Figure 2 and Figure 3As shown, the carrier 9 includes a boat support 10, a material box 15, and outer electrode plates 13 and inner electrode plates 14 spaced apart. The ends of the outer electrode plates 13 and inner electrode plates 14 are connected to the electrode rods 7 via conductive blocks. The outer electrode plates 13 and inner electrode plates 14 are spaced 5-50 mm apart, and their potentials are opposite. The material box 15 is placed in the groove formed by the inner electrode plates 14 and the boat support 10, with the cut surface of the battery cell facing the inner electrode plate 14 and having the same potential as the inner electrode plate 14. When the power is turned on, an alternating electric field is formed between the cut surface of the battery cell and the outer electrode plate 13, and between the outer electrode plate 13 and the inner electrode plate 14.

[0023] Furthermore, the conductive block includes a lower conductive graphite block 11 and an upper conductive graphite block 12. With the furnace opening of the reactor tube 3 as the front end and the furnace tail of the reactor tube 3 as the rear end, lower conductive graphite blocks 11 and upper conductive graphite blocks 12 are provided at both the front and rear ends of the boat support 10; as shown... Figure 5 As shown, the outer electrode plate 13 has a first connecting plate 131 and a second connecting plate 132 at its front and rear ends, respectively, with the first connecting plate 131 located below the outer electrode plate 13 and the second connecting plate 132 located above the outer electrode plate 13; Figure 6 As shown, the inner electrode plate 14 has a third connecting plate 141 and a fourth connecting plate 142 at its front and rear ends, respectively. The third connecting plate 141 is located above the inner electrode plate 14, and the fourth connecting plate 142 is located below the inner electrode plate 14. At the front end of the reactor tube 3, the first connecting plate 131 is connected to the lower conductive graphite block 11, and the third connecting plate 141 is connected to the upper conductive graphite block 12. An insulating support seat 16 is provided between the lower conductive graphite block 11 and the boat support 10 to achieve insulation between the boat support 10 and the lower conductive graphite block 11. The height of the lower conductive graphite block 11 is greater than the distance between the outer electrode plate 13 and the inner electrode plate 14 to prevent discharge between the inner and outer electrode plates and the boat support 10. At the rear end of the reactor tube 3, the lower conductive graphite block 11 and the upper conductive graphite block 12 are respectively connected to an electrode rod 7. The second connecting plate 132 is connected to the upper conductive graphite block 12, and the fourth connecting plate 142 is connected to the lower conductive graphite block 11. A conductive support seat 17 is provided between the lower conductive graphite block 11 and the boat support 10 to realize the conduction between the boat support 10 and the lower conductive graphite block 11. The height of the lower conductive graphite block 11 is greater than the distance between the outer electrode plate 13 and the inner electrode plate 14.

[0024] An outer electrode plate 13 and an inner electrode plate 14 form a set of discharge electrode plates. In this embodiment, a total of four sets of discharge electrode plates are provided. Each set of discharge electrode plates corresponds to a cut surface of the battery cell. Along the width direction of the carrier, two material boxes 15 can be placed at the same time, and both cut surfaces of the battery cell can be passivated, which significantly improves production capacity.

[0025] In this embodiment, the opposite sides of the material box 15 are designed as through structures, and the inner electrode plate 14 has multiple hollow through holes. The battery cells are stacked inside the material box 15, and the cut surfaces of the battery cells face the hollow through holes of the inner electrode plate 14, that is, the cut surfaces of the battery cells and the inner electrode plate 14 serve as electrodes with the same potential. Furthermore, the distance between the cut surfaces of the battery cells and the inner electrode plate 14 is 0-10 mm.

[0026] like Figure 2 As shown, the outer electrode plate 13 and the inner electrode plate 14 are connected by an insulating ring 18 and a connecting rod 19. The connecting rod 19 fixes the outer electrode plate 13 and the inner electrode plate 14 and provides support. The insulating ring 18 is used to fix the gap between the outer electrode plate 13 and the inner electrode plate 14 and to provide insulation. Specifically, both the insulating ring 18 and the connecting rod 19 can be made of ceramic material.

[0027] like Figure 4 As shown, the bottom of the boat support 10 is provided with multiple positioning frames 101. The size of the positioning frames 101 matches the bottom of the material box 15 so as to fix the position of the material box 15.

[0028] like Figure 7 As shown, this embodiment also provides a coating method based on the above-mentioned photovoltaic cell double-sided coating equipment, including the following steps: Step S1: After the solar cells are cut, they are placed horizontally in the material box 15 and stacked into a stack. The cut edge of the solar cell faces the through side of the material box 15. A cover plate is set on the top solar cell in the material box 15 to prevent plating. Then, multiple material boxes 15 are placed on the boat support 10 and the carrier 9 is sent into the reactor tube 3.

[0029] Step S2: The temperature of the reactor tube 3 is raised to 120℃~300℃ to ensure that the actual surface temperature of the battery cell is raised to 120℃~300℃, and the reactor tube 3 is evacuated to a vacuum state.

[0030] Step S3: Introduce hydrogen gas to perform hydrogen plasma pretreatment on the cut surface of the battery cell to remove the natural oxide layer and surface dirt. The hydrogen pretreatment pressure is 50-300 Pa, the radio frequency power is 100-5000 W, and the pretreatment time is 10-90 s.

[0031] Step S4: Deposit an intrinsic hydrogenated amorphous silicon layer as the first passivation layer to suppress the epitaxial growth of amorphous silicon. When depositing the intrinsic hydrogenated amorphous silicon layer, pure silane is introduced as the reaction gas, the deposition pressure is 30-200 Pa, the radio frequency power is 100-6000 W, and the thickness of the deposited intrinsic hydrogenated amorphous silicon layer is 1-3 nm.

[0032] In other embodiments, an oxygen-doped amorphous silicon layer may be deposited as the first passivation layer, in which case silane and carbon dioxide or nitrous oxide are introduced as the reaction gas, the flow rate ratio of silane to carbon dioxide or nitrous oxide is 1 to 4:1, the deposition pressure is 30 to 200 Pa, the radio frequency power is 100 to 6000 W, and the thickness of the deposited oxygen-doped amorphous silicon layer is 2 to 5 nm.

[0033] Step S5: Deposit an intrinsic amorphous silicon layer as the second passivation layer. Compared to the intrinsic amorphous silicon of the first passivation layer, the deposition rate is slower and the film is denser. During the deposition of the intrinsic amorphous silicon layer, silane is introduced as the reactive gas and hydrogen as the dilution gas. The deposition pressure is 30–200 Pa, the flow ratio of silane to hydrogen is 1:2–10, the RF power is 100–5000 W, and the thickness of the deposited intrinsic amorphous silicon layer is 15–100 nm.

[0034] In other embodiments, intrinsic amorphous silicon plus doped amorphous silicon can be deposited as the second passivation layer. In this case, silane is first introduced as the reactant gas and hydrogen as the dilution gas. The deposition pressure is 30-200 Pa, the flow ratio of silane to hydrogen is 1:2-10, the RF power is 100-5000 W, and the thickness of the deposited intrinsic amorphous silicon layer is 5-20 nm. Then, silane, hydrogen, and phosphine are introduced. The deposition pressure is 30-200 Pa, the flow ratio of silane to hydrogen is 1:2-10, the flow ratio of silane to phosphine is 1-4:1, the RF power is 100-5000 W, and the thickness of the deposited doped amorphous silicon layer is 5-20 nm. Finally, another layer of intrinsic amorphous silicon is deposited on the outer layer with a thickness of 5-60 nm to cover the doped layer and avoid cross-contamination in subsequent processes.

[0035] Step S6: Introduce hydrogen gas to perform hydrogen plasma pretreatment on the deposited second passivation layer. This involves hydrogen implantation and densification of the amorphous silicon layer. The hydrogen pretreatment pressure is 30–200 Pa, the radio frequency power is 100–5000 W, and the pretreatment time is 10–90 s.

[0036] Step S7: Introduce the reaction gas silane and nitrous oxide or ammonia or a mixture of gases; dilute the gas with argon or nitrogen or hydrogen or a mixture of the above gases; the flow rate ratio of silane to dilute gas is 1:0 to 5; the flow rate ratio of silane to nitrous oxide (or ammonia) is 1:2 to 10; the deposition pressure is 50 to 200 Pa; the radio frequency power is 100 to 4000 W; and the thickness of the silicon oxide or silicon nitride layer is 10 to 100 nm.

[0037] Step S8: Take out the carrier 9 and unload the materials, and test and classify the battery cells.

[0038] The coating equipment in this embodiment is compatible with PECVD deposition of single-layer or stacked passivation films such as amorphous silicon, silicon nitride, silicon oxynitride, and silicon oxide. It is also compatible with PEALD deposition of single-layer or stacked passivation films of aluminum oxide and aluminum nitride. The passivation film preparation method is also compatible with ALD deposition coating, which can achieve uniform coating on both sides of the cutting edge at the same time, meet the edge passivation requirements of multi-piece, greatly improve production capacity and reduce costs.

[0039] Example 2 This embodiment provides a coating method for a photovoltaic cell dual-side coating device, including the following steps: Step S1: After the solar cells are cut, they are placed horizontally in the material box 15 and stacked into a stack. The cut edge of the solar cell faces the through side of the material box 15. A cover plate is set on the top solar cell in the material box 15 to prevent plating. Then, multiple material boxes 15 are placed on the boat support 10 and the carrier 9 is sent into the reactor tube 3.

[0040] Step S2: The temperature of the reactor tube 3 is raised to 260°C to ensure that the actual surface temperature of the cell reaches 260°C, and the reactor tube 3 is evacuated to a vacuum state.

[0041] Step S3: Introduce hydrogen gas to perform hydrogen plasma pretreatment on the cut surface of the battery cell to remove the natural oxide layer and surface dirt. The hydrogen pretreatment pressure is 100Pa, the radio frequency power is 2000W, and the pretreatment time is 30s.

[0042] Step S4: Introduce pure silane as the reaction gas, with a deposition pressure of 70 Pa and a radio frequency power of 3000 W. The thickness of the deposited intrinsic hydrogenated amorphous silicon layer is 2-3 nm.

[0043] Step S5: Introduce silane as the reactant gas and hydrogen as the dilution gas. The deposition pressure is 70 Pa, the flow rate ratio of silane to hydrogen is 1:4, the RF power is 2000 W, and the thickness of the deposited intrinsic amorphous silicon layer is 10 nm. Then, introduce silane as the reactant gas, hydrogen as the dilution gas, and phosphine as the dopant gas. The deposition pressure is 70 Pa, the flow rate ratio of silane to hydrogen is 1:4, the flow rate ratio of silane to phosphine is 2:1, the RF power is 2000 W, and the thickness of the deposited doped amorphous silicon layer is 10 nm. Finally, deposit another layer of intrinsic amorphous silicon on the outer layer, with a thickness of 10 nm.

[0044] Step S6: Introduce hydrogen gas to perform hydrogen plasma pretreatment on the deposited second passivation layer. This involves hydrogen implantation and densification of the amorphous silicon layer. The hydrogen pretreatment pressure is 150 Pa, the radio frequency power is 3000 W, and the pretreatment time is 20 s.

[0045] Step S7: Introduce the reaction gases silane and ammonia, and the dilution gas is hydrogen. The flow ratio of silane to hydrogen is 1:3, and the flow ratio of silane to ammonia is 1:2. The deposition pressure is 90 Pa, the radio frequency power is 2000 W, and the silicon nitride layer thickness is 30 nm.

[0046] Step S8: Take out the carrier 9 and unload the materials, and test and classify the battery cells.

[0047] Table 1. Comparison of battery efficiency before and after passivation

[0048] Comparing the battery efficiency before and after passivation, using amorphous silicon as the passivation layer to passivate the double-cut edges of the battery cell resulted in an efficiency increase of 0.310%. The on-state voltage, current, and filling uniformity were significantly improved, mainly due to the significant increase in filling uniformity. This indicates that the edge passivation film structure prepared in this embodiment has a superior passivation effect on the cut edges.

[0049] Example 3 This embodiment provides a coating method for a photovoltaic cell dual-side coating device, including the following steps: Step S1: After the solar cells are cut, they are placed horizontally in the material box 15 and stacked into a stack. The cut edge of the solar cell faces the through side of the material box 15. A cover plate is set on the top solar cell in the material box 15 to prevent plating. Then, multiple material boxes 15 are placed on the boat support 10 and the carrier 9 is sent into the reactor tube 3.

[0050] Step S2: The temperature of the reactor tube 3 is raised to 220°C to ensure that the actual surface temperature of the cell reaches 220°C, and the reactor tube 3 is evacuated to a vacuum state.

[0051] Step S3: Introduce oxygen into the cavity to perform plasma pretreatment on the cut surface. The pretreatment pressure is 90 Pa, the radio frequency power is 8000 W, and the pretreatment time is 4 s. Repeat the treatment 3 times for a total of 12 s. In other embodiments, nitrous oxide can also be introduced to pretreat the cut surface. The pretreatment pressure is 30~200 Pa, the radio frequency power is 100~12000 W, and the pretreatment time is 3~30 s.

[0052] Step S4: First, nitrogen and TMA (trimethylaluminum) are introduced into the cavity at a pressure of 90 Pa for 4 seconds. Then, nitrogen is introduced for purging at a pressure of 90 Pa for 8 seconds. Next, oxygen is introduced for discharge at a pressure of 90 Pa, a radio frequency power of 8000 W, and a 4-second power-on time. Finally, nitrogen is introduced for purging at a pressure of 90 Pa for 8 seconds. The above process is repeated to deposit a 40 nm aluminum oxide layer.

[0053] Step S5: Deposit silicon oxide as a protective layer. Silane and nitrous oxide are introduced into reactor tube 3 at a flow ratio of 1:7, pressure of 90 Pa, and RF power of 4000 W to deposit a 30 nm silicon oxide protective layer.

[0054] In other embodiments, aluminum nitride can also be deposited as a protective layer. First, nitrogen and TMA (trimethylaluminum) are introduced into the cavity at a pressure of 30–200 Pa for 2–10 s. Then, nitrogen is introduced for purging at a pressure of 30–200 Pa for 3–15 s. Next, ammonia is introduced for discharge at a pressure of 30–200 Pa, a radio frequency power of 100–12000 W, and a purging time of 2–10 s. Finally, nitrogen is introduced for purging at a pressure of 30–200 Pa for 3–15 s. This process is repeated, with each cycle depositing an aluminum nitride layer of 0.08–0.15 nm thickness. By increasing the number of cycles, an aluminum nitride layer of 10–40 nm can be deposited. Silicon nitride or silicon oxynitride can also be deposited as a protective layer.

[0055] Step S6: Take out carrier 9 and unload the materials, and test and classify the battery cells.

[0056] Table 2. Comparison of battery efficiency before and after passivation

[0057] Comparing the battery efficiency before and after passivation, using aluminum oxide + silicon oxide as the passivation layer to passivate the double-cut edges of the battery cell resulted in an efficiency increase of 0.283%, with significant improvements in on-state voltage, current, and filling uniformity. The improvement in filling uniformity was the most significant, indicating that the edge passivation film structure prepared in this embodiment has a superior passivation effect on the cut edges.

[0058] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A photovoltaic cell double-sided coating equipment, characterized in that, The furnace body (1) includes a reactor tube (3) inside; the reactor tube (3) has an air inlet and an air outlet (8) at both ends; the reactor tube (3) has a carrier (9) with discharge function inside, and the carrier (9) is connected to an external power source through an electrode rod (7), and the battery cell is placed inside the carrier (9); when the power is turned on, an alternating electric field is formed between the cut surface of the battery cell and the carrier (9), which ionizes the process gas inside the reactor tube (3) to form plasma, thereby achieving edge passivation of the battery cell.

2. The photovoltaic cell double-sided coating equipment according to claim 1, characterized in that, The carrier (9) includes a boat support (10), a material box (15), and an outer electrode plate (13) and an inner electrode plate (14) spaced apart. The ends of the outer electrode plate (13) and the inner electrode plate (14) are connected to the electrode rod (7) through conductive blocks. The potentials of the outer electrode plate (13) and the inner electrode plate (14) are opposite. The material box (15) is placed in the groove formed by the inner electrode plate (14) and the boat support (10), and the cut surface of the battery cell faces the inner electrode plate (14) and has the same potential as the inner electrode plate (14). When the power is turned on, an alternating electric field is formed between the cut surface of the battery cell and the outer electrode plate (13), and between the outer electrode plate (13) and the inner electrode plate (14).

3. The photovoltaic cell double-sided coating equipment according to claim 2, characterized in that, The material box (15) has a through structure on both sides opposite to each other. The inner electrode plate (14) has multiple hollow through holes. The battery cells are stacked in the material box (15) and the cut surface of the battery cells faces the hollow through holes of the inner electrode plate (14).

4. The photovoltaic cell double-sided coating equipment according to claim 3, characterized in that, The cut surface of the battery cell is spaced 0-10 mm from the inner electrode plate (14).

5. The photovoltaic cell double-sided coating equipment according to claim 2, characterized in that, The outer electrode plate (13) and the inner electrode plate (14) are connected by an insulating ring (18) and a connecting rod (19).

6. The photovoltaic cell double-sided coating equipment according to claim 5, characterized in that, The outer electrode plate (13) and the inner electrode plate (14) are spaced 5 to 50 mm apart.

7. The photovoltaic cell double-sided coating equipment according to any one of claims 2 to 6, characterized in that, The bottom of the boat support (10) is provided with multiple positioning frames (101) to fix the position of the material box (15).

8. A coating method based on the photovoltaic cell double-sided coating equipment according to any one of claims 1 to 7, characterized in that, Includes the following steps: Step S1: After the battery cells are cut, they are placed horizontally in the material box (15) and stacked into a stack. The cut edge of the battery cell faces the through side of the material box (15). A cover plate is set on the top battery cell in the material box (15) to prevent plating. Then, multiple material boxes (15) are placed on the boat support (10) and the carrier (9) is sent into the reactor tube (3). Step S2: The temperature of the reactor tube (3) is raised to 120℃~300℃ and evacuated to a vacuum state; Step S3: Introduce hydrogen gas to perform hydrogen plasma pretreatment on the cut surface of the battery cell; Step S4: Deposit an intrinsic hydrogenated amorphous silicon layer or an oxygen-doped amorphous silicon layer as the first passivation layer; Step S5: Deposit an intrinsic amorphous silicon layer or an intrinsic amorphous silicon layer plus a doped amorphous silicon layer as a second passivation layer; Step S6: Introduce hydrogen gas to perform hydrogen plasma pretreatment on the deposited second passivation layer; Step S7: Deposit silicon oxide or silicon nitride as a mask layer; Step S8: Take out the carrier (9) and unload the materials, and test and classify the battery cells.

9. The coating method according to claim 8, characterized in that, In step S4, if an intrinsic hydrogenated amorphous silicon layer is deposited, pure silane is introduced as the reaction gas, the deposition pressure is 30-200 Pa, the radio frequency power is 100-6000 W, and the thickness of the deposited intrinsic hydrogenated amorphous silicon layer is 1-3 nm. If an oxygen-doped amorphous silicon layer is deposited, silane and carbon dioxide or nitrous oxide are introduced as reaction gases. The flow rate ratio of silane to carbon dioxide or nitrous oxide is 1 to 4:1, the deposition pressure is 30 to 200 Pa, the radio frequency power is 100 to 6000 W, and the thickness of the deposited oxygen-doped amorphous silicon layer is 2 to 5 nm.

10. The coating method according to claim 8, characterized in that, In step S5, if an intrinsic amorphous silicon layer is deposited, silane is introduced as the reaction gas and hydrogen as the dilution gas. The deposition pressure is 30-200 Pa, the flow ratio of silane to hydrogen is 1:2-10, the radio frequency power is 100-5000 W, and the thickness of the deposited intrinsic amorphous silicon layer is 15-100 nm. If depositing intrinsic amorphous silicon plus doped amorphous silicon, first introduce silane as the reactant gas and hydrogen as the dilution gas. The deposition pressure is 30–200 Pa, the flow ratio of silane to hydrogen is 1:2–10, the RF power is 100–5000 W, and the thickness of the deposited intrinsic amorphous silicon layer is 5–20 nm. Then introduce silane, hydrogen, and phosphine. The deposition pressure is 30–200 Pa, the flow ratio of silane to hydrogen is 1:2–10, the flow ratio of silane to phosphine is 1–4:1, the RF power is 100–5000 W, and the thickness of the deposited doped amorphous silicon layer is 5–20 nm. Finally, deposit another layer of intrinsic amorphous silicon on the outer layer with a thickness of 5–60 nm.

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