A method and treatment apparatus for reducing moisture residue in a solar cell manufacturing process

Abstract

This invention relates to the field of solar energy technology and discloses a method and apparatus for reducing residual moisture in the manufacturing process of solar cells. The method includes: immersing a washed silicon substrate (with a textured surface) in an alcohol solution in a solution zone, simultaneously ultrasonically cleaning it to make the water on the silicon substrate surface miscible with the alcohol; generating alcohol vapor at a first temperature in a vapor zone above the solution zone, and introducing nitrogen gas for protection; lifting the silicon substrate into the vapor zone at a first speed, allowing the alcohol vapor to penetrate into the gaps in the textured surface; after the entire silicon substrate is lifted into the vapor zone, pulling it away from the vapor zone at a second speed (greater than the first speed); and purging the silicon substrate surface with nitrogen gas at a second temperature (lower than the first temperature); the alcohol is at least one selected from methanol, ethanol, isopropanol, ethylene glycol, 1,2-propanediol, glycerol, n-propanol, and tert-butanol. This method effectively avoids surface water residue, improves the electrical performance and yield of the cells, and reduces processing costs.

Description

Technical Field

[0001] This invention relates to the field of solar energy technology, and specifically to a method and apparatus for reducing residual moisture in the manufacturing process of solar cells. Background Technology

[0002] A solar cell is a device that converts light energy into electrical energy; the output current is directly proportional to the amount of light entering the solar cell. To allow more light to enter the cell, a pyramidal textured surface (such as a textured surface on the front of the cell) is typically created. Figure 2-3 As shown, texturing reduces light reflection loss on the battery surface by repeatedly reflecting and refracting incident light between the uneven surfaces. This extends the optical path and creates a light-trapping effect, trapping more photons inside the battery and increasing light absorption and utilization. Texturing is typically achieved by utilizing the different reaction rates of each facet of the silicon cell structure in an alkaline solution. To further ensure light remains within the battery, a polished surface is typically created on the back. When sunlight passes through the silicon substrate, the smooth back surface reflects the light back into the battery; this step is called polishing. To reduce organic contamination during battery fabrication, such as metal ion contamination, wet chemical processes are used multiple times during the manufacturing process to clean and process the battery or silicon substrate surface.

[0003] However, in wet chemical processes, residual water on the battery surface can negatively impact subsequent battery processes and the battery's final electrical performance, for example:

[0004] a. Watermarks / water stains form on the battery surface (e.g.) Figure 1 As shown): When the residual water film evaporates, the Na+ ions dissolved in the water... + Ca 2+ They crystallize on the battery surface, forming white spots.

[0005] b) Increased battery contact resistance: Moisture forms structures such as silicon oxide at the metal-silicon interface, which hinders carrier collection and leads to increased contact resistance.

[0006] c) Increased reflectivity of the battery surface: Watermarks damage the pyramid-shaped textured surface, increase light reflection, and thus increase light loss.

[0007] Although silicon itself is hydrophobic (the contact angle of intrinsic silicon is approximately 110°), water residue can still occur during solar cell manufacturing. This is mainly due to a combination of factors, including surface modification, microstructure, and contamination effects.

[0008] 1) After texturing, a nano-scale SiO2 layer is formed, which helps to remove moisture residue on the battery surface.

[0009] 2) The pyramid-shaped textured surface of the solar cell generates a capillary effect, locking moisture in the gaps between the pyramids of the textured surface.

[0010] 3) Metal ion contamination can locally impair the hydrophobicity of silicon (e.g., Na+). + Hydrolysis generates hydrophilic hydroxyl groups. These factors all contribute to residual moisture on the silicon surface.

[0011] Currently, the commonly used method, as shown in announcement number CN112490326B, is to use hot high-purity nitrogen to purge the battery surface, using the blowing force of nitrogen and a certain temperature to remove residual moisture from the battery surface.

[0012] The core mechanism of nitrogen purging drying is the mechanical stripping of moisture by high-speed airflow. However, the penetrating power of high-speed airflow is weak, making it difficult to penetrate deep into the gaps between the fibers. After purging, a water film with a thickness of about 10 nm will still remain on the surface. This is mainly because the capillary force of the fibers locks in the moisture.

[0013] The capillary force F = 2γCOSθ / r; where γ is the surface tension of the material, and the surface tension of water is 72 mN / m; θ is the contact angle; and r is the radius of the pyramidal gaps in the velvet surface, which is generally calculated as 0.5-1 μm (e.g., 1 μm). Therefore, when the contact angle θ = 10°, the capillary force F for water retention by the velvet surface is F = 2 × 72 × cos10° / 1 × 10 -6 The pressure is approximately 142 kPa, while the purging force of nitrogen is only about 30-50 kPa, so it cannot completely clean the area.

[0014] Therefore, nitrogen purging must be combined with drying at a certain temperature. However, drying can cause dissolved metal ions (such as alkali metal ions used in texturing and polishing processes, such as sodium) to be released into the water. + K + (etc.) Remains on the battery surface, forming a leakage path. Furthermore, Na... + Hydrolysis produces hydrophilic hydroxyl groups (-OH), which require temperatures above 150°C to decompose completely. However, typical drying tanks usually operate at temperatures below 100°C, leaving some of the hydrophilic hydroxyl groups to retain moisture. Higher drying temperatures would increase energy consumption and costs.

[0015] Therefore, to remove as much surface moisture as possible, the maximum possible nitrogen purging force is required. However, even with frequent maintenance, a certain proportion of dust will still exist in the drying tank. Excessive purging force can damage the battery surface, leading to a decline in battery electrical performance. Moreover, the battery or silicon substrate surface is easily oxidized, forming a non-conductive oxide film that damages its electrical properties. Therefore, nitrogen purging requires the use of high-purity nitrogen, which is difficult to recycle, resulting in resource waste and increased costs. Summary of the Invention

[0016] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and processing device for reducing moisture residue in the solar cell manufacturing process.

[0017] Based on this, the present invention discloses a method for reducing residual moisture in the solar cell manufacturing process, comprising the following process steps:

[0018] Step 1: Immerse the washed silicon substrate in the alcohol solution in the solution area and perform ultrasonic cleaning during the immersion process to allow the alcohol to fully penetrate to the surface of the silicon substrate, so that the water on the surface of the silicon substrate and the alcohol are miscible to form an alcohol-water mixture;

[0019] The silicon substrate is a texturized silicon substrate, so that a pyramid-shaped textured surface is formed on the surface of the silicon substrate;

[0020] Step 2: Above the solution zone is the vapor zone; alcohol vapor with a first temperature is generated in the vapor zone, and nitrogen gas is introduced for protection to remove oxygen from the vapor zone;

[0021] Step 3: Slowly lift the soaked silicon substrate into the steam zone at the first speed, so that the alcohol vapor can fully penetrate into the gaps in the textured surface of the silicon substrate.

[0022] Step 4: After the entire silicon substrate is fully introduced into the vapor zone, the silicon substrate is quickly pulled away from the vapor zone at a second speed to reduce the risk of alcohol condensation droplet formation; the first speed is less than the second speed.

[0023] Step 5: Transfer the silicon substrate removed from the steam zone to a nitrogen drying device, and purge the surface of the silicon substrate with nitrogen at a second temperature to remove the alcohol-water mixture from the surface of the silicon substrate; the second temperature is lower than the first temperature.

[0024] The alcohol is at least one of methanol, ethanol, isopropanol, ethylene glycol, 1,2-propanediol, glycerol, n-propanol, and tert-butanol.

[0025] Preferably, the alcohol is ethanol; the alcohol solution is dehydrated industrial ethanol.

[0026] Preferably, in step 1, the silicon substrate is the silicon material used to prepare solar cells.

[0027] More preferably, in step 1, the soaking temperature is 25±2℃, the soaking time is 80-120s, and the ultrasonic power of the ultrasonic cleaning is 80-100W.

[0028] More preferably, in step 2, the first temperature of the alcohol vapor (which is an alcohol other than n-propanol or tert-butanol mentioned above) is 60±2℃, and the height of the alcohol vapor in the vapor zone is 300-400mm. When the alcohol is n-propanol, the first temperature is less than or equal to 40℃; or, when the alcohol is tert-butanol, the first temperature is less than or equal to 20℃.

[0029] More preferably, in step 3, the first speed is 2-3 mm / s.

[0030] More preferably, in step 4, the second speed is 15-20 mm / s.

[0031] More preferably, in step 5, the second temperature of the nitrogen purging is 40±5℃, the nitrogen flow rate is 0.3-0.5m / s, and the purging time is 100-120s.

[0032] The present invention also discloses a processing device for a method of reducing residual moisture in solar cell manufacturing process, including an alcohol processing chamber; the alcohol processing chamber includes a tank, the upper part of which is provided with a steam zone, the steam zone being connected to an external steam generator to generate alcohol vapor; the lower part of which is provided with a solution zone, the solution zone containing an alcohol solution.

[0033] Preferably, a base and a telescopic bracket are installed at the bottom of the solution area. The telescopic bracket is installed above the base and can be moved up and down. A basket for loading silicon substrate is also installed on the top of the telescopic bracket.

[0034] In summary, this invention utilizes the miscibility of alcohols (such as ethanol) with water and their volatility to effectively remove moisture from the battery surface. The mechanism of this invention's method for removing moisture using alcohols is explained below, using ethanol as an example:

[0035] 1. Ethanol (alcohol) and water are miscible in any proportion, and ethanol vapor can also be effectively dissolved in the liquid water remaining on the surface of the battery.

[0036] 2. Water has a high surface tension (72 mN / m), while ethanol has a low surface tension (21.1 mN / m). When the battery is slowly pulled upwards from a chamber (or ethanol vapor zone) filled with saturated ethanol vapor, the ethanol vapor rapidly dissolves into the thin water film remaining in the pyramidal textured microstructures (such as the pyramidal gaps in the textured surface, referred to as textured gaps) on the battery surface. This dissolution process causes a sharp decrease in the local surface tension of the water-ethanol mixture. Due to the non-uniformity of surface tension (the surface tension of the water film is high, but the surface tension of the mixture containing dissolved ethanol is low), a pulling force is generated from the high surface tension region to the low surface tension region. This pulling force drives the low surface tension ethanol to gradually erode into the water film on the battery surface (especially inside the textured gaps), eventually "pulling" the water away from the battery surface.

[0037] 3. Ethanol's boiling point (78.3℃) is much lower than water's (100℃), and it is highly volatile. When a battery coated with a low-surface-tension ethanol-water mixture is lifted above a high-temperature ethanol vapor zone or a dry zone, this ethanol-water mixture evaporates very easily and quickly. Due to the low surface tension of the ethanol-water mixture, its evaporation process does not generate enough force to form watermarks.

[0038] 4. After being transferred from the ethanol vapor zone, it enters the nitrogen drying protection zone. The temperature does not need to be too high. Simple inert gas purging is sufficient to make the water-ethanol mixture evaporate quickly.

[0039] 5. Water-ethanol mixtures, ethanol vapor, and liquefied ethanol can all be collected, purified, and reused. Although the price of ethanol is higher than that of high-purity nitrogen, the fact that ethanol can be reused actually reduces the cost.

[0040] Compared with the prior art, the present invention has at least the following beneficial effects:

[0041] This invention provides a method for reducing residual moisture in the solar cell manufacturing process. While balancing cost and process efficiency, the method utilizes ethanol vapor to further reduce the adverse effects of moisture on solar cells, such as defects and low efficiency. This method has the following advantages:

[0042] 1. The battery surface is drier, reducing the negative impact of moisture on subsequent battery processes and battery electrical performance.

[0043] 2. The overall cost of battery manufacturing processes has decreased.

[0044] 3. Reduced water vapor on the battery surface leads to a decrease in dissolved metal ions, resulting in less residual metal ions on the battery surface, improved battery electrical performance, and thus, increased battery efficiency.

[0045] 4. Increased battery yield.

[0046] Therefore, the method for reducing residual moisture in the solar cell manufacturing process of the present invention can solve the problem of surface water residue caused by the large amount of wet chemical cleaning process required in the solar cell manufacturing process, which leads to watermark contamination and reduced cell efficiency; and overcome the defects of existing nitrogen purging and drying, such as metal ion residue causing leakage, excessive purging force causing damage to the cell surface, difficulty in recovering high-purity nitrogen, and increased cost due to high energy consumption. Attached Figure Description

[0047] Figure 1 An EL image (electroluminescent image) showing watermark contamination on the surface of an existing solar cell.

[0048] Figure 2 This is a front view of the pyramid-shaped textured surface of a silicon substrate used in solar cells.

[0049] Figure 3 This is a top view of the pyramid-shaped textured surface of a silicon substrate used in solar cells.

[0050] Figure 4 This is a schematic diagram of the structure of the alcohol processing chamber of the processing apparatus used in a method for reducing residual moisture in the solar cell manufacturing process according to the present invention.

[0051] Figure 5 This is a schematic diagram of the process flow for a method of reducing residual moisture in the solar cell manufacturing process according to the present invention.

[0052] Figure 6 This is a comparison chart of minority carrier lifetime data for silicon substrates used in solar cells obtained by the methods of the examples and comparative examples.

[0053] The following are the diagram numbers: 1. Tank; 2. Flower basket; 3. Telescopic bracket; 4. Base; 5. Silicon substrate; 6. Alcohol solution. Detailed Implementation

[0054] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] This invention discloses a method for reducing residual moisture in solar cell manufacturing processes, using a processing apparatus including an alcohol treatment chamber. See also... Figure 4-5The alcohol processing chamber includes a tank 1, with a steam zone in the upper part and a solution zone in the lower part, containing an alcohol solution 6. The steam zone is connected to an external steam generator to produce alcohol vapor. A base 4 and a telescopic support 3 are mounted at the bottom of the solution zone. The telescopic support 3 is vertically movable above the base 4, and a basket 2 for loading a silicon substrate 5 is mounted on top of the telescopic support 3. The telescopic support 3 pushing the basket 2 vertically is existing technology and will not be described in detail here.

[0056] The present invention provides a method for reducing residual moisture in the manufacturing process of solar cells, comprising the following process steps:

[0057] Step 1: After undergoing a wet chemical process (such as a texturing process to form a pyramid-shaped textured surface on the silicon substrate 5, which may also include other wet chemical processes used in the fabrication of solar cells) and water washing, the silicon substrate 5 enters the pre-dehydration alcohol immersion step:

[0058] In the lower part of the alcohol treatment chamber, the water-washed silicon substrate 5 is immersed in the alcohol solution 6 at 25±2℃ in the solution area for 80-120 seconds, so that the alcohol solution 6 can fully replace the water on the surface of the silicon substrate 5. The silicon substrate 5 is then ultrasonically cleaned with an ultrasonic power of 80-100W during the immersion process to enhance the penetration of the alcohol solution 6 into the gaps in the textured surface, so that the water on the surface of the silicon substrate 5 and the alcohol solution 6 are miscible to form an alcohol-water mixture.

[0059] In step 1, the silicon substrate 5 is placed in the basket 2, and then the basket 2 containing the silicon substrate 5 is placed together with the dehydrated industrial ethanol in the solution area for soaking.

[0060] It should be noted that in the method for reducing residual moisture in the solar cell manufacturing process of the present invention, the alcohol that can be used is at least one selected from methanol (with a surface tension of 22.1 mN / m, miscible with water in any proportion), ethanol (with a surface tension of 21.1 mN / m, miscible with water in any proportion), isopropanol (with a surface tension of 21.7 mN / m, miscible with water in any proportion), ethylene glycol (with a surface tension of 48.4 mN / m, miscible with water in any proportion), 1,2-propanediol (with a surface tension of 36.0 mN / m, miscible with water in any proportion), glycerol (with a surface tension of 63.4 mN / m, miscible with water in any proportion), n-propanol (with a surface tension of 23.8 mN / m, miscible at <41℃), and tert-butanol (with a surface tension of 19.4 mN / m, miscible at <20℃). Ethanol is preferred.

[0061] The silicon substrate 5 used in this invention is the silicon material used to prepare solar cells.

[0062] The main purpose of step 1 is to reduce the load on the subsequent alcohol vapor drying step. In order to reduce the load on the subsequent alcohol vapor drying step, the silicon substrate 5 is immersed in a solution containing alcohol before the alcohol vapor drying step. Relying on the property that alcohol and water are easily miscible, most of the water on the surface of the silicon substrate 5 is removed by the alcohol solution 6.

[0063] Step 2: In the upper part of the alcohol processing chamber, an external steam generator is used to generate alcohol vapor at a temperature of 60±2℃ (at this time, the alcohol vapor is other alcohols other than n-propanol or tert-butanol mentioned above). The height of the alcohol vapor in the steam zone is 300-400mm (designed according to the actual size of the silicon substrate 5) to ensure that the silicon substrate 5 can be fully immersed in the alcohol vapor. High-purity nitrogen gas (with a purity ≥99.999%) is introduced for protection to remove oxygen from the steam zone.

[0064] In practice, when the alcohol is n-propanol, the first temperature is less than or equal to 40°C; or when the alcohol is tert-butanol, the first temperature is less than or equal to 20°C.

[0065] Step 3: Slowly lift the silicon substrate 5, which has been soaked in the solution zone, into the steam zone at a speed of 2-3 mm / s to ensure that the alcohol vapor in the steam zone fully penetrates into the textured gaps on the surface of the silicon substrate 5 to fully replace the residual moisture in the textured gaps.

[0066] In step 3, see Figure 4-5 The telescopic bracket 3 slowly lifts the basket 2 containing the silicon substrate 5, thus slowly raising the silicon substrate 5.

[0067] The silicon substrate 5 is initially immersed in the alcohol solution 6. The telescopic support 3 slowly pushes the silicon substrate 5, which is immersed in the solution area, out of the solution area through the basket 2 at a speed of 2-3 mm / s. The slow lifting step can be ended when the entire silicon substrate 5 has completely left the solution area.

[0068] The reason for using a slow lifting speed in step 3 is to allow the alcohol to fully penetrate and contact the residual water vapor in the textured gaps of the silicon substrate 5; and to prevent the alcohol-water vapor mixture droplets from failing to be pulled away from the surface of the silicon substrate 5 due to excessive speed when the pulling force is generated to pull the water vapor away from the surface of the silicon substrate 5, because the pulling force formed by the surface tension difference is relatively small, and the speed is too fast to allow the droplets to migrate out of the surface of the silicon substrate 5 as much as possible.

[0069] Step 4: After completely pulling the entire silicon substrate 5 into the vapor zone, quickly pull the silicon substrate 5 away from the vapor zone at a speed of 15-20 mm / s to reduce the risk of alcohol condensation droplet formation.

[0070] In step 4, when the bottom of the silicon substrate 5 is completely removed from the solution area, the tank 1 is opened (for example, the tank 1 is equipped with a cover, and the tank 1 is opened by opening the cover. Of course, the tank 1 can also adopt other existing detachable structures, which will not be described in detail here). The basket 2 and the silicon substrate 5 are quickly pulled away from the steam area at a speed of 15-20 mm / s by an external robotic arm, and then the silicon substrate 5 is pulled into the nitrogen drying device (such as a nitrogen drying box) in the subsequent step 5.

[0071] Step 4 uses rapid removal because: when the silicon substrate 5 is fully inside the vapor zone, the tank 1 needs to be opened, and an external robotic arm is used to pull the basket 2 containing the silicon substrate 5 into the nitrogen drying chamber. The temperature outside the tank 1 or in the area where the external robotic arm moves is low. Rapid removal from the vapor zone is to prevent the alcohol vapor in the vapor zone from condensing and forming droplets that adhere to the surface of the silicon substrate 5, thus creating watermarks, when the tank 1 is opened.

[0072] Step 5: Transfer the silicon substrate 5, which has been removed from the steam zone, to a nitrogen drying oven. Blow and dry the surface of the silicon substrate 5 with a nitrogen flow rate of 0.3-0.5 m / s at a temperature of 40±5℃ for 100-120 seconds to ensure that the alcohol-water mixture on the surface of the silicon substrate 5 is completely removed and dried.

[0073] The following uses ethanol as an example to illustrate the process steps of a method for reducing residual moisture in solar cell manufacturing according to an embodiment of the present invention (for the specific structure of the alcohol processing chamber of the processing equipment used in this embodiment, please refer to the above-described specific embodiments):

[0074] Example

[0075] This invention provides a method for reducing residual moisture in the solar cell manufacturing process, see [link to relevant documentation]. Figure 4-5 It includes the following process steps:

[0076] Step 1: After the silicon substrate 5 undergoes wet chemical processing and water washing, it enters the pre-dehydration ethanol immersion step:

[0077] After being washed with water, the silicon substrate 5 was immersed in dehydrated industrial ethanol at 25°C in the solution area for 100 seconds to allow the dehydrated industrial ethanol to fully replace the water on the surface of the silicon substrate 5. Then, the silicon substrate 5 was ultrasonically cleaned during the immersion process using 100W ultrasonic power to enhance the penetration of dehydrated industrial ethanol into the gaps in the textured surface, so that the water on the surface of the silicon substrate 5 and the dehydrated industrial ethanol are miscible to form an ethanol-water mixture.

[0078] The main purpose of step 1 is to reduce the load on the subsequent ethanol vapor drying.

[0079] Step 2: Generate ethanol vapor at a temperature of 60°C in the steam zone. The height of the ethanol vapor in the steam zone is 300 mm to ensure that the silicon substrate 5 can be fully immersed in the ethanol vapor. High-purity nitrogen gas (with a purity of ≥99.999%) is introduced for protection to remove oxygen from the steam zone.

[0080] Step 3: Slowly pull the silicon substrate 5, which has been soaked in the solution zone, into the steam zone at a speed of 2 mm / s. This ensures that the ethanol vapor in the steam zone fully penetrates into the textured gaps on the surface of the silicon substrate 5 to completely replace any residual moisture. The slow pulling step ends when the entire silicon substrate 5 has completely left the solution zone.

[0081] Step 4: After completely pulling the entire silicon substrate 5 into the vapor zone, quickly pull the silicon substrate 5 away from the vapor zone at a speed of 15 mm / s to reduce the risk of ethanol condensation droplet formation.

[0082] Step 5: Transfer the silicon substrate 5, which has been removed from the steam zone, to a nitrogen drying oven and blow it dry for 100 seconds with a nitrogen flow rate of 0.4 m / s at a temperature of 40°C to ensure that the ethanol-water mixture on the surface of the silicon substrate 5 is completely removed and dried.

[0083] Comparative Example

[0084] This comparative example describes a method for reducing residual moisture in the solar cell manufacturing process. It involves purging the silicon substrate surface with hot, high-purity nitrogen gas (with a purity ≥ 99.999%) at 85°C for 300 seconds, using the blowing force and temperature of the nitrogen gas to remove residual moisture from the silicon substrate surface.

[0085] Performance testing

[0086] 1. Performance test comparison data of silicon substrates in the examples and comparative examples (which adopted the conventional nitrogen purging and drying process) are as follows: Figure 6 As shown. The performance testing methods for silicon substrates are as follows:

[0087] The same silicon substrate (1Ω / sq) was used in the examples and the comparative examples. After texturing and cleaning, a passivation film of alumina + silicon nitride was prepared on both the front and back sides of the silicon substrate. After heat treatment in a sintering furnace (the peak temperature of sintering was 870℃), the minority carrier lifetime of the silicon substrate was tested using a Sinton-W120 instrument.

[0088] See Figure 6The minority carrier lifetime of the silicon substrate treated with the conventional nitrogen purging and drying process (as shown in the comparative example) is 832.88 μs, while that treated with the stepped ethanol vapor drying process (as shown in the embodiment) is 853.94 μs. It is evident that, compared to the comparative example, the silicon substrate treated with the stepped ethanol vapor drying process of the embodiment (i.e., a method for reducing residual moisture in solar cell manufacturing) is drier, thus improving the electrical properties of the silicon substrate (such as minority carrier lifetime) by 2.53%.

[0089] 2. Using the method of reducing residual moisture in the solar cell manufacturing process according to an embodiment of the present invention to treat the silicon substrate not only makes the silicon substrate or cell surface drier, resulting in improved electrical performance, but also reduces processing costs, as shown in Table 1 below:

[0090] Table 1. Process Costs (based on 1MW capacity)

[0091]

[0092] Each processing unit has an annual output of 0.5GW = 500MW. The equipment has a service life of 5 years, and the annual depreciation cost is 1 / 5.

[0093] The cost of the traditional nitrogen purging and drying process is: 160,000 + 550 × 500 + 20,000 = 455,000, or 910 yuan / MW.

[0094] The ethanol recovery unit is calculated based on a recovery rate of 80%. The process cost of this embodiment is: 240,000 + (350 × 20% × 500) + 80,000 = 355,000, or 710 yuan / MW.

[0095] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0096] The technical solution provided by the present invention has been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method of reducing moisture residue in a solar cell manufacturing process, comprising: The process includes the following steps: Step 1: Immerse the washed silicon substrate in the alcohol solution in the solution area and perform ultrasonic cleaning during the immersion process to allow the alcohol to fully penetrate to the surface of the silicon substrate, so that the water on the surface of the silicon substrate and the alcohol are miscible to form an alcohol-water mixture; The silicon substrate is a texturized silicon substrate, so that a pyramid-shaped textured surface is formed on the surface of the silicon substrate; Step 2: Above the solution zone is the vapor zone; alcohol vapor with a first temperature is generated in the vapor zone, and nitrogen gas is introduced for protection to remove oxygen from the vapor zone; Step 3: Slowly lift the soaked silicon substrate into the steam zone at the first speed, so that the alcohol vapor can fully penetrate into the gaps in the textured surface of the silicon substrate. Step 4: After the entire silicon substrate is fully introduced into the vapor zone, the silicon substrate is quickly pulled away from the vapor zone at a second speed to reduce the risk of alcohol condensation droplet formation; the first speed is less than the second speed. Step 5: Transfer the silicon substrate removed from the steam zone to a nitrogen drying device, and purge the surface of the silicon substrate with nitrogen at a second temperature to remove the alcohol-water mixture from the surface of the silicon substrate; the second temperature is lower than the first temperature. The alcohol is at least one of methanol, ethanol, isopropanol, ethylene glycol, 1,2-propanediol, glycerol, n-propanol, and tert-butanol.

2. The method of claim 1, wherein the method further comprises, The alcohol is ethanol; the alcohol solution is dehydrated industrial ethanol.

3. The method of claim 1, wherein the method further comprises, In step 1, the silicon substrate is the silicon material used to prepare solar cells.

4. A method for reducing residual moisture in solar cell manufacturing according to any one of claims 1-3, characterized in that, In step 1, the soaking temperature is 25±2℃ and the soaking time is 80-120s; the ultrasonic power of the ultrasonic cleaning is 80-100W.

5. A method for reducing residual moisture in solar cell manufacturing according to any one of claims 1-3, characterized in that, In step 2, the first temperature of the alcohol vapor is 60±2℃, and the height of the alcohol vapor in the vapor zone is 300-400mm.

6. A method for reducing residual moisture in solar cell manufacturing according to any one of claims 1-3, characterized in that, In step 3, the first velocity is 2-3 mm / s.

7. A method for reducing residual moisture in solar cell manufacturing according to any one of claims 1-3, characterized in that, In step 4, the second speed is 15-20 mm / s.

8. A method for reducing residual moisture in solar cell manufacturing according to any one of claims 1-3, characterized in that, In step 5, the second temperature of the nitrogen purging is 40±5℃, the nitrogen flow rate is 0.3-0.5m / s, and the purging time is 100-120s.

9. The processing apparatus used in the method for reducing residual moisture in the solar cell manufacturing process according to any one of claims 1-8, characterized in that, It includes an alcohol processing chamber; the alcohol processing chamber includes a tank, the upper part of which is provided with a steam zone, which is connected to an external steam generator to generate alcohol vapor; the lower part of the tank is provided with a solution zone, which contains an alcohol solution.

10. A processing apparatus according to claim 9, characterized in that, The bottom of the solution area is equipped with a base and a telescopic bracket. The telescopic bracket is installed on top of the base and can be moved up and down. A basket for loading silicon substrate is also installed on the top of the telescopic bracket.

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