Perovskite cell slit coating device and process method

Abstract

The perovskite cell slit coating device comprises a base station, and a front purging frame, a coating frame, a rear purging frame and an annealing frame which are sequentially arranged along the base station, and the substrate is sequentially subjected to purging before coating, coating, purging after coating and laser annealing below the frame body. The problems that in the process of preparing large-size perovskite through an industrialized slit coating one-step method, organic solvents of a wet film at the coating starting point and the coating ending point have volatilization difference, then the thickness of the wet film is not uniform, pinholes and grain boundary defects are generated, and the quality stability of the large-size perovskite film is affected are solved.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic manufacturing, and in particular relates to a slit coating device and process for perovskite solar cells. Background Technology

[0002] Perovskite solar cells are a new type of solar cell that uses perovskite semiconductor materials as the light-absorbing layer. With their unique crystal structure and photoelectric properties, perovskite solar cells exhibit significant advantages such as high photoelectric conversion efficiency, simple manufacturing process, and low cost. They have broad application prospects in fields such as ground-mounted photovoltaic power stations, distributed power generation, and power supply for portable electronic devices, and are regarded as one of the most promising new photovoltaic technologies for large-scale commercial application.

[0003] With the rapid development of perovskite solar cell technology, among many thin film preparation technologies, slot coating technology stands out from vacuum deposition technology due to its high cost and low production capacity, blade coating due to its insufficient precision, and inkjet printing speed limitations. Slot coating systems employ a closed design, which can effectively prevent the intrusion of external contaminants and ensure the purity of the film. At the same time, it has strong adaptability to the viscosity of the coating solution, which can meet the coating requirements of perovskite precursor solutions with different components. It also has the characteristics of high speed and high precision, and can achieve uniform coating on large-area substrates.

[0004] However, in existing slot coating techniques for preparing wet films of perovskite solutions, the organic solvent on the surface of the wet film continuously evaporates. During coating and transportation, due to the influence of the substrate's dimensions, the organic solvent at the coating start point evaporates before that at the coating end point, resulting in inconsistent organic solvent concentrations at both ends of the coating. This leads to ion migration and ultimately uneven thickness of the perovskite dry film. After the coating process, the perovskite wet film is dried and crystallized as soon as possible. However, since the coating process is generally shorter than the drying and crystallization process, some perovskite wet film remains in the buffer chamber awaiting drying and crystallization. During this waiting period, the organic solvent in the perovskite wet film in the buffer chamber inevitably continues to evaporate. This is detrimental to inducing the perovskite wet film to reach a supersaturated state for directional nucleation, resulting in differences in the crystallinity of subsequent perovskite films. Summary of the Invention

[0005] The purpose of this invention is to provide a slot coating device and process for perovskite solar cells, in order to solve the technical problem of the difference in the volatilization of organic solvents in the wet film at the starting and ending points of the coating in the one-step slot coating process for preparing large-size perovskite solar cells in industrial applications.

[0006] To achieve the above objectives, the specific technical solution of the perovskite solar cell slit coating apparatus and process method of the present invention is as follows:

[0007] A perovskite solar cell slot coating apparatus includes a base for placing a substrate, and a front purge frame, a coating frame, a rear purge frame, and an annealing frame arranged sequentially along the base.

[0008] The front purging frame is provided with a purging nozzle facing the base, which purifies the surface of the substrate with high-pressure gas.

[0009] The coating rack is provided with a slit coating blade facing the substrate for coating a perovskite wet film on the substrate surface;

[0010] The rear purge frame is equipped with a high-pressure nitrogen extractor facing the base, which is used for purging the solution on the surface of the perovskite wet film.

[0011] The annealing rack is equipped with a laser radiation device facing the base, which causes the residual solution on the surface of the perovskite wet film to evaporate simultaneously through laser annealing.

[0012] As a further improvement of the present invention, the front purge frame, the coating frame, the rear purge frame, and the annealing frame move along the base via a frame moving track.

[0013] As a further improvement of the present invention, the upper surface of the substrate is provided with a substrate moving track for moving the substrate, and the substrate passes under the front purge frame, the coating frame, the rear purge frame and the annealing frame in sequence along the substrate moving track.

[0014] As a further improvement of the present invention, the high-pressure nitrogen extractor is provided with a plurality of nitrogen nozzles arranged in an array on the end face facing the base, the number of nitrogen nozzles being adjustable, with a density of 50 to 200 nozzles / m³. 2 The nitrogen nozzle is surrounded by an extraction groove.

[0015] As a further improvement of the present invention, the laser radiation device includes an infrared temperature sensor to monitor the surface temperature of the substrate.

[0016] A perovskite solar cell slit coating process, using the aforementioned perovskite solar cell slit coating apparatus, includes the following steps:

[0017] S1. Preparation of perovskite solution: Dissolve PbI2, PbBr2, FAI, and CsI in an organic solvent to obtain a perovskite solution;

[0018] S2. Slit coating knife liquid injection: Seal the liquid outlet of the slit coating knife, open the exhaust valve, inject perovskite solution into the hollow cavity of the slit coating knife, and expel air bubbles from the cavity;

[0019] S3. Pre-coating purging: The purging nozzles on the front purging frame purify the surface of the substrate to be coated to remove impurities and dust.

[0020] S4. Coating: The coating rack applies a perovskite wet film to the substrate surface using a slit coating knife;

[0021] S5. Post-coating purging: The post-purging rack uses a high-pressure nitrogen extractor to uniformly purge the surface of the perovskite wet film to remove the solution from the surface of the perovskite wet film.

[0022] S6. Laser annealing: The annealing rack irradiates the perovskite wet film with a laser radiation device.

[0023] As a further improvement of the present invention, the preparation temperature is 20-30℃ and the humidity is 30-50%RH; the moving speed of the front purging frame, coating frame, rear purging frame and annealing frame relative to the substrate is 0.1-2m / min.

[0024] As a further improvement of the present invention, the molar ratio of PbI2, PbBr2, FAI, and CsI in the perovskite solution prepared in S1 is 1.1–1.4: 0.15–0.25: 1.2–1.5: 0.1–0.15, the volume ratio of DMF to DMSO in the organic solvent is 4:1–8:1, and 2-ME is added to the perovskite solution at a volume ratio of 0.1–0.5 vol%.

[0025] As a further improvement of the present invention, in S2, a perovskite solution is injected into the slit coating blade cavity at a rate of 5 to 100 ml / s.

[0026] The direction of the purge nozzle in S3 is adjustable, with an angle of 90 to 150° with the substrate. The purge gas is nitrogen, with a nitrogen pressure of 0.3 to 0.7 MPa.

[0027] The S4 slit coating blade has a liquid injection rate of 10–20 ml / min and a coating height of 100–200 μm.

[0028] In S6, the laser is a linear or area spot with a wavelength of 400–700 nm, the laser power is 5–50 W, and the substrate surface temperature is controlled at 100–150 °C.

[0029] As a further improvement of the present invention, the nitrogen pressure of the high-pressure nitrogen extractor in S5 is 0.3-0.7 MPa, the purging height is 5-30 mm, and the nitrogen temperature is 25℃-100℃.

[0030] Beneficial effects:

[0031] The front purge rack uses high-pressure gas to purge the substrate surface, removing impurities and laying a clean foundation for subsequent coating. The slit coating blade of the coating rack achieves precise coating of the perovskite wet film, ensuring the initial integrity of the wet film formation. The high-pressure nitrogen extractor of the rear purge rack specifically treats the solution on the wet film surface, optimizing the wet film state. The laser radiation device of the annealing rack performs laser annealing, simultaneously completing the evaporation of residual solvent and perovskite crystallization, achieving one-step post-processing. The seamless integration of each stage of the entire process avoids wet film defects (such as uneven solvent evaporation and surface contamination) caused by process breaks in traditional processes, significantly improving the forming quality and consistency of the perovskite thin film. This simplifies the process flow, enabling simultaneous solvent evaporation and crystallization, avoiding uneven thickness caused by separate treatment of residual solvent in the wet film. Simultaneously, laser annealing induces directional crystallization of perovskite molecules, improving the crystallization quality of the thin film and ensuring the photoelectric performance of the battery.

[0032] The substrate does not need to be transferred between different devices. It can be processed by passing under each frame in sequence on the same substrate, which simplifies the production operation, reduces the difficulty of technical control in industrial production, and reduces process fluctuations caused by improper equipment adaptation, thereby improving production stability. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a perovskite battery slit coating device according to the present invention.

[0034] Figure 2 This is a schematic diagram of a high-pressure nitrogen extractor.

[0035] The markings in the diagram are as follows: 1. Base; 11. Frame moving track; 2. Front brushing frame; 21. Blowing nozzle; 3. Coating frame; 31. Slit coating knife; 4. Rear brushing frame; 41. High-pressure nitrogen extractor; 411. Nitrogen nozzle; 412. Vacuum tank; 5. Annealing frame; 51. Laser radiation device. Detailed Implementation

[0036] To better understand the purpose, structure, and function of this invention, a further detailed description of this invention is provided below with reference to the accompanying drawings.

[0037] Example 1:

[0038] like Figure 1The perovskite solar cell slot coating apparatus shown has a base 1, which is a rigid cuboid structure adapted to the size of the substrate, used to support the perovskite solar cell substrate to be coated, providing a stable working platform for subsequent processes. Two parallel frame moving tracks 11 are provided on both sides of the base along the length direction. A front purging frame 2, a coating frame 3, a rear purging frame 4, and an annealing frame 5 are arranged sequentially along the frame moving tracks 11. The lower ends of each frame are connected to the frame moving tracks 11 and move along the length direction of the base 1 under the drive of the frame moving tracks 11, passing over the substrate to be coated placed on the base 1 in sequence, completing the pre-coating purging, coating, post-coating purging, and laser annealing of the substrate.

[0039] The front purging frame 2 spans across the base 1 along its short side, with both ends erected on the frame movement track 11. A row of purging nozzles 21 is positioned above the base 1, facing it. The nozzles are evenly spaced, allowing adjustment of the purging angle towards the substrate. The adjustment range is 90–150°. In this embodiment, it is vertically positioned. The frame integrates a gas pipeline, one end connected to a nitrogen source, and the other end connected to the purging nozzles 21. A pressure regulating valve is installed on the pipeline. High-pressure nitrogen is used to purge the substrate surface, removing dust, impurities, and residual moisture, providing a clean substrate surface for subsequent coating processes and preventing wet film defects caused by impurities.

[0040] The coating rack 3 is located behind the front blower rack and has a similar structure to the front blower rack 2. A slit coating blade 31 is positioned above the substrate 1, facing the substrate 1. The width of the slit-type liquid outlet matches the width of the substrate, and the outlet gap can be adjusted via a fine-tuning knob. The slit coating blade 31 has an inner cavity to contain the perovskite solution. An injection port and an exhaust valve are located on the side of the inner cavity, and an outlet control valve is located at the bottom. The perovskite precursor solution is injected into the cavity through the liquid supply system. After air bubbles are expelled through the exhaust valve, the outlet control valve is opened, allowing for precise coating to form a continuous and uniform perovskite wet film during substrate movement.

[0041] The rear purge frame 4 is located behind the coating frame and has a similar structure to the coating frame 3. A high-pressure nitrogen extractor 41 is positioned above the base 1, facing the base 1. Figure 2 As shown, the high-pressure nitrogen extractor 41 has an array of nitrogen nozzles 411 on its end face facing the base. A ring of suction grooves 412 surrounds the nozzles, and the suction grooves 412 are connected to a vacuum pump via pipelines. The frame integrates nitrogen pipelines, connecting to a nitrogen source, a temperature controller, and a pressure regulating valve. By spraying nitrogen gas at a controllable temperature and pressure onto the surface of the perovskite wet film through the high-pressure nitrogen extractor 41, excess solution on the surface of the wet film is quickly and uniformly removed. At the same time, excess gas is extracted and volatile solution vapors are discharged through the suction grooves, preventing solvent accumulation on the surface of the wet film and thus avoiding uneven thickness.

[0042] The annealing rack 5 is located behind the rear purge rack 4 and has a similar structure. A laser radiation device 51 is positioned above the substrate 1, facing the substrate 1. This device includes a laser generator and an infrared temperature sensor. The laser generator emits a linear light spot, and an optical lens group is used to adjust the uniformity of the light spot. The infrared temperature sensor monitors the substrate surface temperature in real time and is connected to the power controller of the laser generator via a signal line. Laser annealing is achieved by emitting a laser onto the perovskite wet film through the laser radiation device 51. Simultaneously, it promotes the rapid evaporation of residual solvent on the wet film surface. The infrared temperature sensor monitors the substrate surface temperature in real time and adjusts the laser power accordingly to ensure stable temperature during the crystallization process.

[0043] A slit coating process for perovskite solar cells, using the above-mentioned coating device, with the temperature controlled at 25°C and the humidity controlled at 40%RH;

[0044] Step 1: Prepare the perovskite precursor solution. Measure N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) and mix them at a volume ratio of 4:1 as the organic solvent. Weigh out 1.2M lead iodide (PbI2), 0.2M lead bromide (PbBr2), 1.3M formamidinium iodide (FAI), and 0.12M cesium iodide (CsI) at molar concentrations. Add the above solutes to the mixed solvent, and simultaneously add 0.3 vol% of 2-ME at a volume ratio. Stir at 25°C and 600 rpm for 5 hours until the solutes are completely dissolved to obtain a homogeneous and stable perovskite solution.

[0045] Step 2: First, close the liquid outlet control valve of the slit coating knife through the control system and open the exhaust valve; start the liquid supply system and inject the perovskite solution prepared in the previous step into the cavity of the slit coating knife at a rate of 30 ml / s; during the solution injection process, the air inside the cavity and the tiny air bubbles entrained in the solution are squeezed and continuously discharged through the exhaust valve until the solution overflows from the exhaust valve; close the exhaust valve, stop the liquid injection, and maintain the pressure inside the cavity stable.

[0046] Step 3: Adjust the air outlet direction of the front purging frame nozzles according to the substrate size, making it perpendicular to the substrate surface, and set the nitrogen pressure to 0.5 MPa; place the substrate on the substrate platform, start the track drive motor, and move the front purging frame from the end of the platform to the front end at a speed of 1 m / min, covering the substrate; when the substrate enters under the front purging frame, start the nitrogen source, and the purging nozzles spray high-pressure nitrogen onto the substrate surface to thoroughly purge the substrate and remove surface dust, impurities, and moisture.

[0047] Step 4: Adjust the gap between the liquid outlet of the slit coating blade to achieve a coating height of 100 μm; set the injection speed of the cavity to 20 ml / min; move the front purge frame at a speed of 1 m / min, and when the purged portion of the substrate reaches below the slit coating blade, open the liquid outlet control valve. The liquid supply system continuously replenishes the cavity with solution at the set injection speed. Under the pressure of the cavity, the solution is evenly squeezed out from the slit outlet; the substrate surface receives the squeezed solution, forming a continuous and uniform perovskite wet film with a width consistent with the substrate width.

[0048] Step 5: Adjust the nitrogen pressure of the rear purge frame to 0.5 MPa, the purge height to 10 mm, and control the nitrogen temperature to 50°C; start the vacuum pump to create negative pressure in the extraction tank; the rear purge frame moves with the coating frame at a speed of 1 m / min, and enters below the rear purge frame after the wet film portion of the substrate has been coated. The array of nitrogen nozzles uniformly sprays high-pressure nitrogen onto the surface of the perovskite wet film to quickly extract the organic solvents on the surface of the wet film; the volatile solvent vapors are promptly removed by the extraction tank to avoid remaining on the surface of the wet film and ensure a uniform surface condition of the wet film.

[0049] Step Six: Adjust the laser wavelength of the laser radiation device to 550nm and the laser power to 30W; set the target temperature control of the substrate surface to 130℃, and use an infrared temperature sensor to collect the substrate surface temperature data in real time; the annealing rack follows the purge rack at a speed of 0.1m / min. After the wet film coating of the substrate is completed, the purge part enters below the annealing rack, and the laser radiation device emits a linear spot to uniformly irradiate the perovskite wet film; the laser energy causes the residual solvent on the surface of the wet film to evaporate rapidly, while inducing the perovskite precursor molecules to nucleate and grow in a directional manner; when the infrared temperature sensor detects that the substrate surface temperature is higher than 130℃, the control system automatically reduces the laser power; when the temperature is lower than 130℃, the laser power is automatically increased to ensure temperature stability during the annealing process; after the substrate has completely passed through the annealing rack, laser annealing is completed, forming a fully crystalline perovskite dry film.

[0050] Example 2:

[0051] The upper surface of the substrate is provided with a substrate moving track for moving the substrate. The substrate moves along the substrate moving track and passes under the front purge rack, coating rack, rear purge rack and annealing rack in sequence to complete the pre-coating purge, coating, post-coating purge and laser annealing of the substrate.

[0052] The difference from Embodiment 1 is that in this embodiment, the substrate is the moving part, while the front purge frame, coating frame, rear purge frame, and annealing frame are fixedly placed along the base. The rest of the device structure remains unchanged. In the process, the substrate moves along the substrate track at the same relative speed as in Embodiment 1, passing sequentially below the purge nozzle, slit coating knife, high-pressure nitrogen extractor, and laser radiation device. Everything else remains the same.

[0053] The process flow of this invention is seamless from solution preparation to laser annealing, eliminating the need for substrate transport and exposure. This avoids thickness variations in the wet film caused by uneven solvent evaporation and reduces efficiency losses during process transitions, making it suitable for large-scale production. Furthermore, the process and equipment are highly compatible, with each step synchronized, improving coating efficiency and mitigating the impact of evaporation differences from start to finish through stable solvent control and crystallization management, ensuring the coating and forming quality of large-size wet films. In addition, automated parameter control eliminates the need for human experience, ensuring consistent processing of large-size substrates across different batches and meeting the industrial requirements for stable quality of large-size perovskite films.

[0054] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A slit coating apparatus for perovskite solar cells, characterized in that, It includes a base for placing a substrate, and a front purge frame, a coating frame, a rear purge frame and an annealing frame arranged sequentially along the base. The front purging frame is provided with a purging nozzle facing the base, which purifies the surface of the substrate with high-pressure gas. The coating rack is provided with a slit coating blade facing the substrate for coating a perovskite wet film on the substrate surface; The rear purge frame is equipped with a high-pressure nitrogen extractor facing the base, which is used for purging the solution on the surface of the perovskite wet film. The annealing rack is equipped with a laser radiation device facing the base, which causes the residual solution on the surface of the perovskite wet film to evaporate simultaneously through laser annealing.

2. The perovskite solar cell slit coating apparatus according to claim 1, characterized in that, The front purging frame, the coating frame, the rear purging frame, and the annealing frame move along the base via a frame movement track.

3. The perovskite solar cell slit coating apparatus according to claim 1, characterized in that, The upper surface of the substrate is provided with a substrate moving track for moving the substrate. The substrate moves along the substrate moving track and passes under the front purge frame, the coating frame, the rear purge frame and the annealing frame in sequence.

4. The perovskite solar cell slit coating apparatus according to claim 1, characterized in that, The high-pressure nitrogen extractor has a plurality of nitrogen nozzles arranged in an array on the end face facing the base. The number of nitrogen nozzles is adjustable, with a density of 50–200 nozzles / m³. 2 The nitrogen nozzle is surrounded by an extraction groove.

5. The perovskite solar cell slit coating apparatus according to claim 1, characterized in that, The laser radiation device includes an infrared temperature sensor to monitor the surface temperature of the substrate.

6. A slit coating process for perovskite solar cells, characterized in that, Using the perovskite solar cell slit coating apparatus according to any one of claims 1 to 5, the method includes the following steps: S1. Preparation of perovskite solution: Dissolve PbI2, PbBr2, FAI, and CsI in an organic solvent to obtain a perovskite solution; S2. Slit coating knife liquid injection: Seal the liquid outlet of the slit coating knife, open the exhaust valve, inject perovskite solution into the hollow cavity of the slit coating knife, and expel air bubbles from the cavity; S3. Pre-coating purging: The purging nozzles on the front purging frame purify the surface of the substrate to be coated to remove impurities and dust. S4. Coating: The coating rack applies a perovskite wet film to the substrate surface using a slit coating knife; S5. Post-coating purging: The post-purging rack uses a high-pressure nitrogen extractor to uniformly purge the surface of the perovskite wet film to remove the solution from the surface of the perovskite wet film. S6. Laser annealing: The annealing rack irradiates the perovskite wet film with a laser radiation device.

7. The perovskite solar cell slit coating process according to claim 1, characterized in that, The preparation temperature is 20–30℃ and the humidity is 30–50%RH; the moving speed of the front purge frame, coating frame, rear purge frame, and annealing frame relative to the substrate is 0.1–2 m / min.

8. The perovskite solar cell slit coating process method according to claim 1, characterized in that, The molar ratio of PbI2, PbBr2, FAI, and CsI in the perovskite solution prepared by S1 is 1.1–1.4: 0.15–0.25: 1.2–1.5: 0.1–0.

15. The volume ratio of DMF to DMSO in the organic solvent is 4:1–8:

1. 2-ME is added to the perovskite solution at a volume ratio of 0.1–0.5 vol%.

9. The perovskite solar cell slit coating process according to claim 1, characterized in that, In S2, perovskite solution is injected into the slit coating blade cavity at a rate of 5-100 ml / s. The direction of the purge nozzle in S3 is adjustable, with an angle of 90 to 150° with the substrate. The purge gas is nitrogen, with a nitrogen pressure of 0.3 to 0.7 MPa. The S4 slit coating blade has a liquid injection rate of 10–20 ml / min and a coating height of 100–200 μm. In S6, the laser is a linear or area spot with a wavelength of 400–700 nm, the laser power is 5–50 W, and the substrate surface temperature is controlled at 100–150 °C.

10. The perovskite solar cell slit coating process according to claim 1, characterized in that, The nitrogen pressure of the S5 medium-high pressure nitrogen extractor is 0.3-0.7 MPa, the purging height is 5-30 mm, and the nitrogen temperature is 25℃-100℃.

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