Coating die head for slit coating equipment and coating method of coating die head

Abstract

The invention belongs to the technical field of solution method thin film deposition equipment, and particularly relates to a coating die head for slit coating equipment and a coating method thereof, a first die head, a gasket and a second die head are connected in sequence, the lower end of the gasket is provided with a notch, and a coating lip is formed between the lower ends of the first die head and the second die head; the face, facing the gasket, of the first die head is a liquid outlet end, a liquid storage groove and a liquid outlet channel are formed in the first die head, one end of the liquid outlet channel communicates with the liquid storage groove, and the other end of the liquid outlet channel communicates with the liquid outlet end of the first die head. A gas inlet cover is mounted on the first die head in a sealing manner, and gas is pumped into the liquid storage tank through the gas inlet cover for pressurization; the first die head is further provided with an ultrasonic generator used for removing bubbles of the precursor solution. The low-pressure ultrasonic defoaming technology is adopted, the pinhole defect in the film is effectively reduced, meanwhile, precursor liquid left in equipment such as pipelines and injection pumps in the traditional coating technology is reduced through the gas extrusion method, and therefore the laboratory research cost is remarkably reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of slit coating equipment, thin film deposition preparation and solar cell preparation, in particular to a coating die head for slit coating equipment and a coating method thereof. Background Art

[0002] The laboratory-certified efficiency of perovskite solar cells has reportedly reached 27%, but high-quality large-area production remains the main factor restricting its large-scale commercialization. Compared with technologies such as vacuum deposition, blade coating and inkjet printing, slit coating technology has significant advantages in speed and precision. Its closed coating system can prevent the ingress of contaminants and can adapt to different coating fluid viscosities, making it one of the most suitable technologies for industrial production. Despite this, the application of existing slit coating technology in laboratory research still faces several problems, especially in the defoaming treatment and utilization efficiency of the precursor solution.

[0003] In the traditional slot coating process, it is usually necessary to first reversely suck the precursor liquid into the syringe, then connect the syringe to the coating die through a pipe, start the syringe pump to squeeze the precursor liquid in the syringe and apply it to the substrate through the coating lip. However, the precursor liquid usually needs to be filtered before coating, and the use of porous filter heads often leads to a large number of bubbles in the precursor liquid. Bubbles in the coating process often cause "pinhole" defects on the surface of the film, affecting the quality and stability of the film. Moreover, the complex and lengthy pipeline system may not only cause uneven flow of the precursor liquid, but also increase the difficulty of equipment cleaning, further reducing research and production efficiency.

[0004] In addition, there is often a problem of residual precursor liquid in traditional slit coating equipment. Since the precursor liquid in the syringe and pipeline cannot be completely discharged, part of the material is wasted, which not only significantly increases the experimental cost, but also affects the efficiency of the coating process. Especially in short-cycle laboratory research, the problem of liquid residue is more prominent. This problem makes researchers face high material waste and operational difficulties during the experiment, and there is an urgent need to improve existing technologies to improve material utilization and reduce experimental costs. Summary of the invention

[0005] In view of the above problems existing in traditional slot coating, the object of the present invention is to provide a coating die head for slot coating equipment and a coating method thereof.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] The coating die of the present invention comprises an air inlet cover, a first die, a gasket and a second die, wherein the first die, the gasket and the second die are connected in sequence, the gasket is clamped between the first die and the second die, the lower end of the gasket is provided with a notch, and a coating lip is formed between the lower end of the first die and the lower end of the second die; the side of the first die facing the gasket is a liquid outlet end, and a liquid storage tank and a liquid outlet channel are respectively provided inside the first die, the liquid storage tank is used to accommodate the filtered precursor liquid, one end of the liquid outlet channel is connected to the liquid storage tank, and the other end is connected to the liquid outlet end of the first die; an air inlet cover is sealedly installed on the first die, and gas is pumped into the liquid storage tank through the air inlet cover to increase pressure, so that the precursor liquid in the liquid storage tank is extruded through the liquid outlet channel, the liquid outlet end of the first die and the coating lip; an ultrasonic generator for defoaming the precursor liquid is also installed on the first die.

[0008] Wherein: the top end of the liquid storage tank extends to the top surface of the first die head, the bottom of the liquid storage tank is an inclined surface, and one end of the liquid outlet channel is connected to the lowest point of the inclined surface.

[0009] The liquid outlet channel is "U"-shaped, one end of the "U"-shaped opening is connected to the liquid storage tank, the other end of the "U"-shaped opening is connected to the liquid outlet end of the first die head, and the height of one end of the "U"-shaped opening is lower than the height of the other end.

[0010] A liquid uniformity groove is provided on one side of the first die head facing the gasket, and the other end of the liquid outlet channel is communicated with the liquid uniformity groove.

[0011] The liquid uniformizing groove is an arc-shaped groove, a liquid outlet is provided at the bottom of the liquid uniformizing groove, and the other end of the liquid outlet channel is connected to the liquid outlet.

[0012] The air inlet cover is sealed and installed on the top surface of the first die head, and an air inlet hole connected to the liquid storage tank is opened on the air inlet cover; the ultrasonic generator is installed on the other side of the first die head opposite to the liquid homogenizing groove.

[0013] The lower end of the gasket is in an inverted "U" shape, the opening of the inverted "U" shape is the notch, and the projection of the liquid-uniform groove on the gasket is located in the inverted "U" shape.

[0014] The lower end of the first die head in contact with the gasket extends downward to form an extension part A, and the lower end of the second die head in contact with the gasket extends downward to form an extension part B. The extension part A, the extension part B and the notch at the lower end of the gasket together form a coating lip.

[0015] The coating method of the coating die head of the slit coating equipment of the present invention comprises the following steps:

[0016] Step A, sealing the coating lip and adding the filtered precursor liquid into the liquid storage tank;

[0017] Step B, installing an air inlet cover on the first die head, wherein the air inlet hole is connected to an injection pump;

[0018] Step C, starting the ultrasonic generator on the first die head, and starting the injection pump in reverse, so that the liquid reservoir is kept in a low pressure state, and performing low-pressure ultrasonic debubbling on the precursor liquid in the liquid reservoir;

[0019] Step D, after debubbling, the injection pump works forward, pumps gas into the liquid storage tank through the air inlet, uniformly squeezes the precursor liquid, and makes the precursor liquid flow out to the coating lip through the liquid outlet channel and the liquid outlet end of the first die head, and completes the coating in coordination with the movement of the substrate.

[0020] Wherein: a liquid uniformity groove is formed on a side of the first die head facing the gasket, and in step D, the extruded precursor liquid flows out uniformly in the liquid uniformity groove and is evenly coated on the substrate.

[0021] The advantages and positive effects of the present invention are:

[0022] 1. Effective degassing and reduction of film defects. The present invention uses low-pressure ultrasonic degassing technology to effectively remove bubbles in the precursor solution before coating; the ultrasonic wave generated by the ultrasonic generator combined with the low-pressure environment in the liquid storage tank can destroy the bubble structure, thereby alleviating the formation of "pinhole" defects caused by bubbles during the coating process and improving the uniformity and quality of the film.

[0023] 2. Improve the utilization rate of precursor liquid and reduce material waste. Through reasonable liquid storage tank structure design and gas pressure extrusion method, the present invention effectively reduces the problem of residual precursor liquid in the traditional coating process; compared with traditional coating equipment, the present invention can significantly reduce the waste of unused precursor liquid in pipes and syringes, which not only reduces experimental costs, but also improves the utilization efficiency of materials, which is particularly important for laboratory research.

[0024] 3. Simplify equipment cleaning and reduce operational difficulty. The coating die head structure of the present invention is relatively simple, and adopts a tightly fitting gasket and die head connection design, which avoids the complex pipeline system in traditional equipment, thereby simplifying the cleaning and maintenance of the equipment; in addition, it reduces the residual precursor liquid in the pipeline, improves the cleaning efficiency, and reduces the cost and time of equipment maintenance.

[0025] 4. Stability and sustainability. The air inlet cap used in the present invention can pressurize the liquid storage tank by pumping in gas, making the flow of the precursor liquid more stable and uniform, ensuring the high precision of the coating process; compared with the traditional slit coating technology, the coating method of the present invention reduces the risk of contamination while ensuring liquid supply, greatly reduces the difficulty of cleaning the coating die and liquid flow pipeline, and ensures the consistency and long-term stability of the film coating.

[0026] 5. Strong adaptability and wide application. The present invention is not only suitable for coating of perovskite solar cells, but can also be widely used in other thin film preparation fields that require high-precision coating, such as OLED, photoelectric sensors, displays, etc. Its high efficiency, energy saving and low cost make it a coating technology with great potential in large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the three-dimensional structure of the coating die head of the present invention;

[0028] Figure 2 One of the exploded views of the coating die head of the present invention;

[0029] Figure 3 This is the second exploded view of the coating die head of the present invention;

[0030] Figure 4 This is one of the three-dimensional structural schematic diagrams of the first die head in the coating die head of the present invention;

[0031] Figure 5 The second schematic diagram of the three-dimensional structure of the first die head in the coating die head of the present invention;

[0032] Figure 6 It is a structural front view of the first die head in the coating die head of the present invention;

[0033] Figure 7 for Figure 6 Right view of;

[0034] Figure 8 for Figure 7 It is a top view;

[0035] Fig. 9 for Figure 6 A-A sectional view;

[0036] Among them: 1 is the air inlet cover, 11 is the air inlet hole, 2 is the first die head, 21 is the ultrasonic generator, 22 is the liquid storage tank, 23 is the liquid outlet channel, 24 is the liquid outlet, 25 is the liquid uniforming groove, 26 is the extension part A, 3 is the gasket, 31 is the coating lip, 4 is the second die head, and 41 is the extension part B. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the accompanying drawings.

[0038] like Figures 1 to 9 As shown, the present invention provides a low-cost, high-utilization coating die for a slit coating device, the device basis of which is the slit coating device, and the coating die is installed on a liftable bracket of the slit coating device. The coating die head includes an air inlet cover 1, a first die head 2, a gasket 3 and a second die head 4, the first die head 2, the gasket 3 and the second die head 4 are connected in sequence, the gasket 3 is clamped between the first die head 1 and the second die head 4, the lower end of the gasket 3 is provided with a notch, and a coating lip 31 is formed between the lower end of the first die head 1 and the lower end of the second die head 4; the side of the first die head 2 facing the gasket 3 is the liquid outlet end, and the interior of the first die head 2 is respectively provided with a liquid storage tank 22 and a liquid outlet channel 23, the liquid storage tank 22 is used to accommodate the filtered precursor liquid, one end of the liquid outlet channel 23 is connected to the liquid storage tank 22, and the other end is connected to the liquid outlet end of the first die head 2; the first die head 2 is sealed with an air inlet cover 1, and the air inlet cover 1 is provided with an air inlet hole 11 connected to the liquid storage tank 22, and gas is pumped into the liquid storage tank 22 through the air inlet hole 11; the first die head 2 is also provided with an ultrasonic generator 21 for debubbling the precursor liquid.

[0039] The first die head 2 and the second die head 4 of the present embodiment are both rectangular parallelepipeds, and a plurality of bolt holes are respectively provided on the first die head 2, the gasket 3 and the second die head 4. The first die head 2, the gasket 3 and the second die head 4 are fixed together by bolts inserted through the bolt holes, and the gasket 3 is tightly fitted with the first die head 2 and the second die head 4 respectively.

[0040] In this embodiment, the top of the liquid storage tank 22 extends to the top surface of the first die head 2, the bottom of the liquid storage tank 22 is an inclined surface, and one end of the liquid outlet channel 23 is connected to the lowest point of the inclined surface.

[0041] The air intake cover 1 of this embodiment is a rectangular parallelepiped, and its volume is smaller than the first die head 2; the bottom surface of the air intake cover 1 is provided with a square sealing groove outside the air intake hole 11, and a sealing ring is placed in the sealing groove, and the size of the sealing groove is larger than the size of the liquid storage tank 22 on the top surface of the first die head 2. Bolt holes are respectively opened on the top surfaces of the air intake cover 1 and the first die head 2, and the air intake cover 1 is fixedly connected to the first die head 2 by bolts inserted through the bolt holes, and the sealing is achieved by the sealing ring.

[0042] In this embodiment, a liquid-distributing groove 25 is provided on one side of the first die head 2 facing the gasket 3. The liquid-distributing groove 25 is an arc-shaped groove, and a liquid outlet 24 is provided at the bottom of the groove in the liquid-distributing groove 25. The liquid outlet channel 23 in this embodiment is "U"-shaped, and one end of the "U"-shaped opening is connected to the liquid storage tank 22, and the other end of the "U"-shaped opening is connected to the liquid outlet 24; the height of one end of the "U"-shaped opening is lower than the height of the other end. The ultrasonic generator 21 is installed on the other side opposite to the surface where the liquid-distributing groove 25 is located, and the ultrasonic frequency generated is 20 to 120 KHz.

[0043] The lower end of the gasket 3 of this embodiment is in an inverted "U" shape, and the thickness of the gasket 3 is 20 to 500 microns. The material of the gasket 3 includes but is not limited to one of polyimide, polydimethylsiloxane, and polytetrafluoroethylene. The opening of the inverted "U" shape is a notch, and the projection of the liquid homogenizing groove 25 on the gasket 3 is located in the inverted "U" shape. The lower end of the first die head 2 of this embodiment, which is in contact with the gasket 3, extends downward to form an extension A26, and the lower end of the second die head 4, which is in contact with the gasket 3, extends downward to form an extension B41. The extension A26, the extension B41 and the notch at the lower end of the gasket 3 together form a coating lip 31.

[0044] The coating method of the coating die head of the present invention comprises the following steps:

[0045] Step A, sealing the coating lip 31 and adding the filtered precursor liquid into the liquid storage tank 22;

[0046] Step B, installing the air inlet cover 1 on the first die head 1, and the air inlet hole 11 is connected to the injection pump;

[0047] Step C, starting the ultrasonic generator 21 on the first die head 1, and reversely starting the injection pump to keep the liquid reservoir 22 in a low pressure state, and treating the precursor liquid in the liquid reservoir 22 by low-pressure ultrasonic debubbling to remove bubbles in the precursor liquid;

[0048] Step D, after debubbling, the injection pump works forward, pumps gas into the liquid reservoir 22 through the air inlet 11, pressurizes the liquid reservoir 22, and uniformly squeezes the precursor liquid, so that the precursor liquid in the liquid reservoir 22 flows out through the liquid outlet channel 23, the liquid outlet 24, and the liquid uniformity groove 25 to the coating lip 31 and then is uniformly squeezed out. With the cooperation of the movement of the substrate, the precursor liquid can be evenly coated on the surface of the substrate to form a wet film, and then the next drying process is carried out.

[0049] In step D, by controlling the speed of gas pumped into the air inlet cap 1, the liquid discharge speed of the coating lip 31 can be regulated, thereby controlling the film thickness.

[0050] The gas pumped into the liquid storage tank 22 of the present invention may be one of nitrogen, argon, oxygen, air or dry air, and the minimum gas pumping speed of the injection pump into the liquid storage tank 22 is 0.001 mL / min.

[0051] The present invention uses low-pressure ultrasonic debubbling technology to effectively reduce the "pinhole" defects in the film. At the same time, the gas extrusion method is used to reduce the residual precursor liquid in the pipeline, injection pump and other equipment in the traditional coating technology, thereby significantly reducing the laboratory research cost.

Claims

1. A coating die head for a slot coating device, characterized in that: The invention comprises an air inlet cover (1), a first die head (2), a gasket (3) and a second die head (4); the first die head (2), the gasket (3) and the second die head (4) are connected in sequence; the gasket (3) is clamped between the first die head (1) and the second die head (4); a notch is provided at the lower end of the gasket (3), and a coating lip (31) is formed between the lower end of the first die head (1) and the lower end of the second die head (4); the side of the first die head (2) facing the gasket (3) is a liquid outlet end; the first die head (2) is provided with a liquid storage tank (22) and a liquid outlet channel (23) inside. The liquid storage tank (22) is used to contain the precursor liquid after filtration; one end of the liquid outlet channel (23) is connected to the liquid storage tank (22), and the other end is connected to the liquid outlet end of the first die head (2); an air inlet cover (1) is sealedly installed on the first die head (2), and gas is pumped into the liquid storage tank (22) through the air inlet cover (1) to increase pressure, thereby causing the precursor liquid in the liquid storage tank (22) to be extruded through the liquid outlet channel (23), the liquid outlet end of the first die head (2) and the coating lip (31); the first die head (2) is also equipped with an ultrasonic generator (21) for debubbling the precursor liquid.

2. The coating die head for the slot coating equipment according to claim 1, characterized in that: The top end of the liquid storage tank (22) extends to the top surface of the first die head (2), the bottom of the liquid storage tank (22) is an inclined surface, and one end of the liquid outlet channel (23) is connected to the lowest point of the inclined surface.

3. The coating die head for the slot coating equipment according to claim 1, characterized in that: The liquid outlet channel (23) is in a "U" shape, one end of the "U"-shaped opening is connected to the liquid storage tank (22), and the other end of the "U"-shaped opening is connected to the liquid outlet end of the first die head (1), and the height of one end of the "U"-shaped opening is lower than the height of the other end.

4. The coating die head for slot coating equipment according to claim 1, characterized in that: A liquid uniformity groove (25) is provided on one side of the first die head (2) facing the gasket (3), and the other end of the liquid outlet channel (23) is in communication with the liquid uniformity groove (25).

5. The coating die head for slot coating equipment according to claim 4, characterized in that: The liquid uniforming groove (25) is an arc-shaped groove, a liquid outlet (24) is provided at the bottom of the liquid uniforming groove (25), and the other end of the liquid outlet channel (23) is connected to the liquid outlet (24).

6. The coating die head for slot coating equipment according to claim 1, characterized in that: The air inlet cover (1) is sealingly mounted on the top surface of the first die head (2), and an air inlet hole (11) connected to the liquid storage tank (22) is provided on the air inlet cover (1); the ultrasonic generator (21) is mounted on the other side of the first die head (2) opposite to the liquid homogenizing groove (25).

7. The coating die head for slot coating equipment according to claim 1, characterized in that: The lower end of the gasket (3) is in an inverted "U" shape, the opening of the inverted "U" shape is the notch, and the projection of the liquid homogenizing groove (25) on the gasket (3) is located within the inverted "U" shape.

8. The coating die head for slot coating equipment according to claim 1, characterized in that: The lower end of the first die head (2) on the side in contact with the gasket (3) extends downward to form an extension portion A (26), and the lower end of the second die head (4) on the side in contact with the gasket (3) extends downward to form an extension portion B (41). The extension portion A (26), the extension portion B (41) and the notch at the lower end of the gasket (3) together form a coating lip (31).

9. A coating method for a coating die head of a slot coating device according to any one of claims 1 to 8, characterized in that: The following steps are included Step A, sealing the coating lip (31) and adding the filtered precursor liquid into the liquid storage tank (22); Step B, installing an air inlet cover (1) on the first die head (1), wherein the air inlet hole (11) is connected to an injection pump; Step C, starting the ultrasonic generator (21) on the first die head (1), and starting the injection pump in reverse, so that the liquid storage tank (22) is kept in a low pressure state, and the precursor liquid in the liquid storage tank (22) is defoamed by low-pressure ultrasound; In step D, after debubbling, the injection pump works in the forward direction, pumping gas into the liquid storage tank (22) through the air inlet (11), uniformly squeezing the precursor liquid, so that the precursor liquid flows out through the liquid outlet channel (23) and the liquid outlet end of the first die head (1) to the coating lip (31), and the coating is completed in coordination with the movement of the substrate.

10. The coating method according to claim 9, characterized in that: A liquid homogenizing groove (25) is provided on a side of the first die head (2) facing the gasket (3). In step D, the extruded precursor liquid flows out evenly in the liquid homogenizing groove (25) and is evenly coated on the substrate.

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