Coating apparatus and coating method

Abstract

According to an embodiment of the present invention, a coating apparatus and a coating method that are capable of forming a uniform coating film by a meniscus method are provided. The coating apparatus comprises: a coating bar; a substrate conveying member that conveys a substrate; a plurality of nozzles that supply coating liquid onto the surface of the coating bar; a coating liquid supply member that supplies the coating liquid to the nozzles; and a coating liquid supply amount adjustment member that adjusts the amount of the coating liquid to be supplied to each of the nozzles and is provided on the upstream side of each of the nozzles.

Description

Coating device and coating method

[0001] SUMMARY OF THE INVENTION Embodiments of the present invention relate to a coating apparatus and a coating method that can be used in forming devices.

[0002] Organic thin-film solar cells and organic / inorganic hybrid solar cells using organic semiconductors are expected to be low-cost solar cells because inexpensive coating methods can be used to form the active layer. To realize organic thin-film solar cells and organic / inorganic hybrid solar cells at low cost, it is necessary to uniformly apply the coating materials that form the organic active layer and other layers. The thickness of each layer ranges from a few nanometers to a few hundred nanometers, and it is necessary to form such extremely thin layers uniformly over a large area. For example, meniscus coating is known as a roll-to-roll (R2R) coating method that can coat extremely thin layers over a large area at low cost. This meniscus coating method involves supplying liquid from multiple nozzles to a coating bar head to obtain a single large-area coating film, which is simple and easy to use, and the equipment structure is simple. However, achieving a uniform film thickness can be difficult, and a coating device that can form a more uniform coating film is desired.

[0003] Japanese Patent Application Laid-Open No. 2006-167532

[0004] The embodiments of the present invention provide a coating apparatus and a coating method that can form a uniform coating film by a meniscus coating method and that also require simple maintenance.

[0005] The embodiments provided by the present invention are as follows. [1] A coating device for supplying a coating liquid to a surface of a substrate and forming a coating film by a meniscus method, comprising: a coating bar; a substrate transport member for transporting the substrate; a plurality of nozzles for supplying the coating liquid to the surface of the coating bar; and a coating liquid supply member for supplying the coating liquid to the nozzles, wherein the coating device comprises coating liquid supply rate adjustment members upstream of each of the nozzles for adjusting the amount of coating liquid supplied to the nozzles. [2] The coating device described in [1], further comprising a coating bar position adjustment member for controlling the position of the coating bar. [3] The coating device described in [1] or [2], further comprising a nozzle position detection member for detecting contact between the coating bar and at least one of the nozzles. [4] The coating device described in any of [1] to [3], further comprising a nozzle position adjustment member for independently changing the distance between the plurality of nozzles and the coating bar. [5] The coating device according to any one of [1] to [4], further comprising a coating liquid supply member for supplying the coating liquid to the nozzles, the total number of the coating liquid supply members being less than the total number of the nozzles. [6] The coating device according to any one of [1] to [5], wherein the coating bar is arranged so as not to rotate. [7] The coating device according to any one of [1] to [6], wherein the nozzle is needle-shaped with the opening of the coating liquid outlet cut at an angle of 75 degrees or more and 105 degrees or less. [8] The coating device according to any one of [1] to [7], wherein the nozzle is removable. [9] A coating method for forming a meniscus of coating liquid between a coating bar and a substrate, transporting the substrate, and applying the coating liquid to the surface of the substrate, the coating liquid being supplied to a plurality of nozzles, and the coating liquid being supplied from the plurality of nozzles to the surface of the coating bar, and the amount of coating liquid supplied to each of the plurality of nozzles being adjusted upstream of each nozzle.

[10] The coating method according to [9], wherein the total number of coating liquid supply members is less than the total number of the nozzles.

[0006] Fig. 1 is a schematic side view illustrating a coating apparatus according to a first embodiment. Fig. 2 is a schematic top view illustrating the coating apparatus according to the first embodiment. Fig. 3 is a flowchart illustrating a coating method according to a second embodiment.

[0007] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0008] The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be different depending on the drawing.

[0009] In the present specification and the drawings, elements similar to those described above with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0010] First Embodiment Fig. 1 is a schematic side view illustrating a coating apparatus according to a first embodiment. Fig. 2 is a schematic top view illustrating the coating apparatus according to the first embodiment.

[0011] 1 , a coating apparatus 100 according to an embodiment includes a nozzle position adjusting member 108, a coating bar 101, a mechanism 107 for detecting the distance to a nozzle 103, a coating liquid supplying member 104 such as a liquid feed pump, and equipment transporting members such as transport rollers 102a and 102b for transporting a substrate 102. A coating liquid supply amount adjusting member 105, such as an adjustment valve, is disposed upstream of each nozzle.

[0012] As shown in Fig. 2, the coating device in this embodiment is equipped with a plurality of nozzles 103. In addition, a plurality of coating liquid supply members such as liquid supply pumps 104 may also be provided. The total number of nozzles may be greater than the total number of liquid supply pumps. In this case, the piping from one pump to each nozzle is branched, and it is preferable that the coating liquid piping be branched into two.

[0013] 1 and 2 , in the embodiment, the coating liquid supply amount adjusting member 105 is installed upstream of the nozzle 103. The plurality of nozzles 103 can face the coating bar 101. As shown in FIG. 2 , the plurality of nozzles 103 can supply the coating liquid 110 toward the coating bar 101.

[0014] As shown in Figure 2, the multiple nozzles 103 are aligned along a first direction. The first direction is, for example, the Y-axis direction. One direction perpendicular to the Y-axis direction is defined as the X-axis direction. The movement direction of the substrate can coincide with the X-axis. The direction perpendicular to the Y-axis direction and the X-axis direction is defined as the Z-axis direction. The coating bar 101 extends along, for example, the Y-axis direction.

[0015] As shown in FIG. 1 , a meniscus 110M of a coating liquid 110 can be formed between a substrate 102 and a coating bar 101. When the meniscus 110M comes into contact with the substrate 102 and the substrate 102 is moved in a movement direction (the direction of the arrow in the figure), a coating film 111 is formed on the substrate 102. The coating film 111 is solidified, for example, by drying, to obtain a desired film (solid film). For example, by moving the substrate 102 along the movement direction, a coating film 111 with a large area can be formed on the substrate 102.

[0016] The coating bar applies the coating liquid 110 to almost the entire surface of the substrate 102, but when using conventional coating methods, the film thickness may not be uniform. A major cause of this is variation in the discharge amount between each nozzle 103. The liquid supply amount for each nozzle is largely determined by the liquid supply pump, but varies depending on the number, length, and height of the pipes, as well as the diameter or clogging state of the pipes or nozzles. A coating liquid supply amount adjustment member, such as a valve 105 that adjusts the liquid amount, can adjust this, making it possible to reduce variation in the discharge amount of the coating liquid between each nozzle. In particular, when the number of liquid supply pumps is smaller than the number of nozzles, variation tends to be smaller, which is preferable.

[0017] The adjusting valve 105 may be a ball valve, globe valve, gate valve, butterfly valve, needle valve, diaphragm valve, motor valve, etc. The flow rate may also be adjusted by compressing a resin pipe with pressure.

[0018] The coating device according to the embodiment preferably further includes a coating bar position adjusting member 106 that controls the gap between the coating bar 101 and the substrate 102. A gap ring, a micrometer, or the like can be used as this member.

[0019] In an embodiment, the number of the plurality of nozzles 103 can be three or more. This allows a coating film 111 with a large area to be formed stably. In the example of Fig. 2, the number of the plurality of nozzles 103 is four. In an embodiment, the number may be any integer of three or more.

[0020] In an embodiment, the nozzle may be a slot die or may be needle-shaped. Using multiple needle-shaped nozzles 103 allows, for example, the discharge amount of the coating liquid 110 to be controlled with high precision. When the nozzles are needle-shaped, for example, even if there are a large number of nozzles, the tips of the nozzles can easily come into contact with the coating bar 101. Needle-shaped nozzles provide high flexibility. High flexibility can prevent the nozzle from being damaged by, for example, vibration of the coating bar 101. In needle-shaped nozzles, the nozzle length is, for example, 10 mm or more and 100 mm or less, and the nozzle inner diameter is, for example, 0.5 mm or more and 2 mm or less. The angle between the end face of the nozzle tip and the extension direction of the nozzle is, for example, approximately 90 degrees (for example, 75 degrees or more and 105 degrees or less). This shape can, for example, prevent scratches on the coating bar 101.

[0021] When multiple nozzles are arranged, variations tend to occur in the distance between the coating bar 101 and the tip of each nozzle. If there is variation, the meniscus 110M formed by each nozzle is likely to become disturbed, and as a result, the coating film 111 is likely to become non-uniform.

[0022] 1 and 2, if a nozzle position adjustment member 108 that adjusts the position of each nozzle and a nozzle position detection member 107 that detects the distance between the application bar 101 and each nozzle 103 are provided, the variations in the position and distance between the tip of each nozzle and the application bar can be reduced, enabling uniform application. Specifically, the position of each nozzle detected by a nozzle position detection member such as a camera is adjusted by a nozzle position adjustment member that physically adjusts the position of each nozzle.

[0023] In an embodiment, the coating apparatus may further include a member for detecting contact between the coating bar and each nozzle. Contact can be easily detected, for example, by measuring the electrical resistance between the nozzle and the coating bar, and coating conditions can be adjusted based on this detection, thereby reducing variation. When the nozzle and the coating bar are in contact, the coating liquid can be applied directly to the coating bar, making it less likely for the coating liquid to repel.

[0024] In an embodiment, a component for measuring the electrical resistance between each nozzle and the coating bar can be used to detect contact between the coating bar and each nozzle. If each nozzle and coating bar are made of conductive stainless steel or the like and the nozzles are insulated, measuring the electrical resistance between the coating bar and each nozzle will reveal a sharp drop in electrical resistance the moment they make contact. Furthermore, since electrical resistance changes as the contact state changes, it is possible to monitor the contact state. For example, if the nozzle is pressed so strongly against the coating bar that it bends too much, the coating bar will contact not only the tip of the nozzle but also its side, resulting in very low electrical resistance. In this case, the coating liquid is likely to be ejected from the tip of the nozzle to areas other than the coating bar, resulting in uneven coating. The optimal electrical resistance varies depending on the shape and material of the nozzle and coating bar, so it is desirable to measure it in advance.

[0025] It is desirable to install wiring between each nozzle and the coating bar in advance to connect them to an electrical resistance measuring device. An opening and closing section is provided in the wiring, so that each nozzle can be moved before coating to check contact with the coating bar. Furthermore, if electrical resistance is measured during coating, any abnormalities in the contact between the nozzle and coating bar can be detected. The electrical resistance measuring device can also be an external device separate from the coating device.

[0026] In the coating device according to the embodiment, it is preferable that the nozzles are removable. Nozzles are prone to clogging due to their small openings. In the coating device according to the embodiment, when such clogging occurs, the discharge rate of each nozzle can be adjusted using a coating liquid supply member or a coating liquid supply rate adjustment member. However, if the clogging becomes significant or if discharge becomes completely impossible, the nozzles must be cleaned or replaced. In such cases, it is preferable that the nozzles are removable, as this facilitates maintenance.

[0027] The coating device 100 may further include a drying member 112. The drying member 112 is capable of drying the coating liquid 111 applied to the substrate 102. The drying member 112 may include, for example, an air nozzle or a far-infrared lamp.

[0028] In the embodiment, the cross-sectional shape of the coating bar 101 is arbitrary. The cross-sectional shape may be, for example, a circle, a flattened circle, or a polygon. The cross-sectional shape may have a curved portion corresponding to the meniscus forming portion and a linear portion. For example, the cross-sectional shape of the surface of the coating bar 101 facing the substrate 102 may be curved.

[0029] The applicator bar can be arranged so that it does not rotate. By not having the applicator bar rotate like a roller, the meniscus becomes more stable.

[0030] The coating bar 101 includes, for example, at least one selected from the group consisting of stainless steel, aluminum, titanium, and glass. This allows for easy processing when preparing the coating bar 101. In one example, the surface of the coating bar 101 is a mirror finish. In another example, the surface of the coating bar 101 may include a textured structure.

[0031] Second Embodiment The second embodiment relates to a coating method. In the coating method according to the embodiment, coating is performed using, for example, the coating apparatus 100 (and its modifications) described in relation to the first embodiment.

[0032] FIG. 3 is a flowchart illustrating the coating method (S30) according to the second embodiment.

[0033] In a coating method according to an embodiment, a meniscus of a coating liquid is formed between a coating bar and a substrate, the substrate is transported, and the coating liquid is applied to the surface of the substrate. The coating liquid is then supplied to a plurality of nozzles, and the coating liquid is supplied from the plurality of nozzles to the surface of the coating bar. At this time, the supply amount of the coating liquid supplied to each of the plurality of nozzles is adjusted upstream of each nozzle.

[0034] Prior to carrying out this method, the amount of coating liquid supplied to each nozzle is first adjusted (S31)." The amount of coating liquid supplied can be adjusted by a coating liquid supplying member such as a pump or a coating liquid supply amount adjusting member disposed upstream of the nozzle.

[0035] Next, the distance between the coating bar and each nozzle is detected, and the distance is adjusted as necessary (S32). The distance can be detected using a nozzle position detection member or the like. The distance can be adjusted using a coating bar position adjustment member or a nozzle position adjustment member.

[0036] Then, once the amount of coating liquid supplied has been adjusted and adjustment of the positions of the coating bar and each nozzle has been completed, the step (S33) of supplying the coating liquid and coating the substrate can be carried out.

[0037] Specific examples of the coating apparatus and coating method according to the embodiment will be described below.

[0038] For example, a solar cell can be formed by coating using the coating device 100. In one example, the number of pumps is four. A pipe connected to one pump is connected to four nozzles. The total number of nozzles is 16. The nozzles are attached to a single cantilever bar. An actuator for movement and wiring for measuring electrical resistance are attached to each nozzle. A liquid volume adjustment valve is attached to each nozzle. The wiring is connected to an electrical resistance meter. A nozzle position detection member, such as a camera, is attached to observe the positional relationship between the nozzle and the coating bar.

[0039] For example, the substrate 102 is a roll of PET film. The width of the PET film is, for example, 330 mm. A light-transmitting electrode having a width of 300 mm is formed on the PET film using a roll-to-roll sputtering device. The sheet resistance of the electrode is, for example, 10 Ω / □. The electrode has, for example, a laminated structure of ITO film / Ag alloy / ITO film. For example, multiple electrodes are provided. The length of each of the multiple electrodes is, for example, approximately 10 mm. The spacing between the multiple electrodes is, for example, 50 μm.

[0040] The cross-sectional shape of the coating bar 101 is circular. The radius of the circle is 10 mm. The length of the coating bar 101 is 300 mm. The coating bar 101 includes, for example, stainless steel (e.g., SUS303).

[0041] The nozzle includes a stainless steel locking element. The nozzle is 50 mm long. The coating liquid is piped through a polytetrafluoroethylene tube. A liquid volume adjustment valve is installed between the tube and the nozzle. The valve and the tube are connected by a detachable joint. The tube is then connected to a pump.

[0042] In one example, a hole transport layer is formed by the coating liquid 110. In this case, the coating liquid 110 is an aqueous solution containing PEDOT and PSS.

[0043] For example, the relative positional relationship between the coating bar 101 and the substrate 102 is controlled by a gap ring or an actuator.

[0044] For example, the nozzles are placed in a horizontal position. In this state, the coating liquid 110 is supplied and the air in the nozzles is discharged. Then, the pump and the liquid volume control valve are adjusted so that the coating liquid is discharged uniformly from each nozzle.

[0045] After this, the tip of the needle nozzle is lowered and tilted, for example, by 20° from the horizontal. The cantilever bar is brought close to the coating bar. Next, each nozzle is brought close to the coating bar one by one until they come into contact and the electrical resistance becomes 10 to 50 Ω.

[0046] While the substrate 102 is being transported, the coating liquid 110 is continuously supplied by a pump. The moving speed of the substrate 102 is, for example, 5 m / min. The drying member 112 blows heated dry air onto the applied coating liquid 110. A solidified coating film is obtained from the coating liquid 110.

[0047] In an embodiment, after the above coating, another coating liquid may be further coated. The other coating liquid may include, for example, a semiconductor material. The other coating liquid may include, for example, PTB7 ([poly{4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-1t-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl}]) and PC70BM ([6,6]phenyl C71 butyric acid methyl ester). PTB7 is, for example, a p-type semiconductor. PC70BM is, for example, an n-type semiconductor. The other coating liquid may further include, for example, monochlorobenzene. The amount of PTB7 per 1 mL of monochlorobenzene is 8 mg. The amount of PC70BM per 1 mL of monochlorobenzene is 12 mg. Another coating liquid is a dispersion containing an organic semiconductor.

[0048] The other coating liquid becomes, for example, a semiconductor film for a solar cell. In coating the other coating liquid, the minimum gap distance between the coating bar 101 and the substrate 102 is 300 μm. The moving speed of the substrate 102 is, for example, 5 m / min. After coating, drying is performed by a drying member 112.

[0049] For example, there are organic thin-film solar cells using organic semiconductors and organic / inorganic hybrid solar cells. These solar cells can be produced by coating methods to produce high-performance solar cells.

[0050] In an embodiment, the coating liquid 110 may be applied to the substrate 102 at a position where the substrate 102 is transported in the vertical direction. This allows, for example, the effect of gravity to be applied to the meniscus, making it easier to obtain a uniform film even at high speeds.

[0051] According to the embodiment, a coating device and a coating method capable of forming a uniform coating film are provided.

[0052] The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, the specific configurations of the elements included in the coating device, such as the pipe, pump, nozzle, and holder, are within the scope of the present invention as long as a person skilled in the art can implement the present invention in a similar manner and obtain similar effects by appropriately selecting them from known ranges.

[0053] Furthermore, any combination of two or more elements of each specific example within the scope of technical feasibility is also included within the scope of the present invention as long as it includes the gist of the present invention.

[0054] In addition, all coating devices and coating methods that can be implemented by a person skilled in the art by appropriately modifying the design based on the coating head, coating device, and coating method described above as embodiments of the present invention also fall within the scope of the present invention, as long as they include the gist of the present invention.

[0055] In addition, within the scope of the concept of the present invention, a person skilled in the art may come up with various modifications and alterations, and it will be understood that these modifications and alterations also fall within the scope of the present invention.

[0056] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

[0057] DESCRIPTION OF SYMBOLS 100... Coating device 101... Coating bar 102... Substrate 102a, 102b... Conveying mechanism 103... Nozzle 104... Pump 105... Coating liquid supply amount adjusting member 106... Coating bar position adjusting member 107... Nozzle distance detecting member 108... Nozzle position adjusting member 109... Liquid reservoir 110... Coating liquid 111... Coating film 112... Drying member

Claims

1. A coating device for supplying a coating liquid to a surface of a substrate and forming a coating film by a meniscus method, A coating bar; A substrate transport member that transports the substrate; a plurality of nozzles for supplying the coating fluid to a surface of the coating bar; a coating liquid supplying member for supplying the coating liquid to the nozzle; a coating liquid supply amount adjusting member for adjusting the amount of coating liquid supplied to the nozzle is provided upstream of each of the nozzles; the total number of the coating liquid supplying members is smaller than the total number of the nozzles.

2. The coating apparatus according to claim 1 , further comprising a coating bar position adjustment member for controlling a position of the coating bar.

3. The coating device according to claim 1 , further comprising a nozzle position detection member that detects contact between the coating bar and at least one of the nozzles.

4. 3. The coating device according to claim 1, further comprising a nozzle position adjustment member for independently changing a distance between the plurality of nozzles and the coating bar.

5. (delete)

6. 3. The coating device according to claim 1, wherein the coating bar is arranged not to rotate.

7. 3. The coating apparatus according to claim 1, wherein the nozzle has a needle shape in which an opening surface of the coating liquid discharge port is cut at an angle of 75 degrees or more and 105 degrees or less.

8. The coating device according to claim 1 or 2, wherein the nozzle is removable.

9. A coating method in which a meniscus of a coating liquid is formed between a coating bar and a substrate, the substrate is transported, and the coating liquid is applied to a surface of the substrate, the coating liquid being supplied from a coating liquid supply member to a plurality of nozzles, the coating liquid being supplied from the plurality of nozzles to a surface of the coating bar, and the amount of coating liquid supplied to each of the plurality of nozzles being adjusted upstream of each nozzle, wherein the total number of the coating liquid supply members is less than the total number of the nozzles.