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 are provided. This coating apparatus 100 comprises: a coating bar; a substrate conveying member that conveys a substrate; and a coating liquid supply member that supplies coating liquid to the coating bar. The coating apparatus 100 further comprises a leveling bar downstream of the coating bar with respect to a coating process, and the leveling bar is positioned at a position at which the coating liquid forms a meniscus between the leveling bar and the substrate.

Description

Technical Field

[0001] Embodiments of the present invention relate to a coating apparatus and a coating method that can be used for device formation.

Background Art

[0002] Organic thin-film solar cells and organic / inorganic hybrid solar cells using organic semiconductors are expected to be low-cost solar cells because an inexpensive coating method can be applied to form the active layer. In order to realize organic thin-film solar cells and organic / inorganic hybrid solar cells at low cost, it is required to uniformly coat the coating material for forming the organic active layer and other layers. The film thickness of each layer is about several nm to several hundred nm, and it is required to form such a very thin layer with good uniformity over a large area. For example, the meniscus coating method and the slit coating method are known as roll-to-roll (R2R) coating methods capable of coating an extremely thin layer over a large area at low cost. However, it may be difficult to obtain a uniform film thickness by simply adopting these conventionally known methods, and a coating apparatus that can apply a liquid using a more uniform coating bar and form a uniform coating film is desired.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Embodiments of the present invention provide a coating apparatus and a coating method capable of forming a uniform coating film.

Means for Solving the Problems

[0005] Embodiments provided by the present invention are as follows. [1] A coating device comprising a coating bar, a substrate conveying member for conveying a substrate, and a coating liquid supply member for supplying a coating liquid to the coating bar, further comprising a homogenizing bar downstream of the coating of the coating bar, wherein the homogenizing bar is arranged at a position where the coating liquid forms a meniscus between the homogenizing bar and the substrate. [2] The coating device according to [1], further comprising a homogenizing bar position adjusting member for controlling the distance between the homogenizing bar and the substrate. [3] The coating device according to [1] or [2], wherein the homogenizing bar is arranged so as not to rotate. [4] The coating device according to any one of [1] to [3], further comprising a coating bar position adjusting member for controlling the position of the coating bar. [5] The coating device according to any one of [1] to [4], wherein the coating liquid is supplied from a plurality of nozzles. [6] The coating device according to [5], wherein the opening surfaces of the plurality of nozzles are in a needle shape cut at 75 degrees or more and 105 degrees or less. [7] The coating device according to [5] or [6], wherein the nozzle is removable. [8] The coating device according to any one of [5] to [7], further comprising a nozzle for supplying the coating liquid to the homogenizing bar. [9] The coating device according to any one of [1] to [4], wherein the coating liquid is supplied from a slit die head.

[10] The coating device according to any one of [1] to [9], wherein the homogenizing bar is curved.

[11] In a coating method of forming a coating film by coating a coating liquid on the surface of a substrate using a coating bar, a homogenizing bar is arranged downstream of the coating of the coating bar, and a meniscus is formed between the substrate and the homogenizing bar by the coating liquid supplied from the primary coating film formed by the coating bar to form a secondary coating film.

[12] The coating method according to

[11] , wherein a coating liquid is supplied from a plurality of nozzles to the surface of the coating bar, and the coating liquid is supplied between the coating bar and the substrate from the surface to form the primary coating film.

[13] The coating method according to

[12] , wherein after adjusting the positions of the plurality of nozzles and detecting the distance between the coating bar and the plurality of nozzles, the coating liquid is supplied.

[14] The coating method according to

[13] , wherein the detection of the distance is performed by measuring the electrical resistance between the nozzle and the coating bar.

[15] The coating method according to any one of

[12] to

[14] , wherein the plurality of nozzles are installed on a single cantilever fixing plate capable of rotation, horizontal movement, or vertical movement.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

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

[0008] Note that the drawings are schematic or conceptual, and the relationships between the thicknesses and widths of the respective parts, the ratios of the sizes between the parts, etc. are not necessarily the same as those in reality. Also, even when representing the same part, the dimensions and ratios may be represented differently in the drawings.

[0009] In the present specification and each figure, the same reference numerals are assigned to the same elements as those described above with respect to the previously presented figures, and detailed descriptions are omitted as appropriate.

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

[0011] As shown in FIG. 1, the coating apparatus 100 according to the embodiment includes a coating bar 101, a substrate conveying member 102 for conveying a substrate, a coating liquid supply member 104 for supplying the coating liquid 103 stored in the liquid reservoir 112 to the coating bar, and a leveling bar 105. The leveling bar 105 is disposed at a position where a meniscus is formed between the leveling bar and the substrate. In this example, a primary coating film is formed by the so-called meniscus method using the coating bar. The coating liquid 103 is supplied from the nozzle 106 to the surface of the coating bar 101, and the coating liquid flows into the space between the coating bar 101 and the substrate 107 from the surface of the coating bar to form a meniscus 103Ma. Each member is arranged such that the primary coating film 108a is formed as the substrate is conveyed in the direction of the arrow.

[0012] In the embodiment, the cross-sectional shape of the coating bar 101 is arbitrary. The cross-sectional shape is, for example, circular, flattened circular, or polygonal. A part of the cross-sectional shape corresponding to the meniscus forming portion may be curved and the other part may be linear. For example, the cross-sectional shape of the surface of the coating bar 101 facing the substrate 107 may be curved.

[0013] The coating bar can be arranged so as not to rotate. By not rotating the coating bar like a roller, the stability of the meniscus is improved.

[0014] The coating bar 101 includes at least one selected from the group consisting of, for example, stainless steel, aluminum, titanium, and glass. This facilitates the processing when preparing the coating bar 101. In one example, the surface of the coating bar 101 is a mirror surface. In another example, the surface of the coating bar 101 may include an uneven structure.

[0015] Then, as shown in FIGS. 1 and 2, the leveling bar 105 is installed downstream of the coating bar 101 in the coating direction.

[0016] The coating liquid 103 is applied to substantially the entire surface of the substrate 107 by the coating bar 101 to form a coating film 108a. However, the coating film 108a may lack uniformity. In the present embodiment, the formed coating film 108a contacts the leveling bar 105 disposed downstream of the coating bar as the substrate is conveyed. As shown in FIG. 1, a meniscus 103Mb of the coating liquid 103 can be formed between the substrate 107 and the leveling bar 105. Due to the surface tension of the coating liquid, it spreads in the lateral direction of the gap between the leveling bar 105 and the substrate 107, creating a uniform meniscus 103Mb. When the meniscus 103Mb contacts the substrate 107, a secondary coating film 108b with high uniformity by the coating 103 is formed on the substrate 107. By solidifying the coating film 108b, for example, by drying, the target film (solid film) can be obtained. For example, this can be achieved by disposing a drying member 109 downstream of the leveling bar.

[0017] In this way, for example, by moving the substrate 107 along the moving direction (the direction of the arrow in the figure), a coating film 108b with a large area can be formed on the substrate 107. The coating apparatus illustrated in FIGS. 1 and 2 forms a primary special film by the meniscus method. However, in order to improve the uniformity of the primary coating film, it can further include a nozzle position adjusting member 110 for adjusting the position of the nozzle 106, a nozzle position detecting member 111 for detecting the distance between the coating bar 101 and the nozzle 106, and the like.

[0018] When using a nozzle to form a single coating film, as shown in FIG. 2, a plurality of nozzles 106 or a plurality of pumps 104 can be provided. The plurality of nozzles 106 can face the coating bar 101. As shown in FIG. 2, the plurality of nozzles 106 can supply the coating liquid 103 toward the coating bar 101. Additionally, an additional nozzle for supplying the coating liquid to the leveling bar 105 can also be provided. By arranging such an additional nozzle, a meniscus can be formed between the substrate and the leveling bar before forming the single coating film before the start of coating.

[0019] As shown in FIG. 2, the plurality of nozzles 106 are arranged along the 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 moving 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, for example, along the Y-axis direction.

[0020] In an embodiment, the number of the plurality of nozzles 106 can be 3 or more. Thereby, a large-area single coating film 108a can be stably formed. In the example of FIG. 2, the number of the plurality of nozzles 106 is 4. In an embodiment, the number can be any integer of 3 or more.

[0021] In an embodiment, the nozzle can be a slot die or a needle shape. By using a plurality of needle-shaped nozzles 106, for example, the discharge amount of the coating liquid 103 can be controlled with high precision. When the nozzle is needle-shaped, for example, the tips of the plurality of nozzles can be easily brought into contact with the coating bar 101. In the needle-shaped nozzle, high flexibility can be obtained. Due to the high flexibility, for example, damage to the nozzle due to vibration of the coating bar 101 can be suppressed. In the needle-shaped nozzle, the length of the nozzle is, for example, 10 mm or more and 100 mm or less, and the inner diameter of the nozzle is, for example, 0.5 mm or more and 2 mm or less. The angle between the end face of the tip of the nozzle and the extending direction of the nozzle is, for example, about 90 degrees (for example, 75 degrees or more and 105 degrees or less). With such a shape, for example, damage to the coating bar 101 can be suppressed.

[0022] However, when there are a plurality of nozzles, variations are likely to occur in the distances between the coating bar 101 and the tips of the respective nozzles. When there are variations, the meniscus 103Ma formed from each nozzle is likely to be disturbed, and as a result, the coating film 108a is likely to become non-uniform.

[0023] As shown in FIGS. 1 and 2, if a nozzle position adjusting member 110 for adjusting the positions of the respective nozzles and a nozzle position detecting member 111 for detecting the distances between the coating bar 101 and the respective nozzles 106 are provided, variations in the positions and distances between the tip of each nozzle and the coating bar can be reduced, and uniform coating can be achieved.

[0024] In an embodiment, a member for detecting that the coating bar and each nozzle are in contact can be further provided. Since contact can be easily detected, for example, by measuring the electrical resistance between the nozzle and the coating bar, variations can be reduced by adjusting the coating conditions based on this. When in contact, the coating liquid can be directly applied to the coating bar, and repelling of the coating liquid is less likely to occur.

[0025] In an embodiment, as a member for detecting that the coating bar comes into contact with each nozzle, a member for measuring the electrical resistance between each nozzle and the coating bar can be provided. If each nozzle and the coating bar are made of conductive stainless steel or the like and each nozzle is insulated from others, measuring the electrical resistance between the coating bar and each nozzle will cause a sharp decrease in the electrical resistance at the moment of contact. Also, since the electrical resistance changes as the contact state changes, it becomes possible to monitor the contact state. For example, in a state where the nozzle is pressed strongly against the coating bar so much that it bends greatly, the coating bar contacts not only the tip of the nozzle but also its side surface, and the electrical resistance becomes very small. In this case, the coating liquid is likely to be discharged from the tip of the nozzle to other places than the coating bar, and non-uniform coating is likely to occur. Since the optimal electrical resistance varies depending on the shape and material of the nozzle and the coating bar, it is desirable to measure it in advance.

[0026] It is desirable to install wiring for connecting to an electrical resistance measuring device in advance between each nozzle and the coating bar. An opening / closing part is provided in the wiring, and before coating, each nozzle can be moved to confirm contact with the coating bar. Also, if the electrical resistance is measured during coating, it is possible to detect a case where there is an abnormality in the contact between the nozzle and the coating bar. The electrical resistance measuring device can also be an external device separate from the coating device.

[0027] In addition, in the coating device according to the embodiment, it is preferable that the nozzle is removable. The nozzle is likely to be clogged due to its small opening. In the coating device according to the embodiment, when such clogging occurs, the discharge amount of each nozzle can be adjusted by the coating liquid supply member and the coating liquid supply amount adjustment member. However, when the clogging becomes significant or the discharge cannot be performed completely, it is necessary to clean or replace it. In such a case, it is preferable that the nozzle is removable because it facilitates maintenance.

[0028] The above description has explained the case of forming a primary coating film 108a by supplying a coating liquid from a plurality of nozzles shown in FIGS. 1 and 2 using the meniscus method. However, the primary coating film may be formed by another method. For example, instead of a plurality of nozzles, a coating bar may be used for slit coating, and a slit die head having a manifold inside and supplying the coating liquid to the surface of the substrate through the slit from the manifold may be used. Further, instead of the nozzles in FIGS. 1 and 2, a slit die head may be used to supply the coating liquid to the coating bar.

[0029] The coating apparatus 100 may further include a drying member 109. The drying member 109 can dry the coating film 108b applied to the substrate 107. The drying member 109 may include, for example, an air nozzle or an infrared lamp.

[0030] The distance between the coating bar 101 and the leveling bar 105 can be freely changed. Moreover, it is preferable to provide a member for controlling the distance between the leveling bar 105 and the substrate 107. For this purpose, a gap ring, a micrometer, or the like can be used.

[0031] The leveling bar may be linear or curved. When it is linear, it is easy to obtain uniformity in the thickness of the coating film. When it is curved, for example, it is easy to change the thickness such as making the center thicker, but uniformity in the coating direction is easily obtained.

[0032] In the embodiment, the cross-sectional shape of the leveling bar 105 is arbitrary. The cross-sectional shape is, for example, circular, oval, or polygonal. A part of the cross-sectional shape may be curved and other parts may be linear. For example, the cross-sectional shape of the surface of the leveling bar 105 facing the substrate 107 may be curved.

[0033] The leveling bar can be arranged so as not to rotate. By not rotating the leveling bar like a roller, the stability of the meniscus is improved.

[0034] The homogenization bar 105 includes at least one selected from the group consisting of, for example, stainless steel, aluminum, titanium, and glass. This facilitates the processing when preparing the homogenization bar 105. In one example, the surface of the homogenization bar 105 is a mirror surface. In another example, the surface of the homogenization bar 26 may include an uneven structure.

[0035] (Second Embodiment) The second embodiment relates to a coating method. In the coating method according to the embodiment, for example, coating is performed using the coating device 10 (and its modifications) described with respect to the first embodiment.

[0036] FIG. 3 is a flowchart illustrating the coating method (S30) according to the second embodiment. In the coating method of forming and applying a meniscus of a coating liquid, a step (S31) of detecting and adjusting the distance between the coating bar and the meniscus homogenization bar and the substrate, a step (S32) of detecting and adjusting the distance between the coating bar and each nozzle, a step (S33) of creating a meniscus between the substrate and the homogenization bar, and a step (S34) of supplying the coating liquid and performing coating on the substrate are included. By performing the step of S33 before the step of S34, the meniscus M22 is stably generated in the coating process. In order to form a meniscus between the substrate and the homogenization bar before the start of coating in this way, it is preferable to arrange an additional nozzle for supplying the coating liquid to the homogenization bar.

[0037] In the embodiment, the distance between the coating bar and each nozzle can be detected by measuring the electrical resistance between the coating bar and the nozzle. Also, each nozzle can be installed on a single cantilever fixing plate capable of rotation, horizontal movement, or vertical movement. With such an arrangement, it is possible to adjust the positions of all the nozzles simultaneously.

[0038] Hereinafter, specific examples of the coating device and the coating method according to the embodiment will be described.

[0039] For example, a solar cell can be formed by coating with a coating apparatus 100. In one example, the number of pumps is 4. The tubes connected to one pump are connected to four nozzles. The total number of nozzles is 16. The nozzles are installed on a single cantilever bar. Each nozzle is provided with an actuator for movement and wiring for measuring electrical resistance. The wiring is connected to an electrical resistance measuring device. A nozzle position detecting member, such as a camera, is installed for observing the positional relationship between the nozzle and the coating bar.

[0040] For example, the substrate 107 is a roll-shaped PET film. The width of the PET film is, for example, 330 mm. An electrode that is light-transmissive and has a width of 300 mm is formed on the PET film by a roll-to-roll compatible sputtering apparatus. 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, a plurality of electrodes are provided. The length of one of the plurality of electrodes is, for example, about 10 mm. The interval between the plurality of electrodes is, for example, 50 μm.

[0041] The cross-sections of the coating bar 101 and the leveling bar 105 are circular. The radius of the circle is 10 mm. The lengths of the coating bar 101 and the leveling bar 105 are 300 mm. The coating bar 101 and the leveling bar 105 contain, for example, stainless steel (e.g., SUS303).

[0042] The nozzle contains a stainless steel locking base. The length of the nozzle is 50 mm. The pipe for the coating liquid is a polytetrafluoroethylene tube. The nozzle and the pipe are connected by a detachable joint. The pipe is connected to a pump.

[0043] In one example, a hole transport layer is formed by the coating liquid 103. In this case, the coating liquid 103 is an aqueous solution containing PEDOT and PSS.

[0044] For example, a relative positional relationship between the coating bar 101 and the leveling bar 105, and the substrate 107 is controlled by a gap ring or an actuator.

[0045] For example, the nozzle is placed in a horizontal state. In such a state, the coating liquid 103 is supplied and the air in the nozzle is discharged.

[0046] After that, the tip of the needle nozzle is lowered and tilted 20° from the horizontal. The cantilever bar is brought closer to the coating bar. Next, each nozzle is brought closer to the coating bar one by one and brought into contact so that the electrical resistance becomes 10 to 50 Ω.

[0047] The coating liquid is supplied to the leveling bar 105 with a syringe to create a meniscus 103Mb between the leveling bar and the substrate 107.

[0048] While transporting the substrate 107, the coating liquid 103 is continuously supplied by a pump. The moving speed of the substrate 107 is, for example, 5 m / min. The dried member 109 blows heated dry air onto the applied coating liquid 103. A coating film solidified from the coating liquid 103 is obtained.

[0049] In the embodiment, after the above coating, another coating liquid may be further applied. The another coating liquid contains, for example, a semiconductor material. The another coating liquid contains, 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 another coating liquid further contains, for example, monochlorobenzene. The amount of PTB7 is 8 mg with respect to 1 mL of monochlorobenzene. The amount of PC70BM is 12 mg with respect to 1 mL of monochlorobenzene. The another coating liquid is a dispersion containing an organic semiconductor.

[0050] Another coating solution, for example, becomes a semiconductor film of a solar cell. In the application of another coating solution, the minimum gap distance between the coating bar 101 and the substrate 107 is 300 μm. The moving speed of the substrate 107 is, for example, 5 m / min. After coating, drying is performed by the drying member 109.

[0051] For example, there are an organic thin-film solar cell using an organic semiconductor or an organic / inorganic hybrid solar cell. By manufacturing these solar cells by a coating method, a high-performance solar cell can be manufactured. In an embodiment, the coating solution 103 may be applied to the substrate 107 at a position where the substrate 107 is conveyed in the vertical direction. Thereby, for example, the effect of gravity is applied to the meniscus, and it becomes easy to obtain a uniform film even at high speed.

[0052] According to an embodiment, a coating apparatus and a coating method capable of forming a uniform coating film are provided.

[0053] As described above, the embodiments of the present invention have been described with reference to specific examples. However, the present invention is not limited to these specific examples. For example, regarding the specific configurations of each element such as tubes, pumps, nozzles, and holding parts included in the coating apparatus, those skilled in the art can appropriately select from the known range to similarly implement the present invention and obtain the same effects. As long as it is possible, it is included in the scope of the present invention.

[0054] In addition, a combination of any two or more elements of each specific example within a technically possible range is also included in the scope of the present invention as long as it includes the gist of the present invention.

[0055] In addition, based on the coating head, coating apparatus, and coating method described above as embodiments of the present invention, all coating apparatuses and coating methods that those skilled in the art can appropriately design and modify and implement also belong to the scope of the present invention as long as they include the gist of the present invention.

[0056] In addition, within the scope of the idea of the present invention, those skilled in the art can conceive of various modifications and alterations, and it is understood that those modifications and alterations also fall within the scope of the present invention.

[0057] Although some embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and its equivalent scope.

Explanation of Reference Numerals

[0058] 100... Coating device 101... Coating bar 102... Substrate conveying member 103... Coating liquid 104... Coating liquid supply member 105... Levelling bar 106... Nozzle 107... Substrate 108a... Primary coating film 108b Secondary coating film 109... Drying member 110... Nozzle position adjusting member 111... Nozzle position detecting member 112... Liquid reservoir

Claims

1. A coating apparatus comprising a coating bar, a substrate conveying member for conveying a substrate, and a coating liquid supply member for supplying a coating liquid to the coating bar, further comprising a homogenizing bar downstream of the coating bar in the coating direction, wherein the homogenizing bar is disposed at a position where a meniscus of the coating liquid is formed between the homogenizing bar and the substrate, and further comprising a homogenizing bar position adjusting member for controlling the distance between the homogenizing bar and the substrate.

2. (Deleted)

3. The coating apparatus according to claim 1, wherein the homogenizing bar is disposed so as not to rotate.

4. The coating apparatus according to claim 1 or 3, further comprising a coating bar position adjusting member for controlling the position of the coating bar.

5. The coating apparatus according to claim 1 or 3, wherein the coating liquid is supplied from a plurality of nozzles.

6. The coating apparatus according to claim 5, wherein the opening surfaces of the plurality of nozzles are in a needle shape cut at 75 degrees or more and 105 degrees or less.

7. The coating apparatus according to claim 5, wherein the nozzle is removable.

8. The coating apparatus according to claim 5, further comprising a nozzle for supplying the coating liquid to the homogenizing bar.

9. The coating apparatus according to claim 1 or 3, wherein the coating liquid is supplied from a slit die head.

10. The coating apparatus according to claim 1 or 3, wherein the homogenizing bar is curved.

11. A coating method for forming a coating film by coating a coating liquid on the surface of a substrate using a coating bar, wherein a homogenizing bar is disposed downstream of the coating bar in the coating direction, a meniscus is formed between the substrate and the homogenizing bar by the coating liquid supplied from the primary coating film formed by the coating bar, and a secondary coating film is formed while controlling the distance between the homogenizing bar and the substrate.

12. The coating method according to claim 11, wherein the coating liquid is supplied from a plurality of nozzles to the surface of the coating bar, and the primary coating film is formed by supplying the coating liquid between the coating bar and the substrate from the surface.

13. The coating method according to claim 12, wherein the positions of the plurality of nozzles are adjusted, the distance between the coating bar and the plurality of nozzles is detected, and then the coating liquid is supplied.

14. The coating method according to claim 13, wherein the detection of the distance is performed by measuring the electrical resistance between the nozzle and the coating bar.

15. The coating method according to claim 12, wherein the plurality of nozzles are installed on a single cantilever fixing plate capable of rotation, horizontal movement, or vertical movement.

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