Surface treatment method and surface treatment mask structure

Abstract

To provide a surface treatment method capable of suppressing degradation of a protected area due to reactive oxygen species, and a surface treatment mask structure suitable for use with the same.SOLUTION: The surface treatment method is for treating a surface to be treated by irradiating the surface to be treated with UV light, in which a protected area is provided on a portion of the surface. The surface treatment method includes a surface treatment step for irradiating the surface to be treated with UV light while suppressing or preventing the incidence of UV light onto the protected area and inhibiting or preventing the movement of gas molecules into the protected area.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a surface treatment method and a mask structure for surface treatment. [Background technology]

[0002] In recent years, solar cells have attracted attention as photoelectric conversion elements that convert light energy into electric power. Solar cells are composed of a photoelectrode and a counter electrode, each of which has a layer that contributes to the movement of electrons and holes formed on a substrate. For example, a dye-sensitized solar cell, which is one type of solar cell, typically has a structure in which a photoelectrode is formed on a photoelectrode substrate, which has a semiconductor layer with a sensitizing dye adsorbed thereon, an electrolyte layer, and a counter electrode is formed on a counter electrode substrate, which has a catalyst layer, arranged in this order.

[0003] In the manufacture of solar cells, a semiconductor layer or a catalyst layer is formed on an electrode substrate, which may optionally have a conductive film or the like, and then the electrode substrate is surface-treated by irradiating it with UV (Ultra Violet) light. Such surface treatment can improve the adhesion of the electrode substrate to resins or the like, thereby improving the sealing properties of a cell in which a laminate of a photoelectrode, an electrolyte layer, and a counter electrode is surrounded by a partition wall made of resin or the like. However, there is a risk that the sensitizing dye contained in the semiconductor layer of the photoelectrode, in particular, may be deteriorated by exposure to light.

[0004] Therefore, a method has been proposed in which the surface to be treated is sufficiently treated with UV light while protecting the region to be protected, such as the semiconductor layer of the photoelectrode, from UV light. M is the maximum width, and above the base is width W M The present invention discloses a surface treatment method in which a mask having a width smaller than the width of the target surface is placed on a region to be protected on the target surface, and the target surface is treated using a low-pressure mercury lamp. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7056188 specification Summary of the Invention [Problem to be solved by the invention]

[0006] Here, the inventors have found through their investigations that when surface treatment is performed using UV light, active oxygen such as ozone generated from the air by the UV light may come into contact with the area to be protected, such as the semiconductor layer of a photoelectrode, and this may cause deterioration of the area to be protected. However, when surface treatment is performed with the mask disclosed in Patent Document 1 placed on the area to be protected, although the mask can suppress deterioration of the area to be protected due to irradiation with UV light, it is not possible to suppress deterioration of the area to be protected due to active oxygen.

[0007] Therefore, an object of the present invention is to provide a surface treatment method that can suppress deterioration of a region to be protected due to active oxygen, and a surface treatment mask structure that can be suitably used for the surface treatment method. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to solve the above problems, and have discovered that if the migration of active oxygen to the area to be protected is inhibited or prevented when treating a surface to be treated with UV light, contact of the active oxygen with the area to be protected can be suppressed, and as a result, deterioration of the area to be protected due to active oxygen can be suppressed, leading to the completion of the present invention.

[0009] That is, the present invention aims to advantageously solve the above-mentioned problems, and provides: [1] a surface treatment method for surface-treating a surface to be treated, which has a protection target area provided on a portion of its surface, by irradiating UV light onto the surface to be treated, the surface treatment method including a surface treatment step of irradiating UV light onto the surface to be treated while suppressing or preventing the incidence of UV light onto the protection target area and inhibiting or preventing the movement of gas molecules into the protection target area. In this way, if the movement of gas molecules to the area to be protected is inhibited or prevented when performing surface treatment using UV light, it is possible to suppress deterioration of the area to be protected due to active oxygen.

[0010] [2] In the surface treatment method of [1] above, the surface treatment step preferably includes a masking step of covering the protection target area with a mask, and an irradiation step of irradiating the treatment surface with UV light after the masking step, wherein the mask preferably includes a mask portion located between the protection target area and a UV light source to suppress or prevent the incidence of UV light, and an enclosing portion located between the mask portion and the treatment surface to inhibit or prevent the transmission of gas molecules. In this way, by masking the protection target area using a predetermined mask, the mask portion can suppress the incidence of UV light, while the enclosing portion can effectively suppress deterioration of the protection target area due to active oxygen.

[0011] [3] In the surface treatment method of [2] above, it is preferable that the mask portion and the surrounding portion are integrally formed. By using a mask in which the mask portion and the surrounding portion are integrally formed, deterioration of the protection target area due to active oxygen can be effectively suppressed. In addition, the mask can be easily manufactured.

[0012] [4] In the surface treatment method of [2] or [3] above, the surrounding portion is preferably made of a gasket material. In this way, by using a mask whose surrounding portion is made of a gasket material, deterioration of the protection target area due to active oxygen can be effectively suppressed.

[0013] [5] In any of the surface treatment methods [2] to [4] above, the surrounding portion is preferably made of a deformable material. In this way, by using a mask whose surrounding portion is made of a deformable material, deterioration of the protection target area due to active oxygen can be effectively suppressed.

[0014] [6] In the surface treatment method according to any one of the above [2] to [5], the mask portion has a base width W Mis the maximum width, and above the base is the width W M It is preferable that the width of the portion is smaller than . In this way, by using a mask whose mask portion has the above-described structure, it is possible to sufficiently treat the surface to be treated while protecting the region to be protected.

[0015] The present invention aims to advantageously solve the above-mentioned problems. [7] The surface-processing mask structure of the present invention is a surface-processing mask structure used when surface-processing a surface to be processed, comprising a mask and an ultraviolet-transmitting mask support that supports the mask, the mask comprising a mask portion located on the mask support side and suppressing or preventing the incidence of UV light, and a surrounding portion located on the opposite side of the mask portion from the mask support side and inhibiting or preventing the transmission of gas molecules. The surface-processing mask structure described above can improve the efficiency and accuracy of mask placement and alignment, thereby improving the surface processing efficiency of the surface to be processed. The surface-processing mask structure described above can be suitably used in any of the surface-processing methods described above in [1] to [6]. The term "ultraviolet transmittance" means that the transmittance of ultraviolet light (e.g., wavelength 254 nm) emitted from an ultraviolet lamp and transmitted through the mask support is 70% or more, as measured using an ultraviolet intensity meter ("UVC-254" manufactured by Custom Co., Ltd.).

[0016] [8] In the surface treatment method of any one of the above [1] to [6], it is preferable that the surface to be treated is a photoelectrode substrate of a dye-sensitized solar cell, and the region to be protected is a semiconductor layer containing a sensitizing dye. In this way, if the surface to be treated is a photoelectrode substrate of a dye-sensitized solar cell, and the region to be protected is a semiconductor layer containing a sensitizing dye, the photoelectrode substrate can be surface-treated while suppressing deterioration (fading) of the sensitizing dye in the semiconductor layer of the dye-sensitized solar cell due to active oxygen. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a surface treatment method capable of suppressing deterioration of a region to be protected due to active oxygen, and a surface treatment mask structure that can be suitably used for the surface treatment method. [Brief explanation of the drawings]

[0018] [Figure 1] 1(a) is a schematic cross-sectional view of a mask of the first embodiment, FIG. 1(b) is a schematic plan view of the bottom surface of the mask of FIG. 1(a), FIG. 1(c) is a schematic cross-sectional view of a modified example of the mask of the first embodiment, and FIG. 1(d) is a schematic cross-sectional view showing an example of a state in which a region to be protected on a processing surface is covered with the mask of FIG. 1(a). [Figure 2] 2(a) is a schematic cross-sectional view of a mask of a second embodiment, FIG. 2(b) is a schematic plan view of the bottom surface of the mask of FIG. 2(a), and FIG. 2(c) is a schematic cross-sectional view showing an example of a state in which a region to be protected on a processing surface is covered with the mask of FIG. 2(a). [Figure 3] 3(a) is a schematic cross-sectional view of a mask according to a third embodiment, and FIG. 3(b) is a schematic cross-sectional view showing an example of a state in which a region to be protected on a processing surface is covered with the mask of FIG. 3(a). [Figure 4] 4(a) is a schematic cross-sectional view of a mask according to a fourth embodiment; FIG. 4(b) is a schematic cross-sectional view showing an example of a state in which a region to be protected on a surface to be processed is covered with the mask of FIG. 4(a); FIG. 4(c) is a schematic cross-sectional view of a mask according to a fifth embodiment; and FIG. 4(d) is a schematic cross-sectional view showing an example of a state in which a region to be protected on a surface to be processed is covered with the mask of FIG. 4(c). [Figure 5] 1 is a schematic cross-sectional view showing an example of a state in which a mask is placed on a region to be protected on a surface to be processed. [Figure 6] FIG. 10 is a partially omitted plan view illustrating the relationship between the bottom surface of the mask and the area to be protected when the mask is placed on the area to be protected. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail. The surface treatment method of the present invention can be suitably carried out in any case where surface treatment using UV light may be required. In particular, the surface treatment method of the present invention can be suitably used when forming electrodes for solar cells such as dye-sensitized solar cells, organic thin-film solar cells, and perovskite solar cells. In particular, the treatment method of the present invention is preferably used when forming electrodes for dye-sensitized solar cells.

[0020] Hereinafter, as an example, a case where an electrode for a dye-sensitized solar cell is surface-treated using the surface treatment method of the present invention will be specifically described. An example of an electrode for a dye-sensitized solar cell is a photoelectrode including a porous semiconductor layer to which a dye is adsorbed. Each component of the photoelectrode can be a known configuration such as that described in International Publication No. 2015 / 029415.

[0021] The photoelectrode is composed of a photoelectrode substrate, a conductive film, and a porous semiconductor layer laminated in this order. The photoelectrode substrate is not particularly limited, and examples thereof include glass substrates, metal foils, meshes, and flexible substrates. Specifically, flexible glass substrates and transparent resin substrates can be used as the photoelectrode substrate, with transparent resin substrates being particularly preferred. Examples of transparent resins used to form the transparent resin substrate include synthetic resins such as cycloolefin polymer (COP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndiotactic polystyrene (SPS), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate (PAr), polysulfone (PSF), polyethersulfone (PES), polyetherimide (PEI), and transparent polyimide (PI). A buffer layer may be provided between the conductive film and the porous semiconductor layer. The buffer layer serves to prevent short-circuiting between the conductive film and the porous semiconductor layer. The buffer layer also serves to improve the adhesion between the conductive film and the porous semiconductor layer. The thickness of the porous semiconductor layer is not particularly limited, but is usually 0.1 to 50 μm, preferably 5 to 30 μm. The thickness of the photoelectrode substrate is not particularly limited, but is usually 10 to 1,000 μm. Examples of the conductive film include known conductive films made of composite metal oxides such as indium-tin oxide (ITO) and indium-zinc oxide (IZO), carbon materials such as carbon nanotubes and graphene, or metal materials such as metal foil. Examples of the porous semiconductor layer include, but are not limited to, porous semiconductor layers made of semiconductor fine particles. Examples of the semiconductor fine particles include, but are not limited to, particles of metal oxides such as titanium oxide, zinc oxide, and tin oxide. The dye adsorbed to the porous semiconductor layer is a compound (sensitizing dye) that can be excited by light and transfer electrons to the porous semiconductor layer. The sensitizing dye is not particularly limited, but may be a dye commonly used in dye-sensitized solar cells, such as a metal complex dye. Generally, these dyes are likely to deteriorate when exposed to ultraviolet rays and to active oxygen such as ozone generated by irradiation with ultraviolet rays.Therefore, the region of the porous semiconductor layer (dye-adsorbed porous semiconductor layer) formed on the photoelectrode substrate needs to be protected during the surface treatment.

[0022] Therefore, in the surface treatment method of the present invention, when a surface to be treated, which has a protection target area provided on a portion of its surface, is irradiated with UV light to treat the surface to be treated, a surface treatment step is carried out in which the UV light is irradiated onto the surface to be treated while suppressing or preventing the incidence of UV light onto the protection target area and inhibiting or preventing the movement of gas molecules to the protection target area. By carrying out such a surface treatment step, it is possible to suppress deterioration of the protection target area due to contact of UV light and active oxygen with the protection target area.

[0023] Here, the method of irradiating the treatment surface with UV light while suppressing or preventing incidence of UV light on the area to be protected and inhibiting or preventing movement of gas molecules to the area to be protected is not particularly limited, and examples thereof include a method of irradiating the treatment surface with UV light while covering the area to be protected with a mask. That is, in the surface treatment method of the present invention, the surface treatment step preferably includes a masking step of covering the area to be protected with a mask, and an irradiation step of irradiating the treatment surface with UV light after the masking step.

[0024] (Masking process) In the masking process, a mask is placed on the surface to be treated so as to cover both the upper and lateral sides of the region to be protected (e.g., a porous semiconductor layer containing a sensitizing dye) on the surface. Simply placing a mask on the region to be protected, as in the past, does not adequately prevent active oxygen such as ozone from inflowing from the sides. However, by covering both the upper and lateral sides, the incidence of UV light on the region to be protected can be suppressed or prevented while inhibiting or preventing the migration of gas molecules such as active oxygen to the region to be protected in the irradiation process described below. As a result, deterioration of the region to be protected due to UV light and active oxygen can be suppressed. Here, the mask is preferably positioned so that its center coincides with the center of the region to be protected. This is because equalizing the proportion of the area blocked by the mask around one region to be protected allows for uniform treatment of the surface to be treated. Furthermore, as described below, if the mask is supported by a mask support, it becomes relatively easy to center the mask and the region to be protected by, for example, aligning a support larger than the mask with the surface to be treated. It is preferable to use a mask that covers both the top and sides of the area to be protected with a single component, but it is also possible to use a mask that is made up of a combination of two or more components: a component that surrounds the sides of the area to be protected and a component that covers the information in the area to be protected.

[0025] <Mask> The mask includes a mask portion located between the area to be protected and the UV light source to suppress or prevent the incidence of UV light, and a surrounding portion located between the mask portion and the surface to be treated to inhibit or prevent the transmission of gas molecules.

[0026] [Mask section] The masking portion is a member that suppresses or prevents UV light from entering the area to be protected, and the masking portion can suppress deterioration of the area to be protected due to UV light coming into contact with the area to be protected. The mask portion is not particularly limited, but the width of the base W M is the maximum width, and the width W above the base MBy using such a mask portion, even when low-energy irradiation light is irradiated using a low-pressure mercury lamp in the irradiation step described later, the surface to be treated can be sufficiently treated while protecting the area to be protected from UV light. M " is a component of the cross-sectional shape of the mask part that appears on the virtual plane P when a virtual plane P is set that is perpendicular to the surface to be processed and that passes through the center of the bottom surface of the mask part and crosses the bottom surface of the mask part, and corresponds to the width of the side that is adjacent to or close to the area to be protected. The cross-sectional shape of the mask part on the virtual plane P has a width W M It is preferable that the mask has a width smaller than the width W of the base of the mask portion. M is the maximum width, and the width W above the base M It is preferable that the width of the portion satisfy the relationship that the width of the portion is smaller than the width of the portion having the width ...

[0027] The shape of the mask portion may be various. For example, the cross-sectional shape of the mask portion that appears on the virtual plane P may be a rectangle, a trapezoid, a triangle, other polygons, or other random shapes. More specifically, the cross-sectional shape of the mask portion may be a shape such that the width W of the base M A trapezoid with a base of W; width W M a triangle with base W; and width W M is the base, and a predetermined distance (for example, a distance equivalent to 1 / 3 of the height of the mask portion) is provided upward from the base to a width W M and then width W M A part with a width smaller than (for example, width W M A trapezoidal portion having a lower base of, or width W M Among these, from the viewpoint of more effectively treating the surface to be treated, the cross-sectional shape of the mask part is preferably a shape having a width W of the base MIt is preferable that the contour of the mask portion other than the base constituting the cross-sectional shape of the mask portion is a trapezoid with a lower base W. The contour of the mask portion other than the base constituting the cross-sectional shape of the mask portion can be a straight line, a curve, or a random line. Among these, it is preferable that the contour constituting the cross-sectional shape of the mask portion is a straight line. If the contour is a straight line, scattering of light incident on the side surface of the mask portion can be suppressed, and the surface treatment efficiency of the surface to be treated can be improved. Furthermore, when the upper end of the cross-sectional shape of the mask portion is constituted by a side rather than a vertex (i.e., when it is a shape having a part corresponding to the upper base, such as a trapezoid), the length of the side is determined by the width W. M It is preferably 3 / 4 or less, and more preferably 1 / 2 or less, because in this case, the efficiency of incidence of light rays onto the surface to be treated can be increased.

[0028] The mask portion described above can be formed from a mask portion-forming material that has an ultraviolet transmittance of 20% or less for UV light with a wavelength of 254 nm, as measured by an ultraviolet intensity meter (UVC-254, manufactured by Custom Co.) after the ultraviolet light emitted from an ultraviolet lamp and transmitted through the mask support. Examples of such mask portion-forming materials include aluminum, chromium, and ultraviolet-curable resins.

[0029] The mask portion is not particularly limited, and a commercially available piece or pieces of the desired shape obtained by molding the above-mentioned mask portion-forming material according to a known molding method such as die-casting or etching can be used.

[0030] [Enclosure] The surrounding portion is a member provided below the mask portion and inhibits or prevents gas molecules from entering the region to be protected from the side. The surrounding portion can suppress deterioration of the region to be protected due to active oxygen. The surrounding portion is not particularly limited, and can be provided, for example, by creating a recess by countersinking the bottom surface of the mask piece that is the material of the mask portion, or by attaching a gasket member or a deformable member to the bottom surface of the mask portion. In particular, from the viewpoint of further suppressing deterioration of the region to be protected due to active oxygen, it is preferable that the surrounding portion be formed by attaching a gasket member or a deformable member to the bottom surface of the mask portion. Hereinafter, the surrounding portion will be specifically described through the description of an embodiment of a mask that can be used in the present invention.

[0031] [First embodiment] Fig. 1(a) is a schematic cross-sectional view of a mask according to a first embodiment, and Fig. 1(b) is a schematic plan view of the bottom surface of the mask shown in Fig. 1(a). As shown in Fig. 1(a), the mask 2 according to the first embodiment comprises a mask portion 2a having a trapezoidal cross-sectional shape and a surrounding portion 2b, the surrounding portion 2b being integrally formed with the mask portion 2a. As shown in Fig. 1(b), the surrounding portion 2b extends in an annular shape around the entire outer periphery of the bottom surface of the mask 2a.

[0032] The width of the surrounding portion 2b (D1 in Figs. 1(a) and 1(c)) is not particularly limited, but is preferably 0.1 mm or more and 1.0 mm or less.

[0033] Furthermore, the height of the surrounding portion 2b (D2 in Figures 1(a) and 1(c)) is not particularly limited and may be set appropriately depending on the size of the area to be protected, but it is preferable that it is at least 0.01 mm larger than the thickness (height) of the area to be protected, and is preferably between 0.1 mm and 0.5 mm.

[0034] 1(c), the tip portion of the surrounding portion 2b (the portion in contact with the substrate 10) is preferably formed into a cross-sectional shape that makes point contact with the substrate 10 by R-chamfering or the like, more preferably a downwardly convex broken line or curved shape, and even more preferably a U-shape (with a semicircular tip portion) or V-shape (with a triangular tip portion). This further enhances the adhesion between the surrounding portion 2b and the substrate 10, thereby further inhibiting or preventing the movement of gas molecules such as active oxygen to the protection target region 1.

[0035] 1(d), the mask 2 is placed on the substrate (surface to be treated) 10 so as to cover the area to be protected 1. The weight of the mask 2 brings the surrounding portion 2b and the substrate 10 into close contact, inhibiting or preventing the movement of gas molecules such as active oxygen from between the surrounding portion 2b and the substrate 10 to the area to be protected 1. As a result, deterioration of the area to be protected 1 is suppressed. If the weight of the mask 2 alone is not sufficient to ensure close contact between the surrounding portion 2b and the substrate 10, a weight can be placed on the mask 2 or a mask support (described later), or a mechanical force can be applied to press the outer periphery of the mask 2 toward the substrate 10 (downward in FIG. 1(d)). The weight is not particularly limited as long as it does not prevent UV light from reaching the surface to be treated. For example, a metal block or the like that is placed only on the outer periphery of the mask 2, or synthetic quartz glass with a light transmittance of 90% or more at a wavelength of 185 nm can be used.

[0036] The surrounding portion 2b is not particularly limited, and can be formed integrally with the mask portion 2a by providing a recess by, for example, countersinking the bottom surface of a mask piece used as the raw material for the mask portion 2a. Therefore, the surrounding portion 2b is usually formed as a single member using the same material as the mask portion 2a. Furthermore, the surrounding portion 2b makes it easy to manufacture the mask.

[0037] [Second embodiment] The second embodiment differs from the first embodiment in that a surrounding portion 2c made of a gasket material is used instead of the surrounding portion 2b formed integrally with the mask portion 2a. Other aspects are similar to those of the first embodiment, so redundant description will be omitted. Figure 2(a) is a schematic cross-sectional view of the mask of the second embodiment, and Figure 2(b) is a schematic plan view of the bottom surface of the mask of Figure 2(a). As shown in Figure 2(a), the mask 2 of the second embodiment comprises a mask portion 2a having a trapezoidal cross-sectional shape and a surrounding portion 2c, which is made of a gasket material. As shown in Figure 2(b), the surrounding portion 2c is made of a frame-shaped gasket material and extends annularly around the entire outer periphery of the bottom surface of the mask portion 2a. The gasket material is a frame-shaped member that surrounds the area to be protected from the sides without coming into contact with the area to be protected.

[0038] The width of the surrounding portion 2c (D3 in Figs. 2(a) and 2(c)) is not particularly limited, but is preferably 0.3 mm or more and 1.0 mm or less.

[0039] The height of the surrounding portion 2c (D4 in FIGS. 2(a) and 2(c)) is not particularly limited and may be set appropriately depending on the size of the area to be protected, but is preferably 0.1 mm or more and 2 mm or less.

[0040] The gasket member is not particularly limited, and a gasket member made of a material that deforms under a low load can be suitably used. By using a gasket member made of a material that deforms under a low load, when the mask 2 is placed on the substrate (surface to be treated) 10 so as to cover the protection target area 1, the mask 2 deforms due to its own weight, etc., further enhancing the adhesion between the surrounding portion 2c and the substrate 10. As a result, the movement of gas molecules such as active oxygen to the protection target area 1 can be further inhibited or prevented, and deterioration of the protection target area 1 can be further suppressed. The material constituting the gasket member preferably satisfies at least one of the following characteristics (1) and (2). (1) A material having a hardness of preferably 50 points or less, more preferably 20 points or less, and even more preferably 10 points or less, as measured by a Type E durometer in accordance with JIS K 6253; (2) 25% compressive load, preferably 10 N / cm 2 More preferably, 5 N / cm 2 More preferably, it is 2 N / cm or less. 2 Materials that are

[0041] Specific examples of the gasket member include a UV-curable liquid gasket (CIPG), a gasket made of gel, and a gasket made of foam rubber. The gel material is not particularly limited, and examples thereof include polystyrene gel, silicone gel, and urethane gel. The foamed rubber material is not particularly limited, and examples thereof include foamed ethylene propylene diene terpolymer, silicone rubber, nitrile butadiene copolymer, silicone rubber, fluororubber, and the like.

[0042] 2(a), the tip portion of the surrounding portion 2c (the portion in contact with the substrate 10) preferably has a cross-sectional shape that makes point contact with the substrate 10, more preferably a downwardly convex broken line or curved shape, and even more preferably a U-shape (with a semicircular tip portion) or a V-shape (with a triangular tip portion). This allows the mask 2 to make point contact with the substrate 10, further increasing the adhesion between the surrounding portion 2c and the substrate 10, further inhibiting or preventing the movement of gas molecules such as active oxygen toward the region to be protected 1, and further suppressing deterioration of the region to be protected 1.

[0043] 2(d), the mask 2 is placed on the substrate (surface to be treated) 10 so as to cover the protection target area 1. This surrounds the protection target area 1, inhibiting or preventing the movement of gas molecules such as active oxygen to the protection target area 1, thereby suppressing deterioration of the protection target area 1.

[0044] The surrounding portion 2c is not particularly limited, and can be formed, for example, by adhering a gasket member to the bottom surface of the mask portion 2a using an adhesive or the like.

[0045] [Third embodiment] The third embodiment differs from the first embodiment in that a surrounding portion 2d made of a deformable material is used instead of the surrounding portion 2b formed integrally with the mask portion 2a. Other aspects are similar to those of the first embodiment, so redundant explanations will be omitted. FIG. 3(a) is a schematic cross-sectional view of a mask according to the third embodiment. As shown in FIG. 3(a), the mask 2 comprises a mask portion 2a having a trapezoidal cross-sectional shape and a surrounding portion 2d, and the surrounding portion 2d is made of a deformable material. Also, as shown in FIG. 3(a), the surrounding portion 2d is typically formed over the entire bottom surface of the mask portion 2a. The deformable member is provided over the entire bottom surface of the mask portion and deforms upon contact with the area to be protected, thereby surrounding (covering) the area to be protected.

[0046] The height (thickness) of the surrounding portion 2d is not particularly limited and may be set appropriately depending on the size of the area to be protected, but is preferably 0.2 mm or more and 2 mm or less.

[0047] The material constituting the deformable member is not particularly limited as long as it is a material that can deform so that the surrounding portion 2d follows the shape of the area to be protected due to the weight of the mask 2 or the like, but it is preferable that the material satisfy at least one of the following characteristics (1) and (2). (1) A material having a hardness of preferably 50 points or less, more preferably 20 points or less, and even more preferably 10 points or less, as measured by a Type E durometer in accordance with JIS K 6253; (2) 25% compressive load, preferably 10 N / cm 2 More preferably, 5 N / cm 2 More preferably, it is 2 N / cm or less. 2 Materials that are

[0048] Specific examples of the material of the deformable member are not particularly limited, and include the gel material and foam rubber material described above in the "second embodiment."

[0049] 3(b), the mask 2 is placed on the substrate (surface to be treated) 10 so as to contact and cover the protection target area 1. Here, since the surrounding portion 2d is made of a deformable member, it deforms to follow the outer shape of the protection target area 1 due to the weight of the mask 2 or the like, and surrounds the protection target area 1. This inhibits or prevents the movement of gas molecules such as active oxygen to the protection target area 1, and suppresses deterioration of the protection target area 1.

[0050] The surrounding portion 2d is not particularly limited, and can be formed by adhering a deformable material to the entire bottom surface of the mask portion 2a using an adhesive or the like.

[0051] [Other embodiments] The mask may be a combination of two or more of the above-described surrounding portions 2b, 2c, and 2d. Below, a mask (fourth embodiment) in which a mask portion 2a having a trapezoidal cross section is combined with surrounding portions 2b and 2d, and a mask (fifth embodiment) in which a mask portion 2a having a trapezoidal cross section is combined with surrounding portions 2b and 2c will be described.

[0052] -Fourth embodiment- The fourth embodiment differs from the first embodiment in that it further uses a surrounding portion 2d made of a deformable material in addition to the surrounding portion 2b formed integrally with the mask portion 2a. Other aspects are similar to those of the first embodiment, so redundant explanations will be omitted. FIG. 4(a) is a schematic cross-sectional view (a) of a mask according to the fourth embodiment. As shown in FIG. 4(a), the mask 2 comprises a mask portion 2a and surrounding portions 2b and 2d. Also, as shown in FIG. 4(a), the surrounding portion 2d is provided so as to cover the bottom surface of the mask portion 2a and the inner surface (bottom surface and inner side surface) of the surrounding portion 2b. 4(b), the mask 2 is placed on the substrate (surface to be treated) 10 so as to cover the protection target area 1. This surrounds the protection target area 1, inhibiting or preventing the movement of gas molecules such as active oxygen to the protection target area 1, thereby suppressing deterioration of the protection target area 1.

[0053] -Fifth embodiment- The fifth embodiment differs from the first embodiment in that it further uses a surrounding portion 2c made of a gasket material in addition to the surrounding portion 2b formed integrally with the mask portion 2a. Other aspects are similar to those of the first embodiment, so redundant explanations will be omitted. Fig. 4(c) is a schematic cross-sectional view of a mask according to the fifth embodiment. As shown in Fig. 4(c), a surrounding portion 2c made of a gasket material is further provided on the bottom surface of the surrounding portion 2b. 4(d), the mask 2 is placed on the substrate (surface to be treated) 10 so as to cover the protection target area 1. This surrounds the protection target area 1, inhibiting or preventing the movement of gas molecules such as active oxygen to the protection target area 1, thereby suppressing deterioration of the protection target area 1.

[0054] [Preferable combination of mask and surrounding parts] The mask has a base width W from the viewpoint of sufficiently protecting the target area from UV light and active oxygen while sufficiently treating the surface to be treated. M The maximum width is W above the base M A mask formed by combining a mask portion 2a having a width smaller than 1 / 2 or a mask portion 2a having a rectangular cross-sectional shape with one or more of surrounding portions 2b, 2c, and 2d is preferred; a mask formed by combining a mask portion 2a having a trapezoidal or rectangular cross-sectional shape with one or more of surrounding portions 2b, 2c, and 2d is more preferred; a mask formed by combining a mask portion 2a having a trapezoidal cross-sectional shape with surrounding portions 2b, 2c, or 2d is even more preferred, and a mask formed by combining a mask portion 2a having a trapezoidal cross-sectional shape with surrounding portions 2c or 2d and, optionally, surrounding portion 2b is even more preferred.

[0055] Mask Height Here, the height of the mask is preferably 1.0 mm or more, more preferably 2.0 mm or more, preferably 10 mm or less, and more preferably 6.0 mm or less. Here, the height of the mask is the distance from the bottom (lowest part) of the surrounding portion to the highest part of the mask. More specifically, for example, as shown in FIG. 1(a), when the cross-sectional shape of the mask is trapezoidal and the mask portion has an upper surface, the height of the mask is the distance from the bottom surface of the surrounding portion to the upper surface of the mask. If the mask height is equal to or greater than the above lower limit, the surface to be treated can be more effectively treated. Note that when the cross-sectional shape of the mask portion is trapezoidal, the mask portion may be in the shape of a quadrangular pyramid truncated. Here, the term "frustum" refers to a three-dimensional shape obtained by removing a similarly reduced cone that shares a vertex from a cone.

[0056] [Mask support] Furthermore, it is preferable that the mask is supported by an ultraviolet-transmitting mask support at the end of the mask opposite to the side facing the surface to be treated. If the mask is supported by the mask support, the efficiency and accuracy of mask placement and alignment can be improved, thereby further improving the surface treatment efficiency of the surface to be treated. Note that a structure in which a mask is supported by a mask support is referred to as a "surface treatment mask structure."

[0057] As described above, the mask support material that can be used to form the mask support can be an ultraviolet-transmitting material that has an ultraviolet transmittance of 70% or more for UV light with a wavelength of 254 nm, as measured by an ultraviolet intensity meter (UVC-254, Custom Co.) for ultraviolet light emitted from an ultraviolet lamp and transmitted through the mask support. Examples of such mask support materials include quartz glass and plate-shaped materials made of synthetic optical crystals such as sapphire (Al2O3), calcium fluoride (CaF2), magnesium fluoride (MgF2), barium fluoride (BaF2), or lithium fluoride (LiF). When using a mask supported by a mask support material, the mask height can be set to be equal to or greater than the above-mentioned lower limit to increase the amount of oxygen present in the space defined vertically by the surface to be treated and the mask support, thereby further improving the processing efficiency of the surface to be treated within this space. Furthermore, when forming a mask structure for surface treatment by supporting a mask with a mask support, the mask can be aligned to a desired position according to a known method, and then adhered to the mask support with an adhesive such as an acrylic adhesive, an epoxy adhesive, a fluorine-based adhesive, an olefin-based adhesive, a silicone-based adhesive, or a polyamide resin. Alternatively, the mask support may be adhered to the mask portion (the side opposite to the side on which the surrounding portion is to be formed) with the above-mentioned adhesive before forming the surrounding portion. The adhesive is not particularly limited, and may be a dry-hardening adhesive or a reaction-hardening adhesive such as a two-component hardening adhesive.

[0058] FIG. 5 is a schematic cross-sectional view showing an example of a state in which the above-described surface processing mask structure is placed on a region to be protected on a surface to be processed. As shown in FIG. 5, a porous semiconductor layer 1, which is the region to be protected, is placed on the surface of a photoelectrode substrate 10 (optionally having a conductive film, not shown), which is the surface to be processed. A mask 2 is placed to surround the porous semiconductor layer 1. Light rays irradiated in the irradiation step, which will be described later, reach the photoelectrode substrate 10 along the optical path shown by the arrows. FIG. 5 also shows the positional relationship between the surface processing mask structure and the surface to be processed when surface processing is performed using the surface processing mask structure in which the mask 2 is supported by a mask support 20. Although FIG. 5 illustrates two porous semiconductor layers 1 and two masks 2, the number and arrangement of the porous semiconductor layers 1 and masks 2 in the present invention are not limited to the illustrated embodiment. That is, the number of porous semiconductor layers 1 and masks 2 may each be one, or the number of porous semiconductor layers 1 and masks 2 may each be three or more. The masks 2 may be arranged in one row, or in three or more rows.

[0059] FIG. 6 shows a partially omitted plan view illustrating the relationship between the mask and the area to be protected on the surface to be treated (photoelectrode substrate) when the mask is placed on the area to be protected. FIG. 6 shows a photoelectrode substrate 10 (optionally having a conductive film, not shown) having a porous semiconductor layer 1, which is four areas to be protected, aligned at equal intervals, and the bottom surface of a mask 2 placed on the porous semiconductor layer (area to be protected) 1. For clarity, FIG. 6 does not show the mask support 20. As shown in FIG. 6, the mask 2 is typically formed so that its bottom surface is larger (offset) than the area to be protected 1 in a plan view. The offset amount (the length of the distance D5 in FIG. 6) from the area to be protected 1 of the bottom surface of the mask 2 is preferably 0.05 mm or more, more preferably 0.1 mm or more, preferably 1.0 mm or less, and more preferably 0.2 mm or less. If the offset amount is equal to or greater than the above-mentioned lower limit, the area to be protected can be well protected. If the offset amount is equal to or less than the upper limit, a sufficient area to be surface-treated can be secured, and the surface to be treated can be sufficiently surface-treated.

[0060] (irradiation process) In the irradiation process, a UV light source is used to irradiate the surface to be treated with UV light from above the mask, thereby performing surface treatment. The UV light source is not particularly limited, and either an excimer UV lamp or a low-pressure mercury lamp can be used. Among these, it is preferable to use a low-pressure mercury lamp. Here, a low-pressure mercury lamp refers to a lamp that has a mercury vapor pressure of 1 Pa or more and 100 Pa or less during lighting, and emits light by utilizing an arc discharge in mercury vapor. The irradiation wavelength range of a low-pressure mercury lamp is, for example, 160 nm or more and 600 nm or less, and can exhibit a high-intensity spectrum, particularly around 185 nm and 254 nm. In addition, the illuminance of a low-pressure mercury lamp is 5 mW / cm 2The irradiation conditions using a low-pressure mercury lamp are not particularly limited, and the irradiation time and irradiation pattern (ON-OFF pattern) can be appropriately changed to achieve the desired surface treatment state. An excimer UV lamp is a lamp that uses a discharge excimer, and the irradiation wavelength range of the excimer UV lamp is, for example, 100 nm to 300 nm. For surface treatment applications, an excimer UV lamp may use xenon as the discharge gas and exhibit a high-intensity spectrum around 172 nm. The atmosphere in which the surface treatment process is carried out is not particularly limited, and may be, for example, a standard atmospheric atmosphere at room temperature and normal pressure in accordance with JIS Z 8703 and JIS W 0201.

[0061] The photoelectrode obtained through the above irradiation step can then be combined with a counter electrode and an electrolyte layer of known configurations to produce a dye-sensitized solar cell according to known methods. [Example]

[0062] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0063] <Measurement of water droplet contact angle> The water droplet contact angle was measured for the substrates before and after the surface treatment produced in the examples and comparative examples in accordance with JIS R 3257. A smaller water droplet contact angle indicates a better surface treatment. For the substrates after the surface treatment, the water droplet contact angle was measured at a position within the gap between the dye-adsorbed porous semiconductor layers (regions to be protected). <Preparation of a substrate having a surface to be treated> [Formation of pre-semiconductor layer pattern] A polyethylene naphthalate (PEN) film (so-called "ITO-PEN film"; PEN film thickness: 200 μm; conductive film thickness: 200 nm) was prepared, having a conductive film formed by sputtering indium tin oxide (ITO). The sheet resistance of this ITO-PEN film was 15 Ω / sq. A binder-free titanium oxide paste (PECC-C01-06, manufactured by Pexel Technologies) was applied to a thickness of 150 μm on the ITO surface (conductive film surface) of the prepared ITO-PEN film using a Baker-type applicator, forming a pre-semiconductor layer pattern for forming a porous semiconductor layer. The pre-semiconductor layer pattern consisted of 12 pre-semiconductor layers arranged in a 2-column, 6-row array. The length of the horizontal sides of the pre-semiconductor layer was 10,000 μm, the length of the vertical sides was 50,000 μm, the interval between the horizontal sides in the length direction was 1,000 μm, and the interval between the vertical sides in the length direction was 1,000 μm. [Fabrication of dye-adsorbed porous semiconductor layer] The pre-semiconductor layer pattern obtained above was dried at room temperature for 10 minutes, and then heated in a thermostatic chamber at 150°C for 5 minutes to obtain a laminate having an ITO-PEN film and a porous semiconductor layer. The obtained laminate was immersed in a solution containing a sensitizing dye (sensitizing dye: ruthenium complex (N719, manufactured by Solaronics), solvent: ethanol) at 40°C for 120 minutes to form a sensitizing dye layer, and a photoelectrode was obtained as a substrate having a treated surface. <Evaluation of discoloration of dye-adsorbed porous semiconductor layers> For the substrates after surface treatment in the Examples and Comparative Examples, the fading of the cells (dye-adsorbed porous semiconductor layers) was evaluated by visual inspection based on the following criteria: The smaller the degree of fading after surface treatment, the more suppressed the deterioration due to active oxygen is. A: No difference in the color of the cell periphery before and after surface treatment is observed. B: The outer periphery of the cell has faded white, accounting for less than 1.0% of the cell area, before and after surface treatment. C: The outer periphery of the cell has faded white, accounting for 1.0% to less than 3.0% of the cell area, before and after surface treatment. D: The outer periphery of the cell has faded white, accounting for 3.0% or more of the cell area, before and after surface treatment.

[0064] Example 1 <Mask structure manufacturing> A metal piece fitting jig was set on the lower table of the lamination device and fixed in place by vacuum suction. The bottom surface of the trapezoidal aluminum piece was countersunk into the fitting hole of the metal piece fitting jig, and a trapezoidal aluminum piece was inserted as a mask, forming a 0.2 mm high (depth) surrounding portion (see Figure 1(a)) integrally formed with the mask portion. Then, a quartz glass (with a light transmittance of 90% or more at a wavelength of 254 nm) mask support was set on the upper table of the lamination device and fixed in place by vacuum suction. A thin layer of two-component curing adhesive was applied to the top surface of the trapezoidal aluminum piece. After aligning the mark (round hole) on the outer periphery of the aluminum piece fitting jig with the mark (round hole) on the outer periphery of the quartz glass while monitoring with a camera, the upper table was lowered, and the quartz glass and trapezoidal aluminum piece were bonded together to obtain a mask composite in which the trapezoidal aluminum piece was supported by the mask support. The trapezoidal aluminum piece had a quadrangular pyramid shape. The suction on the upper table of the lamination device was then released and the upper table was raised. The resulting mask composite was left to harden the two-component curing adhesive. After leaving it for a sufficient time for the two-component curing adhesive to harden, the aluminum piece fitting jig was removed. <Surface treatment> The mask structure produced above was aligned on the substrate having the surface to be treated produced above, and positioned so that the center of each dye-adsorbed porous semiconductor layer coincided with the center of each mask, yielding a substrate / mask structure laminate. The offset of the bottom of the mask portion relative to the dye-adsorbed porous semiconductor layer was 0.1 mm. A weight was then placed on the mask structure while ensuring no misalignment occurred, and the substrate / mask structure / weight laminate was introduced into a UV-ozone cleaning device (manufactured by Technovision, "UV-312") using a low-pressure mercury lamp as a light source. The peak wavelengths were 253.7 nm and 184.9 nm, the irradiation distance was 35 mm, the treatment time was 3 minutes, and the illuminance was 30 mW / cm. 2Under irradiation conditions of 100 nm (irradiation distance: 25 mm), the surface treatment was performed on the substrate / mask structure / weight laminate. The water droplet contact angle of the obtained surface-treated surface was measured as described above. Then, the color fading of the dye-adsorbed porous semiconductor layer that had been surface-treated according to the above procedure was evaluated. The results are shown in Table 1.

[0065] Example 2 A mask structure for surface processing was obtained in the same manner as in Example 1, except that instead of the surrounding portion formed integrally with the mask portion in Example 1, a 2 mm thick gel (CRG-N0502, manufactured by Tanac Co., Ltd.) was bonded as a deformable member to the entire bottom surface of the mask portion using a two-component curing adhesive to form the surrounding portion (see FIG. 3(a)). Then, evaluations similar to those in Example 1 were performed. The results are shown in Table 1.

[0066] Example 3 A mask structure for surface treatment was obtained in the same manner as in Example 1, except that instead of the surrounding portion formed integrally with the mask portion in Example 1, a 0.5 mm thick foam rubber (SCF100, manufactured by Nitto Denko Corporation) was bonded as a deformable member to the entire bottom surface of the mask portion using a two-component curing adhesive to form the surrounding portion (see FIG. 3(a)). Then, evaluations similar to those in Example 1 were performed. The results are shown in Table 1.

[0067] Example 4 A mask structure for surface treatment was obtained in the same manner as in Example 1, except that instead of the surrounding portion formed integrally with the mask portion in Example 1, a 0.5 mm thick UV-curable liquid gasket (CIPG) was applied and cured as a gasket member to the outer periphery of the bottom surface of the mask portion of the obtained mask composite to form a surrounding portion (see FIGS. 2(a) and 2(b)). Then, evaluations similar to those in Example 1 were performed. The results are shown in Table 1.

[0068] Example 5 In Example 1, in addition to the surrounding portion formed integrally with the mask portion by countersinking, a surrounding portion was further formed by adhering foamed rubber as a deformable member with a two-component curing adhesive so as to cover the bottom surface of the mask portion and the inner surface (bottom surface and inner side surface) of the surrounding portion (see FIG. 4(a)). Except for this, a mask structure for surface treatment was obtained in the same manner as in Example 1. Then, evaluations similar to those in Example 1 were performed. The results are shown in Table 1.

[0069] Example 6 A surface treatment mask structure was obtained in the same manner as in Example 4, except that the offset amount of the bottom surface of the mask portion relative to the dye-adsorbed porous semiconductor layer was changed from 0.1 mm to 0.3 mm. Then, the same evaluations as in Example 1 were carried out. The results are shown in Table 1.

[0070] Example 7 A mask structure for surface processing was obtained in the same manner as in Example 1, except that rectangular aluminum pieces (cuboid shapes) were used to form the mask portions instead of the trapezoid aluminum pieces in Example 1. The same evaluations as in Example 1 were then carried out. The results are shown in Table 1.

[0071] Example 8 A mask structure for surface processing was obtained in the same manner as in Example 2, except that rectangular aluminum pieces (cuboid shapes) were used to form the mask portions instead of the trapezoid aluminum pieces in Example 2. The same evaluations as in Example 1 were then carried out. The results are shown in Table 1.

[0072] Example 9 A mask structure for surface processing was obtained in the same manner as in Example 3, except that rectangular aluminum pieces (cuboid shapes) were used to form the mask portions instead of the trapezoid aluminum pieces in Example 3. The same evaluations as in Example 1 were then carried out. The results are shown in Table 1.

[0073] Example 10 A mask structure for surface processing was obtained in the same manner as in Example 4, except that rectangular aluminum pieces (cuboid shapes) were used to form the mask portions instead of the trapezoidal aluminum pieces in Example 4. The same evaluations as in Example 1 were then carried out. The results are shown in Table 1.

[0074] (Comparative Example 1) A mask structure for surface treatment was obtained in the same manner as in Example 1, except that no countersinking was performed on the bottom surface of the mask piece and no surrounding portion was provided. Then, the same evaluations as in Example 1 were performed. The results are shown in Table 1.

[0075] (Comparative Example 2) In Example 7, a mask structure for surface treatment was obtained in the same manner as in Example 1, except that no countersinking was performed on the bottom surface of the mask piece and no surrounding portion was provided. Then, the same evaluations as in Example 7 were performed. The results are shown in Table 1. [Table 1]

[0076] The results shown in Table 1 show that in Examples 1 to 10, in which the surface treatment of a substrate having a treatment surface was performed while inhibiting or preventing the movement of gas molecules to the dye-adsorbed porous semiconductor layer, deterioration (fading) of the dye-adsorbed porous semiconductor layer due to active oxygen can be suppressed. [Industrial Applicability]

[0077] According to the present invention, it is possible to provide a surface treatment method capable of suppressing deterioration of a region to be protected due to active oxygen, and a surface treatment mask structure that can be suitably used for the surface treatment method. [Explanation of symbols]

[0078] 1. Protected area (porous semiconductor layer) 2. Mask 2a Mask part 2b, 2c, 2d surrounding area 10 Surface to be treated (base material) 20 Mask support D1 2b width D2 2b height D3 2c width D4 2c height D5 Offset amount

Claims

1. A surface treatment method for treating a surface to be treated, the surface having a protection target area provided on a portion of the surface, by irradiating the surface with UV light, comprising: A surface treatment method comprising a surface treatment step of irradiating the surface to be treated with UV light while suppressing or preventing incidence of UV light on the area to be protected and inhibiting or preventing movement of gas molecules to the area to be protected.

2. The surface treatment step includes a masking step of covering the region to be protected with a mask; an irradiation step of irradiating the treatment surface with UV light after the masking step, 2. The surface treatment method according to claim 1, wherein the mask comprises: a mask portion located between the region to be protected and a UV light source, which suppresses or prevents incidence of UV light; and a surrounding portion located between the mask portion and the treatment surface, which inhibits or prevents transmission of gas molecules.

3. The surface treatment method according to claim 2 , wherein the mask portion and the surrounding portion are integrally formed.

4. 3. The surface treatment method according to claim 2, wherein the surrounding portion is made of a gasket member.

5. 3. The surface treatment method according to claim 2, wherein the surrounding portion is made of a deformable member.

6. The mask portion has a base width W Ｍ is the maximum width, and the width W Ｍ The surface treatment method according to claim 2 , wherein the surface has a width smaller than

7. A surface treatment mask structure used when performing surface treatment on a surface to be treated, a mask and an ultraviolet-transmitting mask support that supports the mask; The mask structure for surface processing includes a mask portion located on the mask support side and suppressing or preventing the incidence of UV light, and a surrounding portion located on the opposite side of the mask portion from the mask support side and inhibiting or preventing the transmission of gas molecules.

8. the treated surface is a photoelectrode substrate for a dye-sensitized solar cell, 7. The surface treatment method according to claim 1, wherein the region to be protected is a semiconductor layer containing a sensitizing dye.

9. 7. The surface treatment method according to claim 1, wherein the surface treatment step uses the mask structure for surface treatment according to claim 6.

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