JP5543823B2 - Method for producing porous layer-containing laminate - Google Patents

Description

  The present invention relates to a method for producing a porous layer-containing laminate having a porous layer, and more specifically, a method for producing a porous layer-containing laminate capable of making a porous layer difficult to crack, and porous The present invention relates to a layer-containing laminate and a dye-sensitized solar cell.

  Dye-sensitized solar cells are considered to be promising candidates for next-generation solar cells because they can be manufactured relatively easily, the raw materials are cheap, and the photoelectric conversion efficiency is high.

  The photoelectrode in the dye-sensitized solar cell has a semiconductor layer on which a sensitizing dye is adsorbed. Titanium oxide or the like is used as the material for the semiconductor layer.

  In the dye-sensitized solar cell, the role of the semiconductor layer constituting the photoelectrode is to absorb the sensitizing dye, accept the electron injection from the excited sensitizing dye, transport the electron to the conductive layer, and convert the iodide ion to the dye. Such as providing an electron transfer (reduction) reaction field, light scattering and light confinement.

  In order for the semiconductor layer to play these roles, it is necessary to control the porous structure by forming a plurality of holes in the semiconductor layer. In the dye-sensitized solar cell, the holes formed in the semiconductor layer play an important role for obtaining a light scattering effect and function as a diffusion path for the electrolyte. In particular, in order to sufficiently increase the photoelectric conversion efficiency in the dye-sensitized solar cell, it is necessary to form the porous structure with high accuracy.

  A method for forming a plurality of holes in the semiconductor layer is disclosed in Patent Document 1 below.

  Patent Document 1 discloses that a porous semiconductor is formed by applying a paste containing semiconductor particles, an organic binder resin, and a solvent on a substrate, volatilizing the solvent, and further eliminating the organic binder resin at a high temperature. A method of forming a layer is described.

  In addition, in order to enhance the function of the photoelectrode, it has been studied to make the semiconductor layer multi-layered. For example, Patent Document 2 below discloses a method of making the inner layer and the outer layer of a semiconductor electrode that is a semiconductor layer different. Here, in order to increase the photoelectric conversion efficiency in the dye-sensitized solar cell, the semiconductor particles used for the inner layer are different from the semiconductor particles used for the outer layer.

JP 2001-261436 A JP 2003-142170 A

  In Patent Documents 1 and 2, stress is likely to occur due to the semiconductor particles necking each other in the firing step for sintering the semiconductor particles. For this reason, peeling may occur at the interface between the semiconductor layer and the conductive layer, or the porous layer may be cracked. Cracks in the porous layer are more prominent as the thickness of the porous layer is increased and the volume of the porous layer is increased. When such a crack of a porous layer arises, the photoelectric conversion efficiency of a photoelectrode will fall.

  In Patent Document 2, the inner layer and the outer layer of the semiconductor layer are different. However, if the semiconductor particles used for the inner layer are different from the semiconductor particles used for the outer layer and a multilayer semiconductor layer is simply formed, cracks may occur in the porous layer.

  The objective of this invention is providing the manufacturing method of the porous layer containing laminated body which can make it hard to produce a crack in a porous layer, a porous layer containing laminated body, and a dye-sensitized solar cell.

  According to a wide aspect of the present invention, there is provided a method for producing a porous layer-containing laminate in which two or more porous layers including a first porous layer and a second porous layer are laminated on a substrate. A step of applying a first paste containing semiconductor particles, an organic binder resin, and a solvent on a member to be coated, to form a first paste layer, and the first paste layer or the first paste Applying a second paste containing semiconductor particles, an organic binder resin, and a solvent on the first porous layer obtained by firing the paste layer to form a second paste layer; and the second paste Before or after applying the step of baking the first paste layer to sinter the semiconductor particles contained in the first paste layer to form the first porous layer; and Semiconductor particles contained in the second paste layer by firing the second paste layer And forming a second porous layer, and when applying the first paste, the first paste layer has a convex portion or a concave portion on the upper surface, or the above A method for producing a porous layer-containing laminate is provided in which the first paste is applied non-uniformly so that the first paste layer is a convex portion.

  In a specific aspect of the method for producing a porous layer-containing laminate according to the present invention, the first paste layer has a convex portion or a concave portion on the upper surface, or the first paste layer is a convex portion. In addition, the first paste may be applied with a non-uniform thickness or may be partially applied discontinuously.

  In another specific aspect of the method for producing a porous layer-containing laminate according to the present invention, the first paste is discontinuously and partially applied so that the first paste layer is a convex portion. The

  In still another specific aspect of the method for producing a porous layer-containing laminate according to the present invention, the first paste is non-uniform so that the first paste layer has a convex portion or a concave portion on the upper surface. It is applied with a proper thickness.

  In another specific aspect of the method for producing a porous layer-containing laminate according to the present invention, the first paste layer has a substantially cylindrical or substantially conical convex portion on the upper surface, or the first paste. The first paste is applied non-uniformly so that the layer is a substantially cylindrical or substantially conical protrusion.

  In another specific aspect of the method for producing a porous layer-containing laminate according to the present invention, the second paste is applied so that the upper surface of the second paste layer is substantially smooth.

  In still another specific aspect of the method for producing a porous layer-containing laminate according to the present invention, the second paste is applied so that the second paste layer has a convex portion or a concave portion on the upper surface.

  In still another specific aspect of the method for producing a porous layer-containing laminate according to the present invention, the first and second pastes are applied by screen printing or extrusion.

  In still another specific aspect of the method for producing a porous layer-containing laminate according to the present invention, titanium oxide particles are used as the semiconductor particles.

  In another specific aspect of the method for producing a porous layer-containing laminate according to the present invention, the first paste layer before firing is heated to a temperature lower than the firing temperature, and the second before firing. And a step of heating the paste layer to a temperature lower than the firing temperature.

  In still another specific aspect of the method for producing a porous layer-containing laminate according to the present invention, before applying the second paste, the first paste layer is baked to form the first paste layer. The semiconductor particles contained in are sintered to form the first porous layer.

  In another specific aspect of the method for producing a porous layer-containing laminate according to the present invention, the application target member is the base material, or the base material, the semiconductor particles, the organic binder resin, and the solvent on the base material. When the application target member has the paste layer, the laminated body of at least one paste layer formed of a paste containing or at least one porous layer obtained by firing the paste layer, The method further includes the step of firing the paste layer and sintering the semiconductor particles contained in the paste layer to form a porous layer.

  In still another specific aspect of the method for producing a porous layer-containing laminate according to the present invention, the upper surface of the application target member is substantially smooth.

  The porous layer-containing laminate according to the present invention forms a paste layer by applying a base material and one or more kinds of paste containing semiconductor particles, an organic binder resin, and a solvent on the base material. Then, the paste layer is fired, and two or more porous layers formed by firing the semiconductor particles contained in the paste layer are provided. At least one porous layer excluding the uppermost layer is formed by non-uniformly applying the paste.

  The dye-sensitized solar cell according to the present invention includes the porous layer-containing laminate obtained by the method for producing a porous layer-containing laminate as an electrode for a dye-sensitized solar cell.

  In the method for producing a porous layer-containing laminate according to the present invention, a first paste containing semiconductor particles, an organic binder resin, and a solvent is applied nonuniformly on a member to be coated, and a convex portion or a concave portion is formed on the top surface Forming a first paste layer having a convex portion or a semiconductor particle and an organic binder on the first paste layer or the first porous layer obtained by firing the first paste layer Since the method includes a step of applying a second paste containing a resin and a solvent to form a second paste layer and a step of firing the first and second paste layers, Cracks can be made difficult to occur. Furthermore, the thickness of the entire porous layer can be increased without causing cracks in the porous layer.

FIG. 1 is a cross-sectional view schematically showing an example of a porous layer-containing laminate obtained by the method for producing a porous layer-containing laminate according to an embodiment of the present invention. 2A to 2E are cross-sectional views for explaining each step of the method for producing a porous layer-containing laminate according to one embodiment of the present invention. FIGS. 3A and 3B are cross-sectional views showing modifications of the paste layer that has a convex portion or a concave portion on the upper surface or is a convex portion. FIGS. 4A and 4B are cross-sectional views showing modifications of the paste layer that has a convex portion or a concave portion on the upper surface or is formed on the upper surface of the porous layer that is the convex portion. 5 (a) and 5 (b) are a bottom view and a front view showing an example of a laminate of an emulsion and a mesh that has a convex portion or a concave portion on the upper surface or is used to form a paste layer that is a convex portion. It is sectional drawing. FIG. 6 is a cross-sectional view schematically showing an example of a dye-sensitized solar cell using a porous layer-containing laminate obtained by the method for producing a porous layer-containing laminate according to an embodiment of the present invention. . 7 is an enlarged image of the porous layer in the porous layer-containing laminate obtained in Example 1. FIG. FIG. 8 is an enlarged image of the porous layer in the porous layer-containing laminate obtained in Comparative Example 1.

  Hereinafter, the present invention will be clarified by describing specific embodiments and examples of the present invention with reference to the drawings.

  In the method for producing a porous layer-containing laminate according to the present invention, a porous layer-containing laminate in which two or more porous layers including the first and second porous layers are laminated on a substrate is produced. To do.

  In FIG. 1, an example of the porous layer containing laminated body obtained by the manufacturing method of the porous layer containing laminated body which concerns on one Embodiment of this invention is shown typically.

  As shown in FIG. 1, the porous layer-containing laminate 1 includes a base material 2, a porous layer 3 laminated on the upper surface 2 a of the base material 2, and a porous material laminated on the upper surface 3 a of the porous layer 3. A layer 4, a porous layer 5 laminated on the upper surface 4 a of the porous layer 4, and a porous layer 6 laminated on the upper surface 5 a of the porous layer 5 are provided. Here, a plurality of porous layers 3 to 6, specifically, four porous layers 3 to 6 are laminated on the upper surface 2 a of the substrate 2. The porous layer 5 has a plurality of convex portions 5b and a plurality of concave portions 5c on the upper surface 5a. The recessed part 5c is arrange | positioned between the convex parts 5b.

  In the surface direction of the entire porous layers 3 to 6 (direction perpendicular to the thickness direction), and further in the surface direction of the porous layers 5 and 6 (direction orthogonal to the thickness direction), the porous layer 5 and the porous layer 6 There are regions where are alternately arranged. The convex portion 5 b of the porous layer 5 enters the porous layer 6 in the surface direction of the entire porous layer 6. The porous layer 6 enters the porous layer 5 in the surface direction of the entire porous layer 5. The interface where the porous layer 5 and the porous layer 6 are laminated is not linear. The porous layer 5 is laminated on the entire area of the upper surface 4a of the porous layer 4, and the porous layer 5 is a continuous porous layer. The porous layer 6 is a discontinuous porous layer.

  The substrate 2 includes a substrate body 7 and a conductive layer 8 laminated on the upper surface 7 a of the substrate body 7. The porous layer 3 is laminated on the upper surface 8 a of the conductive layer 8.

  Each of the porous layers 3 to 6 is porous and has a plurality of pores. In FIG. 1, the illustration of the holes is omitted for convenience.

  The porous layer-containing laminate 1 can be obtained as follows.

  First, the base material 2 described above is prepared. Furthermore, 1 type, or 2 or more types of paste containing a semiconductor particle, organic binder resin, and a solvent is prepared. The paste for forming the porous layers 3 to 6 may be the same or different. In order to form the porous layers 3 to 6, one type of paste may be used, or two or more types of pastes may be used. The porous layers 3 to 6 may be formed of the same paste or different pastes.

  Next, as shown in FIG. 2A, a paste is applied to the upper surface 2a of the base material 2 to form a paste layer 3A. Here, the paste 3A is uniformly applied. Further, the paste is applied so that the upper surface 3Aa of the paste layer 3A becomes substantially smooth. After forming the paste layer 3A, it is preferable to heat the paste layer 3A to a temperature lower than the firing temperature in order to suppress the flow of the paste layer or volatilize the solvent. In order to volatilize the solvent, each paste layer before firing is preferably heated to a temperature lower than the firing temperature. By removing the solvent, the excessive flow of the paste layer 3A can be suppressed, and the paste can be easily applied to the upper surface 3Aa of the paste layer 3A. Note that in this specification, a paste layer heated to a temperature lower than the firing temperature in order to suppress the flow of the paste layer or volatilize the solvent is also referred to as a paste layer.

  In the present embodiment, the paste layer 3A is not baked before the paste is applied to the upper surface 3Aa of the paste layer 3A to form the paste layer 4A. After forming the paste layer 3A and before forming the paste layer 4A, the paste layer 3A is baked to sinter the semiconductor particles contained in the paste layer 3A to form the porous layer 3. Also good. A paste layer 4A may be formed by applying a paste to the upper surface 3a of the porous layer 3.

  Thereafter, as shown in FIG. 2B, the paste is applied to the upper surface 3Aa of the paste layer 3A to form the paste layer 4A. Here, the paste 4A is uniformly applied. Further, the paste is applied so that the upper surface 4Aa of the paste layer 4A becomes substantially smooth. After forming the paste layer 4A, it is preferable to heat the paste layer 4A to a temperature lower than the firing temperature in order to suppress the flow of the paste layer or volatilize the solvent.

  In the present embodiment, the paste layer 4A is not baked before the paste is applied to the upper surface 4Aa of the paste layer 4A to form the paste layer 5A. After forming the paste layer 4A and before forming the paste layer 5A, the paste layer 4A is fired to sinter the semiconductor particles contained in the paste layer 4A, thereby forming the porous layer 4 Also good. A paste layer 5A may be formed by applying a paste to the upper surface 4a of the porous layer 4.

  In the present embodiment, the two paste layers 3A and 4A are formed before the paste layer 5A is formed. Before forming the paste layer that has the convex portion or the concave portion on the upper surface, or specifically, the paste layer 5A having the convex portion 5Ab and the concave portion 5Ac on the upper surface 5Aa, the paste layer In addition, the porous layer may not be formed, and the upper surface 2a of the substrate 2 may have a convex portion or a concave portion on the upper surface, or a paste layer that is a convex portion. Three or more paste layers or porous layers may be formed on the upper surface 2a of the substrate 2 before the paste layer having the convex portions or the concave portions on the upper surface or forming the paste layer that is the convex portion.

  Next, as shown in FIG. 2C, the paste is applied to the upper surface 4Aa of the paste layer 4A to form the paste layer 5A. Here, the paste is applied so that the upper surface 5Aa of the paste layer 5A has the convex portion 5Ab and the concave portion 5Ac between the convex portions 5Ab. In addition, a continuous paste layer 5A is formed. Specifically, the paste 5A is continuously applied with a non-uniform thickness so that the paste layer 5A has a substantially cylindrical convex portion 5Ab on the upper surface 5Aa. In order to suppress the flow of the paste layer or to volatilize the solvent after forming the paste layer 5A, it is preferable to heat the paste layer 5A to a temperature lower than the firing temperature.

  As shown in FIG. 3A, the paste may be applied with a non-uniform thickness so that the paste layer 11 has a substantially conical convex portion 11b or concave portion 11c on the upper surface 11a. The paste layer 11 has a substantially conical convex portion 11b and a concave portion 11c between the convex portions 11b on the upper surface 11a. That is, the shape of the convex portion on the upper surface of the paste layer and the shape of the paste layer that is the convex portion are not limited to a substantially cylindrical shape, and can be various shapes. The shape of the convex portion on the upper surface of the paste layer and the shape of the paste layer that is the convex portion may be, for example, a polygonal column shape or a hemispherical shape. It is preferable to apply the paste with a non-uniform thickness so that the paste layer has a substantially cylindrical or substantially conical convex portion on the upper surface, or a substantially cylindrical or substantially conical convex portion.

  Further, as shown in FIG. 3B, the discontinuous paste layer 12 may be formed by applying the paste discontinuously and partially so that the paste layer 12 is a convex portion 12a. That is, the paste may be partially applied to the upper surface 4Aa of the paste layer 4A or the upper surface 4a of the porous layer 4, and there is a portion where the paste is not applied to the upper surface 4Aa of the paste layer 4A or the upper surface 4a of the porous layer 4. May be. It is preferable to apply the paste with a non-uniform thickness or discontinuously apply it partially so that the paste layer has convex portions or concave portions on the upper surface, or the paste layer is convex portions. The paste may be applied with a non-uniform thickness so that the paste layer has convex portions or concave portions on the upper surface, or the paste may be applied discontinuously and partially so that the paste layer is convex portions. .

  Next, as shown in FIG. 2 (d), the paste layers 3A to 5A are fired all at once to sinter the semiconductor particles contained in the paste layers 3A to 5A. 5 is formed. Thus, before applying paste and forming paste layer 6A, it is preferred to bake paste layers 3A-5A or paste layer 5A. The firing efficiency of the porous layer-containing laminate can be increased by firing two or more paste layers at once without firing each paste layer. Further, by baking the paste layer 5A, the shape retainability of the convex portions 5Ab and the concave portions 5Ac imparted to the upper surface 5Aa of the paste layer 5A is enhanced. Further, for example, even if a paste is applied to the upper surface 5a of the porous layer 5 in order to form the paste layer 6A, the shape of the substantially columnar convex portion 5b is not easily broken. However, the paste layer 6A may be formed by applying a paste to the upper surface 5Aa of the paste layer 5A before firing. After forming the paste layer 6A, the paste layer 5A may be fired.

  Next, as shown in FIG. 2E, a paste is applied to the upper surface 5a of the porous layer 5 to form a paste layer 6A. The paste layer 6A is a discontinuous paste layer. When the paste layer 5A is not fired, the paste is applied to the upper surface 5Aa of the paste layer 5A to form the paste layer 6A. Here, the paste is applied so that the upper surface 6Aa of the paste layer 6A becomes substantially smooth. The upper surface 6Aa of the porous layer 6 is generally smooth. Further, a paste is applied so as to fill the concave portion 5b of the upper surface 5a of the porous layer 5. The paste layer 6A is not formed on the convex portion 5b. The upper surface 5a of the porous layer 5 and the upper surface 6Aa of the paste layer 6A are connected substantially smoothly.

  As shown in FIG. 4 (a), the paste is applied to the upper surface 5a of the porous layer 5 so that the upper surface 21a of the paste layer 21 is substantially smooth so as to further fill the concave portion 5c and onto the convex portion 5b. Then, the paste layer 21 may be formed. The paste layer 21 may be formed on the upper surface 5Aa of the paste layer 5A. The continuous paste layer 21 may be formed by continuously applying the paste to the upper surface 5Aa of the paste layer 5A or the upper surface 5a of the porous layer 5. The paste layer may be formed so that the upper surface 5Aa of the paste layer 5A or the upper surface 5a of the porous layer 5 and the upper surface 6Aa of the paste layer 6A are connected substantially smoothly.

  Further, as shown in FIG. 4B, the paste layer 22 is formed by applying the paste on the upper surface 5a of the porous layer 5 so that the paste layer 22 has the convex portion 22b or the concave portion 22c on the upper surface 22a. May be. The paste layer 22 may be formed on the upper surface 5Aa of the paste layer 5A. A continuous or discontinuous paste layer may be formed on the upper surface 5Aa of the paste layer 5A or the upper surface 5a of the porous layer 5 so that the paste layer has convex portions or concave portions on the upper surface. Alternatively, the paste may be applied to the upper surface 5Aa of the paste layer 5A or the upper surface 5a of the porous layer 5 with a substantially uniform thickness to form a paste layer having convex portions or concave portions on the upper surface.

  Next, the paste layer 6B is fired to sinter the semiconductor particles contained in the paste layer 6B, thereby forming the porous layer 6. Thus, the porous layer containing laminated body 1 shown in FIG. 1 can be obtained.

  The main feature of this embodiment is that when forming two or more porous layers, in order to form at least one of the porous layers excluding the uppermost layer, the paste layer is formed on the upper surface. It is to apply the paste non-uniformly so that it has a convex part or a concave part or the paste layer is a convex part. The porous layer-containing laminate is characterized in that at least one porous layer excluding the uppermost layer of two or more porous layers is formed by non-uniformly applying a paste. Have. Thus, by applying the paste non-uniformly, stress due to necking of the semiconductor particles is less likely to occur. As a result, peeling hardly occurs at the interface between the porous layer and the base material, and cracking does not easily occur in the porous layer.

  As a result, when the obtained porous layer-containing laminate is used for a photoelectrode, the photoelectric conversion efficiency can be stabilized and high photoelectric conversion efficiency can be stably obtained. If there is no peeling at the interface between the porous layer and the substrate and there is no cracking of the porous layer, the light confinement effect is further enhanced.

  The above effect is obtained not only when the paste is applied non-uniformly as shown in FIG. 2 (c) but also when the paste is applied non-uniformly as shown in FIGS. 3 (a) and 3 (b). be able to. Further, not only when the paste is applied as shown in FIG. 2 (e) but also when the paste is applied as shown in FIGS. 4 (a) and 4 (b), the above effect can be obtained.

  In the porous layer-containing laminate 1, the paste layers 3A and 4A formed on the substrate 2, that is, the laminate of the substrate 2 and the paste layers 3A and 4A corresponds to the application target member, and the paste layer 5A. Corresponds to the first paste layer, the porous layer 5 corresponds to the first porous layer, the paste layer 6A corresponds to the second paste layer, and the porous layer 6 corresponds to the second porous layer. Equivalent to. When applying the paste to form the paste layer 3A, even if the paste is applied unevenly so that the paste layer 3A has a convex portion or a concave portion on the upper surface or the paste layer 3A is a convex portion Good. In this case, from another viewpoint, the paste layer 3A corresponds to the first paste layer, and the paste layer 4A formed on the upper surface 3Aa of the first paste layer 3A corresponds to the second paste layer. To do. Further, when applying the paste to form the paste layer 4A, the paste is applied non-uniformly so that the paste layer 4A has a convex portion or a concave portion on the upper surface, or the paste layer 4A is a convex portion. May be. In this case, from another viewpoint, the paste layer 4A corresponds to the first paste layer, and the paste layer 5A formed on the upper surface 4Aa of the first paste layer 4A corresponds to the second paste layer. To do.

  The member to be coated is at least one paste layer formed by a base material, or a base material and a paste containing semiconductor particles, an organic binder resin, and a solvent on the base material, or at least one obtained by firing the paste layer. It is a laminated body with the porous layer of a layer. When the application target member has a paste layer, the method further includes a step of firing the paste layer to sinter the semiconductor particles contained in the paste layer to form a porous layer.

  Further, after forming the paste layer 6A or the porous layer 6, the paste is applied to the upper surface 6Aa of the paste layer 6A or the upper surface 6a of the porous layer 6 to further form one or more porous layers. May be. One or two or more porous layers may be further laminated on the upper surface 6 a of the porous layer 6.

  In order to form the paste layers 3A to 6A, the paste is preferably applied by screen printing or extrusion. In order to form the paste layer 5A, and in order to form a paste layer having a convex portion or a concave portion on the upper surface or a paste layer that is a convex portion, the paste may be applied by screen printing or extrusion (tokoroten) method. preferable. Thereby, a convex part or a recessed part can be formed with high precision. However, the method of applying the paste is not limited to screen printing or extrusion.

  In order to form a paste layer having convex portions or concave portions on the upper surface, or a convex portion, a mesh in which an emulsion having a plurality of through holes is laminated on one side is suitably used when applying the paste. That is, as shown in FIGS. 5A and 5B in a bottom view and a front sectional view, a mesh 41 in which an emulsion 42 having a plurality of through holes 42a is laminated on one side 41a is preferably used. By using the laminate of the emulsion 42 and the mesh 41, the paste can be applied to the portion where the emulsion 42 (coating regulating member) is not provided, that is, the plurality of through holes 42a, and corresponds to the shape of the through holes 42a. A convex part and a concave part or a convex part can be formed in a paste layer.

  From the viewpoint of further suppressing cracks in the porous layers 3 to 6, the height of the convex portion 5 Ab or the depth of the concave portion 5 Ac in the paste layer 5 A, and the height of the convex portion 5 b or the concave portion 5 c in the porous layer 5. The depth is preferably 2 to 20 μm.

  The heating temperature for suppressing the flow of the paste layer or volatilizing the solvent, that is, the heating temperature when heating the paste layer to a temperature lower than the firing temperature is 250 ° C. or more lower than the firing temperature. It is preferable that the temperature is 350 ° C. or more lower than the firing temperature.

  The firing temperature for firing the paste layer and sintering the semiconductor particles contained in the paste layer is preferably 200 to 500 ° C. The firing temperature is more preferably 300 ° C. or higher, and more preferably 450 ° C. or lower. The firing time is preferably 10 minutes to 10 hours. The firing time is more preferably 30 minutes or longer, still more preferably 1 hour or longer, more preferably 3 hours or shorter.

  Hereinafter, the details of the paste for forming the porous layers 3 to 6 will be described.

(paste)
The paste for forming the porous layers 3 to 6 includes semiconductor particles, an organic binder resin, and a solvent.

(1) Semiconductor particle The said semiconductor particle is a raw material which sinters by baking and becomes a porous layer which is a semiconductor layer. The semiconductor particles are not particularly limited. Examples of the material of the semiconductor particles include metal oxides such as TiO ₂ , MgO, ZnO, SnO ₂ , WO ₃ , Nb ₂ O _5, and TiSrO _3, and materials obtained by doping these metal oxides with N or S. Etc. Material of the semiconductor particles is preferably TiO _2. From the viewpoint of controlling the porous structure with high accuracy, it is preferable to use titanium oxide particles as the semiconductor particles.

  The shape of the semiconductor particles is not particularly limited, and examples thereof include a spherical shape or a similar shape thereof, a regular octahedral shape or a similar shape thereof, a star shape or a similar shape thereof, a needle shape, a plate shape, and a fiber shape.

  In order to increase the surface area in the first and second porous layers, the primary particle size of the semiconductor particles is preferably 3 to 500 nm, and more preferably 3 to 200 nm.

  Three types of crystal forms of the titanium oxide particles are known: anatase, rutile and brookite. The crystal form of the titanium oxide particles is preferably anatase type. Anatase-type titanium oxide has higher reaction activity than rutile-type titanium oxide, and electron injection from the dye occurs efficiently. For this reason, anatase type titanium oxide is suitably used in dye-sensitized solar cell applications.

  In 100% by weight of the paste, the content of the semiconductor particles is preferably 5 to 40% by weight. In 100% by weight of the paste, the more preferable lower limit of the content of the semiconductor particles is 10% by weight, and the more preferable upper limit is 30% by weight. When the content of the semiconductor particles satisfies the above lower limit, the paste can be applied to an appropriate film thickness, and it is not necessary to add an organic binder resin or the like excessively for adjusting the viscosity.

(2) Organic Binder Resin In order to stabilize the dispersion state of the semiconductor particles and further to form a porous structure in the porous layer, the paste preferably contains an organic binder resin.

  The organic binder resin is not particularly limited, but is modified with polyvinyl alcohol acetal such as ethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, polyethylene glycol, polyvinyl alcohol, polyvinyl butyral, gelatin, polyacrylic acid, polyacrylamide And dextrin.

  In 100% by weight of the paste, the content of the organic binder resin is preferably 3 to 30% by weight. When the content of the organic binder resin satisfies the lower limit, the dispersion stability of the paste is further increased. When content of the said organic binder resin satisfy | fills the said upper limit, the viscosity of a paste will not become high too much and it can apply | coat a paste to a base material easily.

(3) Solvent The paste preferably contains a solvent. Examples of the solvent include alcohols, amides, sulfoxides, amines, cyclic ethers, esters, natural alcohols, and water. Examples of the alcohols include butyl alcohol, benzyl alcohol, and butyl carbitol. Examples of the amides include dimethylformamide and dimethylacetamide. Examples of the sulfoxides include dimethyl sulfoxide. Examples of the amines include n-methyl-2-pyrrolidone. Examples of the cyclic ethers include dioxane. Examples of the glycol ethers include ethyl cellosolve and methyl cellosolve. Examples of the esters include dibutyl phthalate. Examples of the natural alcohols include terpineol.

  The content of the solvent in 100% by weight of the paste is preferably 30 to 89% by weight. The more preferable upper limit of the solvent content in 100% by weight of the paste is 85% by weight. When the content of the solvent satisfies the above lower limit, the fluidity of the paste becomes appropriate, and it becomes easy to apply the paste on the application target member. When the content of the solvent satisfies the above upper limit, the viscosity of the paste becomes appropriate, the paste can be easily applied to an appropriate film thickness, the viscosity of the paste becomes appropriate, and the dispersion stability of the paste is further enhanced. Become.

(4) Other components The paste may contain organic resin particles or organic resin fibers in order to control the porous structure. Furthermore, the paste may contain additives other than the semiconductor particles, the organic binder resin, and the solvent as necessary.

  Examples of the additive include a dispersant such as a surfactant, a dispersion stabilizer, an antifoaming agent, an antioxidant, a colorant, and a viscosity modifier. In order to stabilize the paste, the paste preferably further contains a dispersant.

  The dispersant is not particularly limited, and examples thereof include propylene glycol fatty acid esters, glycerin fatty acid esters, polyglycerin fatty acid esters, polyoxyethylene glycerin fatty acid esters, sorbitan fatty acid esters, and polyoxyethylene sorbitan fatty acid esters. , Polyoxyethylene sorbite fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene alkyl ether phosphoric acids, polyoxyethylene alkyl ether carboxylic acids, polyethylene glycol fatty acid esters, etc. Can be mentioned.

(Base material)
One useful application of the porous layer-containing laminate is a photoelectrode for a dye-sensitized solar cell. However, the use of the porous layer-containing laminate is not particularly limited, and the porous layer-containing laminate can be widely used as a material for an electrochemical element.

  When the porous titanium oxide laminate is used as a photoelectrode of a dye-sensitized solar cell, visible light needs to enter the semiconductor layer. For this reason, it is preferable that the base material used in the porous titanium oxide laminate is a transparent base material that transmits visible light. The material of the substrate is preferably glass, and the substrate is preferably a glass substrate. In particular, in order to increase the photoelectric conversion efficiency of the dye-sensitized solar cell, the higher the visible light transmittance of the base material, the better. The visible light transmittance of the base material is preferably 70% or more.

  The material of the base material is not particularly limited. The material of the substrate is preferably a material that transmits visible light. Examples of the material for the substrate include plastic and glass.

  The plastic that is the material of the substrate is not particularly limited, and examples thereof include polyacrylic resin, polycarbonate resin, polyester resin, polyimide resin, polystyrene resin, polyvinyl chloride resin, and polyamide resin. Among them, polyester resins, particularly polyethylene terephthalate (PET), are produced and used in large quantities as transparent heat-resistant films. From the viewpoint of producing a thin, light and flexible dye-sensitized solar cell, the substrate is preferably a PET film.

  The glass that is the material of the substrate is not particularly limited, and common glasses such as soda lime glass, borosilicate glass, quartz glass, borosilicate glass, Vycor glass, alkali-free glass, blue plate glass, and white plate glass are used. Can be mentioned.

  The substrate preferably has conductivity, and is preferably a conductive substrate. When the porous titanium oxide laminate is used in a dye-sensitized solar cell, the semiconductor layer is in contact with the conductive material in order to extract electrons generated by the photoreaction in the semiconductor layer, which is a photoelectrode material, It is necessary for electrons to be extracted to the outside through the conductive material.

  In order to have conductivity, the base material preferably has a conductive layer on the surface, and preferably has a base body and a conductive layer laminated on the surface of the base body. The substrate is preferably a conductive substrate having a substrate body and a conductive layer laminated on the surface of the substrate body. When the entire surface layer of the substrate in contact with the semiconductor layer has conductivity, the internal resistance decreases, and as a result, the total photoelectric conversion efficiency is improved in the dye-sensitized solar cell.

  Examples of the material for the conductive layer include metals, metal oxides, and conductive polymers. In the case of using the porous titanium oxide laminate for a dye-sensitized solar cell, the base material having a conductive layer is preferably transparent. Therefore, the material of the conductive layer is preferably a transparent conductive material such as a metal oxide or a conductive polymer. In forming the porous titanium oxide laminate, the conductive layer is preferably made of a metal oxide in order to fire the first and second pastes. Metal oxides have higher heat resistance than conductive polymers.

  Materials well known as transparent conductive materials that are metal oxides include indium oxide / tin oxide (sometimes called ITO), fluorine-doped tin oxide (sometimes called FTO), zinc oxide, and tin oxide. Antimony-doped tin oxide (sometimes referred to as ATO), indium oxide / zinc oxide (sometimes called IZO), gallium oxide / zinc oxide (sometimes called GZO), titanium oxide, etc. Are preferably used.

(Dye-sensitized solar cell)
A dye-sensitized solar cell that is one of the useful applications of the porous layer-containing laminate will be described below.

  In FIG. 6, an example of the dye-sensitized solar cell using the porous layer containing laminated body obtained by the manufacturing method of the porous layer containing laminated body which concerns on one Embodiment of this invention is shown.

  A dye-sensitized solar cell 51 shown in FIG. 6 includes a porous layer-containing laminate 1X. The porous titanium oxide laminate 1X has a porous layer 3X to 6X in which the sensitizing dye is adsorbed to the porous layers 3 to 6 of the porous titanium oxide laminate 1 to form the porous layers 3X to 6X. It is a titanium oxide laminate. The porous layers 3X to 6X have a plurality of holes. The porous layers 3X to 6X are dye-sensitized solar cell electrode materials. Moreover, the dye-sensitized solar cell 51 has the porous layer-containing laminate 1X as an electrode for a dye-sensitized solar cell.

  The dye-sensitized solar cell 51 includes a base 52 and a conductive layer 53 stacked on one surface 52a of the base as a counter electrode of the porous layer-containing laminate 1X that is an electrode for a dye-sensitized solar cell. It has a laminated body provided with. An electrolyte solution 54 is disposed between the porous layers 5X and 6X and the conductive layer 53. A lead wire 55 for supplying electric power generated by photoelectric conversion to an external circuit is connected to the conductive layer 6 and the conductive layer 53.

  When power is generated by the dye-sensitized solar cell 51, for example, light is generated from the back surface 2b side opposite to the porous layer 3X to 6X side of the substrate 2 as indicated by an arrow Y in FIG. Is irradiated.

  As the dye, a dye generally used in a dye-sensitized solar cell can be used. Examples of the dye include cis-di (thiocyanato) -bis (2,2′-bipyridyl-4,4′-dicarboxylic acid) ruthenium (II) (sometimes referred to as N3), cis-di (thiocyanato)- Bis (2,2′-bipyridyl-4,4′-dicarboxylic acid) ruthenium bis-tetrabutylammonium salt (sometimes referred to as N719), tri (thiocyanato)-(4,4 ′, 4 ″ -tri And ruthenium dye systems such as carboxy-2,2 ′: 6 ′, 2 ″ -terpyridine) ruthenium (sometimes called black dye). In addition, as the above dyes, various types such as coumarin, polyene, cyanine, hemicyanine, thiophene, indoline, xanthene, carbazole, perylene, porphyrin, phthalocyanine, merocyanine, catechol and squarylium Organic dyes and the like can be mentioned. Furthermore, a donor-acceptor composite dye obtained by combining these dyes can be used as the dye.

  Examples of the electrolyte solution include non-aqueous electrolyte solvents such as acetonitrile or propionitrile. Examples of the electrolyte solution include a solution in which a liquid electrolyte such as ionic liquid such as dimethylpropylimidazolium iodide or butylmethylimidazolium iodide is mixed with a supporting electrolyte such as lithium iodide and iodine. It is done.

  Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples.

Example 1
A base material having a base body and a conductive layer on the surface of the base body was prepared.

A TiO ₂ HT paste (manufactured by Solanonix) was applied to the upper surface of the conductive layer of the substrate by screen printing with a uniform thickness of about 2 μm to form a paste layer A having a substantially smooth upper surface. Thereafter, the paste layer A was heated at 130 ° C. for 3 minutes to volatilize the solvent.

Next, a TiO ₂ T paste (manufactured by Solanonix) is applied with a uniform thickness of about 8 μm to the upper surface of the paste layer A where the solvent is volatilized by screen printing to form a paste layer B having a substantially smooth upper surface. did. Thereafter, the paste layer B was heated at 130 ° C. for 3 minutes to volatilize the solvent.

Next, a TiO ₂ D paste (manufactured by Solanonix) is applied to the upper surface of the paste layer B where the solvent has been volatilized by screen printing with a uniform thickness of about 2 μm to form a paste layer C whose upper surface is substantially smooth. did. Thereafter, the paste layer C was heated at 130 ° C. for 3 minutes to volatilize the solvent.

A mesh 41 in which an emulsion 42 having a plurality of through holes 42a shown in FIGS. 5A and 5B was laminated on one side 41a was prepared. The diameter D of the through hole of the emulsion was 100 μm. The distance W1 between the two centers of the adjacent through holes 42a was 130 μm, and the shortest distance W2 of the portion where the through holes 42a were not provided was 80 μm. Next, a TiO ₂ D paste (manufactured by Solanix) is continuously applied to the upper surface of the paste layer C where the solvent is volatilized by screen printing with a non-uniform thickness using the laminate of the emulsion 42 and the mesh 41 described above. It applied and formed the continuous paste layer D which has a substantially cylindrical convex part on the upper surface, and a recessed part between this convex part. The thickness of the paste layer where there is no projection is about 12 μm, the thickness of the paste layer D where there is a projection is about 20 μm, and the height of the projection and the depth of the recess are about 8 μm. Thereafter, the paste layer D was heated at 130 ° C. for 3 minutes to volatilize the solvent.

  Next, the paste layers A to D were collectively heated at 500 ° C. for 30 minutes, the organic binder resin was extinguished, and the titanium oxide particles were sintered to form the porous layers A to D. The porous layer D had a substantially cylindrical convex portion on the upper surface.

Next, a TiO ₂ R paste (manufactured by Solanonix) was applied to the upper surface of the porous layer D to form a discontinuous paste layer E having a substantially smooth upper surface. The upper surface of the porous layer D and the upper surface of the paste layer E were connected substantially smoothly. The paste layer D was not formed on the convex portion on the upper surface of the porous layer D. The paste was applied so as to fill the concave portion on the upper surface of the porous layer D. Thereafter, the paste layer E was heated at 130 ° C. for 3 minutes to volatilize the solvent.

  Next, the paste layer E was heated at 500 ° C. for 30 minutes so that the organic binder resin disappeared and the titanium oxide particles were sintered to form the porous layer E. The upper surface of the porous layer E was substantially smooth. The total thickness of the porous layers A to E was about 23 μm. In the surface direction of the porous layers D and E (direction orthogonal to the thickness direction), the porous layers D and the porous layers E were alternately arranged. The convex portion of the porous layer D entered the porous layer E in the surface direction of the entire porous layer E. The porous layer E entered the porous layer D in the surface direction of the entire porous layer D.

(Comparative Example 1)
A base material having a base body and a conductive layer on the surface of the base body was prepared.

A TiO ₂ HT paste (manufactured by Solanonix) was applied to the upper surface of the conductive layer of the substrate by screen printing with a uniform thickness of about 2 μm to form a paste layer A having a substantially smooth upper surface. Thereafter, the paste layer A was heated at 130 ° C. for 3 minutes to volatilize the solvent.

Next, a TiO ₂ T paste (manufactured by Solanonix) is applied with a uniform thickness of about 8 μm to the upper surface of the paste layer A where the solvent is volatilized by screen printing to form a paste layer B having a substantially smooth upper surface. did. Thereafter, the paste layer B was heated at 130 ° C. for 3 minutes to volatilize the solvent.

Next, a TiO ₂ D paste (manufactured by Solanonix) is applied with a uniform thickness of about 10 μm to the upper surface of the paste layer B where the solvent has been volatilized by screen printing to form a paste layer C having a substantially smooth upper surface. did. Thereafter, the paste layer C was heated at 130 ° C. for 3 minutes to volatilize the solvent.

  Next, the paste layers A to C were collectively heated at 500 ° C. for 30 minutes, the organic binder resin was extinguished, and the titanium oxide particles were sintered to form porous layers A to C. The upper surface of the porous layer C was substantially smooth.

Next, a TiO ₂ R paste (manufactured by Solanonix) is applied to the upper surface of the porous layer C where the solvent has been volatilized by screen printing with a uniform thickness of about 3 μm, and a paste layer D whose upper surface is substantially smooth is applied. Formed. Thereafter, the paste layer D was heated at 130 ° C. for 3 minutes to volatilize the solvent.

  Next, the paste layer D is heated at 500 ° C. for 30 minutes to extinguish the organic binder resin and sinter the titanium oxide particles to form the porous layer D to obtain a porous layer-containing laminate. It was. The total thickness of the porous layers A to D was about 23 μm.

(Evaluation)
It was evaluated whether the porous layer in the porous layer-containing laminate was cracked.

  Moreover, the obtained porous layer containing laminated body was immersed in the pigment | dye (N719) for 18 hours. After 18 hours, the porous layer-containing laminate was taken out, a cell was assembled using a sealing material and an ionic electrolyte, and power generation characteristics were evaluated using a solar simulator.

  As a result, in the porous layer-containing laminate of Example 1, no crack was observed in the porous layer. In the porous layer-containing laminate of Example 1, the conductive layer and the porous layer of the base material were not peeled off. The enlarged image which image | photographed the porous layer of the porous layer containing laminated body of Example 1 was shown in FIG. On the other hand, in the porous layer-containing laminate of Comparative Example 1, cracks were seen in the porous layer. The enlarged image which image | photographed the porous layer of the porous layer containing laminated body of the comparative example 1 was shown in FIG.

  The power generation performance Eff of the three cells using the porous layer-containing laminate of Example 1 was 9.4%, 9.4%, and 9.4%, respectively. In contrast, the power generation performance Eff of the three cells using the porous layer-containing laminate of Comparative Example 1 was 9.1%, 9.3%, and 9.3%, respectively. The three cells using the porous layer-containing laminate of Comparative Example 1 have variations in power generation performance, and compared with the three cells using the porous layer-containing laminate of Example 1, the power generation performance is It was low.

DESCRIPTION OF SYMBOLS 1,1X ... Porous layer containing laminated body 2 ... Base material 2a ... Upper surface 2b ... Back surface 3-6 ... Porous layer 3a-6a ... Upper surface 5b ... Convex part 5c ... Concave part 3A-6A ... Paste layer 3Aa-6Aa ... Upper surface 5Ab: Convex part 5Ac ... Concave part 3X-6X ... Porous layer 7 ... Substrate body 7a ... Upper surface 8 ... Conductive layer 11 ... Paste layer 11a ... Upper surface 11b ... Convex part 11c ... Concave part 12 ... Paste layer 12a ... Convex part 21 ... Paste layer 21a ... Upper surface 22 ... Paste layer 22a ... Upper surface 22b ... Convex portion 22c ... Concave portion 51 ... Dye-sensitized solar cell 52 ... Base material 52a ... Surface 53 ... Conductive layer 54 ... Electrolyte solution 55 ... Lead wire

Claims (13)

A method for producing a porous layer-containing laminate in which two or more porous layers including first and second porous layers are laminated on a substrate,
A step of applying a first paste containing semiconductor particles, an organic binder resin, and a solvent on a coating target member having the base material to form a first paste layer;
A second paste layer containing a semiconductor particle, an organic binder resin, and a solvent is applied onto the first paste layer or the first porous layer obtained by firing the first paste layer. Forming a step;
Before or after applying the second paste, the first paste layer is fired to sinter the semiconductor particles contained in the first paste layer to form the first porous layer. And a process of
Firing the second paste layer to sinter the semiconductor particles contained in the second paste layer to form a second porous layer,
When the first paste is applied, the first paste is not used so that the first paste layer has a convex portion or a concave portion on the upper surface, or the first paste layer is a convex portion. Apply evenly,
A method for producing a porous layer-containing laminate, wherein the second paste is applied so as to fill in or between the convex portions or concave portions of the first paste layer formed by non-uniform application.   The first paste is applied with a non-uniform thickness or has a non-uniform thickness so that the first paste layer has protrusions or depressions on the top surface, or the first paste layer is a protrusion. The manufacturing method of the porous layer containing laminated body of Claim 1 which apply | coats partially continuously.   The method for producing a porous layer-containing laminate according to claim 2, wherein the first paste is applied partially and discontinuously so that the first paste layer is a convex portion.   The method for producing a porous layer-containing laminate according to claim 2, wherein the first paste is applied with a non-uniform thickness so that the first paste layer has a convex portion or a concave portion on an upper surface.   The first paste is not coated so that the first paste layer has a cylindrical or conical convex portion on the upper surface, or the first paste layer is a cylindrical or conical convex portion. The manufacturing method of the porous layer containing laminated body of any one of Claims 1-4 apply | coated uniformly.   The method for producing a porous layer-containing laminate according to any one of claims 1 to 5, wherein the second paste is applied so that an upper surface of the second paste layer is smooth.   The method for producing a porous layer-containing laminate according to any one of claims 1 to 5, wherein the second paste is applied so that the second paste layer has a convex portion or a concave portion on an upper surface.   The method for producing a porous layer-containing laminate according to any one of claims 1 to 7, wherein the first and second pastes are applied by screen printing or extrusion.   The method for producing a porous layer-containing laminate according to any one of claims 1 to 8, wherein titanium oxide particles are used as the semiconductor particles. Heating the first paste layer before firing to a temperature lower than the firing temperature;
The method for producing a porous layer-containing laminate according to any one of claims 1 to 9, further comprising a step of heating the second paste layer before firing to a temperature lower than a firing temperature.   Before applying the second paste, the first paste layer is baked to sinter the semiconductor particles contained in the first paste layer to form the first porous layer. The manufacturing method of the porous layer containing laminated body of any one of Claims 1-10. The member to be coated is fired at least one paste layer or the paste layer formed of the base material, or the base material and a paste containing semiconductor particles, an organic binder resin, and a solvent on the base material. A laminate with at least one porous layer;
When the member to be coated has the paste layer, the method further comprises a step of firing the paste layer and sintering the semiconductor particles contained in the paste layer to form a porous layer. The manufacturing method of the porous layer containing laminated body of any one of claim | item 1 -11.   The manufacturing method of the porous layer containing laminated body of any one of Claims 1-12 whose upper surface of the said application | coating target member is smooth.