JP5851938B2 - Metal substrate for dye-sensitized solar cell - Google Patents

Description

  The present invention relates to a metal substrate for a dye-sensitized solar cell, and more particularly, to a metal substrate for a dye-sensitized solar cell including a metal layer having corrosion resistance with respect to an electrolyte of a dye-sensitized solar cell element.

  Conventionally, a metal substrate for a dye-sensitized solar cell including a metal layer having corrosion resistance with respect to an electrolyte of the dye-sensitized solar cell element is known (for example, see Patent Document 1).

  In the above-mentioned Patent Document 1, a glass substrate having a striped platinum electrode formed on the surface opposite to the light incident side, disposed on the light incident side, and disposed on the opposite side to the light incident side, is made of Ti. A titanium substrate (metal substrate for dye-sensitized solar cell), a titania film disposed on the surface of the titanium substrate, and a titania film and a platinum electrode disposed so as to face each other, A dye-sensitized solar cell comprising a filled iodine electrolyte is disclosed. A sensitizing dye that absorbs light is adsorbed on the titania film. Patent Document 1 discloses that a metal substrate made of titanium alloy or stainless steel can be used instead of a titanium substrate made of Ti. These metal substrates made of Ti, Ti alloy or stainless steel have corrosion resistance to the electrolyte of the dye-sensitized solar cell element.

JP 2010-55935 A

  However, in the dye-sensitized solar cell disclosed in Patent Document 1, the corrosion resistance of the dye-sensitized solar cell element to the electrolyte can be maintained by the metal substrate made of Ti, Ti alloy, or stainless steel. In addition, since Ti, titanium alloy, or stainless steel constituting the metal substrate has a relatively large electric resistance, there is a disadvantage that electrical loss is likely to occur in the metal substrate. For this reason, there exists a problem that the electric power generation efficiency of a dye-sensitized solar cell falls.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to provide a dye-sensitized solar cell while maintaining the corrosion resistance to the electrolyte of the dye-sensitized solar cell element. It is providing the metal substrate for dye-sensitized solar cells which can improve the power generation efficiency of this.

A metal substrate for a dye-sensitized solar cell according to one aspect of the present invention is formed of a metal that is disposed on the positive electrode side of a dye-sensitized solar cell element and has corrosion resistance to the electrolyte of the dye-sensitized solar cell element. The non-porous first metal layer is formed of a metal having an electric resistance lower than that of the first metal layer, and is opposite to the dye-sensitized solar cell element of the first metal layer And a second metal layer bonded to the first metal layer and a third metal layer in contact with the second metal layer and bonded to the opposite side of the first metal layer. the substrate surface of the solar cell element side, irregularities are formed, the thickness of the second metal layer is Ru der least 50% of the thickness of the clad material.

  In the metal substrate for dye-sensitized solar cell according to one aspect of the present invention, as described above, the non-porous first metal layer and the metal having an electric resistance lower than that of the first metal layer are formed. Unlike the case where the metal substrate for a dye-sensitized solar cell is composed of only the first metal layer, by providing a clad material including the second metal layer bonded to the first metal layer, the dye sensitization Since a part of the metal substrate for the sensitive solar cell is the second metal layer that is lower than the electrical resistance of the first metal layer, the electrical resistance of the metal substrate for the dye-sensitized solar cell is composed only of the first metal layer. It can be made lower than the electric resistance of the metal substrate for dye-sensitized solar cell. Thereby, it can suppress that the electrical loss in the metal substrate for dye-sensitized solar cells increases. As a result, the power generation efficiency of the dye-sensitized solar cell can be improved as compared with the case where the metal substrate for the dye-sensitized solar cell is composed of only the first metal layer.

  In the metal substrate for a dye-sensitized solar cell according to one aspect of the present invention, as described above, the first metal layer is formed of a metal having corrosion resistance to the electrolyte of the dye-sensitized solar cell element. In addition, even when the second metal layer is formed on the metal substrate for the dye-sensitized solar cell by bonding the second metal layer to the side opposite to the dye-sensitized solar cell element of the first metal layer. Further, the corrosion resistance to the electrolyte of the dye-sensitized solar cell element can be maintained. As a result, the power generation efficiency of the dye-sensitized solar cell can be improved while maintaining the corrosion resistance of the dye-sensitized solar cell element to the electrolyte.

  Moreover, in the metal substrate for dye-sensitized solar cells according to one aspect of the present invention, as described above, by forming irregularities on the substrate surface of the first metal layer on the dye-sensitized solar cell element side, Since the surface area of the substrate surface can be increased by the unevenness of the surface, for example, when the substrate surface is covered with the catalyst layer, the surface area of the catalyst layer can be increased. As a result, since the transfer of electrons via the catalyst layer can be more easily performed, the power generation efficiency of the dye-sensitized solar cell can be further improved.

  In the metal substrate for a dye-sensitized solar cell according to the above aspect, the surface area / plane area of the first metal layer on the substrate surface on the dye-sensitized solar cell element side is preferably 1.03 or more. If comprised in this way, the surface area of a substrate surface can be enlarged reliably. The plane area is an area on a plane when a predetermined range in which the surface area is measured is projected onto the plane.

  In this case, preferably, the surface area / planar area on the substrate surface of the first metal layer on the dye-sensitized solar cell element side is 1.05 or more. If comprised in this way, the surface area of a substrate surface can be enlarged effectively.

  In the metal substrate for a dye-sensitized solar cell according to the above aspect, the ten-point average roughness Rzjis is preferably 0.50 μm or more on the substrate surface on the dye-sensitized solar cell element side of the first metal layer. is there. If comprised in this way, the surface area of a substrate surface can be enlarged reliably.

  In this case, the ten-point average roughness Rzjis is preferably 1.20 μm or more on the substrate surface of the first metal layer on the dye-sensitized solar cell element side. If comprised in this way, the surface area of a substrate surface can be enlarged effectively.

  In the metal substrate for a dye-sensitized solar cell according to the above aspect, the arithmetic average roughness Ra is preferably 0.10 μm or more on the surface of the substrate on the dye-sensitized solar cell element side of the first metal layer. . If comprised in this way, the surface area of a substrate surface can be enlarged reliably.

  In this case, the arithmetic average roughness Ra is preferably 0.22 μm or more on the substrate surface of the first metal layer on the dye-sensitized solar cell element side. If comprised in this way, the surface area of a substrate surface can be enlarged effectively.

  In the metal substrate for a dye-sensitized solar cell according to the above aspect, a catalyst layer is preferably formed on the substrate surface of the first metal layer on the dye-sensitized solar cell element side. If comprised in this way, since a catalyst layer is formed on the substrate surface by which the surface area was enlarged by the unevenness | corrugation, the surface area of a catalyst layer can be enlarged. As a result, since the transfer of electrons via the catalyst layer can be more easily performed, the power generation efficiency of the dye-sensitized solar cell can be further improved.

In the metal substrate for a dye-sensitized solar cell according to the above aspect, preferably, the clad material including the first metal layer , the second metal layer, and the third metal layer constitutes the positive electrode of the dye-sensitized solar cell element. doing. In the metal substrate for a dye-sensitized solar cell configured by the clad material including the first metal layer , the second metal layer, and the third metal layer constituting the positive electrode of the dye-sensitized solar cell element as described above, By forming the second metal layer from a metal having an electric resistance lower than that of the first metal layer, the electric resistance of the metal substrate for the dye-sensitized solar cell is changed to a dye made of only the first metal layer. It can be made lower than the electrical resistance of the metal substrate for sensitized solar cells. Thereby, the power generation efficiency of the dye-sensitized solar cell can be improved.

  In the metal substrate for a dye-sensitized solar cell according to the above aspect, the first metal layer is preferably formed of Ti or a Ti alloy, and the second metal layer is Cu, Cu alloy, Al or Al alloy. It is formed by any one of these. If comprised in this way, unlike the case where the metal substrate for dye-sensitized solar cells consists only of a 1st metal layer, a part of metal substrate for dye-sensitized solar cells has low electrical resistance, Cu alloy, Since it is the second metal layer formed of any one of Al or Al alloy, the dye-sensitized type consisting of only the first metal layer can be easily provided with the electric resistance of the metal substrate for the dye-sensitized solar cell. It can be made lower than the electrical resistance of the metal substrate for solar cells.

In the metal substrate for a dye-sensitized solar cell according to the above aspect, the difference between the thermal expansion coefficient of the third metal layer and the thermal expansion coefficient of the first metal layer is preferably the thermal expansion coefficient of the second metal layer. It is smaller than the difference from the thermal expansion coefficient of the first metal layer. If comprised in this way, when the metal substrate for dye-sensitized solar cells is thermally deformed, the metal for dye-sensitized solar cells is caused by the deformation of the second metal layer relative to the first metal layer. The entire substrate can be prevented from being deformed by the third metal layer having a thermal expansion coefficient close to that of the first metal layer.

In the metal substrate for a dye-sensitized solar cell according to the above aspect , the third metal layer is preferably made of a metal having higher corrosion resistance than the metal constituting the second metal layer. If comprised in this way, it can suppress by a 3rd metal layer that a 2nd metal layer corrodes resulting from an external environment etc.

In the configuration in which the first metal layer is formed of Ti or a Ti alloy and the second metal layer is formed of any one of Cu, Cu alloy, Al, or Al alloy , preferably, the first metal layer is Ti Alternatively, the second metal layer is formed of any one of Cu, Cu alloy, Al, or Al alloy, and the third metal layer is formed of Fe, ferritic stainless steel, Ti, or Ti. It is made of any one of the alloys. If comprised in this way, since the metal substrate part for dye-sensitized solar cells is a 2nd metal layer formed with any one of Cu, Cu alloy, Al, or Al alloy with low electrical resistance, The electric resistance of the metal substrate for dye-sensitized solar cells can be made lower than the electric resistance of the metal substrate for dye-sensitized solar cells consisting of only the first metal layer. Further, when the metal substrate for the dye-sensitized solar cell is thermally deformed, the second metal layer formed of any one of Cu, Cu alloy, Al, or Al alloy is deformed with respect to the first metal layer. Fe, ferrite having a thermal expansion coefficient close to the thermal expansion coefficient of the first metal layer formed of Ti or Ti alloy is caused by deformation of the entire metal substrate for the dye-sensitized solar cell. It can suppress by the 3rd metal layer currently formed by any one of type | system | group stainless steel, Ti, or Ti alloy.

  According to the present invention, as described above, the power generation efficiency of the dye-sensitized solar cell can be improved while maintaining the corrosion resistance of the dye-sensitized solar cell element with respect to the electrolyte.

It is sectional drawing which showed the structure of the dye-sensitized solar cell by 1st Embodiment of this invention. It is the perspective view which showed typically the structure of the metal substrate by 1st Embodiment of this invention. It is sectional drawing which showed the structure of the metal substrate by 1st Embodiment of this invention. It is the expanded sectional view which showed the structure of the metal substrate by 1st Embodiment of this invention. It is sectional drawing which showed the structure of the metal substrate by 2nd Embodiment of this invention. It is the figure which showed the calculated value of the volume resistivity in the metal substrate of a 3 layer structure by the simulation performed in order to confirm the effect of this invention. It is a graph of the volume resistivity in the metal substrate of a 3 layer structure by the simulation performed in order to confirm the effect of this invention. It is the figure which showed the calculated value of the volume resistivity in the metal substrate of the two-layer structure by the simulation performed in order to confirm the effect of this invention. It is a graph of the volume resistivity in the metal substrate of the two-layer structure by the simulation performed in order to confirm the effect of this invention. It is the perspective view which showed the measuring method of the volume resistivity in the direction along the upper surface of the metal substrate of the 3 layer structure performed in order to confirm the effect of this invention. It is the figure which showed the experimental result of the volume resistivity in the direction along the upper surface of the metal substrate of the 3 layer structure performed in order to confirm the effect of this invention. It is the figure which showed the experimental result of the power generation efficiency of the dye-sensitized solar cell performed in order to confirm the effect of this invention. It is the figure which showed the experimental result of the power generation efficiency of the dye-sensitized solar cell at the time of changing the surface roughness performed in order to confirm the effect of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
First, the structure of the dye-sensitized solar cell 100 according to the first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the dye-sensitized solar cell 100 according to the first embodiment of the present invention includes a solar cell element 1 arranged on the light incident side (Z1 side) and the opposite side (Z2) to the light incident side. And a metal substrate 2 arranged on the side). The solar cell element 1 is an example of the “dye-sensitized solar cell element” of the present invention, and the metal substrate 2 is the “cladding material” and “metal substrate for the dye-sensitized solar cell” of the present invention. It is an example.

  The solar cell element 1 is formed by a glass substrate 11 disposed on the light incident side and transmitting light, an upper electrode 12 formed on the lower surface (Z2 side) of the glass substrate 11, and a platinum thin film, A platinum catalyst layer 13 formed on the upper surface of the substrate 2. Further, instead of the platinum catalyst layer 13, a catalyst layer formed of graphite may be used. The platinum catalyst layer 13 is an example of the “catalyst layer” in the present invention.

Further, the solar cell element 1 further includes an iodine electrolyte 14 filled between the upper electrode 12 and the platinum catalyst layer 13, an end portion on the lower surface of the upper electrode 12, and an end portion on the upper surface of the platinum catalyst layer 13. A sealing material 15 is disposed so as to be connected, and seals the iodine electrolyte 14 between the glass substrate 11 and the metal substrate 2. The iodine electrolyte 14 contains iodide ions (I ₃ ⁻ ) and iodine ions (I ⁻ ). The iodine electrolyte 14 is an example of the “electrolyte” in the present invention.

The upper electrode 12 is made of FTO (tin oxide added with a trace amount of fluorine) that has corrosion resistance to the iodine electrolyte 14 and can transmit light. The volume resistivity of FTO is about 800 × 10 ⁻⁸ Ω × m. The upper electrode 12 functions as a negative electrode of the solar cell element 1, and the metal substrate 2 is configured to function as a positive electrode of the solar cell element 1.

  The upper electrode 12 and the metal substrate 2 are connected to terminals 3a and 3b for taking out electric power generated in the dye-sensitized solar cell 100, respectively. For this reason, in order to pass an electric current between the predetermined area | region of the metal substrate 2, and the terminal 3b, it is the direction (X direction, Y direction, and the component of the Y direction and the component of the Y direction) along the XY plane. Current must flow in the direction of

  Innumerable particulate titanium dioxide 12 a is fixed to the lower surface side of the upper electrode 12. Moreover, the light absorption part 12b is adsorbed on the surface of the titanium dioxide 12a. This light absorption part 12b consists of pigment | dyes, such as a ruthenium complex, and has a function which absorbs the light which consists of visible light etc., and discharge | releases an electron. In addition, the titanium dioxide 12 a has a function of transmitting electrons emitted from the light absorption unit 12 b to the upper electrode 12.

The solar cell element 1 is a dye-sensitized solar cell element. A specific power generation mechanism of the solar cell element 1 will be described. First, when the solar cell element 1 is irradiated with light, the light absorption part 12b absorbs light, whereby electrons are emitted from the light absorption part 12b, and the light absorption part 12b enters an oxidized state. And the electron discharge | released from the light absorption part 12b reaches | attains the upper electrode 12 (negative electrode) through the titanium dioxide 12a. Thereafter, the electrons pass through an external circuit (not shown) from the upper electrode 12 via the terminal 3a. Then, the electrons reach the metal substrate 2 (positive electrode) through the terminal 3b. Here, using the platinum of the platinum catalyst layer 13 as a catalyst, the iodide ion (I ₃ ⁻ ) of the iodine electrolyte 14 receives electrons, and three iodine ions (3I ⁻ ) are formed. Then, electrons are supplied from the iodine ions (I ⁻ ) to the oxidized light-absorbing part 12 b, so that the original light-absorbing part 12 b is returned and three iodine ions (I ⁻ ) are converted into iodide ions (I ₃ ⁻ ). Return to. The solar cell element 1 is configured to generate electric power by repeating this series of cycles.

  As shown in FIGS. 2 and 3, the metal substrate 2 includes a Ti layer 21, a Cu layer 22, and a stainless steel layer 23 in order from the upper side (Z1 side) that is the platinum catalyst layer 13 side of the solar cell element 1. Is formed by. That is, the Ti layer 21 is disposed in contact with the lower surface of the platinum catalyst layer 13. The Ti layer 21 is an example of the “first metal layer” of the present invention, the Cu layer 22 is an example of the “second metal layer” of the present invention, and the stainless steel layer 23 is the “first metal layer” of the present invention. It is an example of “three metal layers”.

  Further, this metal substrate 2 is a clad material having a three-layer structure in which a Ti layer 21, a Cu layer 22, and a stainless steel layer 23 each having a flat plate shape are joined in a laminated state in the thickness direction (Z direction). It is comprised by.

  The Ti layer 21 is made of non-porous Ti and has corrosion resistance against the iodine electrolyte 14. Further, as shown in FIG. 4, the upper surface 2a (surface on the Z1 side) of the Ti layer 21 on the platinum catalyst layer 13 side is roughened, whereby irregularities are formed on the upper surface 2a. The upper surface 2a is an example of the “substrate surface” in the present invention.

  Specifically, the arithmetic average roughness Ra of the upper surface 2a of the Ti layer 21 on the platinum catalyst layer 13 side is about 0.22 μm, the ten-point average roughness Rzjis is about 1.20 μm, and the surface area / plane area is It is formed to be about 1.05. Here, the surface area / plane area means a value obtained by dividing the surface area of the upper surface 2a in an arbitrary square region by the plane area of the square region. The arithmetic average roughness Ra, ten-point average roughness Rzjis, and surface area / planar area of the upper surface 2a may be about 0.10 μm or more, about 0.50 μm or more, and about 1.03 or more, respectively.

  Further, the platinum catalyst layer 13 is formed so as to cover the upper surface 2a having irregularities. As a result, the surface area of the platinum catalyst layer 13 becomes larger than that when no irregularities are formed on the upper surface 2a. In addition, when the platinum catalyst layer 13 is a powder form, it is thought that platinum adheres to a part of upper surface 2a, without forming in a thin film form (layer form). Even in this case, since the upper surface 2a is roughened, platinum easily adheres to the upper surface 2a, so that the surface area of platinum increases.

  The Cu layer 22 is made of Cu. The stainless steel layer 23 is made of SUS430 (JIS standard), which has higher corrosion resistance than Cu. Specifically, the stainless steel layer 23 is formed of an Fe alloy that is a ferritic stainless steel containing about 16% to about 18% Cr.

  Here, in the first embodiment, as shown in FIG. 3, the thickness t1 in the thickness direction (Z direction) of the metal substrate 2 is configured to be about 100 μm. Further, the thickness t2 in the thickness direction (Z direction) of the Cu layer 22 is configured to be about 40 μm, which is about 40% of the thickness t1 of the metal substrate 2. The thickness t2 of the Cu layer 22 is preferably about 20% (about 20 μm) or more and about 70% (about 70 μm) or less of the thickness t1 of the metal substrate 2. The thickness t2 of the Cu layer 22 is more preferably about 30% (about 30 μm) or more and about 60% (about 60 μm) or less of the thickness t1 of the metal substrate 2.

  The thickness t3 in the thickness direction (Z direction) of the Ti layer 21 and the thickness t4 in the thickness direction of the stainless steel layer 23 are configured to be substantially the same. That is, the thickness t3 of the Ti layer 21 and the thickness t4 of the stainless steel layer 23 are both configured to be about 30 μm, which is about 30% of the thickness t1 of the metal substrate 2. The thickness t3 of the Ti layer 21 is preferably about 20% (about 20 μm) or more of the thickness t1 of the metal substrate 2. In addition, the thickness t5 (see FIG. 4) of the platinum catalyst layer 13 formed on the upper surface 2a of the Ti layer 21 is formed to be about 1 nm or more and about 300 nm or less.

Further, the volume resistivity R1 of the Ti layer 21 is about 54 × 10 ⁻⁸ Ω × m. Further, the volume resistivity R2 of the Cu layer 22 is about 1.7 × 10 ⁻⁸ Ω × m. The volume resistivity R3 of the stainless steel layer 23 is about 60 × 10 ⁻⁸ Ω × m. That is, the volume resistivity R2 of the Cu layer 22 is configured to be about 1/20 or less of the volume resistivity R1 of the Ti layer 21 and the volume resistivity R3 of the stainless steel layer 23.

The thermal expansion coefficient of the Ti layer 21 is about 8.9 × 10 ⁻⁶ / ° C. The thermal expansion coefficient of the Cu layer 22 is about 17 × 10 ⁻⁶ / ° C. The thermal expansion coefficient of the stainless steel layer 23 is about 10.4 × 10 ⁻⁶ / ° C. That is, the difference (= about 1.5 × 10 ⁻⁶ / ° C.) between the thermal expansion coefficient of the Ti layer 21 and the stainless steel layer 23 is approximately the thermal expansion coefficient of the Cu layer 22 and the thermal expansion coefficient of the stainless steel layer 23. And the difference (= about 8.1 × 10 ⁻⁶ / ° C.).

Further, as shown in FIG. 2, in the X direction along the upper surface 2a orthogonal to the thickness direction (Z direction), the volume resistivity R1 of the Ti layer 21, the volume resistivity R2 of the Cu layer 22, and the stainless steel layer 23 The combined volume resistivity Ryz in the X direction obtained by synthesizing the volume resistivity R3 is about 2 × 10 ⁻⁸ Ω × m. Note that the combined volume resistivity Ryz in the X direction is the volume resistivity of the metal substrate 2 with respect to the current Ix flowing through the YZ plane along the direction (X direction) orthogonal to the YZ plane. That is.

  Further, the Y direction and the direction in which the X direction component and the Y direction component are combined is the direction along the upper surface 2a orthogonal to the thickness direction (Z direction), similarly to the X direction. Therefore, the combined volume resistivity in the Y direction (the volume resistivity of the metal substrate 2 with respect to the current flowing along the Y direction) and the combined volume resistivity in the direction in which the X direction component and the Y direction component are combined (in the combined direction). Both of the volume resistivity of the metal substrate 2 with respect to the current flowing along the same direction are the same as the combined volume resistivity Ryz in the X direction. Therefore, hereinafter, only the combined volume resistivity Ryz in the X direction is considered as the combined volume resistivity in the direction along the upper surface 2a orthogonal to the thickness direction (Z direction).

Further, in the thickness direction (Z direction), the combined volume resistivity Rxy in the thickness direction obtained by combining the volume resistivity R1 of the Ti layer 21, the volume resistivity R2 of the Cu layer 22, and the volume resistivity R3 of the stainless steel layer 23. Is configured to be approximately 18 × 10 ⁻⁸ Ω × m. That is, the combined volume resistivity Ryz (about 2 × 10 ⁻⁸ Ω × m) in the X direction is smaller than the combined volume resistivity Rxy (about 18 × 10 ⁻⁸ Ω × m) in the thickness direction (Z direction). It is configured as follows. The synthetic volume resistivity Rxy in the thickness direction is the volume of the metal substrate 2 with respect to the current Iz flowing through the XY plane along the direction (thickness direction: Z direction) orthogonal to the XY plane. It is resistivity.

  Next, with reference to FIG. 1 and FIG. 3, the manufacturing process of the dye-sensitized solar cell 100 by 1st Embodiment of this invention is demonstrated.

  First, a non-porous roll-shaped Ti plate, a roll-shaped Cu plate, and a roll-shaped stainless steel plate (not shown) of SUS430 are prepared. The thickness of the Cu plate is about 40% of the total thickness of the Ti plate, Cu plate and stainless steel plate. Further, the thickness of the Ti plate and the thickness of the stainless steel plate are both about 30% of the total thickness of the Ti plate, the Cu plate and the stainless steel plate.

  And it rolls and it joins continuously with the rolling mill which is not illustrated in the state laminated | stacked in order of Ti board, Cu board, and stainless steel board. At this time, the Ti plate, the Cu plate and the stainless steel plate are cold-rolled while applying a predetermined pressure. As a result, as shown in FIG. 3, a Ti layer 21 having a thickness t3 of about 30 μm, a Cu layer 22 having a thickness t2 of about 40 μm, and a stainless steel layer 23 having a thickness t4 of about 30 μm are joined together. A clad material (metal substrate 2) having a thickness t1 of 100 μm is continuously formed. Then, as shown in FIG. 4, shot blasting is performed on the upper surface 2a (the surface on the Z1 side) of the clad material (metal substrate 2) on the platinum catalyst layer 13 side. At this time, the arithmetic average roughness Ra, the ten-point average roughness Rzjis, and the surface area / planar area on the upper surface 2a of the Ti layer 21 are about 0.22 μm, about 1.20 μm, and about 1.05, respectively. The upper surface 2a is roughened to form irregularities.

  Thereafter, a platinum catalyst layer 13 of a platinum thin film is formed on the upper surface 2a of the clad material (metal substrate 2) by sputtering or paste application. Thereby, the platinum catalyst layer 13 is formed on the upper surface 2a having irregularities. Then, a clad material (metal substrate 2) on which the platinum catalyst layer 13 is formed is continuously formed and wound into a roll.

  On the other hand, an FTO upper electrode 12 is formed on the lower surface of the prepared glass substrate 11 by sputtering or the like. Thereafter, a coating material containing particulate titanium dioxide powder is coated on the lower surface of the upper electrode 12 and then dried and fired. Thereby, the particulate titanium dioxide 12 a is fixed on the lower surface of the upper electrode 12. And the light absorption part 12b which consists of a pigment | dye is made to adsorb | suck to the surface of the titanium dioxide 12a by immersing the glass substrate 11 in the solution containing pigment | dyes, such as a ruthenium complex. Thereby, the glass substrate 11 in which the upper electrode 12, the titanium dioxide 12a, and the light absorption part 12b were formed is formed. And the sealing material 15 is arrange | positioned on the lower surface of the glass substrate 11 at predetermined intervals.

  Thereafter, the glass substrate 11 is placed on the upper surface of the clad material (metal substrate 2) with the rolls unrolled so that a predetermined interval is formed between the glass substrate 11 and the clad material (metal substrate 2). Then, after the clad material is cut at positions corresponding to both ends of the glass substrate 11, the iodine electrolyte 14 is filled into a space formed by the glass substrate 11, the metal substrate 2, and the sealing material 15. Thereby, the solar cell element 1 is formed. Finally, the dye-sensitized solar cell 100 shown in FIG. 1 is manufactured by connecting the terminals 3a and 3b to the upper electrode 12 and the metal substrate 2, respectively.

In the first embodiment, as described above, the metal substrate 2 that functions as the positive electrode of the solar cell element 1 includes the non-porous Ti layer 21 and the volume resistivity R1 of the Ti layer 21 (about 54 × 10 ⁻⁸ Ω). And a Cu layer 22 formed of Cu having a volume resistivity R2 (about 1.7 × 10 ⁻⁸ Ω × m) lower than that of × m) and bonded to the Ti layer 21, thereby providing a metal. Unlike the case where the substrate 2 is composed only of the Ti layer 21, a part of the metal substrate 2 is a Cu layer 22 formed of Cu lower than the electrical resistance of the Ti layer 21. It can be made lower than the electric resistance of the metal substrate made of only the Ti layer. Thereby, it is possible to suppress an increase in electrical loss in the metal substrate 2. As a result, the power generation efficiency of the dye-sensitized solar cell 100 can be improved as compared with the case where the metal substrate 2 is composed only of the Ti layer 21.

  In the first embodiment, as described above, the upper surface 2a of the Ti layer 21 on the platinum catalyst layer 13 side is roughened to form irregularities on the upper surface 2a. Since the surface area of the upper surface 2a to be covered can be increased, the surface area of the platinum catalyst layer 13 can be increased. As a result, since the transfer of electrons through the platinum catalyst layer 13 can be more easily performed, the power generation efficiency of the dye-sensitized solar cell 100 can be further improved.

  In the first embodiment, as described above, the arithmetic average roughness Ra of the upper surface 2a of the Ti layer 21 on the platinum catalyst layer 13 side is about 0.22 μm, and the ten-point average roughness Rzjis is about 1.20 μm. Since the surface area / plane area is about 1.05, the surface area of the upper surface 2a covered with the catalyst layer by the irregularities of the upper surface 2a can be effectively increased, so that the platinum catalyst layer 13 The surface area can be effectively increased.

In the first embodiment, as described above, the Ti layer 21 is formed of Ti having corrosion resistance with respect to the iodine electrolyte 14, and the Cu layer 22 is opposite to the solar cell element 1 of the Ti layer 21. Even when the Cu layer 22 is formed on the metal substrate 2, the corrosion resistance to the iodine electrolyte 14 of the solar cell element 1 can be maintained. As a result, the power generation efficiency of the dye-sensitized solar cell 100 can be improved while maintaining the corrosion resistance of the solar cell element 1 with respect to the iodine electrolyte 14.

In the first embodiment, as described above, the difference between the thermal expansion coefficient of the Ti layer 21 and the thermal expansion coefficient of the stainless steel layer 23 of SUS430 (= about 1.5 × 10 ⁻⁶ / ° C.) is calculated using the Cu layer. When the metal substrate 2 is thermally deformed by making it smaller than the difference between the thermal expansion coefficient of 22 and the thermal expansion coefficient of the stainless steel layer 23 (= about 8.1 × 10 ⁻⁶ / ° C.), the Cu layer 22 The deformation of the entire metal substrate 2 due to deformation with respect to the Ti layer 21 can be suppressed by the stainless steel layer 23 of SUS430 having a thermal expansion coefficient close to that of the Ti layer 21.

  In the first embodiment, as described above, the stainless steel layer 23 is formed of ferritic stainless steel having higher corrosion resistance than Cu constituting the Cu layer 22, so that the Cu layer 22 is caused by an external environment or the like. Corrosion can be suppressed by the stainless steel layer 23.

  In the first embodiment, as described above, the thickness t3 of the Ti layer 21 and the thickness t4 of the stainless steel layer 23 are both about 30% (about 30 μm) of the thickness t1 (about 100 μm) of the metal substrate 2. As a result, the deformation of the entire metal substrate 2 is further suppressed by the stainless steel layer 23 having a thermal expansion coefficient close to the thermal expansion coefficient of the Ti layer 21 and having the same thickness t4 as the thickness t3 of the Ti layer 21. Can do. Further, it is difficult to form a clad material by joining the Ti layer 21, the Cu layer 22 and the stainless steel layer 23 due to the difference between the thickness t3 of the Ti layer 21 and the thickness t4 of the stainless steel layer 23. Can be suppressed.

  Further, in the first embodiment, as described above, the thickness t2 of the Cu layer 22 is set to about 40% (about 40 μm) of the thickness t1 (about 100 μm) of the metal substrate 2, so that Cu having low electrical resistance is used. Since the region occupied by the formed Cu layer 22 can be increased to some extent, the electrical resistance of the entire metal substrate 2 can be further reduced. Moreover, since it can suppress that the area | region which the Cu layer 22 occupies becomes excessively large, the occurrence of defects such as breakage in the Ti layer 21 due to the excessively small area occupied by the Ti layer 21 is suppressed. can do. In addition, it is possible to suppress the metal substrate 2 from being easily deformed due to an excessively large area occupied by the Cu layer 22 having a large thermal deformation.

  In the first embodiment, as described above, the volume resistivity R2 of the Cu layer 22 is set to about 1/20 or less of the volume resistivity R1 of the Ti layer 21 and the volume resistivity R3 of the stainless steel layer 23. As a result, the electrical resistance of the metal substrate 2 including the Ti layer 21, the Cu layer 22, and the stainless steel layer 23 can be effectively reduced, so that the electrical loss in the metal substrate 2 is effectively increased. Can be suppressed.

(Second Embodiment)
Next, the structure of the dye-sensitized solar cell 200 according to the second embodiment of the present invention will be described with reference to FIGS. 1 and 5. In the dye-sensitized solar cell 200 according to the second embodiment, unlike the first embodiment, the metal substrate 202 is composed of a clad material having a two-layer structure in which a Ti layer 221 and a Cu layer 222 are joined. The case will be described.

  As shown in FIG. 5, the metal substrate 202 of the dye-sensitized solar cell 200 (see FIG. 1) according to the second embodiment of the present invention is above the solar cell element 1 side (see FIG. 1) (Z1 side). The Ti layer 221 and the Cu layer 222 are arranged in this order. That is, the Ti layer 221 is disposed in contact with the lower surface of the platinum catalyst layer 13. The metal substrate 202 is an example of the “cladding material” and “metal substrate for a dye-sensitized solar cell” in the present invention. The Ti layer 221 is an example of the “first metal layer” in the present invention, and the Cu layer 222 is an example of the “second metal layer” in the present invention.

  The metal substrate 202 is formed of a clad material having a two-layer structure in which a Ti layer 221 and a Cu layer 222 each having a flat plate shape are joined in a stacked state in the thickness direction (Z direction). The Ti layer 221 is made of non-porous Ti, and the Cu layer 222 is made of Cu.

  Here, in the second embodiment, the thickness t2 in the thickness direction (Z direction) of the Cu layer 222 is configured to be about 70 μm, which is about 70% of the thickness t1 (about 100 μm) of the metal substrate 202. The thickness t2 of the Cu layer 222 is preferably about 20% (about 20 μm) or more and about 85% (about 85 μm) or less of the thickness t1 of the metal substrate 202. The thickness t2 of the Cu layer 222 is more preferably about 50% (about 50 μm) or more and about 80% (about 80 μm) or less of the thickness t1 of the metal substrate 202.

  Further, the thickness t3 in the thickness direction (Z direction) of the Ti layer 221 is configured to be about 30 μm, which is about 30% of the thickness t1 (about 100 μm) of the metal substrate 202. The thickness t3 of the Ti layer 221 is preferably about 15% (about 15 μm) or more of the thickness t1 of the metal substrate 202.

  In the second embodiment, the arithmetic average roughness Ra of the upper surface 2a of the Ti layer 221 on the platinum catalyst layer 13 side is about 0.22 μm, the ten-point average roughness Rzjis is about 1.20 μm, and the surface area / Irregularities are formed on the upper surface 2a so that the plane area is about 1.05. In addition, the other structure of the dye-sensitized solar cell 200 of 2nd Embodiment is as substantially the same as the said 1st Embodiment.

  Next, with reference to FIG. 5, the manufacturing process of the dye-sensitized solar cell 200 by 2nd Embodiment of this invention is demonstrated.

  First, a non-porous roll-shaped Ti plate and a roll-shaped Cu plate (not shown) are prepared. The thickness of the Cu plate is about 70% of the total thickness of the Ti plate and the Cu plate. Further, the thickness of the Ti plate is about 30% of the total thickness of the Ti plate and the Cu plate.

  And it rolls and it joins continuously with the rolling mill which is not illustrated in the state which laminated | stacked Ti board and Cu board. At this time, the Ti plate and the Cu plate are cold-rolled while applying a predetermined pressure. As a result, as shown in FIG. 5, a Ti layer 221 having a thickness t3 of about 30 μm and a Cu layer 222 having a thickness t2 of about 70 μm are joined together to form a clad material (metal substrate 202 having a thickness t1 of about 100 μm. ) Is formed continuously. The other manufacturing processes of the second embodiment are the same as those of the first embodiment.

In the second embodiment, as described above, the metal substrate 202 has a non-porous Ti layer 221 and a volume resistivity lower than the volume resistivity R1 (about 54 × 10 ⁻⁸ Ω × m) of the Ti layer 221. By including the Cu layer 222 formed of Cu having R2 (about 1.7 × 10 ⁻⁸ Ω × m) and bonded to the Ti layer 221, the electric resistance of the metal substrate 202 is reduced by the Ti layer. It can be made lower than the electric resistance of the metal substrate made of only. Thereby, since it is possible to suppress an increase in electrical loss in the metal substrate 202, the power generation efficiency of the dye-sensitized solar cell 200 can be improved.

  In the first embodiment, as described above, the upper surface 2a of the Ti layer 221 on the platinum catalyst layer 13 side is roughened to form irregularities on the upper surface 2a, so that the platinum catalyst layer 13 has irregularities on the upper surface 2a. Since the surface area of the upper surface 2a to be covered can be increased, the surface area of the platinum catalyst layer 13 can be increased. As a result, since the transfer of electrons through the platinum catalyst layer 13 can be performed more easily, the power generation efficiency of the dye-sensitized solar cell 200 can be further improved.

  In the second embodiment, as described above, the Ti layer 221 is formed of Ti having corrosion resistance with respect to the iodine electrolyte 14, and the Cu layer 222 is opposite to the solar cell element 1 of the Ti layer 221. Even when the Cu layer 222 is formed on the metal substrate 202, the corrosion resistance to the iodine electrolyte 14 of the solar cell element 1 can be maintained.

  In the second embodiment, as described above, the thickness t2 of the Cu layer 222 is set to about 70% (about 70 μm) of the thickness t1 (about 100 μm) of the metal substrate 202, so that Cu having a low electrical resistance is used. Since the area occupied by the formed Cu layer 222 can be increased, the electrical resistance of the entire metal substrate 202 can be further reduced.

  In the second embodiment, as described above, the thickness t3 of the Ti layer 221 is set to about 30% (about 30 μm) of the thickness t1 (about 100 μm) of the metal substrate 202, thereby making the thickness t3 of the Ti layer 221. Can be suppressed from being excessively small, so that it is possible to suppress the occurrence of defects such as tearing in the Ti layer 221 due to the excessively small thickness t3 of the Ti layer 221. Further, it is possible to suppress the metal substrate 202 from being easily deformed due to an excessively large area occupied by the Cu layer 222 having a large thermal deformation. The remaining effects of the second embodiment are similar to those of the aforementioned first embodiment.

[Example]
Next, with reference to FIGS. 2 to 13, simulation and measurement of volume resistivity and measurement of power generation efficiency performed to confirm the effect of the present invention will be described. Specifically, the volume resistivity of the three-layer metal substrate 2 according to the first embodiment and the volume resistivity of the two-layer metal substrate 202 according to the second embodiment were simulated. Further, the measurement of the volume resistivity in the direction along the upper surface 2a of the metal substrate 2 having the three-layer structure according to the first embodiment, and the power generation efficiency of the dye-sensitized solar cell 100 manufactured using the metal substrate 2 are as follows. Measurement and measurement of power generation efficiency of the dye-sensitized solar cell 100 when the surface roughness of the metal substrate 2 was changed were performed.

(Simulation of volume resistivity)
In the simulation of the volume resistivity of the metal substrate having a three-layer structure described below, as shown in FIG. 6, each of the metal substrates 2 of Examples 1 to 9 corresponding to the metal substrate 2 of the first embodiment is a flat plate. The metal substrate 2 comprised of a clad material having a three-layer structure in which a Ti layer 21, a Cu layer 22, and a stainless steel layer 23 having a shape are joined in a stacked state in the thickness direction was assumed. Here, as the metal substrate 2 of Examples 1 to 9, the thickness t2 (see FIG. 3) of the Cu layer 22 is 10%, 20%, and 30% of the thickness t1 (see FIG. 3) of the metal substrate 2, respectively. The cases of 40%, 50%, 60%, 70%, 80% and 90% were assumed. In Examples 1 to 9, it was assumed that the thickness t3 (see FIG. 3) of the Ti layer 21 and the thickness t4 (see FIG. 3) of the stainless steel layer 23 were the same. Therefore, in the metal substrates 2 of Examples 1 to 9, the thickness t3 of the Ti layer 21 and the thickness t4 of the stainless steel layer 23 are 45%, 40%, 35%, 30%, 25 of the thickness t1 of the metal substrate 2, respectively. Modeling was performed as%, 20%, 15%, 10% and 5%.

  Moreover, as Comparative Example 1 with respect to Examples 1 to 9, a metal substrate (including a Cu layer) composed of a clad material having a two-layer structure in which a Ti layer and a stainless steel layer are joined in a stacked state in the thickness direction. No metal substrate). In the metal substrate of Comparative Example 1, it was assumed that the thickness of the Ti layer and the thickness of the stainless steel layer were both 50% of the thickness of the metal substrate.

  Moreover, in the simulation of the volume resistivity in the metal substrate of a two-layer structure, as shown in FIG. 8, Ti-10 which each has a flat shape as Examples 10-18 corresponding to the metal substrate 202 of the said 2nd Embodiment. The metal substrate 202 comprised of the clad material having a two-layer structure in which the layer 221 and the Cu layer 222 are joined in a stacked state in the thickness direction is assumed. Here, as the metal substrate 202 of Examples 10 to 18, the thickness t2 (see FIG. 5) of the Cu layer 222 is 10%, 20%, and 30% of the thickness t1 (see FIG. 5) of the metal substrate 202, respectively. The cases of 40%, 50%, 60%, 70%, 80% and 90% were assumed. In the metal substrates 202 of Examples 10 to 18, the thickness t3 (see FIG. 3) of the Ti layer 221 is 90%, 80%, 70%, 60%, 50% of the thickness t1 of the metal substrate 202, respectively. Modeling was done to be 40%, 30%, 20% and 10%.

  Moreover, as Comparative Example 2 with respect to Examples 1 to 18, a metal substrate composed only of a Cu layer (a metal substrate not including a Ti layer and a stainless steel layer) was assumed. Moreover, the metal substrate (metal substrate which does not contain Cu layer) which consists only of Ti layer was assumed as the comparative example 3 with respect to Examples 10-18.

Further, in the volume resistivity simulation, in each of Examples 1 to 18 and Comparative Examples 1 to 3, the combined volume resistivity Ryz in the direction along the upper surface of the metal substrate (X direction) and the thickness direction (Z direction). The combined volume resistivity Rxy was calculated. The composite volume resistivity Ryz in the X direction was obtained from the formula “1 / Ryz = a / R1 + b / R2 + c / R3”. Further, the composite volume resistivity Rxy in the Z direction was obtained from the formula “Rxy = a × R1 + b × R2 + c × R3”. In the above formula, a, b and c are the ratios of the thickness of the Ti layer, the thickness of the Cu layer and the thickness of the stainless steel layer, respectively, with respect to the thickness of the metal substrate. R1, R2 and R3 are the volume resistivity of Ti, Cu and stainless steel layer, respectively. Here, 54 × 10 ⁻⁸ Ω × m, 1.7 × 10 ⁻⁸ Ω × m, and 60 × 10 ⁻⁸ Ω × m were used as R1, R2, and R3, respectively.

  From the results of Examples 1 to 9 and Comparative Examples 1 and 2 shown in FIG. 6 and FIG. 7, the Cu layer is formed on the three-layer metal substrate, so that the three-layer metal substrate includes the Cu layer. It was found that both the combined volume resistivity Ryz in the X direction and the combined volume resistivity Rxy in the Z direction were smaller than those in the case where there was no (Comparative Example 1). Similarly, from the results of Examples 10 to 18 and Comparative Examples 2 and 3 shown in FIGS. 8 and 9, by forming a Cu layer on a metal substrate having a two-layer structure, the metal substrate having a two-layer structure is formed of Cu. It was found that both the combined volume resistivity Ryz in the X direction and the combined volume resistivity Rxy in the Z direction were smaller than when the layer was not included (Comparative Example 3). From these results, it has been found that by forming a Cu layer on the metal substrate, it is possible to suppress an increase in electrical loss in the metal substrate.

  Further, from the results of Examples 1 to 18 and Comparative Examples 1 to 3 shown in FIGS. 6 to 9, the synthetic volume is increased by increasing the ratio of the thickness of the Cu layer formed of Cu having a small volume resistivity. It has been found that both the resistivity Ryz and Rxy can be reduced. Further, it was found that the amount of change in the composite volume resistivity Ryz in the X direction increases in a region where the ratio of the thickness of the Cu layer is small and decreases in a region where the ratio of the thickness of the Cu layer is large.

Further, from the results of Examples 2 to 9 and 11 to 18 shown in FIGS. 6 to 9 and the result of Comparative Example 2, the thickness of the Cu layer is set to 20% or more of the thickness of the metal substrate, so that the X direction It was found that the volume resistivity Ryz of can be 8 × 10 ⁻⁸ Ω × m or less. Thereby, by making the thickness of the Cu layer 20% or more of the thickness of the metal substrate, it is possible to further suppress an increase in electrical loss when a current flows mainly in the X direction. found. From this, even when the area of the XY plane (upper surface) orthogonal to the thickness direction of the metal substrate is increased as the solar cell element is enlarged, the thickness of the Cu layer is equal to the thickness of the metal substrate. If it is 20% or more, it is possible to suppress an increase in electrical loss in the metal substrate, and it is considered that more electricity can be obtained from the enlarged dye-sensitized solar cell.

Furthermore, from the results of Examples 5 to 9 and 14 to 18 and the result of Comparative Example 2, the volume resistivity Ryz in the X direction is 4 × by making the thickness of the Cu layer 50% or more of the thickness of the metal substrate. It was found that it was possible to make it 10 ⁻⁸ Ω × m or less. Thereby, by making the thickness of the Cu layer 50% or more of the thickness of the metal substrate, it is possible to further suppress an increase in electrical loss when a current flows mainly in the X direction. I understood.

(Measurement of volume resistivity in the direction along the top surface of the metal substrate)
In the measurement of the volume resistivity in the direction along the upper surface described below, the metal substrate 2 corresponding to the metal substrate 2 of the first embodiment was actually manufactured and the volume resistivity was measured. Specifically, a non-porous Ti plate, Cu plate, and stainless steel plate of SUS430 were prepared. And it joined continuously with the rolling mill in the state laminated | stacked in order of Ti board, Cu board, and stainless steel board. At this time, the Ti plate, the Cu plate, and the stainless plate were rolled cold while applying a predetermined pressure. As a result, a total of 18 metal substrates 2 of Examples 2a, 4a, and 6a corresponding to the metal substrate 2 of the first embodiment were produced.

  Here, in the metal substrate 2 of Example 2a corresponding to Example 2 (see FIG. 6) of the simulation described above, the thickness of the Cu plate is 20% of the total thickness of the Ti plate, Cu plate, and stainless steel plate. The thickness of the Ti plate and the thickness of the stainless steel plate were both 40% of the total thickness of the Ti plate, the Cu plate and the stainless steel plate (twice the thickness of the Cu plate).

  Further, in the metal substrate 2 of Example 4a corresponding to Example 4 (see FIG. 6) of the simulation described above, the thickness of the Cu plate is 40% of the total thickness of the Ti plate, the Cu plate, and the stainless steel plate, The thickness of the Ti plate and the thickness of the stainless plate were both 30% of the total thickness of the Ti plate, the Cu plate and the stainless plate (3/4 times the thickness of the Cu plate).

In addition, in the metal substrate 2 of Example 6a corresponding to Example 6 (see FIG. 6) of the simulation described above, the thickness of the Cu plate is 60% of the total thickness of the Ti plate, the Cu plate, and the stainless steel plate, The thickness of the Ti plate and the thickness of the stainless steel plate were both 20% of the total thickness of the Ti plate, the Cu plate and the stainless steel plate ( 1/3 times the thickness of the Cu plate).

  And in each of the produced 18 metal substrates 2 (6 metal substrates 2 of Example 2a, 6 metal substrates 2 of Example 4a, and 6 metal substrates 2 of Example 6a), a Ti layer The thickness t3 of 21, the thickness t2 of the Cu layer 22, the thickness t4 of the stainless steel layer 23, and the thickness t1 of the metal substrate 2 were measured by a predetermined measuring method.

Further, in each of the produced 18 metal substrates 2, the combined volume resistivity Ryz in the X direction along the upper surface 2a was measured by a four-probe method. Specifically, among the probes 300a to 300d of the volume resistivity measuring device 300 shown in FIG. 10, the constant current I ₀ is placed between the probes 300a and 300b arranged on the outside. The composite volume resistivity Ryz in the X direction was calculated by measuring the potential difference V between the probe 300c and 300d.

  And in each of Example 2a, 4a, and 6a, the measurement result in six metal substrates 2 (thickness t3 of Ti layer 21, thickness t2 of Cu layer 22, thickness t4 of stainless steel layer 23, thickness t1 of metal substrate 2) And the average value of the combined volume resistivity Ryz in the X direction was calculated.

From the results of Examples 2a, 4a, and 6a shown in FIG. 11, even in the actual measurement, the combined volume resistivity Ryz in the X direction is the volume resistivity (57 of the metal substrate made only of the Ti layer and the stainless steel layer). It was found to be smaller than the volume resistivity (54 × 10 ⁻⁸ Ω × m, Comparative Example 3) of the metal substrate consisting only of × 10 ⁻⁸ Ω × m, Comparative Example 1) and Ti layer. Thereby, by actually forming the Cu layer 22 on the metal substrate 2, when the metal substrate 2 does not include the Cu layer 22 (when the metal substrate is composed of only the Ti layer and the stainless steel layer, and when the metal substrate is Ti It has been found that the combined volume resistivity Ryz in the X direction can be reduced compared to the case of consisting of only layers.

  Further, from the experimental results (actual values) of Examples 2a, 4a, and 6a and the simulation results (calculated values) of Examples 2, 4 and 6 of the volume resistivity simulation, the combined volume resistivity Ryz in the X direction is calculated. It was found that the actual measurement value was larger than the calculated value. This is thought to be due to the formation of a compound layer at the interface between the layers of the cladding material.

Further, when the ratio of the thickness t2 of the Cu layer 22 is small (Examples 2 and 2a), the difference (= 8.76 × 10 ⁻⁸ Ω × m) between the actually measured value and the calculated value of the synthetic volume resistivity Ryz is: When the ratio of the thickness t2 of the Cu layer 22 is large (Examples 6 and 6a), it becomes larger than the difference (= 0.57 × 10 ⁻⁸ Ω × m) between the actually measured value and the calculated value of the synthetic volume resistivity Ryz. I understood that. As described above, since the electrical resistance when passing through the Ti layer 21 is added to the actually measured combined volume resistivity Ryz, as described above, the ratios of the thickness t3 of the Ti layer 21 are large. Then, compared with Examples 6 and 6a in which the ratio of the thickness t3 of the Ti layer 21 is small, the electrical resistance when passing through the Ti layer 21 is increased. Therefore, the difference between the measured value and the calculated value of the synthetic volume resistivity Ryz when the ratio of the thickness t2 of the Cu layer 22 is small is the actual measurement of the synthetic volume resistivity Ryz when the ratio of the thickness t2 of the Cu layer 22 is large. It is thought that it became larger than the difference between the value and the calculated value.

(Measurement of power generation efficiency when the ratio of Cu layer thickness is varied)
In the measurement of the power generation efficiency when the ratio of the thickness of the Cu layer described below is varied, as shown in FIG. 12, the metal substrates 2 of Examples 2b to 7b corresponding to the metal substrate 2 of the first embodiment described above. As a metal substrate 2 composed of a clad material having a three-layer structure in which a Ti layer 21, a Cu layer 22, and a stainless steel layer 23 each having a flat plate shape are joined in a laminated state in the thickness direction. did. At this time, in the metal substrates 2 of Examples 2b to 7b, the thickness t1 (see FIG. 3) and the area of the XY plane (see FIG. 2) orthogonal to the thickness direction were made the same.

  Here, as the metal substrate 2 of Examples 2b to 7b, the thickness t2 (see FIG. 3) of the Cu layer 22 is 20%, 30%, 40% of the thickness t1 (see FIG. 3) of the metal substrate 2, respectively. Metal substrates 2 having 50%, 60% and 70% were produced. In addition, as the metal substrate 2 of Examples 2b to 7b, the thickness t3 (see FIG. 3) of the Ti layer 21 and the thickness t4 (see FIG. 3) of the stainless steel layer 23 were made the same. Specifically, in the metal substrates 2 of Examples 2b to 7b, the thickness t3 of the Ti layer 21 and the thickness t4 of the stainless steel layer 23 are set to 40%, 35%, 30%, 25 of the thickness t1 of the metal substrate 2, respectively. %, 20% and 15%.

  Moreover, the metal substrate which consists only of Ti layer which has a flat shape as a metal substrate of the comparative example 4 with respect to Examples 2b-7b was prepared. At this time, the thickness of the metal substrate of Comparative Example 4 and the thickness t1 (see FIG. 3) of the metal substrate 2 of Examples 2b to 7b were made the same. Moreover, the area of the XY plane orthogonal to the thickness direction of the metal substrate of Comparative Example 4 and the area of the XY plane (see FIG. 2) orthogonal to the thickness direction of the metal substrate 2 of Examples 2b to 7b. To be identical. That is, as the metal substrate of Comparative Example 4, a metal substrate different from the metal substrate 2 of Examples 2b to 7b only in that only the Ti layer was produced was produced.

  And the dye-sensitized solar cell corresponding to Examples 2b-7b and the comparative example 4 was each produced using the manufacturing process similar to the manufacturing process of the dye-sensitized solar cell 100 in the said 1st Embodiment. Thereafter, the power generation efficiency of the dye-sensitized solar cells 100 of Examples 2b to 7b when the power generation efficiency of the dye-sensitized solar cell of Comparative Example 4 was set to 100% under the same conditions was measured.

  From the results of Examples 2b to 7b and Comparative Example 4 shown in FIG. 12, by forming the Cu layer 22 on the metal substrate 2, the metal substrate is composed only of the Ti layer (Comparative Example 4, power generation efficiency: 100). %) Was found to increase the power generation efficiency of the dye-sensitized solar cell (Examples 2b to 7b, power generation efficiency: 110% to 115%). This is because the metal substrate 2 including the Cu layer (Examples 2b to 7b) has a volume resistivity Ryz in the X direction and a volume resistivity Rxy in the Z direction as compared with the metal substrate composed only of the Ti layer (Comparative Example 4). This is because an increase in electrical loss in the metal substrate is suppressed. Therefore, it is considered that the dye-sensitized solar cell 100 corresponding to Examples 2b to 7b has higher power generation efficiency than the dye-sensitized solar cell corresponding to Comparative Example 4.

  From the results of Examples 5b to 7b, when the thickness t2 of the Cu layer 22 is 50% or more of the thickness t1 of the metal substrate 2, the power generation efficiency of the dye-sensitized solar cell 100 does not substantially change (115 %) That is, it has been found that the thickness t2 of the Cu layer 22 is preferably 50% or more of the thickness t1 of the metal substrate 2. From the graph of volume resistivity simulation shown in FIG. 7, the change in the composite volume resistivity Ryz in the X direction is very small in the region where the ratio of the thickness t2 of the Cu layer 22 is 50% or more. This is probably because the electrical resistance value when the current flows in the X direction does not change much.

  Further, from the results of Examples 2b to 7b, when the thickness t2 of the Cu layer 22 is 30% or more of the thickness t1 of the metal substrate 2 (Examples 3b to 7b, power generation efficiency: 113% to 115%), Cu Compared with the case where the thickness t2 of the layer 22 is 20% of the thickness t1 of the metal substrate 2 (Example 2b, power generation efficiency: 110%), the power generation efficiency of the dye-sensitized solar cell 100 can be further increased. It could be confirmed. Furthermore, when the thickness t2 of the Cu layer 22 is 50% or more of the thickness t1 of the metal substrate 2 (Examples 5b to 7b, power generation efficiency: 115%), the power generation efficiency of the dye-sensitized solar cell 100 is further increased. It was confirmed that it was possible.

(Measurement of power generation efficiency when the surface roughness of the metal substrate is varied)
In the measurement of power generation efficiency when the surface roughness of the metal substrate described below is varied, three metal substrates 2 of Example 4b corresponding to the metal substrate 2 of the first embodiment were prepared. That is, the thickness t2 (see FIG. 3) of the Cu layer 22 is 40% of the thickness t1 (see FIG. 3) of the metal substrate 2, and the thickness t3 (see FIG. 3) of the Ti layer 21 and the thickness of the stainless steel layer 23. A metal substrate 2 in which t4 (see FIG. 3) is 30% of the thickness t1 of the metal substrate 2 was prepared.

  Then, by performing shot blasting on the upper surface 2a of the Ti layer 21 of the two metal substrates 2 of the three metal substrates 2 of the example 4b, the upper surface 2a of the metal substrate 2 of the example 4b is more than the upper surface 2a. A metal substrate 2 of Example 4c and a metal substrate 2 of Example 4d having an upper surface 2a having a large surface roughness were produced. At this time, the surface roughness of the upper surface 2a of the metal substrate 2 of Example 4d was prepared to be larger than the surface roughness of the upper surface 2a of the metal substrate 2 of Example 4c.

Then, the surface roughness of each upper surface 2a of the metal substrate 2 of Example 4b, the metal substrate 2 of Example 4c, and the metal substrate 2 of Example 4d was measured. Specifically, the arithmetic average roughness Ra and the ten-point average roughness Rzjis of the upper surface 2a are measured using a contact-type surface roughness measuring instrument (surfcom 480A, manufactured by Tokyo Seimitsu Co., Ltd.). Measurement was performed using a laser microscope (VK-9700, manufactured by Keyence Corporation). As the measurement conditions of the surface area, measurement was performed in a surface shape measurement mode using a 50 × objective lens, and measurement was performed so as to obtain an ultra-high-definition measurement quality. The surface area / plane area was determined by dividing the surface area of the metal substrate 2 in a square area of any 240 μm square by the plane area (240 × 240 μm ² ) of the square area.

  Then, a platinum catalyst layer 13 of a platinum thin film was formed on the upper surface 2a of each of the metal substrate 2 of Example 4b, the metal substrate 2 of Example 4c, and the metal substrate 2 of Example 4d by sputtering. Thereafter, dye-sensitized solar cells corresponding to Examples 4b, 4c, and 4d were produced using the same production process as that of the dye-sensitized solar cell 100 in the first embodiment. Thereafter, under the same conditions, the power generation efficiencies of the dye-sensitized solar cells 100 of Example 4c and 4d were measured when the power generation efficiency of the dye-sensitized solar cell of Example 4b was set to 100%.

  The experimental results of Examples 4b, 4c and 4d are shown in FIG. In addition, the triangle mark in the power generation efficiency indicates that the power generation efficiency is 100% or more and less than 105%, which means that the power generation efficiency is not improved so much. A circle indicates that the power generation efficiency was 105% or more, which means that the power generation efficiency was sufficiently improved.

  From the experimental results of Examples 4b, 4c and 4d, by increasing the surface roughness (arithmetic mean roughness Ra, ten-point mean roughness Rzjis and surface area / planar area) of the upper surface 2a of the Ti layer 21 of the metal substrate 2 It was found that power generation efficiency can be improved.

  In addition, from the results of Examples 4c and 4d, when the arithmetic average roughness Ra of the upper surface 2a is 0.10 μm or more, the ten-point average roughness Rzjis is 0.50 μm or more, or the surface area / plane area is It has been found that when any one of 1.03 or more is satisfied, improvement in power generation efficiency can be expected. In particular, when the arithmetic average roughness Ra of the upper surface 2a is 0.22 μm or more, when the ten-point average roughness Rzjis is 1.20 μm or more, and when the surface area / planar area is 1.05 or more. It was found that the power generation efficiency was sufficiently improved. This is because the surface roughness of the upper surface 2a of the Ti layer 21 of the metal substrate 2 is increased, so that the amount of platinum in the platinum catalyst layer 13 attached to the upper surface 2a of the Ti layer 21 is increased. This is considered to be because the transfer of electrons via platinum has been performed more and more.

  The embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments and examples but by the scope of claims for patent, and includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the first and second embodiments, the example in which the “first metal layer” of the present invention is composed of the non-porous Ti layer 21 (221) is shown, but the present invention is not limited to this. Absent. For example, you may comprise so that the "1st metal layer" of this invention may be formed with Ti alloy which is non-porous and has corrosion resistance with respect to an iodine electrolyte.

  In the first and second embodiments, the “second metal layer” of the present invention is configured by the Cu layer 22 (222) formed of Cu. However, the present invention is not limited to this. . For example, you may comprise so that the "2nd metal layer" of this invention may be formed with either one of Cu alloy with low electrical resistance, Al, or Al alloy.

  In the first embodiment, the “third metal layer” of the present invention is configured from the stainless steel layer 23 of SUS430. However, the present invention is not limited to this. For example, you may comprise so that the "3rd metal layer" of this invention may be formed with ferritic stainless steels other than SUS430. Further, for example, the “third metal layer” of the present invention may be formed of any one of Fe, Ti, or Ti alloy other than ferritic stainless steel. At this time, the third metal layer can be formed on the metal substrate at low cost by making the third metal layer inexpensive Fe. Further, the corrosion resistance of the metal substrate can be further improved by making the third metal layer Ti or Ti alloy having high corrosion resistance.

  Moreover, in the said 1st Embodiment, although the metal substrate 2 showed the example comprised by the clad material with which Ti layer 21, Cu layer 22, and stainless steel layer 23 were joined, this invention is not limited to this. . For example, the metal substrate may include another metal layer on the surface opposite to the Cu layer 22 in contact with the stainless steel layer 23, or another metal layer between the Cu layer 22 and the stainless steel layer 23. May be provided.

  In the first embodiment, an example is shown in which the thickness t3 of the Ti layer 21 and the thickness t4 of the stainless steel layer 23 are substantially the same, but the present invention is not limited to this. In the present invention, the thickness t3 of the Ti layer may be different from the thickness t4 of the stainless steel layer. At this time, since Ti is generally more expensive than SUS430 (ferritic stainless steel), it is preferable to make the thickness t3 of the Ti layer smaller than the thickness t4 of the stainless steel layer.

  In the first embodiment, the arithmetic average roughness Ra of the upper surface 2a of the Ti layer 21 is about 0.22 μm, the ten-point average roughness Rzjis is about 1.20 μm, and the surface area / plane area is about 1 .05 is shown, but the present invention is not limited to this. In the present invention, the arithmetic average roughness Ra of the upper surface 2a of the Ti layer 21 may be larger than about 0.22 μm, the ten-point average roughness Rzjis may be larger than about 1.20 μm, The surface area / plane area may be greater than about 1.05.

  In the first embodiment, the arithmetic average roughness Ra, the ten-point average roughness Rzjis, and the surface area / planar area on the upper surface 2a of the Ti layer 21 are about 0.10 μm or more, about 0.50 μm or more, and However, the present invention is not limited to this. For example, the arithmetic average roughness Ra may be about 0.10 μm or more, while the ten-point average roughness Rzjis and the surface area / plane area may be less than about 0.50 μm and less than about 1.03, respectively. It is preferable that at least the surface area / planar area is about 1.03 or more.

1 Solar cell element (Dye-sensitized solar cell element)
2,202 Metal substrate (cladding material, metal substrate for dye-sensitized solar cell)
2a Top surface (substrate surface)
13 Platinum catalyst layer (catalyst layer)
14 Iodine electrolyte (electrolyte)
21, 221 Ti layer (first metal layer)
22, 222 Cu layer (second metal layer)
23 Stainless steel layer (third metal layer)

Claims (13)

A non-porous first metal layer disposed on the positive electrode side of the dye-sensitized solar cell element and formed of a metal having corrosion resistance to the electrolyte of the dye-sensitized solar cell element;
A second metal layer formed of a metal having an electric resistance lower than that of the first metal layer and bonded to the opposite side of the dye-sensitized solar cell element of the first metal layer; ,
A clad material comprising a third metal layer in contact with the second metal layer and bonded to the opposite side of the first metal layer ;
Unevenness is formed on the substrate surface of the first metal layer on the dye-sensitized solar cell element side ,
The thickness of the second metal layer, the Ru der 50% or more of the clad material thickness, metal substrate for dye-sensitized solar cell.   2. The metal substrate for a dye-sensitized solar cell according to claim 1, wherein a surface area / planar area of the first metal layer on the surface of the substrate on the dye-sensitized solar cell element side is 1.03 or more.   3. The dye-sensitized solar cell metal substrate according to claim 2, wherein a surface area / planar area of the first metal layer on the surface of the substrate on the dye-sensitized solar cell element side is 1.05 or more.   4. The dye sensitization according to claim 1, wherein the ten-point average roughness Rzjis is 0.50 μm or more on the substrate surface of the first metal layer on the dye-sensitized solar cell element side. Metal substrate for sensitive solar cells.   5. The metal substrate for dye-sensitized solar cell according to claim 4, wherein a ten-point average roughness Rzjis is 1.20 μm or more on the substrate surface of the first metal layer on the dye-sensitized solar cell element side. .   The dye-sensitized dye according to any one of claims 1 to 5, wherein the arithmetic average roughness Ra is 0.10 µm or more on the substrate surface of the first metal layer on the dye-sensitized solar cell element side. Type metal substrate for solar cell.   The metal substrate for dye-sensitized solar cells according to claim 6, wherein an arithmetic average roughness Ra is 0.22 µm or more on the surface of the substrate on the dye-sensitized solar cell element side of the first metal layer.   The dye-sensitized solar cell according to any one of claims 1 to 7, wherein a catalyst layer is formed on the substrate surface of the first metal layer on the dye-sensitized solar cell element side. Metal substrate. The clad material including the first metal layer , the second metal layer, and the third metal layer constitutes a positive electrode of the dye-sensitized solar cell element according to any one of claims 1 to 8. The metal substrate for dye-sensitized solar cells as described. The first metal layer is formed of Ti or a Ti alloy,
The metal substrate for a dye-sensitized solar cell according to any one of claims 1 to 9, wherein the second metal layer is formed of any one of Cu, Cu alloy, Al, or Al alloy. The difference between the thermal expansion coefficient between the thermal expansion coefficient of the previous SL third metal layer the first metal layer is smaller than the difference between the thermal expansion coefficient of the first metal layer of the second metal layer The metal substrate for dye-sensitized solar cells according to any one of claims 1 to 10. The metal substrate for a dye-sensitized solar cell according to any one of claims 1 to 11, wherein the third metal layer is formed of a metal having higher corrosion resistance than a metal constituting the second metal layer. . The first metal layer is formed of Ti or a Ti alloy,
The second metal layer is formed of any one of Cu, Cu alloy, Al or Al alloy,
The metal substrate for a dye-sensitized solar cell according to claim 10 , wherein the third metal layer is formed of any one of Fe, ferritic stainless steel, Ti, or a Ti alloy.

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