JP2011044434A - Dye-sensitized solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye-sensitized solar cell of low cost yet having high photoelectric conversion efficiency, and its manufacturing method. <P>SOLUTION: An anode electrode layer sandwiching at least a part of a solar cell functional layer comprising a dye-supporting semiconductor layer and an electrolyte layer with a cathode electrode layer has a plurality of openings, and is embedded in the dye-supporting semiconductor layer separated from an anode substrate, with a width of each opening of 10 μm or less. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a dye-sensitized solar cell that converts light energy into electrical energy using a dye.

  It is said that the solar energy that falls on the entire earth is 100,000 times consumed by the whole world. The research and development of a device for converting sunlight, which is an energy resource, into electrical energy that is easy for human beings to use has a history of about 50 years. Renewable energy typified by solar cells is said to be an ideal energy resource with little environmental impact, but so far its use has not progressed much. The most problematic reason for this is high power generation costs. In order to suppress power generation costs, it is necessary to obtain a high level of photoelectric exchange efficiency of solar cells and to reduce the cost of materials and manufacturing methods. Dye-sensitized solar cells are attracting attention as a solution to such problems.

  In order to obtain a high degree of photoelectric exchange efficiency, a structure in which an absorption wavelength region is widened by stacking two or more dye-supporting semiconductor layers in a dye-sensitized solar cell has been conventionally known. Moreover, in order to laminate | stack two or more pigment | dye carrying | support semiconductor layers, it is necessary to thicken electrodes, such as a titanium oxide (TiO2) which is a pigment | dye carrying | support semiconductor layer.

  However, the thickness of the dye-carrying semiconductor layer is limited by the electron diffusion length and is about 10 μm. For this reason, even if the film thickness is simply increased, it is difficult to improve the photoelectric exchange efficiency due to energy loss due to internal resistance.

  As a method for solving such a problem, Patent Document 1 discloses a structure of a dye-sensitized solar cell in which a conductive protrusion is provided on a transparent conductive film.

JP 2000-77691 A

  In the dye-sensitized solar cell described in Patent Document 1, a solar cell functional layer composed of a dye-supporting semiconductor layer and an electrolyte layer is sandwiched between transparent conductive films formed on two transparent substrates. Conductive protrusions extending from the transparent conductive film in contact with the supported semiconductor layer toward the dye-supported semiconductor layer are provided. With this configuration, even when the electrode area of titanium oxide or the like that is the dye-carrying semiconductor layer is expanded, high photoelectric exchange efficiency can be obtained.

  However, the dye-sensitized solar cell disclosed in Patent Document 1 has a problem of an increase in manufacturing steps and an increase in cost because a protrusion is formed on the transparent conductive film.

  Moreover, in the manufacturing cost of a dye-sensitized solar cell, the ratio which a transparent conductive film occupies with respect to the whole cost is high, and as long as a transparent conductive film is used, there also exists a problem that drastic cost reduction is difficult.

  The present invention has been made in view of the circumstances as described above, and an object thereof is to provide a low-cost dye-sensitized solar cell and a method for manufacturing the same while having high photoelectric exchange efficiency.

  In order to solve the above-described problem, a solar cell functional layer including a dye-carrying semiconductor layer and an electrolyte solution layer in contact with the dye-carrying semiconductor layer is opposed to each other at an interval and at least of the solar cell functional layer A dye-sensitized type comprising: an anode electrode layer and a cathode electrode layer that are in contact with each other with a part interposed therebetween; an anode substrate that supports the dye-carrying semiconductor layer; and a cathode substrate that supports the cathode electrode layer It is a solar cell, wherein the anode electrode layer has a plurality of openings and is embedded in the dye-carrying semiconductor layer at a distance from the anode substrate, and the width of the opening is 10 μm or less. A sensitized solar cell is provided.

  In addition, the distance between the anode electrode layer and the electrolytic solution layer may be less than or equal to the electron diffusion length of the dye-carrying semiconductor layer.

  Moreover, you may further have a protective film layer which covers the said anode electrode layer. Further, the openings may be uniformly distributed. Furthermore, the anode electrode layer may be in contact with the electrolytic solution layer.

  In the dye-sensitized solar cell of the present invention, the anode electrode layer sandwiching at least a part of the solar cell functional layer composed of the dye-carrying semiconductor layer and the electrolyte solution layer with the cathode electrode layer has a plurality of openings, and the anode By being embedded in the dye-carrying semiconductor layer away from the substrate, a low-cost dye-sensitized solar cell can be provided while having high photoelectric exchange efficiency.

It is sectional drawing of the dye-sensitized solar cell as 1st Example of this invention. It is an XY plan view of the anode electrode substrate of the dye-sensitized solar cell as the first embodiment of the present invention. It is sectional drawing for every manufacturing process of a dye-sensitized solar cell as 1st Example of this invention. It is sectional drawing for every manufacturing process of a dye-sensitized solar cell as 1st Example of this invention. It is sectional drawing of the dye-sensitized solar cell as 2nd Example of this invention. It is sectional drawing for every manufacturing process of a dye-sensitized solar cell as 2nd Example of this invention.

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

  A dye-sensitized solar cell 10 according to an embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, in a dye-sensitized solar cell 10, a dye-supported titanium oxide layer 12 on which a dye is adsorbed is formed on a transparent glass substrate 11 that is an anode substrate. An anode electrode layer 15 composed of a metal thin film 13 and a titanium nitride (TiN) film 14 that functions as an adhesion layer of the metal thin film 13 is embedded in the dye-supported titanium oxide layer 12 at a distance from the glass substrate 11. ing. The glass substrate 11, the dye-supported titanium oxide layer 12 and the anode electrode layer 15 constitute an anode electrode substrate 16. The anode electrode layer 15 may be covered with a protective film (not shown) such as a titanium film for preventing oxidation.

  A transparent glass substrate 17 that is a cathode substrate is disposed on the glass substrate 11, and a fluorine-doped tin oxide film 18 (hereinafter referred to as “the surface opposite to the dye-supported titanium oxide layer 12)” is formed on the surface of the glass substrate 17. , Referred to as an FTO film 18), and a Pt film 19 is formed on the FTO film 18. A cathode electrode layer 20 is constituted by the FTO film 18 and the Pt film 19. Further, the glass substrate 17 and the cathode electrode layer 20 constitute a cathode electrode substrate 21.

  An electrolyte layer 22 is formed between the anode electrode substrate 16 and the cathode electrode substrate 21. The anode electrode substrate 16 and the cathode electrode substrate 20 are bonded to each other with an adhesive 23. Side surfaces of the anode electrode substrate 16, the cathode electrode substrate 21, and the adhesive 23 are covered with a sealing resin layer 24. The dye-supported titanium oxide layer 12 and the electrolyte layer 22 constitute a solar cell functional layer.

  Further, it is desirable that the distance from the anode electrode layer 15 to the electrolytic solution layer 22 is equal to or shorter than the electron diffusion length in the dye-supported titanium oxide layer 12. For example, the distance may be about 10 μm or less.

  Next, the shape of the anode electrode layer 15 in the XY plane will be described with reference to FIG.

  A portion indicated by a broken line in FIG. 2 is the anode electrode layer 15, and the anode electrode layer 15 includes hole-shaped openings 25 arranged uniformly along the X direction and notch-shaped openings positioned at both ends in the X direction. 26 is provided. The anode electrode layer 15 has a mesh shape by the openings 25. Here, the width of the opening 25 may be equal to or less than the electron diffusion length in the dye-supported titanium oxide layer 12, and for example, the width may be approximately 10 μm or less.

  In addition, lead electrodes 27 are formed at both ends of the anode electrode layer 15 in the X-axis direction by the openings 26. Since the side surface in the X-axis direction is exposed, the extraction electrode portion 27 functions as a connection portion for electrically connecting the anode electrode layer 15 to the outside of the dye-sensitized solar cell 10. For example, the adhesive 23 and the sealing resin layer 24 are not formed on the side surface of the lead electrode portion 27, and an electrical contact portion (not shown) is formed in a portion where the adhesive 23 and the sealing resin layer 24 are not formed. Alternatively, the dye-sensitized solar cell 10 may be electrically connected from the outside. Even when the adhesive 23 and the sealing resin layer 24 are formed, a pinhole or the like may be formed to form an electrical contact portion (not shown) to the lead electrode portion 27 from the outside. good.

  The number of openings 25 and 26 is not limited to the number shown in FIG. 2 and may be appropriately changed according to the photoelectric exchange efficiency of the dye-sensitized solar cell 10 and the wiring shape of the extraction electrode. To do. Alternatively, all the openings 25 may be changed to notch-shaped openings, and the shape of the anode electrode layer 15 in the XY plane may be comb-like, lattice-like, or honeycomb-like.

  Next, a method for manufacturing the dye-sensitized solar cell 10 as an embodiment of the present invention will be described in detail with reference to FIGS.

  First, a titanium oxide paste is applied on the glass substrate 11 by a screen printing method to form a titanium oxide layer 31 (FIG. 3A). For example, the thickness of the titanium oxide layer 31 was calculated in advance by calculating the coating amount so that the thickness after firing was about 10 μm (that is, not more than the electron diffusion length in the dye-supported titanium oxide layer 12). Apply a coating amount. This step is referred to as an oxide semiconductor layer forming step.

  Next, a titanium nitride layer is formed to a thickness of about 100 nm on the titanium oxide layer 31 (FIG. 3B). For example, as a method for forming titanium nitride, there is a method such as sputtering or CVD. A predetermined metal is deposited to a thickness of about 800 nm on the titanium nitride layer 32 to form a metal thin film 33 (FIG. 3C). The film forming method may be sputtering or CVD like titanium nitride. Further, it is desirable to use a metal such as tungsten, iridium, titanium or nickel as the predetermined metal. This process is referred to as an electrode film forming process.

  Next, a resist pattern is formed by transferring a desired wiring pattern using a lithography technique, and an anode electrode layer 15 which is a desired metal wiring is formed by dry or wet etching (FIGS. 3 (d1) and 3 (d2)). . For example, the desired wiring may have a mesh shape by forming a plurality of parallel openings 25. Further, the extraction electrode portion 27 may be formed by forming a plurality of openings 26. This process is referred to as a wiring formation process. Thereafter, a protective film (not shown) for preventing oxidation may be further formed on the anode electrode layer 15 as necessary. For example, the protective film may be a titanium film of about 10 nm.

  Next, an additional titanium oxide paste is further applied on the titanium oxide layer 31 and the anode electrode layer 15 by screen printing to form an additional titanium oxide layer 34 (FIG. 3E). By this step, the anode electrode layer 15 is sandwiched between the titanium oxide layer 31 and the additional titanium oxide layer 34. (That is, the anode electrode layer 15 is embedded away from the glass substrate 11.) Here, the amount of additional titanium oxide applied is the same as that of the titanium oxide layer 31 after the firing. You may apply so that the thickness of 34 may be set to about 10 micrometers (namely, below the electron diffusion length in the pigment | dye carrying | support titanium oxide layer 12). This step is referred to as an additional oxide semiconductor layer forming step.

  Next, the glass substrate 11 after the formation of the additional titanium oxide layer 34 is annealed at about 500 ° C. for about 90 minutes in the air atmosphere, so that the titanium oxide layer 32 and the additional titanium oxide layer 34 have a thickness of about The porous porous titanium oxide layer 35 having a thickness of 20 μm is changed (FIG. 3F). After annealing, the porous titanium oxide layer 35 is dipped for about 20 hours in a solution obtained by dissolving an N-719 dye, which is a Ru-based sensitizing dye, in a mixed solution of acetonitrile and t-butyl alcohol. By such dipping, the porous titanium oxide layer 35 can be changed to the dye-supported titanium oxide layer 12 (FIG. 3G). The anode electrode substrate 16 is formed by the above process. The above process is referred to as an anode electrode substrate forming process.

  Next, an FTO film 18 is formed on the upper surface of the glass substrate 17 (FIG. 4H). Thereafter, Pt is sputtered on the FTO film 18 to form a Pt layer 19 of about 100 mm (FIG. 4I). The cathode electrode substrate 21 is formed by the above steps. The above process is referred to as a cathode electrode substrate forming process.

  Next, the anode electrode substrate 16 and the cathode electrode substrate 21 are bonded together by thermocompression bonding using an adhesive 23 such as a high Milan film (FIG. 4 (j)). In addition, this process is called a connection process, and in the connection process, the anode electrode layer 15 and the cathode electrode layer 20 are bonded to each other with a predetermined interval.

  After the anode electrode substrate 16 and the cathode electrode substrate 21 are bonded to each other, sealing is performed with a UV curable sealing resin so as to surround the anode electrode substrate 16, the cathode electrode substrate 21, and the adhesive 23. 24 is formed (FIG. 4K). This process is called a sealing process.

  After sealing, for example, a pinhole is formed in the cathode electrode substrate 21, and an electrolytic solution is injected from the pinhole by a vacuum injection method. After injection of the electrolytic solution, the pinhole is again sealed with an epoxy resin to form the electrolytic solution layer 21 (FIG. 4L). For example, the electrolytic solution is iodine, lithium iodide, acetonitrile, and tributyl phosphate. (TBP) may be mixed.This process is called an electrolytic injection process.

  In the connection step and the sealing step, the metal contact is not formed on the portion where the extraction electrode portion 27 of the anode electrode layer 15 is exposed, but after the electrolytic injection step without forming the adhesive 23 and the sealing resin layer 24. The anode electrode layer 15 may be connected to the outside of the dye-sensitized solar cell 10.

  As described above, according to the dye-sensitized solar cell of this example, the anode electrode can be used even when the transparent electrode film which is expensive is not provided and the dye-supported titanium oxide layer 12 is thickened. By embedding the layer 15 in the dye-supported titanium oxide layer 12, the distance from the electrolyte layer 21 can be made shorter than the electron diffusion length in the dye-supported titanium oxide layer 12, so that a high degree of photoelectric exchange efficiency can be achieved. In addition, a low-cost dye-sensitized solar cell can be provided.

  In the dye-sensitized solar cell in the first embodiment, the anode electrode layer may be formed so as to be in contact with the electrolyte layer. The dye-sensitized solar cell 40 and the manufacturing method thereof will be described in detail with reference to FIGS. In addition, about the part similar to Example 1, the description is abbreviate | omitted using the same code | symbol.

  As shown in FIG. 5, inside the dye-supported titanium oxide layer 12, an anode electrode layer 43 composed of a metal thin film 41 and a titanium nitride (TiN) film 42 functioning as an adhesion layer of the metal thin film 41, It is separated from the glass substrate 11 and embedded in contact with the electrolyte layer 22. The anode electrode layer 43 may be covered with a protective film (not shown) such as a titanium film for preventing oxidation.

Unlike the first embodiment, the anode electrode layer 43 of the dye-sensitized solar cell 40 in this embodiment is in contact with the electrolyte solution layer 22. With this configuration, electrons excited by the electrolyte layer 22 can easily reach the anode electrode, so that high photoelectric exchange efficiency can be obtained. Further, even when the dye-supported titanium oxide layer 12 is made thick, the anode electrode is always formed at a position in contact with the electrolytic solution layer 22, so that the rate is determined by the electron diffusion length in the dye-supported titanium oxide layer 12. Therefore, the dye-supported titanium oxide layer 12 can be laminated.
Note that the shape of the anode electrode layer 43 in the XY plane is the same as that of the first embodiment, and thus the description thereof is omitted.

  Next, the manufacturing method of the dye-sensitized solar cell 40 as an embodiment of the present invention will be described in detail with reference to FIG.

  First, a titanium oxide paste is applied on the glass substrate 11 by a screen printing method to form a titanium oxide layer 51 (FIG. 6A). For example, the thickness of the titanium oxide layer 51 is calculated in advance so that the thickness is about 20 μm after firing, and the calculated coating amount is applied. This step is referred to as an oxide semiconductor layer forming step.

  Thereafter, the surface of the titanium oxide layer 51 is pressed by a nanoimprint technique using a mold having a predetermined wiring width and wiring pattern, and a plurality of grooves 52 are formed in the titanium oxide layer 51. (FIG. 6 (b-1), (b-2)). This process is referred to as a groove forming process. In addition, it is desirable to perform baking in the range of 100 degreeC to 200 degree | times during this process, and to volatilize the solvent etc. which are contained in a titanium oxide paste.

  Thereafter, the glass substrate 11 after forming the groove 52 having the desired wiring pattern in the titanium oxide layer 51 is annealed in the atmosphere at about 500 ° C. for about 90 minutes, so that the thickness of the titanium oxide layer 51 is increased. The porous porous titanium oxide layer 53 having a thickness of about 20 μm is changed (FIG. 6C).

  Next, titanium nitride is deposited to a thickness of 10 to 100 nm on the groove 52 to form a titanium nitride layer 42 (FIG. 6D). For example, as a method for forming titanium nitride, there is a method such as sputtering or CVD. A predetermined metal is deposited to a thickness of 50 to 500 nm on the titanium nitride layer 32 to form a metal thin film 41 (FIG. 6E). The film forming method may be sputtering or CVD like titanium nitride. Further, it is desirable to use a metal such as tungsten, iridium, titanium or nickel as the predetermined metal. This process is referred to as an electrode film forming process. The thickness of the metal thin film 41 can be arbitrarily determined according to the thickness of the porous titanium oxide layer 53. For example, when the porous titanium oxide layer 53 is designed to have a thickness of about 20 μm and the diffusion length of the electrons after supporting the dye in the porous titanium oxide layer 53 is about 10 μm, the thickness of the metal thin film 41 is designed. Is preferably about 10 μm.

  After annealing, the porous titanium oxide layer 53 is dipped for about 20 hours in a solution in which N719 dye, which is a Ru-based sensitizing dye, is dissolved in a mixed solution of acetonitrile and t-butyl alcohol. By such dipping, the porous titanium oxide layer 53 can be changed to the dye-supported titanium oxide layer 12 (FIG. 6F). The anode electrode substrate 16 is formed by the above process. The above process is referred to as an anode electrode substrate forming process.

Thereafter, the cathode electrode substrate 21 is formed, adhered, sealed, and injected with an electrolytic solution in the same manner as in the first embodiment. Since this process is the same as that of the first embodiment, its description is omitted.
In addition, the formation method of the groove | channel 51 is not restricted to nanoprint technology. For example, the groove 51 may be formed by a combination of photolithography or EB lithography and a dry or wet etching technique.

  As described above, according to the dye-sensitized solar cell of this example, the anode electrode can be used even when the transparent electrode film which is expensive is not provided and the dye-supported titanium oxide layer 12 is thickened. Since the layer 15 is formed at a position in contact with the electrolytic solution layer 21, it is possible to provide a low-cost dye-sensitized solar cell having high photoelectric exchange efficiency.

  In addition, the dye-sensitized solar cell according to this example can have a higher aperture ratio (that is, light transmittance) than the first example.

DESCRIPTION OF SYMBOLS 10 Dye-sensitized solar cell 11 Glass substrate 12 Dye carrying | support titanium oxide layer 13 Metal thin film 14 Titanium nitride (TiN) film | membrane 15 Anode electrode layer 17 Glass substrate 18 Fluorine dope tin oxide film (FTO film | membrane)
19 Pt film 20 Cathode electrode layer 22 Electrolyte layer 23 Adhesive 24 Sealing resin layer

Claims (5)

A solar cell functional layer comprising a dye-carrying semiconductor layer and an electrolyte layer in contact with the dye-carrying semiconductor layer;
An anode electrode layer and a cathode electrode layer that face each other and are in contact with each other with at least one portion of the solar cell functional layer interposed therebetween;
A dye-sensitized solar cell comprising: an anode substrate supporting the dye-carrying semiconductor layer; and a cathode substrate supporting the cathode electrode layer,
The anode electrode layer has a plurality of openings and is embedded in the dye-carrying semiconductor layer apart from the anode substrate;
A dye-sensitized solar cell, wherein the opening has a width of 10 μm or less.   2. The dye-sensitized solar cell according to claim 1, wherein a distance between the anode electrode layer and the electrolytic solution layer is equal to or shorter than an electron diffusion length of the dye-carrying semiconductor layer.   The dye-sensitized solar cell according to claim 1 or 2, wherein the openings are uniformly distributed.   The dye-sensitized solar cell according to any one of claims 1 to 3, further comprising a protective film layer covering the anode electrode layer. The dye-sensitized solar cell according to any one of claims 1 to 4, wherein the anode electrode layer is in contact with the electrolytic solution layer.

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