JP2008257948A - Electrode material and conductive film using this material, and solar cell, and photoelectrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode material or the like which is a conductive film in the case of using for a transparent electrode of a dye-sensitized solar cell, and does not easily corrodes or melts even if contacted to an electrolytic solution. <P>SOLUTION: The conductive film has a conductive film composed of a single or a plurality of conductive substances laminated one or two layers or more on a surface of a base material film consisting of a polymer resin. At least one of the conductive film formed of a conductive substance as an electrode material used as the conductive film has a conductivity as a nature to flow electricity and is a substance having an iodine resistance in which 80% or more in volume ratio of the conductive film remains without melting even if 96 hours has passed in an immersed state in an iodine solution of 80°C (a solution in which iodine, lithium iodite, tetrabutyl-ammonium iodite(TBAI), tributyl phosphate (TBP) are dissolved in acetonitrile solution). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an electrode material, for example, a material for an electrode in a conductive film of a transparent conductive film used for a transparent electrode of a dye-sensitized solar cell, and a sun using an electrode formed using the conductive film. The present invention relates to a battery and a photoelectrode.

  In recent years when interest in global warming is rapidly spreading, attention has been focused on solar power generation as a means of obtaining clean electricity necessary for daily life. This solar power generation uses a solar cell. However, since this solar cell operates only with sunlight, it does not require fuel, and there is a strong demand for the development and commercialization of a more excellent inexhaustible clean energy. ing.

  Conventionally, a transparent conductive glass is used in a solar cell used for solar power generation. Since this transparent conductive glass has the property of transmitting sunlight and passing electricity, it is used as a transparent electrode of a solar cell by utilizing this property.

  As research and development of this solar cell progresses, there is a strong market desire to make it easier to handle, thinner and lighter for further dissemination. Transparent resin that can be said to be much easier to handle because it is not easily broken from glass, which requires careful attention to handling because it easily breaks even with a slight impact A film replaced with a so-called transparent conductive film is increasingly used.

  Briefly describing this solar cell, the types of solar cells are currently classified mainly into silicon-based, compound semiconductor-based, organic semiconductor-based, dye-sensitized types, etc., depending on the semiconductor material used. Among these, silicon systems have been developed for a relatively long time and are still mainstream, but there are problems that there is a limit to improving conversion efficiency and there is a concern about resource depletion. Moreover, although the compound semiconductor solar cell can be expected to have high conversion efficiency, there is a problem that the material cost is high. Although organic semiconductor solar cells have been regarded as promising as low-cost materials at the beginning of development, there is no prospect of improving conversion efficiency, and development is stagnant.

  Under such circumstances, attention has recently been focused on the development of dye-sensitized solar cells. This is because the dye-sensitized solar cell has a simpler device structure than other types of solar cells and can be manufactured without special manufacturing equipment. It was because it was highly expected to be easily increased, and in fact it attracted much attention than the fact that high conversion efficiency was obtained even in a small area, comparable to amorphous silicon solar cells already in practical use. It has become.

  The basic structure and operating principle of this dye-sensitized solar cell are as follows. First, as a negative electrode, a titania particle is applied in a paste form on a substrate provided with a transparent conductive film and sintered to form a titania layer. The titania layer has a large number of pores. When a ruthenium bipyridyl complex is supported on the inner surface of the pores, the dye is supported on the titania surface. On the other hand, as the positive electrode, for example, a material obtained by sputtering platinum on a transparent conductive film on a substrate is used. An electrolytic solution is filled between both electrodes, and an acetonitrile-based solvent is used as the electrolytic solution, and iodine and iodine ions are dissolved as solutes therein.

  The dye-sensitized solar cell having such a configuration operates as follows. That is, when the negative electrode is irradiated with light, the dye supported on the titania layer absorbs light and emits electrons to generate electricity. Next, the emitted electrons travel along the negative electrode through the titania layer, eventually reach the positive electrode as a counter electrode, and are discharged from there into the electrolytic solution. The emitted electrons reduce triiodide ions to form iodide ions, and the reduced iodide ions are oxidized again on the dye. By repeating this process, electricity flows.

  However, in general dye-sensitized solar cells, since an electrolyte containing iodine as a main component is used as described above, a phenomenon in which iodine in the electrolyte easily corrodes the electrodes constituting the solar cell occurs frequently. As a result, the function of the electrode is easily weakened, which is a problem.

  Therefore, for example, an electrode as shown in Patent Document 1 has been proposed as an electrode used in a dye-sensitized solar cell that addresses such a problem.

JP 2006-066278 A

  The above-mentioned Patent Document 1 discloses an electrode for a dye-sensitized solar cell, and if necessary, a semiconductor between an auxiliary electrode and a transparent conductive film, such as a base material / auxiliary electrode / semiconductor film / transparent conductive film. An electrode having a configuration for sandwiching a film is disclosed. Here, for example, titanium oxide or niobium oxide is used as the semiconductor film. By providing such a film, the auxiliary electrode is corroded by iodine or the like in the electrolyte solution used in the dye-sensitized solar cell. It is said that it can be prevented.

  However, such a configuration requires that an unnecessary semiconductor film is originally provided, and that the semiconductor film also reliably protects the auxiliary electrode from the electrolyte that permeates the porous transparent conductive film. Must be stacked securely and with the required thickness, and the laminating process must be careful to ensure such reliability, and the semiconductor film must be secured for this purpose. This leads to problems such as the time and cost required for laminating the film.

  The present invention has been made in view of such problems, and an object thereof is, for example, a conductive film for use in a transparent electrode of a dye-sensitized solar cell, which can be easily contacted with an electrolytic solution. An electrode material that does not corrode or dissolve, and a solar cell or a photoelectrode using a conductive film on which the electrode material is laminated are provided.

  In order to solve the above-mentioned problem, the electrode material according to claim 1 of the present invention has one or two conductive thin films made of one or more conductive substances on the surface of a base film made of a polymer resin. An electrode material used as the conductive thin film in the conductive film laminated as described above, wherein at least one of the conductive thin films formed of the conductive substance as the electrode material has a property of conducting electricity. The conductive thin film having certain conductivity and an iodine solution at 80 ° C. (solution obtained by dissolving iodine, lithium iodide, tetrabutylammonium iodide (TBAI), tributyl phosphate (TBP) in an acetonitrile solution) It is characterized in that it is a substance having iodine resistance in which 80% or more by volume remains undissolved even after 96 hours have been immersed in

  The electrode material according to claim 2 of the present invention is the electrode material according to claim 1, wherein the conductive substance is nickel, titanium, chromium, niobium, platinum, iridium, stainless steel, tantalum, tungsten, or molybdenum. Or an alloy composed of any one or more of the above, or a plurality of alloys composed of any of the above.

  The electrode material according to claim 3 of the present invention is a nickel-titanium alloy in which, in the electrode material according to claim 1, the conductive substance is mixed with 5.0 wt% or more of titanium with respect to nickel. It is characterized by being.

  The conductive film according to claim 4 of the present invention is characterized by using the electrode material according to any one of claims 1 to 3.

  The solar cell according to claim 5 of the present invention is characterized by using the conductive film according to claim 4 as an electrode.

  A photoelectrode according to claim 6 of the present invention is characterized in that the conductive film according to claim 4 is used as an electrode.

  As described above, in the case of the electrode material of the conductive film according to the present invention, the electrode material in the first place has conductivity which is a property of conducting electricity, and an iodine solution (iodine, lithium iodide, iodine) at 80 ° C. 80% or more in volume ratio remains without being dissolved even after 96 hours in a state of being immersed in tetrabutylammonium bromide (TBAI) or tributyl phosphate (TBP) dissolved in acetonitrile solution) Since it is formed of a material having such properties, that is, having iodine resistance at the same time, even if it is used as an electrode of a dye-sensitized solar cell, iodine as a main component constituting an electrolyte solution as in the past It does not corrode even if it comes into contact with the electrode, that is, it acts as an electrode for a long time. In addition, since it is decided to use an electrode material having iodine resistance, there is no need to laminate any protective film to give iodine resistance to the conventional electrode, that is, the manufacturing process is not necessary. It can be said that it is simple, easy to obtain and economical without manufacturing costs.

Embodiments of the present invention will be described below. In addition, embodiment shown here is an example to the last, Comprising: It is not necessarily limited to this embodiment.
(Embodiment 1)
The electrode material of the conductive film according to the present invention will be described as a first embodiment.

  The electrode material for the conductive film according to the present embodiment is formed by laminating one or more conductive thin films made of one or more conductive substances on at least the surface of a base film made of a polymer resin. In the conductive film, an electrode material used as a conductive substance, wherein at least one of the conductive thin films formed of the conductive substance as the electrode material has a property of conducting electricity. And having the conductive material immersed in an iodine solution (iodine, lithium iodide, tetrabutylammonium iodide (TBAI), tributyl phosphate (TBP) dissolved in an acetonitrile solution) at 80 ° C. In this case, 80% or more of the volume ratio remains undissolved even after 96 hours.

  Hereinafter, it demonstrates sequentially, assuming the case where the electrode material which concerns on this Embodiment is used as a structural member of the transparent conductive film which comprises the transparent electrode of a solar cell.

  As for the base material in such a transparent conductive film, it may be a glass or a polymer resin film, but the total weight will increase if possible in view of recent market demands. It is said that a polymer resin film is preferable to glass from the viewpoints of achieving weight reduction and facilitating handling. Therefore, in the following description, the base material is assumed to be a film material. However, this does not deny the use of glass, that is, it should be noted in advance that glass may be used.

  Further, the base film made of the polymer resin as the base material does not necessarily need to be transparent, but for example, if used as a transparent electrode of a solar battery as described later, the solar battery is more transparent than the transparent film. It can be said that it is essential that the light transmittance required in the process must be obtained. The film used as such a substrate is naturally only required to have excellent transparency, for example, a resin such as polyethylene naphthalate (PEN), polyethylene terephthalate (PET) film, polycarbonate film, polystyrene film, polymethyl methacrylate film, etc. A film may be used, and a PEN film is used in this embodiment mode. Moreover, the thickness should just be the thickness according to the thickness of the transparent conductive film required in the apparatus etc. which use the transparent conductive film provided with the electrode material which concerns on this Embodiment, For example, as an electrode of a solar cell If used, the thickness of the transparent conductive film is about 100 μm, and the thickness of the transparent substrate film in that case is preferably about 80 μm or more and 200 μm or less.

  By the way, it is here as a transparent conductive film because it is for solar cell electrodes, but if transparency is not essential when used for other than solar cells, the substrate film does not necessarily need to be highly transparent, A film to be a base material may be selected according to the above, but further explanation is omitted here, and in the following explanation, the electrode material in the present embodiment is finally a dye-sensitized type. The description will be continued with the use as a transparent conductive film electrode used as a transparent electrode for solar cells in mind.

  Then, when this base film is used as a conductive film, a conductive material must naturally be laminated on the surface of the base film. Here, it is assumed that one or two or more conductive thin films made of one or more conductive substances are laminated on the surface of the base film, but here, as described above, the hue-sensitized solar cell transparent Since it is assumed to be used for an electrode, at least one layer has conductivity which is a property of conducting electricity, and the conductive material is dissolved in an iodine solution (iodine, lithium iodide, tetraiodide at 80 ° C.). Iodine resistance, in which 80% or more by volume remains undissolved even after 96 hours in a state of being immersed in butylammonium (TBAI) or tributyl phosphate (TBP) in an acetonitrile solution) It is assumed that an iodine-resistant layer formed of a substance having a property is also provided.

Further explanation will be given regarding the provision of the iodine-resistant layer.
In simple terms, a conductive film refers to a film that has been given the property of conducting electricity by laminating a conductive material on the surface of the film. It is natural to have

  On the other hand, the transparent electrode film of the dye-sensitized solar cell assumed in the present embodiment is eventually exposed to an electrolytic solution mainly composed of iodine constituting the dye-sensitized solar cell. However, if the electrode part constituting the transparent electrode film is exposed to iodine and the conductive substance is easily dissolved and damaged, and as a result, the situation where the conductivity is lost occurs, The conductivity as an electrode cannot be maintained.

  Conventionally, an attempt has been made to protect the conductive material by coating the surface of the conductive material with an iodine-resistant material as a countermeasure, but in this embodiment, the conductive material used for this electrode has the conductivity. In addition, the above-mentioned problem can be addressed by using a material that does not corrode with iodine, that is, a material having iodine resistance.

  The iodine resistance mentioned here is an iodine solution at 80 ° C. (for example, a solution obtained by dissolving iodine, lithium iodide, tetrabutylammonium iodide (TBAI), and tributyl phosphate (TBP) in an acetonitrile solution. Hereinafter, this solution shall be referred to.) It indicates the property that makes it possible to maintain a state in which 80% or more by volume remains undissolved even after 96 hours of immersion in the solution. I refuse.

  Examples of the material that satisfies such conditions include, for example, nickel, titanium, chromium, niobium, platinum, iridium, stainless steel, tantalum, tungsten, or an alloy made of a plurality of alloys, or a plurality of alloys made of any of them. If it is.

  Furthermore, a nickel-titanium alloy in which 5.0 wt% or more of titanium is mixed with nickel is even more preferable.

  In the case of a conductive film obtained by laminating these substances on the surface of a base film using a conventionally known method or the like, the electrode material imparting conductivity has resistance to an iodine solution. Therefore, even if this is used as, for example, a transparent electrode of a dye-sensitized solar cell or in contact with an electrolytic solution used in the dye-sensitized solar cell, the electrode material that is a conductive substance may corrode or dissolve. Since there is almost no deterioration, that is, the performance is not deteriorated, it can be said to be a suitable electrode material for a dye-sensitized solar cell.

  In addition, because of these properties, even when a conductive film using this electrode material is used as a material for a transparent electrode for a dye-sensitized solar cell, electrolysis using iodine essential for the dye-sensitized solar cell is used. Even if it comes into contact with the liquid, the performance does not drop rapidly, and it can be said that it can be suitably used because there is no need to perform an extra layering process. In addition, this is used as a photoelectrode. Even if there is a possibility that the electrode material may be in direct contact with the iodine solution, if the conductive film using the electrode material according to the present embodiment is used, the electrode material itself is resistant to iodine. Therefore, it can be used as a suitable electrode without extra lamination, that is, without causing extra cost and without increasing extra thickness.

  Hereinafter, the electrode material according to the present invention will be further described with reference to examples.

Example 1
The iodine resistance of the electrode material according to the first embodiment was measured by the following method.
As the iodine solution, a solution obtained by dissolving iodine, lithium iodide, tetrabutylammonium iodide (TBAI), and tributyl phosphate (TBP) in an acetonitrile solution was used.

  The target test piece has a size of 1 cm × 7 cm, and a grid having a width of 2 mm is provided on the surface thereof in stripes at intervals of 5 mm so as to be parallel to the short side direction. . Note that the height of the grid in a side view, that is, the thickness of the grid is not less than 50 nm and not more than 200 nm. The reason why the thickness of the grid is wide is that it is necessary to design the thickness so as to correspond to the specific resistance value depending on the material used for the grid.

This test piece was obtained as follows.
First, a PEN film (manufactured by Teijin Limited: product name “Teonex Q65”) having a thickness of 100 μm was prepared as a base film.
Then, a surface corresponding to the grid shape was masked as a water-soluble resin layer on the surface, and a polyvinyl alcohol resin was laminated by a conventionally known silk screen printing method.

  Then, a laminate to be tested was laminated on the entire surface by a conventionally known sputtering method.

And the unnecessary part was removed by washing the obtained laminated body with water, ITO was laminated | stacked for surface protection, and the test piece was obtained.
The test results of each test piece are shown below.

＊ 上記表において
耐ヨウ素性○＝（試験片の）体積比で８０％以上残存した
△＝（試験片の）体積比で６０％以上残存した
×＝（試験片の）体積比で残存量が６０％未満である
薄膜比抵抗実測値（Ω・ｃｍ）＝実測膜厚（ｃｍ）×実測面抵抗（Ω） である
チタン添加量＝ｗｔ％ である

* In the above table, iodine resistance ○ = 80% or more remained in volume ratio (of test piece)
Δ = 60% or more remained in volume ratio (of test piece)
X = remaining amount is less than 60% by volume ratio (of test piece) thin film specific resistance measured value (Ω · cm) = measured film thickness (cm) × measured surface resistance (Ω) Titanium addition amount = wt% Is

  As can be seen from this table, Ni, Ti, Cr, Nb, Pt, Ir, SUS, Ta, W, and Mo show suitable conductivity while having iodine resistance, but other substances such as normal It can be seen that Ag, Cu, and Al, which are often used as conductive substances in conductive films, do not have sufficient iodine resistance. Furthermore, in nickel-titanium alloys, if iodine of 5.0 wt% or more is mixed with nickel, suitable iodine resistance and conductivity are exhibited simultaneously, but in other cases it is insufficient. I understand.

Claims (6)

An electrode material used as the conductive thin film in a conductive film obtained by laminating one or more conductive thin films made of one or more conductive substances on the surface of a base film made of a polymer resin. And
At least one of the conductive thin films formed of the conductive material as the electrode material has conductivity that conducts electricity, and the conductive thin film is treated with an iodine solution (iodine, iodine, 80 ° C.). 80% or more by volume does not dissolve even after 96 hours in a state of being immersed in lithium iodide, tetrabutylammonium iodide (TBAI), tributyl phosphate (TBP) dissolved in acetonitrile solution) The substance also has iodine resistance remaining,
An electrode material. The electrode material according to claim 1,
The conductive substance is nickel, titanium, chromium, niobium, platinum, iridium, stainless steel, tantalum, tungsten, or an alloy made of molybdenum, or an alloy made of any of these,
An electrode material. The electrode material according to claim 1,
The conductive material is a nickel-titanium alloy in which 5.0 wt% or more of titanium is mixed with respect to nickel;
An electrode material. Using the electrode material according to any one of claims 1 to 3,
A conductive film characterized by Using the conductive film according to claim 4 as an electrode,
A solar cell characterized by. Using the conductive film according to claim 4 as an electrode,
A photoelectrode characterized by.