JP2011222430A - Method of forming photocatalyst film in dye-sensitized solar cell - Google Patents

Abstract

A method for forming a photocatalytic film in a dye-sensitized solar cell capable of shortening the adsorption time of a photosensitizing dye is provided.
A transparent electrode, a counter electrode, an electrolyte layer disposed between the electrodes, and a photocatalyst film disposed between the electrodes and on the transparent electrode side. A method for forming a photocatalyst film in a dye-sensitized solar cell comprising: dissolving a metal oxide fine particle serving as a photocatalyst and a photosensitizing dye in an alcohol solution to obtain a mixed solution; In this method, a viscous agent is added to obtain a paste, and then the paste-like mixture is applied to the surface of the transparent electrode 1 and then baked.
[Selection] Figure 1

Description

  The present invention relates to a method for forming a photocatalytic film in a dye-sensitized solar cell.

Generally, a dye-sensitized solar cell includes a transparent electrode in which a transparent conductive film is formed on a transparent substrate such as a glass plate, a counter electrode in which a transparent conductive film is similarly formed on the surface of the transparent substrate, and these It is composed of an iodine-based electrolyte layer disposed between both electrodes, and a photocatalytic film disposed between the two electrodes and on the surface of the transparent electrode. The photocatalytic film includes titanium oxide (TiO ₂ ) and the like. After forming a metal oxide, a photosensitizing dye such as ruthenium (hereinafter referred to as a dye) is adsorbed.

By the way, in order to adsorb the dye to the metal oxide, it is necessary to immerse the metal oxide in the dye solution for several tens of minutes to several tens of hours.
As described above, since it takes time to adsorb the dye to the metal oxide, there is a disadvantage that the manufacturing time becomes long. Therefore, a manufacturing method for shortening the manufacturing time has been proposed (for example, Patent Document 1). reference).

  In this manufacturing method, a semiconductor coating layer in which a metal oxide semiconductor is dispersed in an organic solvent is applied on a transparent conductive substrate and dried to form a semiconductor coating layer. It is made to bake after making it adsorb | suck.

JP 2005-222798 A

  However, according to the manufacturing method described above, after the metal oxide film is formed, the dye is adsorbed without firing, so the metal oxide film is not porous. In other words, there is a problem that the amount of dye adsorbed in the power generation layer decreases, resulting in a decrease in battery performance.

  Therefore, the present invention provides a method for forming a photocatalyst film in a dye-sensitized solar cell that can shorten the adsorption time of the photosensitizing dye and can improve the adsorption amount of the photosensitizing dye in the metal oxide film. For the purpose.

In order to solve the above problems, a method for forming a photocatalyst film in a dye-sensitized solar cell according to claim 1 of the present invention includes a transparent electrode, a counter electrode, an electrolyte layer disposed between both electrodes, and both electrodes. A method for forming a photocatalytic film in a dye-sensitized solar cell comprising a photocatalytic film disposed between and on the transparent electrode side,
After dissolving the metal oxide fine particles to be a photocatalyst and the photosensitizing dye in at least an alcohol liquid to obtain a mixed liquid, water and a viscous agent are added to the mixed liquid to obtain a paste,
Next, the paste-like mixture is applied to the surface of the transparent electrode and then baked.

  A method for forming a photocatalyst film in a dye-sensitized solar cell according to claim 2 is a method in which the precursor of the metal oxide fine particles is mixed into the metal oxide fine particles in the formation method according to claim 1.

  Furthermore, the method for forming a photocatalyst film in a dye-sensitized solar cell according to claim 3 is the method according to claim 1, wherein after the paste-like mixture is baked, a precursor of metal oxide fine particles is further formed on the surface. This is a method of baking again after applying a solution in which the body is dissolved in an alcohol solution.

  According to each of the above forming methods, when forming a photocatalyst film on the surface of a transparent electrode, after preparing a mixed liquid of metal oxide fine particles, photosensitizing dye and alcohol liquid as a photocatalyst, adding water and a viscosity agent Since this paste-like mixture was applied to the surface of the transparent electrode and then the coating film was formed by sintering at a predetermined temperature, a photosensitizing dye adsorption step was required. Therefore, the time required for formation can be shortened, and by mixing the metal oxide fine particles and the photosensitizing dye, the photosensitizing dye spreads over the entire surface of the metal oxide fine particles, and the metal oxide The amount of photosensitizing dye adsorption in the film can be improved.

It is sectional drawing which shows schematic structure of the dye-sensitized solar cell which concerns on embodiment of this invention.

Hereinafter, a method for forming a photocatalytic film in a dye-sensitized solar cell according to an embodiment of the present invention will be described.
First, a schematic configuration of the dye-sensitized solar cell according to the embodiment will be described with reference to FIG.

  As shown in FIG. 1, the dye-sensitized solar cell includes a transparent electrode 1 as a negative electrode, a counter electrode 2 as a positive electrode, an electrolyte layer 3 disposed between the electrodes 1 and 2, and both electrodes 1. , 2 and a photocatalyst film (also referred to as a photocatalyst layer or a power generation layer) 4 disposed on the transparent electrode 1 side.

  The transparent electrode 1 is composed of a transparent substrate 11 and a transparent conductive film 12 formed (arranged) on the surface of the transparent substrate 11, and the counter electrode 2 is formed on the surface of the transparent substrate 21 and the transparent substrate 21. The transparent conductive film 22 is formed (arranged).

  As each of the transparent substrates 11 and 21, a synthetic resin plate, a glass plate, or the like is used as appropriate, but a thermoplastic resin such as a polyethylene naphthalate (PEN) film is preferable in terms of weight reduction and price reduction. In addition to polyethylene naphthalate, polyethylene terephthalate, polyester, polycarbonate, polyolefin and the like can also be used.

Further, as the transparent conductive films 12 and 22, tin-added indium oxide (ITO) is preferably used. In addition, fluorine-added tin oxide (FTO), tin oxide (SnO ₂ ), and indium zinc oxide (IZO) are used. A thin film containing a conductive metal oxide such as zinc oxide (ZnO) can be used.

  As the electrolyte layer 3, for example, an iodine-based electrolyte is used. Specifically, an electrolyte component such as iodine, iodide ion or tertiary butyl pyridine dissolved in an organic solvent such as ethylene carbonate or methoxyacetonitrile is used. The electrolyte layer 3 is not limited to the electrolytic solution, and may be a solid electrolyte.

As the solid electrolyte, for example, is illustrated DMPImI (dimethylpropyl imidazolium iodide), but this addition, LiI, NaI, KI, CsI, metal iodide such as CaI _2, tetraalkylammonium iodide and quaternary ammonium compounds Bromide such as a combination of iodide such as iodine salt and I ₂ , metal bromide such as LiBr, NaBr, KBr, CsBr and CaBr ₂ , and bromide salt of quaternary ammonium compound such as tetraalkylammonium bromide and Br ₂ And the like can be used as appropriate.

The photocatalytic film 4 is formed of an oxide semiconductor layer 41 to which a photosensitizing dye 42 is adsorbed.
Examples of the oxide semiconductor include metal oxides such as titanium oxide (TiO ₂ ), tin oxide (SnO ₂ ), tungsten oxide (WO ₃ ), zinc oxide (ZnO), and niobium oxide (Nb ₂ O ₅ ). As photosensitizing dyes used, ruthenium complexes and iron complexes having a ligand containing a bipyridine structure or a terpyridine structure, metal complexes of porphyrins or phthalocyanines, or organic dyes such as eosin, rhodamine, merocyanine, coumarin, etc. Is used.

Next, a method for forming the photocatalyst film 4 (which can also be called a manufacturing method), which is the gist of the present invention, will be described.
First, after dissolving the metal oxide fine particles and the photosensitizing dye as a photocatalyst in at least an alcohol liquid (water may be mixed) to obtain a liquid mixture (solution), water and a viscosity agent are added to the liquid mixture The paste-like mixture is then applied to the surface of the transparent electrode 1 and then baked at a predetermined temperature for a predetermined time, whereby the photocatalytic film 4 is obtained.

Note that ethylene glycol, ethylene glycol, or acetylacetone is used as the viscosity agent.
The counter electrode 2 has been described as having the transparent conductive film 22 formed on the surface of the transparent substrate 21, but a metal sheet such as aluminum, copper, or tin can also be used. In addition, the counter electrode may be configured by holding a gel-like solid electrolyte on a mesh electrode made of metal such as aluminum, copper, tin, or carbon, or conductively bonded to one surface of the transparent substrate 21. The counter electrode 2 is formed by covering the transparent substrate 21 with an agent layer and transferring a separately formed brush-like carbon nanotube group to the transparent substrate 21 side through the adhesive layer. Also good.

  Here, the case where a dye-sensitized solar cell (which is also a photoelectric conversion element) is assembled will be briefly described. After the transparent electrode 1 having the photocatalyst film 4 formed on the surface by the above-described method and the counter electrode 2 are aligned. The electrodes 1 and 2 are sealed with a heat-sealing film or a sealing material, and the liquid electrolyte is passed between the electrodes 1 and 2 through holes or gaps previously provided in the transparent electrode 1 or the counter electrode 2. It can be injected into.

In addition, when using a solid electrolyte, after superposing | stacking so that the photocatalyst film | membrane 4 and the electrolyte layer 3 may be pinched | interposed between both electrodes 1 and 2, the peripheral parts should just be heated and adhere | attached.
According to the method for forming a photocatalyst film in the dye-sensitized solar cell described above, when the photocatalyst film 4 is formed on the surface of the transparent electrode 1, a mixed liquid of metal oxide fine particles, photosensitizing dye and alcohol solution as a photocatalyst. After forming the paste, water and a viscous agent are added to form a paste. After the paste-like mixture is applied to the surface of the transparent electrode 1, the coating film is sintered at a predetermined temperature for a predetermined time. Therefore, the photosensitizing dye adsorption step is not required, and therefore the production time can be shortened. Also, the surface of the metal oxide fine particles can be obtained by mixing the metal oxide fine particles and the photosensitizing dye. The photosensitizing dye spreads throughout, and the amount of photosensitizing dye adsorption in the metal oxide film can be improved.

  Hereinafter, a method for forming a photocatalyst film in a dye-sensitized solar cell according to a plurality of examples more specifically showing the above embodiment will be described. In each Example shown below, a ruthenium complex was used as a photosensitizing dye.

  First, a method for forming a photocatalyst film according to Example 1 will be described. Photosensitizing dye 18.0 mg and titanium oxide fine particles (made by Nippon Aerosil Co., Ltd .: P-25) 5.4 g having a particle diameter of 20 nm are kneaded in a mortar. For example, 23.2 g of t-butanol solution and 7.1 g of pure water are mixed as an alcohol solution, and the mixture is admixed with a paint shaker or the like, and the mixture is adsorbed with a photosensitizing dye, that is, a titanium oxide paste. Got.

  And after apply | coating this titanium oxide paste to the surface of the PEN-ITO film which is a transparent electrode, a photocatalyst film | membrane is formed by baking at the temperature range of 120-150 degreeC, Preferably it is 150 degreeC and about 10 minutes. did. Thus, a photocatalyst film could be obtained without requiring a photosensitizing dye adsorption step that took at least several hours.

  Next, a method for forming a photocatalytic film according to Example 2 will be described. To the titanium oxide paste obtained in Example 1 described above, titanium (IV) isopropoxy, which is a photocatalyst precursor (metal alkoxide, that is, titanium alkoxide), is provided. By mixing an appropriate amount of a mixed solution (about 0.01 to 5.00% by mass) of TTIP dissolved in a propanol solution, photosensitizing dyes, titanium oxide fine particles, photosensitizing dye and titanium oxide are mixed. A paste with a strong bond of fine particles was obtained. After applying this to a PEN / ITO film, it is necessary to have a photosensitizing dye adsorption process that takes several hours by baking at a temperature range of 120 to 150 ° C, preferably 150 ° C and about 10 minutes. In addition, a photocatalytic film in which the photosensitizing dyes, the titanium oxide fine particles, and the photosensitizing dye and the titanium oxide fine particles were firmly bonded to each other could be obtained.

Here, TTIP is used as the precursor of the photocatalyst, but titanium tetoethoxide, titanium tetrachloride, titanium hydroxide, and the like can be used, for example.
In the case where tin oxide (SnO ₂ ), tungsten oxide (WO ₃ ), zinc oxide (ZnO), niobium oxide (Nb ₂ O ₅ ), or the like is used as an oxide semiconductor other than titanium, the respective precursors are Used.

  Furthermore, in order to enhance the light scattering effect, for example, metal oxide fine particles such as titanium oxide of several nm to several hundred nm may be mixed in the paste.

  Next, a method for forming a photocatalytic film according to Example 3 will be described. After applying the titanium oxide paste obtained in Example 1 described above to the surface of the PEN / ITO film that is a transparent electrode, the temperature is 120 to 150 ° C. Bake in the range, preferably 150 ° C. and for about 10 minutes. And on the photocatalyst film | membrane obtained by baking, the liquid mixture (about 0.01-5.00 weight%) which melt | dissolved titanium (IV) isopropoxide (TTIP) which is a precursor of a photocatalyst in solvents, such as a propanol liquid. ) Is applied using a spray method, a dip method, or the like, and is fired again at a temperature range of 120 to 150 ° C., preferably 150 ° C. and about 10 minutes.

  Thus, since the liquid mixture which melt | dissolves the precursor of a photocatalyst in solvents, such as alcohol liquid, is apply | coated to the surface after baking, the metal oxide fine particle (titanium oxide) which forms the photocatalyst film | membrane obtained by baking The surface is coated with a precursor, so that no photosensitizing dye adsorption step is required, and the bonds between the photosensitizing dyes, between the titanium oxide fine particles, and between the photosensitizing dye and the titanium oxide fine particles are stronger. A photocatalytic film can be obtained.

Here, TTIP is used as the precursor (metal alkoxide) of the photocatalyst, but titanium tetoethoxide, titanium tetrachloride, titanium hydroxide, or the like can be used, for example.
In the case where tin oxide (SnO ₂ ), tungsten oxide (WO ₃ ), zinc oxide (ZnO), niobium oxide (Nb ₂ O ₅ ), or the like is used as an oxide semiconductor other than titanium, the respective precursors are Used.

  Moreover, about the alcohol liquid which is a solvent, you may use not only propanol but t-butyl alcohol, ethoxyethanol, ethanol, etc. Moreover, you may add diethanolamine, acetylacetone, etc. for the purpose of suppressing hydrolysis.

  Furthermore, although the PEN / ITO film was used as the transparent electrode, of course, a glass substrate (for example, FTO glass) may be used. In this case, the paste-like mixture is within a temperature range of 150 to 500 ° C. and 10 It is fired in about 30 minutes.

Here, using the photocatalyst film formed in Example 2 above, when a dye-sensitized solar cell having a film thickness of about several μm and an effective diameter of φ6 mm is prepared, AM is 1.5 and 100 mW / cm ² . As a result of measuring the power conversion efficiency by irradiation with a standard light source, when only a normal low-temperature titanium oxide paste is used, the current density is 8.67 mA / cm ² , the open-circuit voltage is 0.70 V, the fill factor is 0.61, and conversion The efficiency was 3.68% and the time required for the adsorption of the photosensitizing dye was 90 minutes, whereas when the photocatalytic film formed by the method according to the present invention was used, the current density was 9.34 mA / cm ² , open circuit voltage is 0.73V, fill factor is 0.61, conversion efficiency is 4.15%, and photosensitizing dye is adsorbed at the paste preparation stage. No longer needed, suitable for continuous production Formation of photocatalytic film has become possible.

The method for forming the photocatalyst film in the dye-sensitized solar cell corresponding to Example 2 will be briefly described as follows.
This forming method is a photocatalyst in a dye-sensitized solar cell comprising a transparent electrode, a counter electrode, an electrolyte layer disposed between both electrodes, and a photocatalytic film disposed between the electrodes and on the transparent electrode side. A method for forming a film, comprising:
After dissolving the metal oxide fine particles to be a photocatalyst and the photosensitizing dye in at least an alcohol liquid to obtain a mixed liquid, water and a viscous agent are added to the mixed liquid to obtain a paste,
In this paste-like mixture, the above metal oxide fine particle precursor dissolved in an alcohol liquid is mixed,
In this method, the paste-like mixture to which the precursor is added is applied to the surface of the transparent electrode and then baked at a predetermined temperature for a predetermined time.

A method for forming a photocatalyst film in a dye-sensitized solar cell corresponding to Example 3 will be briefly described as follows.
This forming method is a photocatalyst in a dye-sensitized solar cell comprising a transparent electrode, a counter electrode, an electrolyte layer disposed between both electrodes, and a photocatalytic film disposed between the electrodes and on the transparent electrode side. A method for forming a film, comprising:
After dissolving the metal oxide fine particles to be a photocatalyst and the photosensitizing dye in at least an alcohol liquid to obtain a mixed liquid, water and a viscous agent are added to the mixed liquid to obtain a paste,
After applying this paste-like mixture to the surface of the transparent electrode, it is fired at a predetermined temperature and for a predetermined time,
In this method, after applying the metal oxide fine particle precursor dissolved in an alcohol solution to the baked surface, it is baked again at a predetermined temperature for a predetermined time.

DESCRIPTION OF SYMBOLS 1 Transparent electrode 2 Counter electrode 3 Electrolyte layer 4 Photocatalyst film 11 Transparent substrate 12 Transparent conductive film 21 Transparent substrate 22 Transparent conductive film 41 Oxide semiconductor layer 42 Photosensitizing dye

Claims (3)

A method for forming a photocatalyst film in a dye-sensitized solar cell comprising a transparent electrode, a counter electrode, an electrolyte layer disposed between both electrodes, and a photocatalyst film disposed between both electrodes and on the transparent electrode side There,
After dissolving the metal oxide fine particles to be a photocatalyst and the photosensitizing dye in at least an alcohol liquid to obtain a mixed liquid, water and a viscous agent are added to the mixed liquid to obtain a paste,
Next, the paste-like mixture is applied to the surface of the transparent electrode and then baked. A method for forming a photocatalytic film in a dye-sensitized solar cell, comprising:   The method for forming a photocatalyst film in a dye-sensitized solar cell according to claim 1, wherein a precursor of the metal oxide fine particles is mixed into the metal oxide fine particles.   2. The dye according to claim 1, wherein after the paste-like mixture is fired, a mixed solution obtained by dissolving a precursor of metal oxide fine particles in an alcohol liquid is further applied to the surface, and then fired again. A method for forming a photocatalytic film in a sensitized solar cell.

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