JP2012156070A - Method for forming photocatalyst film in dye-sensitized solar battery, and dye-sensitized solar battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a photocatalyst film in a dye-sensitized solar battery which allows the further enhancement of the electron conductivity from a pigment to a transparent conductive film to improve the battery performance, and to provide a dye-sensitized solar battery.SOLUTION: The method for forming, in a dye-sensitized solar battery having a transparent electrode 1, a counter electrode, an electrolytic layer disposed between the electrodes, and a photocatalyst film 4 disposed on the side of the transparent electrode 1 between the electrodes, the photocatalyst film 4 comprises: forming a core layer of a core shell structure by applying a paste mixture including conductive nitride microparticles 41 to a surface of the transparent electrode 1; and forming a shell layer (porous coating film 43) of a core shell structure by coating the core layer with a paste mixture including titanium oxide microparticles and the precursor thereof, followed by burning.

Description

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

In general, a dye-sensitized solar cell is composed of a transparent electrode in which a transparent conductive film is formed on a transparent substrate such as a glass plate, a counter electrode made of a conductive substrate, and an iodine-based solar electrode disposed between these electrodes. It is composed of an electrolyte layer and a photocatalyst film disposed between the electrodes and on the surface of the transparent electrode. As the photocatalyst film, after forming a metal oxide such as titanium oxide (TiO ₂ ), ruthenium The thing which adsorb | sucked photosensitizing dyes, such as these, is known.

  In addition, titanium oxide fine particles are used as the photocatalyst, and a titanium oxide precursor is mixed in order to improve performance (for example, see Patent Document 1).

JP 2004-193321 A

  By the way, according to the thing of the said patent document 1, although the metal oxide (semiconductor electrode film) used for a photocatalyst (semiconductor electrode film) and the electronic conductivity of a transparent conductive film improve, due to the electrical resistance which this metal oxide itself has. There was a loss in the transfer of electrons from the dye to the transparent conductive film through the metal oxide. In particular, this loss is significant when the light quantity is low, and there is a problem that sufficient battery performance cannot be obtained.

  Accordingly, the present invention provides a method for forming a photocatalyst film in a dye-sensitized solar cell and a dye-sensitized solar cell, which can further improve the electron conductivity from the dye to the transparent conductive film and improve the battery performance. Objective.

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,
A mixture containing carbide conductive fine particles and / or nitride conductive fine particles is applied to the surface of the transparent electrode to form a core layer of a core-shell structure,
A mixture containing photocatalyst fine particles and / or a precursor of the photocatalyst fine particles is applied to the core layer and then baked to form a shell layer having a core-shell structure.

A method for forming a photocatalyst film in a dye-sensitized solar cell according to claim 2 of the present invention is the method for forming a photocatalyst film in a dye-sensitized solar cell according to claim 1, wherein the conductive fine particles in the core layer are formed. And a mixture containing carbide conductive fine particles and / or nitride conductive fine particles having a larger particle size than the photocatalyst fine particles of the shell layer is applied to the shell layer to form a core layer having a second core-shell structure. And
Baking after applying a mixture containing photocatalyst fine particles and / or a precursor of the photocatalyst fine particles having a larger particle size than the conductive fine particles of the core layer and the photocatalyst fine particles of the shell layer to the core layer of the second core-shell structure Thus, a shell layer having a second core-shell structure is formed.

  Furthermore, the method for forming a photocatalyst film in a dye-sensitized solar cell according to claim 3 of the present invention is the method for forming a photocatalyst film in a dye-sensitized solar cell according to claim 1, wherein the photocatalyst fine particles and / or Alternatively, a photosensitizing dye is mixed with a mixture containing the precursor of the photocatalyst fine particles.

  Moreover, the formation method of the photocatalyst film in the dye-sensitized solar cell concerning Claim 4 of this invention is a formation method of the photocatalyst film in the dye-sensitized solar cell as described in any one of Claims 1 thru | or 3. The carbide is TiC and the nitride is TiN or TiCN.

Moreover, the dye-sensitized solar cell according to claim 5 of the present invention includes a transparent electrode, a counter electrode, an electrolyte layer disposed between these electrodes, and a photocatalyst disposed between both electrodes and on the transparent electrode side. A dye-sensitized solar cell comprising a film,
The photocatalyst film has conductive fine particles forming a core layer having a core-shell structure, and photocatalyst fine particles forming a shell layer having a core-shell structure and adsorbed with a photosensitizing dye.

  A dye-sensitized solar cell according to claim 6 of the present invention is the dye-sensitized solar cell according to claim 5, wherein the conductive fine particles are carbide or nitride.

  According to the method for forming a photocatalyst film in the dye-sensitized solar cell, the conductive fine particles lower the electric resistance of the photocatalyst film, thereby suppressing the decrease in the electron flow rate from the photosensitizing dye to the transparent electrode, thereby improving the conductivity of the electrons. The battery performance can be further improved.

It is sectional drawing which shows schematic structure of the dye-sensitized solar cell which concerns on embodiment of this invention. It is an enlarged schematic diagram which shows the transparent electrode and photocatalyst film | membrane in the same dye-sensitized solar cell.

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 a conductive substrate 21 made of aluminum, copper, tin or the like. It is composed of

  As the transparent substrate 11, 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.

In addition, tin-doped indium oxide (ITO) is preferably used as the transparent conductive film 12, and in addition to this, fluorine-added tin oxide (FTO), tin oxide (SnO ₂ ), indium zinc oxide (IZO), oxide A thin film containing a conductive metal oxide such as zinc (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.

As shown in FIG. 2, the photocatalyst film 4 is porous with a large number of conductive fine particles 41 and titanium oxide (TiO ₂ ) covering the surfaces of the conductive fine particles 41 and adsorbing the photosensitizing dye 42. It is formed from the quality film 43. That is, the photocatalyst film 4 is formed into a core shell with a porous coating 43 with a porous film (described later) including conductive fine particles 41 as a core.

  Further, as the conductive fine particles 41, titanium nitride (TiN), titanium carbide (TiC), titanium carbonitride (TiCN), or the like is used, and the photosensitizing dye 42 is a coordination containing a bipyridine structure or a terpyridine structure. A ruthenium complex or iron complex having a child, a porphyrin-based or phthalocyanine-based metal complex, or an organic dye such as eosin, rhodamine, merocyanine, or coumarin is used.

Next, a manufacturing method of the photocatalyst film 4 that is the gist of the present invention, that is, a forming method will be described.
First, the conductive fine particles 41 or the metal alkoxide that is a precursor of the conductive fine particles 41 is dissolved in alcohol and water to form a paste-like mixture, and this paste-like mixture is applied to the surface of the transparent electrode 1 and dried. Then, a porous film (which is a core layer having a core-shell structure) including the conductive fine particles 41 is formed by firing at a predetermined temperature.

  On the other hand, titanium oxide fine particles, which are photocatalyst fine particles, are dissolved in alcohol and water and stirred well to obtain a paste-like mixture to obtain a titanium oxide paste. An appropriate amount of this titanium oxide paste is mixed in a solution of a photocatalyst precursor dissolved in propanol, coated on the surface of the porous film, dried, and then fired at a predetermined temperature to obtain a porous material containing photocatalyst fine particles. A coating (which is a shell layer having a core-shell structure) 43 is formed. The porous film and the porous coating 43 are core-shelled with the porous coating 43 with the porous membrane as a core.

  This porous coating 43 is immersed in a mixed solution of photosensitizing dye 42, butanol and acetonitrile. As a result, the photosensitizing dye 42 is adsorbed on the titanium oxide fine particles of the porous coating 43 to form the photocatalytic film 4.

  Here, the thickness of the porous coating 43 can be adjusted by changing the mixing ratio of the titanium oxide paste and the photocatalyst precursor. In addition, although there exist a spray method, a dip method, a spin coat method, a doctor blade method etc. about the coating method mentioned above, there is no restriction | limiting in particular.

  Moreover, although it demonstrated as what uses the electroconductive board | substrate 21, such as aluminum, copper, and tin, as said counter electrode 2, besides this, it is a gel-like solid electrolyte to metal or carbon mesh-like electrodes, such as aluminum, copper, and tin. The counter electrode may be constituted by holding the transparent substrate, a transparent conductive film may be formed on the surface of the transparent substrate, and the transparent substrate may be formed on one side of the transparent substrate with a conductive adhesive layer. The counter electrode 2 may be configured by transferring a separately formed brush-like carbon nanotube group to the transparent substrate side through an adhesive layer.

  Furthermore, when the dye-sensitized solar cell (which is also a photoelectric conversion element) is assembled briefly, after positioning the transparent electrode 1 and the counter electrode 2 having the photocatalyst film 4 formed on the surface by the above-described method, The gap between the electrodes 1 and 2 is 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. Just inject.

  In addition, when using a solid electrolyte or a highly viscous electrolyte solution, after superimposing the photocatalyst film 4 and the electrolyte layer 3 between the electrodes 1 and 2, the peripheral portions may be heated and bonded together. Good.

  According to the method for forming the photocatalyst film 4 in the dye-sensitized solar cell described above, the conductive fine particles 41 reduce the electric resistance of the photocatalyst film 4, thereby suppressing the decrease in the electron flow rate from the photosensitizing dye 42 to the transparent electrode 1. Battery performance (especially current density and fill factor) can be improved.

  Hereinafter, a method of forming the photocatalyst film 4 in the dye-sensitized solar cell according to a plurality of examples showing the above embodiment more specifically will be described. In each example shown below, a ruthenium complex was used as the photosensitizing dye 42.

  First, the method for forming the photocatalyst film 4 according to Example 1 will be described. As the conductive fine particles 41, titanium nitride fine particles having an average particle diameter of 40 nm (preferably 20 to 60 nm) were used. Here, the average particle diameter refers to the number average particle diameter, and is a value measured by FE-SEM (field emission scanning electron microscope) observation. The titanium nitride fine particles are dissolved in t-butanol and pure water to form a paste, which is coated on the surface of the PEN-ITO film as the transparent electrode 1 and dried, and then fired at 150 ° C. to make it porous. A film was formed.

  On the surface of this porous film, 5.4 g of titanium oxide fine particles having an average particle diameter of 20 nm are dissolved in 23.2 g of t-butanol and 7.1 g of pure water, and stirred well with a paint shaker to obtain a titanium oxide paste. It was. Then, an appropriate amount of this titanium oxide paste was mixed with a solution (about 0.01 to 5.00 wt%) of titanium (IV) isopropoxide (TTIP), which is a precursor of the photocatalyst, in propanol. The mixed solution was applied to the surface of the porous film, dried, and then baked at 150 ° C., whereby the porous coating 43 was formed.

  By immersing this porous film 43 in a mixed solution of ruthenium dye N719 (72 mg), t-butanol (100 cc) and acetonitrile (100 cc) at 40 ° C. for 90 minutes, the ruthenium dye is adsorbed on the titanium oxide fine particles. Thus, the photocatalytic film 4 was formed.

  Here, TTIP is used as a precursor of the photocatalyst, but other metal alkoxides such as titanium tetraethoxide, titanium tetrachloride, or titanium hydroxide may be used. Further, t-butanol, ethoxyethanol, ethanol or the like may be used instead of propanol. Furthermore, for the purpose of suppressing hydrolysis, diethanolamine, acetylacetone or the like may be added.

  Next, a method for forming the photocatalyst film 4 according to Example 2 will be described. When obtaining the titanium oxide paste in Example 1 described above, not only titanium oxide fine particles but also ruthenium dyes are converted into t-butanol and pure water. Melted. Thereby, since the photosensitizing dye 42 is adsorbed to the titanium oxide fine particles, the step of immersing the porous film in the mixed solution containing the ruthenium dye is omitted. The others were the same as in Example 1. For this reason, in this Example 2, the coupling | bonding of ruthenium pigment | dye, titanium oxide microparticles | fine-particles, a ruthenium pigment | dye, and a titanium oxide microparticle became strong. Moreover, in this Example 2, the process immersed in the liquid mixture containing a ruthenium pigment | dye became unnecessary, and the creation time of the dye-sensitized solar cell was able to be shortened.

Using the photocatalyst film 4 formed in Example 2 above, a dye-sensitized solar cell having an effective diameter of φ6 mm was prepared and irradiated with a standard light source of AM 1.5, 100 mW / cm ² to measure the cell performance. . In this case, the measured current density is 9.43 mA / cm ² , the open-circuit voltage is 0.72 V, the fill factor is 0.67, the conversion efficiency is 4.56%, and the photosensitizing dye in the photocatalyst film 4 is manufactured. The time required for adsorption of 42 was 0 minutes.

On the other hand, a dye-sensitized solar cell was prepared using a conventional photocatalyst film formed without using the conductive fine particles 41, and a standard light source irradiation of AM 1.5, 100 mW / cm ² was performed to obtain battery performance. Was measured. In this case, the measured current density was 8.67 mA / cm ² , the open circuit voltage was 0.70 V, the fill factor was 0.61, the conversion efficiency was 3.68%, and the photosensitizing dye in the photocatalyst film was manufactured at the time of production. The time required for adsorption was 90 minutes.

  Therefore, the dye-sensitized solar cell using the photocatalyst film 4 obtained in Example 2 generally improved the cell performance as compared with the conventional configuration. In particular, the current density and fill factor were significantly improved.

  In Example 2 described above, since the adsorption step of the photosensitizing dye is not necessary in the production of the dye-sensitized solar cell, it is easy to perform continuous production of the dye-sensitized solar cell.

Next, a method for forming the photocatalytic film 4 according to Example 3 will be described.
The photocatalyst film 4 in this Example 3 is provided with a plurality of laminated bodies composed of a porous film and a porous film in the thickness direction, from the laminated body on the transparent electrode 1 side to the laminated body on the counter electrode 2 side, The particle diameters of the conductive fine particles and the photocatalyst fine particles contained in each laminate gradually increase. As an example, a method for forming the photocatalyst film 4 composed of two laminated bodies will be specifically described.

  That is, after the formation of the porous film and the porous film 43 in Example 1 described above, the second porous film (which is the core layer of the second core-shell structure) is formed on the conductive fine particles on the transparent electrode 1 side. 41 and conductive fine particles having a larger particle size than the photocatalyst fine particles were formed on the porous coating 43 on the transparent electrode 1 side. Next, the second porous coating (which is a shell layer having a second core-shell structure) is formed using the conductive fine particles 41 on the transparent electrode 1 side and the conductive fine particles having a larger particle diameter than the photocatalyst fine particles. Formed on the second porous membrane.

  More specifically, the titanium nitride fine particles, which are the conductive fine particles 41 of the porous film on the transparent electrode 1 side, have an average particle diameter of 40 nm (preferably 20 to 60 nm), and the transparent electrode 1 As the titanium oxide fine particles which are the photocatalyst fine particles of the porous coating 43 on the side, those having an average particle diameter of 15 nm (preferably 5 to 30 nm) were used. The formation of the second porous film is the same as the formation of the porous film on the transparent electrode 1 side, but the titanium nitride fine particles having an average particle diameter of 60 nm (preferably 40 to 80 nm) were used. . The formation of the second porous film is the same as the formation of the porous film 43 on the transparent electrode 1 side, but the titanium oxide fine particles have an average particle diameter of 30 nm (preferably 20 to 50 nm). Was used.

  Therefore, in the dye-sensitized solar cell using the photocatalyst film 4 obtained in Example 3, the conductive particles 41 and the photocatalyst particles having a small particle diameter, that is, high transmittance, are used as the transparent electrode on the light incident side. Since the conductive particles and photocatalyst particles having a large particle size, that is, high reflectance are arranged on the side of the counter electrode 2 on the light emission side, the light confinement effect on the photocatalyst layer 4 is achieved. As a result, the excitation of electrons in the photosensitizing dye 42 was promoted, the conversion efficiency was increased, and the battery performance could be further improved.

DESCRIPTION OF SYMBOLS 1 Transparent electrode 2 Counter electrode 3 Electrolyte layer 4 Photocatalyst film | membrane 12 Transparent conductive film 41 Conductive fine particle 42 Photosensitizing dye 43 Porous film

Claims (6)

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,
A mixture containing carbide conductive fine particles and / or nitride conductive fine particles is applied to the surface of the transparent electrode to form a core layer of a core-shell structure,
A method of forming a photocatalyst film in a dye-sensitized solar cell, comprising applying a photocatalyst fine particle and / or a mixture containing the precursor of the photocatalyst fine particle to the core layer and then firing to form a shell layer having a core-shell structure . A mixture containing carbide conductive fine particles and / or nitride conductive fine particles having a larger particle size than the conductive fine particles of the core layer and the photocatalyst fine particles of the shell layer is applied to the shell layer to form the second core shell. Forming a core layer of structure,
Baking after applying a mixture containing photocatalyst fine particles and / or a precursor of the photocatalyst fine particles having a larger particle size than the conductive fine particles of the core layer and the photocatalyst fine particles of the shell layer to the core layer of the second core-shell structure Then, a shell layer having a second core-shell structure is formed. The method for forming a photocatalytic film in a dye-sensitized solar cell according to claim 1.   3. The method for forming a photocatalyst film in a dye-sensitized solar cell according to claim 1, wherein a photosensitizing dye is mixed in a mixture containing the photocatalyst fine particles and / or a precursor of the photocatalyst fine particles.   The method for forming a photocatalytic film in a dye-sensitized solar cell according to any one of claims 1 to 3, wherein the carbide is TiC and the nitride is TiN or TiCN. 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,
The dye-sensitized solar cell, wherein the photocatalyst film includes conductive fine particles forming a core layer having a core-shell structure, and photocatalyst fine particles forming a shell layer having a core-shell structure and adsorbed with a photosensitizing dye. . The dye-sensitized solar cell according to claim 5, wherein the conductive fine particles are carbide or nitride.

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