JP5194286B2 - Method for producing photoelectrode for dye-sensitized solar cell - Google Patents

Description

The present invention relates to a method for producing a dye-sensitized solar cell photoelectrode.

Conventionally, a titanium oxide photoelectrode in which titanium oxide is used as a component of a semiconductor layer is known as a photoelectrode for a dye-sensitized solar cell. The titanium oxide photoelectrode is a typical photoelectrode for a dye-sensitized solar cell, and generates a high electromotive force in combination with an appropriate sensitizing dye. However, since the titanium oxide photoelectrode needs to be fired at a high temperature, it is difficult to make it flexible by employing, for example, a synthetic resin substrate.
On the other hand, zinc oxide photoelectrodes, in which zinc oxide is used as a component of the semiconductor layer, can be produced electrochemically, unlike titanium oxide photoelectrodes. May be usable.
However, when a zinc oxide photoelectrode is used as a photoelectrode of a dye-sensitized solar cell, the photoelectrode is a combination of titanium oxide and a ruthenium complex sensitizing dye, which is a typical example of a titanium oxide photoelectrode. There is a problem that characteristics such as electromotive force are low.
The following Patent Document 1 discloses that the electromotive force of a dye-sensitized solar cell can be improved by forming a three-dimensional nanopore inside a single zinc oxide crystal to solve the problem of low electromotive force. Has been. This Patent Document 1 also describes that the photoelectrode is formed electrochemically without requiring heat treatment at a high temperature.
On the other hand, in the photoelectrode using a porous semiconductor obtained by sintering metal oxide fine particles such as titanium oxide and tin oxide, further improvement in electromotive force has been studied. Non-Patent Documents 1 to 3 below describe that an electromotive force can be improved by forming a very thin film of a metal oxide such as wide zirconium oxide, niobium pentoxide, and magnesium oxide to form a Core-Shell structure. Yes.

JP 2004006235 A Kay, Andreas; Graetzel, Michael.Dye-Sensitized Core-Shell Nanocrystals: Improved Efficiency of Mesoporous Tin Oxide Electrodes Coated with a Thin Layer of an Insulating Oxide. Chemistry of Materials (2002), 14 (7), 2930-2935. Diamant, Yishay; Chappel, Shlomit; Chen, S.G .; Melamed, Ophira; Zaban, Arie.Core-shell nanoporous electronic properties of the electrode.Coordination Chemistry Reviews (2004), 248 (13-14), 1271-1276. Tennakone, K .; Bandaranayke, PKM; Jayaweera, PVV; Konno, A .; Kumara, GRRA Dye-sensitized composite semiconductor nanostructures.Physica E: Low-Dimensional Systems & Nanostructures (Amsterdam, Netherlands) (2002), 14 (1- 2), 190-196.

  However, a dye-sensitized solar cell including a zinc oxide-based photoelectrode is insufficient in improvement of characteristics such as electromotive force and is not sufficiently durable.

Accordingly, the present invention provides a photoelectrode for a dye-sensitized solar cell using zinc oxide, which is a light electrode for a dye-sensitized solar cell in which characteristics such as electromotive force and stability thereof are improved. It is an object to provide a manufacturing method for manufacturing an electrode.

The invention relating to a method for producing a dye-sensitized solar cell photoelectrode includes a dye-sensitized dye comprising a porous zinc oxide layer on which a sensitizing dye and a metal oxide having a wider band gap than zinc oxide are supported. A method for producing a photoelectrode for a solar cell, comprising the steps of: supporting a metal alkoxide on the porous zinc oxide layer; and decomposing the metal alkoxide, and forming the metal on the porous zinc oxide layer. The step of supporting the oxide and decomposing the metal alkoxide includes an ultraviolet irradiation step of irradiating the porous zinc oxide layer with ultraviolet light in the presence of oxygen .

When the photoelectrode for a dye-sensitized solar cell manufactured by the manufacturing method according to the present invention is used in a dye-sensitized solar cell, the metal oxide having a wider band gap than zinc oxide in the porous zinc oxide layer Is supported, the electromotive force can be improved by suppressing the reverse electron transfer from the surface of the porous zinc oxide layer to the electrolyte.
Moreover, the elution of the sensitizing dye carried on the porous zinc oxide layer into the electrolyte can be suppressed to stabilize the carrying state of the sensitizing dye.
That is, the photoelectrode for dye-sensitized solar cell can be effective for improving the characteristics of the dye-sensitized solar cell and its stability.

Hereinafter, an embodiment of the dye-sensitized solar cell photoelectrode manufactured by a manufacturing method according to the present invention, with reference to FIG. 1 is a schematic cross-sectional view of a dye-sensitized solar cell photoelectrode according to the embodiment I will explain.

The photoelectrode 1 for a dye-sensitized solar cell according to the present embodiment is provided as a component of the dye-sensitized solar cell.
The dye-sensitized solar cell photoelectrode of the present embodiment is usually used in a dye-sensitized solar cell together with a counter electrode and an electrolyte composition.

  The photoelectrode 1 for a dye-sensitized solar cell according to this embodiment includes a conductive substrate 2, a porous zinc oxide layer 3 disposed on one surface side of the conductive substrate 2, and the porous zinc oxide layer 3. A sensitizing dye 4 carried on the metal, and a metal oxide 5 carried on the porous zinc oxide layer 3 and having a wider band gap than zinc oxide.

The conductive substrate 2 is provided with a conductive layer having conductivity on one side, and a substrate that transmits at least light having a wavelength necessary for the photoelectric conversion reaction can be used.
For example, an ITO glass substrate in which a transparent electrode is formed on a substrate such as a transparent glass plate can be used, and a 95% indium oxide and 5% tin oxide compound (ITO) is thinly deposited on the transparent glass plate. And an FTO glass substrate in which tin oxide (FTO) doped with fluorine is thinly deposited on a transparent glass plate. Moreover, it can replace with a transparent glass plate and can use transparent plastics, such as PET, for example as a board | substrate.
The thickness of the conductive substrate 2 is not particularly limited, but is preferably about 0.05 to 10 mm from the viewpoint of light transmittance.

The porous zinc oxide layer 3 is disposed on the transparent electrode of the conductive substrate. The porous zinc oxide layer 3 contains zinc oxide, and the form of the zinc oxide is in various forms such as, for example, a particulate form, a film form having a number of fine voids on the surface and inside, and the like. Can do.
The thickness of the porous zinc oxide layer 3 is not particularly limited, but is preferably about 0.5 to 50 μm from the viewpoints of permeability, conversion efficiency, and the like. Moreover, when used for a solar cell, the porosity is preferably 10 to 80% in that the electrolyte composition can sufficiently penetrate into the porous zinc oxide layer 3. The porosity can be calculated by measuring the film weight and film thickness and dividing by the specific gravity of zinc oxide.
When the zinc oxide is in the form of particles, particles having an appropriate average particle diameter, for example, an average particle diameter of about 1 to 100 nm are exemplified. In addition, particles having different particle sizes can exist. The average particle diameter can be measured by the BET method or the like.
When the zinc oxide is in the form of a film, the specific surface area is preferably about ^{2 to} 200 m ² / g. The specific surface area can be measured by the BET method or the like.

  A variety of sensitizing dyes 4 carried on the porous zinc oxide layer 3 can be used. For example, xanthene dyes eosin Y, fluorescein, erythrosin B, phloxine B, rose bengal, fluorexone, There are coumarin dyes such as coumarin 3 4 3 such as mercurochrome, dibromofluorescein, pyrogallol red, and triphenylmethane dyes such as bromophenol blue, bromothymol blue, and phenolphthalein. Other than these, D102, D131, D149 (trade names, all manufactured by Mitsubishi Paper Industries Co., Ltd.) and the like can be given. Furthermore, cyanine dyes, merocyanine dyes, porphyrins, phthalocyanines, perylene tetracarboxylic acid derivatives, indigo dyes, oxonol dyes and natural anthocyanins, gardenia dyes, turmeric dyes, safflower dyes, carotenoid dyes, cochineal dyes, paprika dyes, ruthenium metals Complex dyes can also be mentioned.

  Examples of the metal oxide 5 supported on the porous zinc oxide layer 3 and having a wider band gap than zinc oxide include aluminum oxide, magnesium oxide, silicon oxide, zirconium oxide, niobium oxide, tantalum oxide, vanadium oxide, titanium oxide, and oxide. Examples include indium.

  Next, the counter electrode and the electrolyte composition used for the dye-sensitized solar cell together with the above-described photoelectrode will be described.

  The counter electrode can be the same as the conductive substrate, that is, a conductive substrate having a conductive layer on one side.

Various electrolyte compositions can be used such as a liquid containing an electrolyte, a gel and a solid obtained by semi-solidifying the electrolyte with a gelling agent.
As a liquid thing, the liquid thing containing oxidation-reduction seed | species is mentioned. Specific examples include a solution in which redox species are dissolved. However, the solution is not particularly limited as long as it can be generally used in a battery, a solar battery, or the like. LiI as redox species, NaI, KI, combinations and LiBr metal iodide and iodine, such as CaI _2, NaBr, KBr, combinations of metal bromides and bromine, such as CaBr _2, the combination of salt and iodine iodide, A combination of bromide ion salt and bromine is preferable, and among these, a combination of LiI and iodine or a combination of iodide ion salt and iodine is preferable. These redox species can be used in several types such as a combination of metal iodide, iodide ion salt and iodine.
Examples of the solvent include carbonate compounds such as propylene carbonate, lactones such as γ-butyrolactone, nitrile compounds such as acetonitrile, alcohols such as ethanol, water, aprotic polar substances, and the like. Carbonate compounds, lactones and nitrile compounds are preferred. Two or more of these solvents can be used in combination.

  As a gel-like thing, what gelatinized the said liquid electrolyte composition with the polymer | macromolecule etc. is mentioned.

  Examples of the solid material include those that are made of a conductive material that can transport electrons, holes, and ions and can be used as an electrolyte of a solar cell. For example, a hole transport material such as polycarbazole and triphenylamine, an electron transport material such as tetranitrofluororenone, a conductive polymer such as polyroll, and a solid electrolyte composition obtained by solidifying a liquid electrolyte composition with a polymer compound And a solid electrolyte composition obtained by solidifying the liquid electrolyte composition with fine particles, and a P-type semiconductor such as copper iodide and copper thiocyanate.

  Next, a manufacturing method for manufacturing the above-described dye-sensitized solar cell photoelectrode will be described.

  The method for forming the film-like porous zinc oxide layer 3 on the conductive substrate 2 is not particularly limited, and various known methods can be mentioned. Specifically, a paste containing zinc oxide particles is applied on the conductive layer of the conductive substrate 2 by a screen printing method, an ink jet method or the like, and then fired, a sol-gel method, an electrochemical oxidation. Examples thereof include a method of forming a film on the conductive layer of the conductive substrate 2 by a method using a reduction reaction.

Here, the method of baking after applying the paste containing zinc oxide particles on the conductive layer of the conductive substrate 2 will be described in more detail.
First, a paste (hereinafter also referred to as “coating solution”) for forming the porous zinc oxide layer 3 is prepared.
As the coating liquid, a dispersion liquid in which zinc oxide particles are dispersed in a dispersion medium can be used.
As the dispersion medium, water or an organic solvent can be used. As the organic solvent, alcohol is preferred. At the time of dispersion in the dispersion medium, a small amount of a dispersion aid may be added as necessary. As this dispersion aid, for example, a surfactant, an acid, and a chelating agent can be used.

Application | coating of a coating liquid can be performed using the arbitrary methods conventionally used in the case of application | coating process. For example, a doctor blade method, a squeegee method, a roller method, a dive method, an air knife method, a blade method, a wire bar method, a slide hopper method, an extrusion method, and a curtain method can be exemplified. Further, a spin method or a spray method using a general-purpose machine may be used, and coating may be performed using wet printing such as intaglio, rubber plate, screen printing, as well as three major printing methods of letterpress, offset and gravure. Among these, a preferable film forming method can be used according to the liquid viscosity and the wet thickness.
The coating is preferably performed so that the amount of porous zinc oxide particles is ² to 200 g / m ² per 1 m ² of the surface of the conductive substrate 2.
After coating the coating liquid, it is preferable to form the porous zinc oxide layer (3) by performing drying and baking by a conventional method. In addition, drying and baking may be implemented simultaneously and may be performed by another process. The firing is preferably performed at 100 to 500 ° C. for 5 to 200 minutes.

In addition, a method for forming the porous zinc oxide layer 3 using an electrochemical redox reaction will be described in more detail.
In order to form the porous zinc oxide layer 3 by this electrochemical oxidation-reduction reaction, in the presence of the conductive substrate 2, a template compound is mixed in advance with an electrolytic solution containing a zinc salt, and cathode electrodeposition is performed. A method of forming a zinc oxide thin film having the template compound adsorbed on the inner surface on the surface of the conductive substrate 2 and then detaching the template compound from the zinc oxide thin film can be exemplified.
The template compound refers to a compound adsorbed on the inner surface of zinc oxide formed by cathode electrodeposition. The template compound does not exist in the bulk of zinc oxide by chemical adsorption, but forms a complex with zinc ions and is adsorbed on the inner surface of zinc oxide.

  More specifically, the cathodic electrodeposition for forming the porous zinc oxide layer 3 is performed in the presence of the conductive substrate 2 in an electrolytic bath containing a zinc salt. As the zinc salt, zinc halides such as zinc chloride, zinc bromide and zinc iodide, zinc nitrate, zinc perchlorate and the like can be used. In the case of using zinc halide, oxygen supply (bubbling) is usually performed. However, for example, in the case of using a sensitizing dye as a template compound, the oxygen bubble increases when it comes into contact. Bubbling is preferably performed so that bubbles do not come into contact with the sensitizing dye because the sensitizing dye may be difficult to be oxidized and detached. As a counter electrode when using a zinc salt, zinc, gold, platinum, silver or the like can be used. This cathode electrodeposition has an effect of forming a regular thin film structure of zinc oxide on the porous zinc oxide layer 3. In addition, the porous structure of the porous zinc oxide layer 3 is prepared by mixing the template compound in the electrolytic bath in advance and performing cathode electrodeposition, and further desorbing the template compound adsorbed on the inner surface of the zinc oxide thin film. It can be formed by carrying out the process to be performed. As a result, the template compound is desorbed from the surface of the zinc oxide thin film, a large number of voids are formed in the zinc oxide thin film, and the specific surface area is extremely porous. The porous zinc oxide layer 3 thus formed has nano-sized voids and has a large specific surface area, so that a large amount of the sensitizing dye 4 can be adsorbed on the surface. If the template compound is a compound having an anchor group such as a carboxyl group, a sulfonic acid group or a phosphoric acid group, the template compound can be removed using an aqueous solution of a base such as sodium hydroxide or potassium hydroxide. However, it is not limited to this, and can be appropriately performed according to the type of template compound. Washing with alkali is preferably performed at pH 10-13.

  Next, a method for supporting the metal oxide 5 having a wider band gap than zinc oxide on the porous zinc oxide layer 3 produced on the conductive substrate 2 will be described.

  First, the step of immersing the conductive substrate 2 on which the porous zinc oxide layer 3 is disposed in the metal alkoxide solution for a predetermined time to support the metal alkoxide on the porous zinc oxide layer 3 (hereinafter referred to as “supporting step”). And then decomposing the metal alkoxide supported on the porous zinc oxide layer 3 by taking out and drying the conductive substrate 2 immersed in a metal alkoxide solution for a predetermined time ( The metal oxide is supported on the porous zinc oxide layer 3 by carrying out a “decomposition step” hereinafter.

The decomposition of the metal alkoxide in the decomposition step is considered to proceed mainly by a hydrolysis reaction. According to this hydrolysis reaction, alcohol is generated as a decomposition product in addition to the metal oxide.
The produced metal oxide is supported on the porous zinc oxide layer 3, while the produced alcohol can be removed from the porous zinc oxide layer 3 by drying.

  The metal alkoxide is not particularly limited as long as the metal oxide produced by decomposition has a wider hand gap than zinc oxide, but aluminum alkoxide and magnesium alkoxide are preferable, and magnesium ethoxide and aluminum isopropoxide are more preferable.

  The solvent of the metal alkoxide is not particularly limited, and a solution in which the metal alkoxide is dissolved can be used, but the concentration is preferably a saturated concentration.

  The time for immersing the conductive substrate 2 provided with the porous zinc oxide layer 3 in the metal alkoxide solution is not particularly limited, but is preferably 0.1 to 10 minutes.

  As a method of drying the porous zinc oxide layer 3 carrying the metal alkoxide, a method of heating the porous zinc oxide layer 3 and a method of irradiating the porous zinc oxide layer 3 with ultraviolet light in the presence of oxygen , Etc. By these methods, decomposition of the metal alkoxide can be promoted, and in addition, removal of decomposition products other than metal oxides such as alcohol can be promoted.

  Among these, in the method of heating the porous zinc oxide layer 3, the heating temperature and the heating time are not particularly limited, but usually the decomposition temperature of the metal alkoxide is higher than the decomposition temperature of the metal alkoxide. It is preferable that the solvent is allowed to evaporate, and the temperature is equal to or higher than the boiling point of the alcohol generated by hydrolysis of the metal alkoxide.

In the method of irradiating the porous zinc oxide layer 3 with ultraviolet light in the presence of oxygen, the intensity of the ultraviolet light is preferably 1 to 100 mWcm ⁻² . The irradiation time is preferably 5 to 500 minutes.
When drying the porous zinc oxide layer 3 on which the metal alkoxide is supported, the metal alkoxide is decomposed by irradiating ultraviolet light in the presence of oxygen to promote the removal of decomposition products such as alcohol. Yes.

  As a method for supporting the metal oxide 5 having a wider band gap than that of zinc oxide on the porous zinc oxide layer 3 formed on the conductive substrate 2, the support is applied to one porous zinc oxide layer 3. A method of repeatedly performing the process and the decomposition process a plurality of times can be employed. By repeatedly performing the supporting step and the decomposing step, the amount of the metal oxide supported on the porous zinc oxide layer 3 can be adjusted, and the desired supporting amount can be easily achieved. .

As a method for adsorbing and supporting the sensitizing dye 4 on the porous zinc oxide layer 3, for example, the porous zinc oxide layer 3 formed on a substrate is dissolved in a solution in which the sensitizing dye 4 is dissolved (dye And a method of immersing in an adsorption solution). The solvent used for dissolving the sensitizing dye 4 may be any solvent that dissolves the sensitizing dye 4, such as alcohols such as ethanol and tertiary butanol, ketones such as acetone, diethyl ether, and tetrahydrofuran. Examples include ethers, nitrogen compounds such as acetonitrile, halogenated aliphatic hydrocarbons such as chloroform, aliphatic hydrocarbons such as hexane, aromatic hydrocarbons such as benzene, esters such as ethyl acetate, and water. These solvents can be used as a mixture of two or more.
The type of the sensitizing dye 4 and the solvent to be used can be appropriately adjusted, and the concentration of the sensitizing dye 4 in the solution is preferably high to some extent, and preferably 0.1 to 10 mM.
When the porous zinc oxide layer 3 is immersed in the solution in which the sensitizing dye 4 is dissolved, the temperature and pressure of the solution and the atmosphere are not particularly limited, and examples thereof include about room temperature and atmospheric pressure. The immersion time can be appropriately adjusted depending on the dye used, the type of solvent, the concentration of the solution, and the like. In addition, in order to perform effectively, it can immerse under heating.

The order of the method of supporting the metal oxide on the porous zinc oxide layer 3 and the method of supporting the sensitizing dye 4 on the porous zinc oxide layer 3 can be preceded.
When the porous zinc oxide layer 3 is loaded with the metal oxide in advance, the metal oxide is present on the surface of the porous zinc oxide layer 3 and further the sensitizing dye is loaded thereon. Further, the adsorption stability of a sensitizing dye having low adsorption stability to zinc oxide can be improved.
When the porous zinc oxide layer 3 is loaded with the sensitizing dye 4 in advance, the sensitizing dye is present on the surface of the porous zinc oxide layer 3, and the metal oxide is further loaded thereon. For this reason, the metal oxide supported on the surface of the porous zinc oxide layer 3 later acts to inhibit the detachment of the sensitizing dye, thereby suppressing the detachment of the sensitizing dye. Will be.

  The thickness of the supported metal oxide is not particularly limited, but is preferably about 0.1 to 10 times the unit cell thickness.

In addition, this invention is not limited to the photoelectrode for dye-sensitized solar cells exemplified above and the production method exemplified above.
Also. Although not described in detail here, various modes used in a general dye-sensitized solar cell photoelectrode and a method for producing the same can be employed within a range that does not impair the effects of the present invention.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

( Reference Example 1)
According to the following method, a photoelectrode for a dye-sensitized solar cell using zinc oxide (hereinafter, a photoelectrode for a zinc oxide-based dye-sensitized solar cell) was produced.

<Preparation of porous zinc oxide layer by electrodeposition method>
FTO glass (Asahi-U, 10 Ω / sq.) Is used for the conductive substrate, and ultrasonically cleaned for 15 minutes each in the order of acetone, 2-propanol, 0.5% Vista solution, and distilled water, and then before electrodeposition The mixture was hydrophilized with 45% nitric acid for 2 minutes.
Thereafter, a zinc oxide thin film is deposited by an electrodeposition method (hereinafter also referred to as “bottom layer”), and a zinc oxide / eosin Y hybrid thin film using eosin Y as a template compound thereon (hereinafter also referred to as “hybrid layer”). Was deposited to form a bottom layer / hybrid layer laminated structure. A rotating electrode device was used for electrolysis.
Prior to deposition of the bottom layer, preliminary electrolysis was performed for the purpose of activating the substrate against oxygen reduction. For this purpose, 0.1 M KCl aqueous solution is used as the electrolyte, and 100 mL / min. 20 minutes oxygen bubbling, using an FTO substrate as a working electrode, Pt wire as a counter electrode, and a saturated calomel electrode (SCE) as a reference electrode, an electrolysis temperature of 70 ° C., an electrolysis potential of −1.2 Vv. s. Electrolysis was performed for 30 minutes at SCE and a rotation speed of 500 ppm. The effective area was 3.8 cm ² (radius 1.1 cm). Oxygen bubbling was continued during electrodeposition.
Thereafter, a high-concentration ZnCl ₂ solution is added to deposit 5 mM ZnCl ₂ for electrodeposition of the bottom layer, the counter electrode is changed to a zinc wire, and the electrolysis potential is −1.0 V (vs. SCE) for 20 minutes. Went.
Next, in order to deposit a zinc oxide / eosin Y hybrid thin film, a high-concentration eosin Y solution was added so as to be 45 μM eosin Y, and electrodeposition was performed for 20 minutes.
The produced laminated film was immersed in an aqueous KOH solution having a pH of 10.5 at room temperature for 24 hours to desorb eosin Y as a template compound from the hybrid layer to make it porous.

<Supporting magnesium oxide with heating on porous zinc oxide layer>
The conductive substrate provided with the porous zinc oxide layer obtained by the above method was immersed in a saturated ethanol solution of magnesium ethoxide, pulled up vertically with tweezers, and then hot set at 90 ° C. Placed on a plate, the solvent ethanol (boiling point 78 ° C.) was evaporated. This process was repeated 20 times. Magnesium ethoxide reacts with moisture in the atmosphere to form magnesium oxide (MgO).

<Supporting of sensitizing dye eosin Y on porous zinc oxide layer>
Eosin Y was used as a sensitizing dye. The conductive substrate on which the porous zinc oxide layer is arranged is dried in an oven at 100 ° C. for 1 hour, then immersed in a 0.5 mM eosin Y / ethanol solution and refluxed for 1 hour to adsorb the sensitizing dye. After washing with ethanol, it was dried at room temperature.

( Reference Example 2)
A part of the production order was changed from that of Reference Example 1, and a photoelectrode for a zinc oxide dye-sensitized solar cell was produced. The difference from Reference Example 1 is that the sensitizing dye is supported on the porous zinc oxide layer before supporting magnesium oxide on the porous zinc oxide layer.

(Example 1 )
A photoelectrode for a zinc oxide-based dye-sensitized solar cell was produced in the same manner as in Reference Example 1 except that the method for supporting magnesium oxide on the porous zinc oxide layer was changed. The method after the change is shown.
<Supporting of magnesium oxide with ultraviolet irradiation on porous zinc oxide layer>
A conductive substrate on which a porous zinc oxide layer is arranged is immersed in a saturated ethanol solution of magnesium ethoxide and pulled up vertically using tweezers, and then UV-ozone cleaner (“NL-UV253” (trade name) UV-ozone treatment was performed by irradiating ultraviolet light in an oxygen atmosphere. The ultraviolet intensity was 3.7 mWcm ⁻² and the irradiation time was 10 minutes. This process was repeated 5 times. By the UV-ozone treatment, removal of organic substances derived from alkoxide and the like is expected.

( Reference Example 3 )
A photoelectrode for a zinc oxide-based dye-sensitized solar cell was produced in the same manner as in Reference Example 1 except that the production method of the porous zinc oxide layer was changed. The method after the change is shown.
<Preparation of porous zinc oxide layer by squeegee method>
Zinc oxide powder (“MZ-500” (trade name), manufactured by Teika Co., Ltd., average particle size 25 nm) was mixed with ethanol containing 0.5 v / v% acetylacetone to give a 32 wt% dispersion. This dispersion was applied to an ultrasonic crusher to obtain a zinc oxide paste. This zinc oxide paste was formed on a slide glass by a squeegee method to form a porous zinc oxide layer, and then dried at room temperature and normal pressure.

( Reference Example 4 )
A zinc oxide dye-sensitized solar cell photoelectrode was prepared in the same manner as in Reference Example 3 except that magnesium ethoxide was changed to aluminum isopropoxide.

( Reference Example 5 )
Photoelectrode for zinc oxide dye-sensitized solar cell as in Reference Example 3 except that the type of sensitizing dye and the method for supporting it were changed and magnesium ethoxide was changed to aluminum isopropoxide. Was made. The change of the type of sensitizing dye and the method for carrying it is shown below.

<Supporting of sensitizing dye D149 on porous zinc oxide layer>
D149 (trade name, manufactured by Mitsubishi Paper Industries Co., Ltd.) was used as the sensitizing dye. The conductive substrate on which the porous zinc oxide layer is arranged is dried in an oven at 100 ° C. for 1 hour, and then 0.5 mM D149 solution (solvent is 1 mM cholate tertiary butanol / acetonitrile ((v / v = 1 / It was immersed in 1)) for 10 minutes to adsorb the sensitizing dye, washed with tertiary butanol, and dried at room temperature.

(Comparative Example 1)
A photoelectrode for a zinc oxide-based dye-sensitized solar cell was prepared in the same manner as in Reference Example 1 except that magnesium oxide was not supported on the porous zinc oxide layer.

(Comparative Example 2)
A photoelectrode for a zinc oxide dye-sensitized solar cell was produced in the same manner as in Reference Example 5 except that magnesium oxide was not supported on the porous zinc oxide layer.

  A dye-sensitized solar cell provided with the prepared dye-sensitized solar cell photoelectrode was prepared, and an open circuit voltage was measured as an index of electromotive force. Further, the adsorption stability of the sensitizing dye of the produced dye-sensitized solar cell photoelectrode was evaluated.

  The dye-sensitized solar cell was produced as follows. The produced dye-sensitized solar cell photoelectrode and a counter electrode modified with Pt using an ion coater on an FTO glass substrate were bonded together via a spacer film (High Milan) to produce a sandwich type cell. As an electrolytic solution, a mixed solution of acetonitrile / ethylene carbonate (v / v = 1/4) containing 0.5 M tetrapropylammonium iodide (TPAI) and 0.05 M iodine was introduced into the cell by capillary action.

<Measurement of open circuit voltage>
In the IV measurement for measuring the open circuit voltage, the effective electrode area was regulated to 0.2 cm ² by superimposing a stainless mask with a 4 mm × 5 mm window on the cell. The evaluation of the IV characteristics was conducted using an IV curve tracer (“1.5”, 100 mWcm ⁻² ) by a solar simulator (“YSS-150A” (trade name), manufactured by Yamashita Denso Co., Ltd.) as a light source. MP-160 "(trade name) manufactured by Eihiro Seiki Co., Ltd. Spectral coincidence and light intensity were controlled by a spectroradiometer “LS-100” (trade name, manufactured by Eihiro Seiki Co., Ltd.). The results of Reference Examples 1 and 2, Example 1, and Comparative Example 1 are shown in Table 1.

<Adsorption stability of sensitizing dye>
The produced dye-sensitized solar cell photoelectrode is immersed in an electrolytic solution, taken out after an appropriate time, and the transmission absorption spectrum is measured with a spectrophotometer “U” in order to examine the concentration change of the dye attached to the photoelectrode. -4000 "(trade name, manufactured by Hitachi, Ltd.). The electrolyte is a 5 mL propylene carbonate solution containing 0.5 M tetrapropylammonium iodide (TPAI) and 0.05 M iodine. The container containing the electrolytic solution is covered with aluminum foil so that light does not enter the inside. In the case of the photoelectrode for dye-sensitized solar cell carrying eosin Y, the time setting of the sample to be measured was 0, 1, 4, 12, and 24 hours later. In the case of D149, 0, 2, 8, 24, and 48 hours later. The results for Reference Example 3 , Reference Example 4 and Comparative Example 1 are shown in FIGS. The results for Reference Example 5 and Comparative Example 2 are shown in FIGS. 3 (a) and 3 (b), respectively.

From the above, the photoelectrode manufactured by the manufacturing method of the present invention is effective in improving the characteristics and stability of the dye-sensitized solar cell using the zinc oxide photoelectrode. Recognize.

Schematic cross-sectional view showing an embodiment of a color Motozo sensitized solar cell photoelectrode. The graph which shows the adsorption stability of the sensitizing dye in the photoelectrode for dye-sensitized solar cells. The graph which shows the adsorption stability of the sensitizing dye in the photoelectrode for dye-sensitized solar cells.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photoelectrode for dye-sensitized solar cells 2 ... Conductive substrate 3 ... Porous zinc oxide layer 4 ... Sensitizing dye 5 ... Metal oxide having a wider band gap than zinc oxide

Claims (5)

A method for producing a photoelectrode for a dye-sensitized solar cell comprising a porous zinc oxide layer on which a sensitizing dye and a metal oxide having a wider band gap than zinc oxide are supported,
Carrying the metal alkoxide on the porous zinc oxide layer and decomposing the metal alkoxide, and carrying the metal oxide on the porous zinc oxide layer ;
The method of producing a photoelectrode for a dye-sensitized solar cell , wherein the step of decomposing the metal alkoxide includes an ultraviolet irradiation step of irradiating the porous zinc oxide layer with ultraviolet light in the presence of oxygen . Wherein before carrying metal alkoxide, the porous manufacturing method of the dye-sensitized solar cell photoelectrode of claim 1, the sensitizing dye to implement the process to be supported on the zinc oxide layer. After loading of the metal alkoxide, the porous manufacturing method of the dye-sensitized solar cell photoelectrode of claim 1, the sensitizing dye to implement the process to be supported on the zinc oxide layer. The method for producing a photoelectrode for a dye-sensitized solar cell according to any one of claims 1 to 3 , wherein the metal oxide is magnesium oxide and the metal alkoxide is magnesium alkoxide. The method for producing a photoelectrode for a dye-sensitized solar cell according to any one of claims 1 to 3 , wherein the metal oxide is aluminum oxide and the metal alkoxide is aluminum alkoxide.

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