JP2001076772A - Oxide semiconductor electrode and dye-sensitized solar battery using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To diffuse and adsorb a dye and a charge transportation phase fully and easily by providing a porous oxide semiconductor layer including hollow grains made of a metal oxide on a conductive substrate to form an electrode. SOLUTION: A conductive substrate 10 comprises a substrate 14 and a conductive membrane 16 formed on the substrate 14. A porous oxide semiconductor layer 12 is formed on the conductive membrane 16. The porous oxide semiconductor layer 12 has a structure connected with a plurality of hollow grains 20 having shells on oxide semiconductor fine grains 18. When this oxide semiconductor electrode 1 is used for a dye-sensitized solar battery, a pigment is carried on the porous oxide semiconductor layer 12, the pigment is kept in contact with a charge transportation phase, the charge transportation in the charge transportation phase is facilitated, and the characteristic of the dye-sensitized solar battery is improved. The average grain size of the hollow grains 20 is preferably set to 200 nm-10 μm. The dye and charge transportation is facilitated even when the oxide semiconductor grains 18 having the grain size easily transmitting from visible light to near infrared light related to photoelectric transfer are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an oxide semiconductor electrode containing hollow particles made of a metal oxide and a dye-sensitized solar cell using the same.

[0002]

2. Description of the Related Art In recent years, the use of a solar cell is expanding because it is a power generation means having little influence on the environment. A typical solar cell is a solid-state device using a pn junction of silicon, and a solar cell having a light energy conversion efficiency exceeding 20% has been developed at present. However, this type of solar cell has a problem that it is difficult to reduce the price and the power generation cost is high because large electric energy is required in the manufacturing process, particularly in the process of refining silicon as a raw material.

On the other hand, a dye-sensitized solar cell proposed by Gretzel et al. (Also referred to as a wet solar cell; Japanese Patent No. 2664194, J. Am. Chem. Soc., 1).
15, 6382-6390 (1993) and Nature, 353, 737 (1991). ) Is expected to be a low power generation cost solar cell because the materials used are inexpensive and large-scale equipment is not used for production.

FIG. 11 shows a cross-sectional view of an example of a dye-sensitized solar cell proposed by Gretzel et al. The dye-sensitized solar cell shown in FIG. 1 has a structure in which an electrolyte 106 containing iodide as an electrolyte is filled between an oxide semiconductor electrode 102 and a counter electrode 104. Oxide semiconductor electrode 102
Comprises a glass substrate 108, a transparent conductive film 110 formed on the glass substrate 108, and an oxide semiconductor layer 112 formed on the transparent conductive film 110. on the other hand,
The counter electrode 104 includes a glass substrate 114 and a glass substrate 114.
It is composed of a transparent conductive film 116 formed thereon.

FIG. 12 is an enlarged schematic cross-sectional view of a portion indicated by B of the dye-sensitized solar cell shown in FIG. The oxide semiconductor electrode 102 shown in FIG. 1 has a large number of solid oxide semiconductor particles, that is, solid oxide semiconductor particles 1 on a transparent conductive film 110 formed on a glass substrate 108.
An oxide semiconductor layer 112 having a structure in which the oxide semiconductor layers 18 are connected to each other is provided. Further, the dye 120 is chemically adsorbed on the surface of the solid particles 118 of the oxide semiconductor. Due to such a structure, voids are generated between the oxide semiconductor solid particles 118,
The oxide semiconductor layer 112 has a large surface roughness coefficient.

When light enters through the glass substrate 108 of the dye-sensitized solar cell shown in FIG. 11, the dye 120 is excited, and electrons are injected from the dye 120 into the oxide semiconductor layer 112. The electrons are supplied to the transparent conductive film 110 by a potential gradient.
, And further reaches the counter electrode 104 to reduce iodide ions in the electrolytic solution 106. The reduced iodide ions are oxidized on the dye 120. A current is generated by repeating the above.

Note that the oxide semiconductor layer 112 is manufactured by a method described below. That is, a slurry of solid oxide semiconductor particles having a diameter of about 10 to 30 nm is applied on the transparent conductive film 110 of the glass substrate 108 on which the transparent conductive film 110 is formed, and then dried and further heat-treated.
Alternatively, it is produced by applying a sol obtained by hydrolyzing a metal alkoxide on the transparent conductive film 110, drying the sol, and further performing a heat treatment.

[0008]

However, the above-mentioned conventional dye-sensitized solar cell has the following problems.

1) Since an oxide semiconductor layer is formed using solid oxide semiconductor particles having an extremely small particle size in order to increase the amount of dye adsorbed, visible to near-infrared light related to photoelectric conversion The light is transmitted through the semiconductor electrode without being sufficiently absorbed. 2) Since the voids inside the oxide semiconductor layer are small, it takes time to adsorb the dye, and the dye cannot be diffused and adsorbed deep into the oxide semiconductor layer. 3) Since the voids inside the oxide semiconductor layer are small, diffusion of a charge transporting phase such as an electrolytic solution is slow.

[0010] The present invention has been made in view of such technical problems, and it is intended to provide an oxide semiconductor particle having a particle size that is easy to transmit without sufficiently absorbing visible to near-infrared light related to photoelectric conversion. It is an object of the present invention to provide an oxide semiconductor electrode capable of sufficiently and easily diffusing and adsorbing a dye and a charge transporting phase even when used. Further, the present invention provides a dye-sensitized solar cell in which incident light is scattered and absorbed in the oxide semiconductor layer by using the oxide semiconductor electrode and the incident light utilization efficiency is high. With the goal.

[0011]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have obtained an electrode having a porous oxide semiconductor layer containing hollow particles made of metal oxide. By using this, it is possible to achieve both sufficient light absorption and sufficient diffusion and adsorption of the dye and the charge transport phase, and by using the electrode, a dye-sensitized solar cell having high utilization efficiency of incident light can be obtained. Were obtained, and the present invention was completed.

That is, the oxide semiconductor electrode of the present invention comprises:
It has a conductive substrate, and a porous oxide semiconductor layer formed on the conductive substrate and including hollow particles made of a metal oxide.

[0013] A dye-sensitized solar cell according to the present invention is a porous oxide semiconductor comprising a first conductive substrate and hollow particles formed of a metal oxide and formed on the first conductive substrate. A first electrode having a layer and a dye carried on the surface and / or inside of the porous oxide semiconductor layer; a second electrode made of a second conductive substrate; and the first electrode And a charge transport phase filled between the second electrodes.

As described above, the conventional method using only solid particles (non-hollow particles) by forming a porous oxide semiconductor layer containing hollow particles made of a metal oxide on a conductive substrate. As compared with (for example, the method disclosed by Gretzel et al., Above), it becomes possible to diffuse and adsorb the dye and the charge transport phase to the oxide semiconductor electrode sufficiently and easily. For this reason, in the dye-sensitized solar cell using the oxide semiconductor electrode, incident light is efficiently absorbed in the oxide semiconductor layer, and the utilization efficiency of the incident light increases.

In the oxide semiconductor electrode and the dye-sensitized solar cell of the present invention, the hollow particles made of metal oxide have an average particle size of 200 nm to 10 μm, and the hollow particles have an average particle size of 2 μm or less. It is preferable to have a shell made of metal oxide fine particles having a diameter.

The wavelength of light contributing to photoelectric conversion is 200 nm
10 μm to 10 μm, by including hollow particles having an average particle size approximately the same as this wavelength in the porous oxide semiconductor layer, the light scattering and confinement effect in the porous oxide semiconductor layer is increased, As a result, the efficiency of use of incident light on the oxide semiconductor electrode is increased, and the performance of the dye-sensitized solar cell tends to be improved.

Further, by setting the average particle diameter of the metal oxide fine particles constituting the shell of the hollow particles made of metal oxide to 2 μm or less, the total surface area of the hollow particles becomes large,
Since the amount of the dye to be supported increases, the efficiency of photoelectric conversion tends to increase.

Further, in the oxide semiconductor electrode and the dye-sensitized solar cell of the present invention, the metal oxide is TiO ₂ ,
SnO ₂ , ZnO, ZrO ₂ , Nb ₂ O ₅ , CeO ₂ , W
It is preferably at least one oxide selected from the group consisting of O ₃ , SiO ₂ and Al ₂ O ₃ or a composite oxide containing these oxides. The above oxides and composite oxides have a photosensitizing effect and / or a photocatalytic effect by a supported dye, and are effective in scattering light. Therefore, use of the oxides and composite oxides increases the efficiency of use of incident light. There is a tendency.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in more detail with reference to the drawings. First, an oxide semiconductor electrode according to the present invention will be described.

FIG. 1 is a sectional view showing a first embodiment of the oxide semiconductor electrode of the present invention. The oxide semiconductor electrode 1 shown in FIG. 1 comprises a conductive substrate 10 and a porous oxide semiconductor layer 12 formed thereon, and the conductive substrate 10
And a conductive film 16 formed on the substrate 14.

The material used for the substrate 14 constituting the conductive substrate 10 is not particularly limited, and various transparent or opaque materials can be used, but glass is preferably used. Although there is no particular limitation on the material used for the conductive film 16, antimony-doped tin oxide (SnO ₂ −
Sb), transparent doping of tin oxide or indium oxide doped with cations or anions having different valences, such as fluorine-doped tin oxide (SnO ₂ -F) and tin-doped indium oxide (In ₂ O ₃ -Sn). Preferably, electrodes are used.

As a method of forming the conductive film 16 on the substrate 14, a method such as vacuum deposition, sputtering, CVD, and sol-gel coating of components for forming the conductive film 16 can be used.

The structure of the porous oxide semiconductor layer 12 is shown in FIG.
FIG. 2 is an enlarged view of a portion indicated by A of the oxide semiconductor electrode 1 of FIG.
Is schematically shown in FIG. Porous oxide semiconductor layer 12
Is the conductive film 16 on the substrate 14 on which the conductive film 16 is formed.
Formed on the porous oxide semiconductor layer 12
Has a structure in which a plurality of hollow particles 20 having a shell made of oxide semiconductor fine particles 18 are connected. When the oxide semiconductor electrode 1 is used in a dye-sensitized solar cell, the porous oxide semiconductor layer 12 carries a dye, and the dye and the charge transport phase are in contact with each other. This facilitates the improvement of the characteristics of the dye-sensitized solar cell.

FIG. 3 is a schematic sectional view showing one of the plurality of hollow particles 20 shown in FIG. The shell of the hollow particles 20 is formed of the oxide semiconductor fine particles 18.
May be connected without gaps, or may be connected with some gaps in the oxide semiconductor fine particles 18.

In the present invention, the average particle diameter of the hollow particles 20 is preferably from 200 nm to 10 μm, more preferably from 300 nm to 2 μm.
When the average particle size of the hollow particles 20 is less than 200 nm, the effect of scattering and confining sunlight in the porous oxide semiconductor layer 12 tends to be limited to short wavelength components, and the average particle size of the hollow particles 20 Exceeds 10 μm, the thickness of the porous oxide semiconductor layer 12 including the hollow particles 20 tends to be unnecessarily large.

In the present invention, the hollow particles 20
More preferably has a particle size of 200 nm to 10 μm, and the specific surface area of the hollow particles 20 is 5 to
It is preferably 200 m ² / g.

Further, in the present invention, the average particle size of the oxide semiconductor fine particles 18 is preferably 2 μm or less, more preferably 5 nm to 2 μm. When the average particle size of the oxide semiconductor fine particles 18 exceeds 2 μm, the total surface area of the hollow particles 20 tends to be small, and therefore the amount of the dye to be supported may be insufficient.

Further, although the material used for the hollow particles 20 is not particularly limited as long as the oxide semiconductor, TiO _2,
SnO ₂ , ZnO, ZrO ₂ , Nb ₂ O ₅ , CeO ₂ , W
It is preferably at least one oxide selected from the group consisting of O ₃ , SiO ₂ and Al ₂ O ₃ or a composite oxide containing these oxides. Since the above-mentioned oxides and composite oxides have a photosensitizing effect and / or a photocatalytic effect by the supported dye, the use efficiency of incident light tends to be increased by using them.

As a method of forming the hollow particles 20 on the surface of the conductive film 16 formed on the substrate 14, for example, hollow particles 20 made of an oxide semiconductor are separately formed, A method of performing heat treatment after application on the upper surface can be adopted.

As a method for producing hollow particles made of a metal oxide, the method disclosed in Japanese Patent Application Laid-Open No. H11-16211 is preferably used. That is, an organic solvent is added to an aqueous solution in which a metal salt such as a metal nitrate is dissolved and / or suspended to form a W / O emulsion, and the W / O emulsion is formed.
It is a method of obtaining hollow particles of a metal oxide by spraying and burning a type emulsion.

As the organic solvent used for preparing the hollow particles, it is preferable to use a hydrocarbon organic solvent such as hexane, octane, kerosene, gasoline and the like. As means for spraying and burning the W / O emulsion, an emulsion combustion reactor disclosed in JP-A-7-81905 can be used. Hollow particles of metal oxide can be obtained from the emulsion.

An organic solvent, water, a surfactant and the like are added to the hollow particles of the metal oxide thus obtained to form a slurry, and the slurry is applied to the surface of the conductive film 16 formed on the substrate 10. By drying and heating at preferably 300 ° C. or more (for example, about 450 ° C.), an oxide semiconductor electrode having a structure shown in FIG. 2 can be obtained.

The oxide semiconductor electrode of the present invention is not limited to the first embodiment. FIG. 4 shows a schematic cross-sectional view of the second embodiment of the oxide semiconductor electrode of the present invention. The oxide semiconductor electrode shown in FIG. 1 has a metal oxide fine particle 1 on a conductive substrate 10 including a substrate 14 and a conductive film 16.
The porous oxide semiconductor layer 12 includes a mixture of hollow particles 21 having a shell made of carbon 9 and solid particles 22 of an oxide semiconductor. When the oxide semiconductor electrode shown in FIG. 4 is used for a dye-sensitized solar cell, the porous oxide semiconductor layer 12 carries a dye.

The material constituting the hollow particles 21 and the solid particles 22 of the oxide semiconductor is not particularly limited.
iO ₂ , SnO ₂ , ZnO, ZrO ₂ , Nb ₂ O ₅ , Ce
It is preferably at least one oxide selected from the group consisting of O ₂ , WO ₃ , SiO ₂ and Al ₂ O ₃ or a composite oxide containing these oxides. Note that the types of oxides constituting the hollow particles 21 and the oxide semiconductor solid particles 22 may be the same or different.

The diameter of the solid particles 22 of the oxide semiconductor is 3 nm.
〜1 μm is preferred. When the particle size of the solid oxide semiconductor particles 22 is less than 3 nm, the light scattering and confinement effects tend to be insufficient, and when it exceeds 1 μm, the surface area of the porous oxide semiconductor layer 12 is extremely small. Therefore, the amount of dye adsorbed may be reduced, and the characteristics of the dye-sensitized solar cell using the oxide semiconductor electrode of the present embodiment may be reduced, or the photocatalytic action of the oxide semiconductor electrode of the present embodiment may be reduced. There is.

In order to form the porous oxide semiconductor layer 12, for example, solid oxide semiconductor particles 22 are added to and mixed with a slurry containing hollow particles 21, and the mixture is added to the surface of the conductive film 16. After the application, the coating may be dried and heated in the same manner as in the first embodiment.

The oxide semiconductor electrode of the present invention is not limited to the first and second embodiments, but can be variously modified. For example, a modification of the first embodiment includes an oxide semiconductor electrode having a plurality of porous oxide semiconductor layers. That is, for example, an oxide semiconductor layer including only oxide semiconductor solid particles formed in contact with the conductive film 16 and a hollow particle layer formed on the oxide semiconductor layer and having a plurality of hollow particles 20 connected thereto are provided. An oxide semiconductor electrode may be used.

Further, as a modification of the second embodiment, similarly, an oxide semiconductor electrode having a plurality of porous oxide semiconductor layers can be mentioned. That is, for example, an oxide semiconductor layer formed of only solid oxide semiconductor particles formed in contact with the conductive film 16 and particles formed by mixing hollow particles 21 and solid oxide semiconductor particles formed thereon. An oxide semiconductor electrode including a layer may be used.

In order to manufacture an oxide semiconductor electrode having such a plurality of porous oxide semiconductor layers, for example,
On a conductive substrate composed of a substrate and a conductive film, a slurry of solid oxide semiconductor particles is applied, followed by drying and further heat treatment to form an oxide semiconductor layer consisting only of solid oxide semiconductor particles, A hollow particle layer may be formed on this layer in the same manner as in the first and second embodiments.

When the above-described oxide semiconductor electrode of the present invention is used, incident light is scattered in the oxide semiconductor layer as described later.
It is possible to manufacture a dye-sensitized solar cell that has a large amount of absorption and high utilization efficiency of incident light. Further, among the above oxide semiconductor electrodes, those having a porous oxide semiconductor layer made of an oxide semiconductor having a photocatalytic action can be used as an electrode of a dye-sensitized solar cell and also used as a photocatalyst, for example. Can be.

Next, the dye-sensitized solar cell according to the present invention will be described. FIG. 5 is a sectional view showing a first embodiment of the dye-sensitized solar cell of the present invention. The dye-sensitized solar cell 50 shown in the figure includes a first electrode 24 and a second electrode 26.
And the side surface is sealed with a sealing material 30 between the first and second electrodes, and the first electrode 24 corresponds to the above-described oxide semiconductor electrode of the present invention.

That is, the first electrode 24 is composed of the first substrate 32 and the first conductive film 3 formed on the first substrate 32.
4 and a porous oxide semiconductor layer 36 formed on the first conductive film 34. The porous oxide semiconductor layer 36 includes hollow particles made of a metal oxide, and a dye is supported on the surface and / or inside of the porous oxide semiconductor layer 36. On the other hand, the second electrode 26 includes a second substrate 38 and a second conductive film 40 formed on the second substrate 38. At least one of the first electrode 24 and the second electrode 26 is a transparent electrode.

The hollow particles made of a metal oxide have a shell in which metal oxide fine particles are connected without gaps and / or a shell in which metal oxide fine particles are connected with a gap. When the metal oxide fine particles are connected with some gaps therebetween, the shell has pores, which makes diffusion and adsorption of the dye and the charge transport phase easier. In addition, since the dye and the charge transport phase can be diffused and adsorbed into the hollow particles, the dye concentration in the porous oxide semiconductor layer increases, and the performance of the dye-sensitized solar cell improves.

The first substrate 32 on the first electrode 24,
The first conductive film 34 and the porous oxide semiconductor layer 36 are the same as the oxide semiconductor electrode substrate 14 and the conductive film 16 of the present invention described above.
And the same as the porous oxide semiconductor layer 12.

The dye carried on the surface and / or inside the porous oxide semiconductor layer 36 has at least two dyes.
It is not particularly limited as long as it is excited by light having a wavelength of 00 nm to 10 μm and emits electrons. Such dyes include di (thiocyanate) -N, N'-bis (2,2'-bipyridyl-4,4'-dicarboxylic acid)
-Ruthenium-based metal complexes such as ruthenium (II), and osmium-based metal complexes. As a method for supporting such a dye, for example, a method in which the porous oxide semiconductor layer 36 is immersed in a solution containing the dye may be mentioned.

The material used for the second substrate 38 is not particularly limited as in the case of the first substrate 32, and various transparent materials or opaque materials can be used, and glass is preferably used as the transparent substrate. . Further, the first substrate 32 and the second substrate 38 may be the same or different.

As the material used for the second conductive film 40, various conductive materials can be used as in the case of the first conductive film 34, and they may be the same or different. Note that the conductive film formed on the transparent substrate must be transparent. As a material for forming a transparent conductive film, a platinum thin film; antimony-doped tin oxide (SnO ₂ −
Sb), metal obtained by doping cations or anions having different valences into tin oxide or indium oxide, such as fluorine-doped tin oxide (SnO ₂ —F) and tin-doped indium oxide (In ₂ O ₃ —Sn). Materials.

As the charge transport phase 28, a liquid, gel or solid ionic conductor, hole transporter or electron transporter can be used. Examples of the liquid ionic conductor include an iodine-based ionic conductor in which tetrapropylammonium iodide and iodine are dissolved in acetonitrile or the like.

The sealing material 30 includes the charge transport phase 2
Any material can be used as long as it can seal the dye-sensitized solar cell so that 8 does not flow out, and is not particularly limited. For example, a thermoplastic resin made of an epoxy resin, a silicone resin, an ethylene / methacrylic acid copolymer, or the like is used. Can be.

When light enters through the first substrate 32 and / or the second substrate 38 of the dye-sensitized solar cell 50 shown in FIG. 5, the light is carried on the surface and / or inside the porous oxide semiconductor layer 36. The dye is excited, and electrons are injected from the dye into the porous oxide semiconductor layer 36. The electrons reach the first conductive film 34 and reach the second conductive film 40 by an external wiring (not shown) connected to the first conductive film 34 and the second conductive film 40. The electrons reduce the electrolyte in the charge transport phase 28, and the reduced electrolyte is oxidized on the dye, and the electrons move to the dye. A current is generated by repeating the above.

The dye-sensitized solar cell of the present invention is not limited to the first embodiment. FIG. 6 shows a cross-sectional view of a modification of the first embodiment of the dye-sensitized solar cell according to the present invention. The dye-sensitized solar cell shown in FIG.
The transmission light reflection layer 42 is provided on the back surface (the surface on which the second conductive film 40 is not formed) of the second electrode 38 of the first embodiment shown in FIG. By providing the transmitted light reflecting layer 42, even if a part of the light incident through the first substrate 32 passes through the porous oxide semiconductor layer 36, this light is reflected again toward the porous oxide semiconductor layer 36. And the performance of the dye-sensitized solar cell is improved.

FIG. 7 shows a second embodiment of the dye-sensitized solar cell of the present invention. Dye-sensitized solar cell 50 shown in FIG.
Has a configuration in which a charge transporting phase 28 is filled between a first electrode 24 and a second electrode 26, and a side surface is sealed with a sealing material 30.

The first electrode 24 includes a first substrate 32, a first conductive film 34 formed on the first substrate 32, and a porous oxide formed on the first conductive film 34. Semiconductor layer 36
It has. The porous oxide semiconductor layer 36 is formed so as to be in contact with the first conductive film 16, and is formed of an oxide semiconductor layer 43 made of only oxide semiconductor solid particles, and a hollow formed by connecting a plurality of hollow particles. And a particulate particle layer 44. A dye is supported on the surface and / or inside of the porous oxide semiconductor layer 36. On the other hand, the second electrode 2
6 includes a second substrate 38 and a second conductive film 40 formed on the second substrate 38. The first electrode 2
The fourth and / or second electrode 26 is a transparent electrode.

FIG. 8 is a sectional view showing a modification of the second embodiment of the dye-sensitized solar cell according to the present invention. The dye-sensitized solar cell shown in FIG. 8 has a transmitted light reflecting layer 42 on the back surface (the surface on which the second conductive film 40 is not formed) of the second electrode 38 of the second embodiment shown in FIG. It is provided with. By providing the transmitted light reflecting layer 42, the performance of the dye-sensitized solar cell is improved.

[0055]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

(Example 1) 315 ml of a nitric acid solution containing titanium ions (titanium ion concentration: 2.0 mol / l)
Then, 185 ml of kerosene and a small amount of a dispersant were added thereto, followed by stirring to obtain an emulsion. This emulsion was sprayed and burned at 700 ° C. using an emulsion burning apparatus to obtain hollow TiO ₂ particles. This hollow Ti
The O ₂ particles were heat-treated in the atmosphere at 400 ° C. for 4 hours and used for the following tests.

The hollow TiO ₂ obtained by the heat treatment was used.
About 60% of the particles are composed of the anatase phase and the rest of the rutile phase. The particle size of the particles is 200 nm to 5 μm (average particle size: 500 nm), and TiO that forms the crust of the particles is used.
₂ The particle size of the fine particles is 5 to 50 nm (average particle size: 10 nm)
Met. The specific surface area of the hollow TiO ₂ particles was 67 m ² / g.

Next, to 3.00 g of hollow TiO ₂ particles,
0.1 ml of acetylacetone, 6.0 m of ion-exchanged water
1, 0.05 ml of a surfactant (Triton-X) was added to form a slurry.

An SnO ₂ coated glass substrate (size: 15)
mm × 25mm) on the adhesive tape (thickness: 80μm)
Is applied as a mask and spacer, and the slurry is applied to an area of 1 cm ² using a bar coater, dried, and heat-treated at 450 ° C. for 30 minutes to form a porous layer on the SnO ₂ coated glass substrate. TiO ₂ layer (thickness: 10μ)
m) was prepared.

This electrode was treated with a dye (ruthenium-based metal complex:
Di (thiocyanate) -N, N'-bis (2,2'-bipyridyl-4,4'-dicarboxylic acid) ruthenium (I
I)) in an ethanol solution (concentration: 3.0 × 10 ⁻⁴ mol)
/ L) for 20 hours to carry the dye on the TiO ₂ layer, and to improve the open-circuit voltage, a solution of t-butylpyridine in acetonitrile (concentration: 5 × 10 ^-2 mol /
After immersion in l) for 15 minutes, the mixture was dried and used as a cathode of a dye-sensitized solar cell.

On the other hand, a SnO ₂ coated glass substrate (size: 15 mm ×
25 mm) as an anode, and the anode and the cathode are opposed to each other (interval: 50 μm). In the meantime, an iodine-based electrolyte (tetrapropyl ammonium iodide 0.6 mol /
5 and 5 × 10 ² mol / l of iodine (a solution of glutaronitrile) and sealing the periphery to obtain FIG.
A dye-sensitized solar cell as shown in (1) was produced.

Further, an anode was formed by forming an alumina sintered body for reflecting transmitted light on a platinum non-deposited surface of a SnO ₂ coated glass substrate on which platinum was deposited to a thickness of 3 nm by an electron beam deposition method. A dye-sensitized solar cell as shown in FIG. 6 was prepared from the iodine electrolytic solution.

(Example 2) Hollow Ti
1.50 g of O ₂ particles and 1.50 g of solid TiO ₂ particles (manufactured by Nippon Aerosil Co., Ltd., P25) were added to (hollow TiO ₂ particles /
Solid TiO ₂ particles = 50/50), 0.1 ml of acetylacetone, 6.0 ml of ion-exchanged water, surfactant (T
(Riton-X) Two kinds of dye-sensitized solar cells were produced in the same manner as in Example 1 except that 0.05 ml of added dye was used.

(Comparative Example 1) Solid TiO was used as a slurry.
₂ particles (Nippon Aerosil Co., Ltd., P25) 3.00g,
0.1 ml of acetylacetone, 6.0 m of ion-exchanged water
1 and two kinds of dye-sensitized solar cells were produced in the same manner as in Example 1, except that a solution containing 0.05 ml of a surfactant (Triton-X) was used.

The simulated sunlight of AM-1.5, 100 mW / cm ² obtained by using a solar simulator was applied to the dye-sensitized solar cells obtained in Examples 1 and 2 and Comparative Example 1. Irradiation was performed and the short-circuit current was measured. By measuring the short-circuit current ratio (short-circuit current with alumina sintered body / short-circuit current without alumina sintered body), how much the short-circuit current changes depending on the presence or absence of the alumina sintered body for transmitted light reflection I checked what to do. Table 1 shows the results.

[0066]

[Table 1]

In the dye-sensitized solar cells using electrodes containing hollow TiO ₂ particles (Examples 1 and 2), the dye-sensitized solar cells using electrodes containing only solid TiO ₂ particles (comparative examples) Light transmitted through the dye-sensitized solar cell was reduced as compared with Example 1), indicating that incident light was effectively used in the electrode.

Example 3 A nitric acid solution containing titanium ions and an equal amount of aluminum ions (titanium ion concentration:
2.0 mol / l, aluminum ion concentration: 2.0 m
(ol / l) 315 ml of kerosene and a small amount of a dispersant were added and stirred to obtain an emulsion. This emulsion is 750 with an emulsion combustion device.
Spray combustion at 0 ° C. gave hollow particles. The hollow particles were heat-treated in the atmosphere at 400 ° C. for 4 hours and used for the following tests.

The particle diameter of the hollow particles obtained by the heat treatment is 200 nm to 5 μm (average particle diameter: 500 nm), and the particle diameter of the fine particles is 5 to 50 nm (average particle diameter: 10 n).
m). The hollow particles have a specific surface area of 59 m.
² / g of a mixed phase of Al ₂ TiO ₅ and TiO ₂ ,
O ₂ was in the rutile phase.

Next, 0.75 g of the hollow particles and 2.25 of solid TiO ₂ particles (P25, manufactured by Nippon Aerosil Co., Ltd.)
5. g of acetylacetone and ion-exchanged water
0 ml, surfactant (Triton-X) 0.05 ml
Was added to form a slurry.

Using this slurry, two types of dye-sensitized solar cells were produced in the same manner as in Example 1. Further, for these dye-sensitized solar cells, AM-1.5, 100 mW / cm obtained using a solar simulator was used.
^The short-circuit current was measured by irradiating the simulated sunlight of No. ² . By measuring the short-circuit current ratio (short-circuit current with alumina sintered body / short-circuit current without alumina sintered body), how much the short-circuit current changes depending on the presence or absence of the alumina sintered body for transmitted light reflection I checked what to do. Table 2 shows the results together with the results of Comparative Example 1.

[0072]

[Table 2]

In a dye-sensitized solar cell using an electrode containing hollow particles (Example 3), a dye-sensitized solar cell using an electrode containing only solid TiO ₂ particles (Comparative Example 1)
As compared with, the light transmitted through the dye-sensitized solar cell was reduced, indicating that the incident light was effectively used in the electrode.

Example 4 0.1 g of acetylacetone, 6.0 ml of ion-exchanged water, 3.0 g of solid TiO ₂ particles (P25, manufactured by Nippon Aerosil Co., Ltd.)
riton-X) was added to obtain a slurry.

After a layer of only 10 μm P25 was formed on the SnO ₂ coated glass substrate using the above slurry, the hollow TiO ₂ layer shown in Example 1 was formed on the layer.
An electrode was produced in the same manner as in Example 1 except that a layer composed of the same hollow TiO ₂ particles was formed. Then, two kinds of dye-sensitized solar cells (dye-sensitized solar cells as shown in FIGS. 7 and 8) were produced in the same manner as in Example 1 using these electrodes.

[0076] (Example 5) as a slurry containing the hollow TiO ₂ particles, hollow TiO ₂ particles 0.75g and solid TiO ₂ particles (Nippon Aerosil Co., Ltd., P25) 2.25
g (hollow TiO ₂ particles / solid TiO ₂ particles = 25/7)
5), 0.1 ml of acetylacetone, ion-exchanged water
0 ml, surfactant (Triton-X) 0.05 ml
Except for using the addition of
Two types of dye-sensitized solar cells were produced.

(Comparative Example 2) The thickness of the layer consisting of only solid TiO ₂ particles (P25 manufactured by Nippon Aerosil Co., Ltd.) was 20 μm.
(Equivalent to the total thickness of the layer made of P25 and the layer of hollow TiO ₂ particles in Examples 4 and 5), and the same as Example 4 except that the layer made of hollow TiO ₂ particles was not formed Thus, two types of dye-sensitized solar cells were produced.

To the dye-sensitized solar cells obtained in Examples 4 and 5 and Comparative Example ² , simulated sunlight of AM-1.5, 100 mW / cm ² obtained using a solar simulator was used. Irradiation was performed and the short-circuit current was measured. By measuring the short-circuit current ratio (short-circuit current with alumina sintered body / short-circuit current without alumina sintered body), how much the short-circuit current changes depending on the presence or absence of the alumina sintered body for transmitted light reflection I checked what to do. Table 3 shows the results.

[0079]

[Table 3]

In the dye-sensitized solar cells using electrodes containing hollow TiO ₂ particles (Examples 4 and 5), the dye-sensitized solar cells using electrodes containing only solid TiO ₂ particles (comparative examples) Light transmitted through the dye-sensitized solar cell was reduced as compared with Example 2), indicating that incident light was effectively used in the electrode.

(Example 6) As slurry, 0.3 g of hollow TiO ₂ particles and 2.7 g of solid TiO ₂ particles (P25, manufactured by Nippon Aerosil Co., Ltd.) were used as in Example 1 (hollow T).
iO ₂ particles / solid TiO ₂ particles = 10/90), acetylacetone 0.1 ml, except that was used by adding ion-exchanged water 6.0 ml, surfactant (Triton-X) 0.05 ml is Example In the same manner as in Example 1, a dye-sensitized solar cell having an alumina sintered body was produced.

(Example 7) Hollow Ti
0.75 g of O ₂ particles and 2.25 g of solid TiO ₂ particles (manufactured by Nippon Aerosil Co., Ltd., P25) (hollow TiO ₂ particles /
Solid TiO ₂ particles = 25/75), acetylacetone 0.1 ml, ion exchanged water 6.0 ml, surfactant (T
(Riton-X) A dye-sensitized solar cell having an alumina sintered body was prepared in the same manner as in Example 1 except that 0.05 ml of the dye was added.

For the dye-sensitized solar cells having the alumina sintered bodies obtained in Examples 1, 2, 6, 7 and Comparative Example 1, AM-1.
5, 100 mW / cm ² of simulated sunlight was irradiated, and the short-circuit current and the conversion efficiency were measured. The results are shown in FIG.
As shown in FIG.

The cathodes of Comparative Example 1, Example 6, Example 7, Example 2, and Example 1 had hollow TiO _2.
The ratio of particles to solid TiO ₂ particles (hollow TiO ₂ particles / solid TiO ₂ particles) was 0/100, 10/9, respectively.
0, 25/75, 50/50 and 100/0.

FIG. 9 and FIG. 10 show that hollow TiO ₂ particles / solid TiO ₂ particles have peaks at 25/75 to 50/50. Since the diameter of the hollow TiO ₂ particles are larger than the diameter of the TiO ₂ particles, hollow TiO ₂
As particles / solid TiO ₂ particles approach 0/100 to 100/0, the total amount of TiO ₂ possessed by the cathode decreases. For this reason, the value when the ratio of the hollow TiO ₂ particles / solid TiO ₂ particles is 100/0 is smaller than the value when the ratio of the hollow TiO ₂ particles / solid TiO ₂ particles is 0/100. Conceivable.

[0086]

As described above, according to the present invention,
Even in the case of using oxide semiconductor particles having a particle size that easily absorbs and transmits visible to near-infrared light related to photoelectric conversion, the dye and the charge transport phase are sufficiently and easily diffused and adsorbed. An oxide semiconductor electrode that can be used is obtained. Further, by using such an oxide semiconductor electrode of the present invention, a dye-sensitized solar cell having a large amount of incident light scattered and absorbed in the oxide semiconductor layer and high utilization efficiency of incident light can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a first embodiment of an oxide semiconductor electrode according to the present invention.

FIG. 2 is a schematic sectional view of a main part of the first embodiment of the oxide semiconductor electrode according to the present invention.

FIG. 3 is a schematic cross-sectional view of hollow particles in the first embodiment of the oxide semiconductor electrode according to the present invention.

FIG. 4 is a schematic sectional view of a main part of a second embodiment of the oxide semiconductor electrode according to the present invention.

FIG. 5 is a sectional view of a first embodiment of a dye-sensitized solar cell according to the present invention.

FIG. 6 is a sectional view of a modification of the first embodiment of the dye-sensitized solar cell according to the present invention.

FIG. 7 is a sectional view of a second embodiment of the dye-sensitized solar cell according to the present invention.

FIG. 8 is a sectional view of a modification of the second embodiment of the dye-sensitized solar cell according to the present invention.

FIG. 9 is a graph showing the relationship between the mixing ratio of hollow TiO ₂ and short-circuit current in a dye-sensitized solar cell.

FIG. 10 shows hollow TiO ₂ in a dye-sensitized solar cell.
4 is a graph showing the relationship between the mixing ratio and the conversion efficiency.

FIG. 11 is a cross-sectional view of a conventional dye-sensitized solar cell.

FIG. 12 is a schematic sectional view of a main part of a conventional dye-sensitized solar cell.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Oxide semiconductor electrode, 10 ... Conductive substrate, 12 ... Porous oxide semiconductor layer, 14 ... Substrate, 16 ... Conductive film, 18 ...
Oxide semiconductor fine particles, 19 ... metal oxide fine particles, 20 ...
Hollow particles, 21 hollow particles, 22 solid oxide semiconductor particles, 24 first electrodes, 26 second electrodes, 28
Charge transport phase, 30 sealing material, 32 first substrate, 34
A first conductive film, 36 a porous oxide semiconductor layer, 38 a second substrate, 40 a second conductive film, 42 a transmitted light reflecting layer,
43: oxide semiconductor layer, 44: hollow particle layer, 50: dye-sensitized solar cell, 102: oxide semiconductor electrode, 104
... counter electrode, 106 ... electrolytic solution, 108 ... glass substrate, 110
... Transparent conductive film, 112 ... Oxide semiconductor layer, 114 ... Glass substrate, 116 ... Transparent conductive film, 118 ... Oxide semiconductor solid particles, 120 ... Dye.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazumasa Takatori 41-Cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Laboratory Co., Ltd. No. 41, Changchun Yokomichi No. 1 F-term in Toyota Central R & D Laboratories Co., Ltd. (Reference) 5F051 AA14 5H032 AA06 AS06 AS16 AS16 CC11 EE16 HH01 HH04

Claims (6)

[Claims] 1. An oxide semiconductor electrode comprising: a conductive substrate; and a porous oxide semiconductor layer formed on the conductive substrate and including hollow particles made of a metal oxide. 2. An average particle diameter of the hollow particles in the porous oxide semiconductor layer is 200 nm to 10 μm,
2. The hollow particles having a shell made of metal oxide fine particles having an average particle diameter of 2 μm or less.
26. The oxide semiconductor electrode according to claim 23. 3. The porous oxide semiconductor layer according to claim 2, wherein
The metal oxide is TiO_Two, SnO_Two, ZnO, ZrO_Two,
Nb_TwoO_Five, CeO_Two, WO_Three, SiO_TwoAnd Al _TwoO_ThreeFrom
At least one oxide selected from the group consisting of
Characterized by being a composite oxide containing these oxides
The oxide semiconductor electrode according to claim 1 or 2, wherein: 4. A semiconductor device comprising: a first conductive substrate; and a porous oxide semiconductor layer formed on the first conductive substrate and including hollow particles made of a metal oxide. A first electrode in which a dye is carried on the surface and / or inside of the semiconductor layer; a second electrode made of a second conductive substrate; and a space between the first electrode and the second electrode A charge-transporting phase, and a dye-sensitized solar cell. 5. The hollow particles have an average particle size of 200 nm.
The dye-sensitized solar cell according to claim 4, wherein the hollow particles have a shell made of metal oxide fine particles having an average particle diameter of 2 µm or less. 6. The method according to claim 1, wherein the metal oxide is TiO ₂ , SnO ₂ ,
ZnO, ZrO ₂ , Nb ₂ O ₅ , CeO ₂ , WO ₃ , SiO ₂
6. The dye-sensitized solar cell according to claim 4, which is at least one oxide selected from the group consisting of Al ₂ O ₃ and a composite oxide containing these oxides.