JP2003142171A - Photo-electrode and dye sensitized solar cell provide with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photo-electrode having excellent use efficiency of incident light and a dye sensitized solar cell having excellent energy conversion effi ciency. SOLUTION: This photo-electrode 10 has a light receiving surface F2, a semiconductor electrode 2 having at least a layer including sensitized dye and oxide semiconductor particles, a transparent electrode 1 adjacently arranged on the light receiving surface F2, and a light reflecting layer 7 arranged adjacently to a rear surface F23 of the semiconductor electrode 2. The light reflecting layer 7 has layer thickness of 3 to 50 μm and contains first particle having a refractive index <=1.8 and second particle having an average particle size >=150 nm and a refractive index >=2.4. A volume ratio of the second particle in the light reflecting layer 7 is 15 to 40%. The dye sensitized solar cell 20 is provided with the photo-electrode 10.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a photoelectrode and a dye-sensitized solar cell provided with the photoelectrode.

[0002]

2. Description of the Related Art In recent years, various developments of solar cells have been promoted with increasing interest in global warming and energy problems. Among the solar cells, dye-sensitized solar cells are expected to be put into practical use because the materials used are inexpensive and they can be manufactured by a relatively simple process.

In a conventional dye-sensitized solar cell, since the absorption coefficient of the sensitizing dye contained in the semiconductor electrode is small, light in the infrared to near-infrared wavelength region enters the semiconductor electrode. Also was not sufficiently absorbed in the semiconductor electrode and was transmitted, and did not contribute to the progress of the photoelectric conversion reaction.

Therefore, in order to put the dye-sensitized solar cell into practical use, various studies have been made to improve the energy conversion efficiency of the cell by improving the absorption efficiency of incident light in the semiconductor electrode provided in the photoelectrode. Is being done. The energy conversion efficiency η of the dye-sensitized solar cell
(%) Is represented by the following formula (1).

[0005] Here, in the following formulas (1), P ₀ is the incident light intensity [mWcm ^-2], V _oc is the open-circuit voltage [V], I _sc is the short circuit current density [mAcm ^-2], F.F. Is Fill Factor
Indicates. η = 100 × (V _oc × I _sc × F.F.) / P ₀ (1)

As the above-mentioned examination, for example, Japanese Patent Laid-Open No. 10-
In 255863, the average particle size is, for example, 80 nm.
The average particle diameter is, for example, 2 on the surface of the semiconductor electrode (light-absorbing particle layer) of the following which is a small semiconductor particle (for example, anatase type titanium oxide particle) as a constituent material, on the electrolyte side.
A layer (light-reflecting particle layer) having large high-refractive-index material particles (for example, rutile-type titanium oxide particles) having a size of 0 to 500 nm (light-reflecting particle layer) is provided to form a photoelectrode, and the light-absorbing particle layer faces the electrolyte There has been proposed a dye-sensitized solar cell intended to improve energy conversion efficiency by reflecting advancing incident light on a light-reflecting particle layer and then entering the light-absorbing particle layer again.

Further, in Japanese Patent Laid-Open No. 2000-106222, semiconductor particles having a large particle size (average particle size;
(300 nm) and semiconductor particles having a small particle size (average particle size; 10 nm or less) are mixed to form a semiconductor electrode, and the incident light incident on the semiconductor electrode is scattered inside, Dye-sensitized solar cells intended to improve energy conversion efficiency have been proposed.

Furthermore, Solar Energy Materials and Solar
Cells 44 (1996) 99-117 include anatase-type titanium oxide particles (when using a particle size of 25 nm and when using a mixture of particles having various particle sizes ranging from about 10 nm to about 120 nm). On the surface of the photoelectrode (photoelectrode, thickness: 10 μm) on the side of the electrolyte having a large refractive index, rutile-type titanium oxide particles (particle diameter: 300 nm) and zirconia particles (particles). (Diameter: 20 nm or less) in a mass ratio of rutile-type titanium oxide particles: zirconia particles = 100: 10 por
ous spacer (light reflecting spacer, thickness: 10μ
m) is provided, and the dye-sensitized solar cell intended to improve the energy conversion efficiency by reflecting the light transmitted from the photoelectrode toward the electrolyte side by the porous spacer and making it enter the photoelectrode again. Proposed.

[0009]

However, the present inventors have found that the dye-sensitized solar cell provided with the photoelectrode disclosed in JP-A-10-255863 described above, JP-A-2000-106.
222 and Solar Energy Materials and Solar Cells 44 (1)
996) In any of the dye-sensitized solar cells with 99-117 photoelectrodes, sufficient absorption efficiency of incident light was not obtained in the semiconductor electrodes that compose the photoelectrodes, and thus it was sufficient as a battery. It was found that the energy conversion efficiency could not be obtained and was still insufficient.

That is, in the case of the dye-sensitized solar cell described in JP-A-10-255863, the light-reflecting particle layer disposed on the electrolyte side reflects light toward the light-absorbing particle layer. The light use efficiency of the light absorbing particle layer is slightly increased, but the light reflecting particle layer cannot absorb the light and sufficiently advance the photoelectric conversion reaction in the layer, and further, the light reflectance is insufficient. Since it is sufficient, it is not possible to obtain sufficient light utilization efficiency as the entire photoelectrode, and there is a problem that sufficient energy conversion efficiency cannot be obtained. Further, there is a problem that the light reflection particle layer that does not absorb light sufficiently may increase the diffusion resistance of the electrolyte solution.

Further, in the case of the dye-sensitized solar cell described in Japanese Patent Laid-Open No. 2000-106222, as compared with the case where there is no large semiconductor particle as a result of light scattering of incident light by the large semiconductor particle in the semiconductor electrode. The light path length passing through the semiconductor electrode is increased and the light utilization efficiency is increased, but some light inevitably leaks out of the semiconductor electrode before it is used in the semiconductor electrode, resulting in a semiconductor There has been a problem that the effect of confining light in the electrode is reduced and sufficient light utilization efficiency cannot be obtained. Also,
In this case, when the number of large semiconductor particles in the semiconductor electrode increases, the total surface area of the semiconductor surface on which the dye is adsorbed decreases, and the light absorption rate decreases, which also causes a problem that energy conversion efficiency decreases. It was

Further, Solar Energy Materials and Solar
Also in the case of the dye-sensitized solar cell described in Cells 44 (1996) 99-117, since the porous spacer arranged on the electrolyte side reflects light toward the photoelectrode, the light utilization efficiency at the photoelectrode is improved. However, the porous spacer cannot absorb the light and sufficiently advance the photoelectric conversion reaction in the layer, and since the light reflectance is insufficient, the porous spacer and the photoelectrode are combined. In addition, there is a problem in that it is impossible to obtain sufficient light utilization efficiency as a whole and sufficient energy conversion efficiency cannot be obtained.

The present invention has been made in view of the above problems of the prior art, and provides a photoelectrode having excellent utilization efficiency of incident light and a dye-sensitized solar cell having excellent energy conversion efficiency. The purpose is to

[0014]

As a result of intensive studies to achieve the above object, the inventors of the present invention have found that particles having a refractive index of 1.8 or less and particles having an average particle diameter of 150 nm or more and a refractive index of 2 or less. And a layer in which the content of each of which is 4 or more is adjusted and contained to greatly improve the reflectance of incident light, and the layer is disposed adjacent to the back surface side facing the light receiving surface of the semiconductor electrode. As a result, they have found that the light confinement effect of incident light as a whole semiconductor electrode can be greatly improved, and have reached the present invention.

That is, the present invention provides a semiconductor electrode having a light-receiving surface, a semiconductor electrode having a light-receiving surface and having at least one layer containing a sensitizing dye and oxide semiconductor particles, and a light-receiving surface of the semiconductor electrode. A transparent electrode disposed adjacent to the surface, and a light reflection layer disposed adjacent to the back surface facing the light receiving surface of the semiconductor electrode (hereinafter referred to as the back surface of the semiconductor electrode), The layer thickness of the light reflecting layer is 3 to 50 μm, and the light reflecting layer has first particles having a refractive index of 1.8 or less (hereinafter referred to as low refractive index particles) and an average particle diameter of 150.
second particles having a refractive index of 2.4 or more and 2.4 or more (hereinafter referred to as high refractive index particles), and the volume ratio of the second particles in the light reflecting layer is 15 to 40.
% Is provided.

The light reflecting layer disposed adjacent to the back surface of the semiconductor electrode has a structure in which the high refractive index particles having a large particle diameter as described above and the low refractive index particles are mixed, whereby the light in this layer is The reflection efficiency can be significantly improved. Therefore, by efficiently reflecting the light incident from the transparent electrode in the light reflection layer and advancing a sufficient amount of light again to the layer of the semiconductor electrode arranged between the light reflection layer and the transparent electrode, It is possible to secure a sufficiently long optical path length of light traveling in the semiconductor electrode. That is,
It is possible to confine a sufficient amount of light in the semiconductor electrode,
It is possible to improve the light utilization efficiency of the entire semiconductor electrode.

The values of the above-mentioned refractive indexes of the low refractive index particles and the high refractive index particles of the present invention are
It is a value defined for incident light in the wavelength region of 400 to 900 nm.

Here, if the thickness of the light reflecting layer is less than 3 μm, the light reflecting efficiency of the light reflecting layer becomes small and the light confining effect becomes insufficient. On the other hand, the thickness of the light reflection layer is 5
When it exceeds 0 μm, the ion diffusion resistance increases, and the export of I ₃ ^{− to} the counter electrode, which is caused by the electron injection from I ⁻ into the dye after photoexcitation and electron injection into the semiconductor, is hindered, and Output characteristics are degraded. From the same viewpoint as above, the thickness of the light reflecting layer is more preferably 5 to 15 μm.

When the refractive index of the low refractive index particles contained in the light reflecting layer exceeds 1.8, the light reflecting efficiency in the light reflecting layer becomes small and the light confining effect becomes insufficient. Further, the refractive index of the high refractive index particles contained in the light reflecting layer is 2.
When it is less than 4, the light reflection efficiency in the light reflection layer becomes small and the light confinement effect becomes insufficient.

When the average particle diameter of the high refractive index particles contained in the light reflection layer is less than 150 nm, the light reflection (light scattering) effect is small and the light confinement effect is insufficient. Further, if the average particle size of the high refractive index particles contained in the light reflecting layer is too large, the number density of the high refractive index particles decreases, so that a uniform light scattering effect in the layer cannot be obtained and the light confinement effect becomes unsatisfactory. The average particle size of the high-refractive-index particles contained in the light-reflecting layer is more preferably from 200 to 400 nm, because it may be sufficient and the mechanical strength of the layer may be insufficient.

Further, when the volume ratio of the high refractive index particles in the light reflection layer is less than 15%, the light reflection (light scattering) effect in the light reflection layer becomes small, and the light confinement effect as the entire semiconductor electrode becomes unsatisfactory. Will be enough. On the other hand, even if the volume ratio of the high-refractive-index particles in the light-reflecting layer exceeds 40%, the light-reflecting (light-scattering) effect in the light-reflecting layer becomes small, and the light-confining effect as the entire semiconductor electrode becomes insufficient. Become.

In the photoelectrode of the present invention, the first particles (low refractive index particles) are silicon dioxide particles and the second particles are
The particles (high refractive index particles) are preferably rutile type titanium oxide particles. By combining these low refractive index particles composed of silicon dioxide particles and high refractive index particles composed of rutile type titanium oxide particles, a light reflecting layer having a high light reflectance can be more reliably formed.

Further, the photoelectrode of the present invention has a layer thickness of 5 to 49.
μm, a sensitizing dye, an oxide semiconductor particle having an average particle diameter of 70 nm or less (hereinafter, referred to as “small diameter particle”), and an oxide semiconductor particle having an average particle diameter of 150 nm or more (hereinafter,
At least one layer including a “large-diameter particle”) is disposed between the transparent electrode and the light reflection layer as a layer forming a semiconductor electrode.

A layer (hereinafter referred to as an LR layer) having such a structure in which large-diameter particles and small-diameter particles are mixed can scatter light inside and absorb the light to be used for photoelectric conversion reaction. It is also possible to do. Therefore, by disposing at least one LR layer between the transparent electrode and the light reflection layer, it is possible to confine a sufficient amount of light in the semiconductor electrode and utilize it in the photoelectric conversion reaction more reliably.

When the semiconductor electrode is composed of a plurality of layers containing a sensitizing dye and oxide semiconductor particles, the LR
The position of the layer is not particularly limited as long as it is between the transparent electrode and the light reflection layer.

In the present specification, in the case where the semiconductor electrode is composed of a plurality of layers containing a sensitizing dye and oxide semiconductor particles, the layer of the semiconductor electrode located closest to the transparent electrode is used. The "innermost layer" is called, and the layer of the semiconductor electrode arranged at the farthest position from the transparent electrode is called "outermost layer".

Further, if the layer thickness of the LR layer is less than 5 μm, the amount of the sensitizing dye adsorbed becomes small and it becomes impossible to effectively absorb light. On the other hand, when the layer thickness of the LR layer exceeds 49 μm,
The electric resistance increases, the loss of carriers injected into the semiconductor increases, and the ion diffusion resistance increases,
The carry-out of I ₃ ^{− to} the counter electrode, which is caused by the electron injection from I ⁻ into the dye after being photoexcited to inject electrons into the semiconductor, is obstructed, and the output characteristics of the battery tend to deteriorate. From the same viewpoint as above, the layer thickness of the LR layer is 7 to
It is more preferably 12 μm.

When the average particle size of the small particles contained in the LR layer exceeds 70 nm, the amount of the sensitizing dye in the electrode decreases. In addition, from the above viewpoint, if the average particle size of the small-sized particles contained in the LR layer is too small, the pore size in the semiconductor electrode layer becomes small, which increases the adsorption time of the sensitizing dye and the electrolyte solution of the sensitizing dye. From the viewpoint that it may be difficult to diffuse into the LR layer, the average particle size of the small particles contained in the LR layer is 1
It is more preferably 0 to 50 nm.

Further, if the average particle size of the large-sized particles contained in the LR layer is less than 150 nm, the light scattering effect is small and the light confinement effect is insufficient. In addition, from the above viewpoint, L
If the average particle size of the large particles contained in the R layer is too large,
Since the mechanical strength of the LR layer may be insufficient, the LR
The average particle size of the large particles contained in the layer is 150 to 450.
More preferably, it is nm.

In this case, the mixing ratio of the large-diameter particles to the total amount of the small-diameter particles and the large-diameter particles in the light reflecting layer is 2
It is preferably 0 to 80% by mass, and more preferably 30 to 60% by mass. Thereby, the light scattering efficiency in the semiconductor electrode can be improved more accurately.

Further, in the photoelectrode of the present invention, the oxide semiconductor particles contained in the LR layer are at least one kind of particles selected from the group consisting of anatase type titanium oxide, zinc oxide, tin oxide and niobium oxide. Preferably there is. By using such particles, it is possible to more reliably form an LR layer that can sufficiently scatter and absorb light.

The photoelectrode of the present invention has a layer thickness of 1 to 5 μm.
m, containing a sensitizing dye and oxide semiconductor particles having an average particle diameter of 70 nm or less, and the proportion of particles having a particle diameter of 100 nm or more in the oxide semiconductor particles is 5% by mass. At least one of the following layers may be arranged between the transparent electrode and the light reflection layer as a layer constituting the semiconductor electrode.

The layer having such a structure (hereinafter referred to as LA layer) can sufficiently suppress the scattering of light inside the layer, absorb the light efficiently, and allow the photoelectric conversion reaction to proceed efficiently. . Therefore, by disposing at least one LA layer between the transparent electrode and the light reflecting layer, it is possible to confine a sufficient amount of light in the semiconductor electrode and utilize it in the photoelectric conversion reaction more reliably.

When the semiconductor electrode is composed of a plurality of layers containing a sensitizing dye and oxide semiconductor particles, the LA
The arrangement position of the layer is not particularly limited as long as it is between the transparent electrode and the light reflection layer, but it is preferable that the layer is arranged at a position closest to the transparent electrode among the plurality of layers forming the semiconductor electrode. In particular, in the case where the semiconductor electrode also includes the above-mentioned LR layer in addition to the LA layer, from the viewpoint of effectively utilizing the light scattered in the LR layer in addition to the light reflecting layer, it is closer to the transparent electrode than the LR layer. It is preferably arranged in a position.

Here, "the particle size is 10 is included in the LA layer.
The term "particles having a particle size of 0 nm or more" refers to primary particles when the primary particles of the oxide semiconductor particles in the LA layer exist in a state where they do not aggregate, and a state where primary particles of the oxide semiconductor particles aggregate in the LA layer. Indicates secondary particles.

Therefore, the "particle size" of the "particles having a particle size of 100 nm or more" refers to the primary particle size when the primary particles of the oxide semiconductor particles in the LA layer do not aggregate. When the primary particles of the oxide semiconductor particles are present in the LA layer in an aggregated state, the secondary particle size is shown.

For example, when a method of applying a dispersion liquid of oxide semiconductor particles contained in the LA layer and then drying / sintering it is used to form the LA layer, the pH of the dispersion liquid is adjusted to adjust the oxide content. The dispersed state of the semiconductor particles can be controlled. Usually, when the dispersion is strongly acidic or strongly alkaline, the primary particles are dispersed without aggregating, and when the dispersion is weakly acidic to weakly alkaline, the primary particles are agglomerated and dispersed.

The LA layer composed of oxide semiconductor particles in which the content of such "particles having a particle diameter of 100 nm or more" is 5% or less, effectively prevents light scattering in the layer. You can

When the layer thickness of the LA layer is less than 1 μm, the amount of the sensitizing dye adsorbed is small and it tends to be impossible to effectively absorb light. On the other hand, when the layer thickness of the LA layer exceeds 5 μm, the electric resistance increases, the loss amount of carriers injected into the semiconductor increases, and the ion diffusion resistance increases, which causes photoexcitation and electron injection into the semiconductor. After that, the carry-out of I ₃ ^{− to} the counter electrode, which is caused by the electron injection from I ⁻ into the dye, is obstructed, and the output characteristics of the battery tend to deteriorate. From the same viewpoint as above, the layer thickness of the LA layer is more preferably 2 to 4 μm.

Further, when the average particle diameter of the oxide semiconductor particles contained in the LA layer exceeds 70 nm, the scattering of light by these particles becomes remarkable, and as a result, the reflectance of light in the LA layer increases, The use efficiency of light is likely to decrease. From the same viewpoint as above, the average particle size of the oxide semiconductor particles contained in the LA layer is 10 to 50.
More preferably, it is nm.

Further, even if the oxide semiconductor particles contained in the LA layer have an average particle diameter of 70 nm or less, if the particles included in the LA semiconductor layer have a particle diameter of 100 nm or more, the light emitted by these particles is Scattering occurs. When the proportion of particles having a particle diameter of 100 nm or more exceeds 5% by mass, the scattering of light by these particles becomes remarkable, and as a result, the light reflectance in the LA layer increases and the light utilization efficiency decreases. The tendency to do so increases.

Furthermore, the present invention has a photoelectrode having a semiconductor electrode having a light-receiving surface and a transparent electrode disposed adjacent to the light-receiving surface of the semiconductor electrode, a counter electrode, and an electrolyte. There is provided a dye-sensitized solar cell in which a semiconductor electrode and a counter electrode are arranged via an electrolyte, and the photoelectrode is the above-described photoelectrode of the present invention. As described above, by using the above-described photoelectrode of the present invention, a dye-sensitized solar cell having excellent energy conversion efficiency can be constructed.

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the photoelectrode and the dye-sensitized solar cell of the present invention will be described in detail below with reference to the drawings. In the following description, the same or corresponding parts will be denoted by the same reference symbols, without redundant description.

[First Embodiment] FIG. 1 is a schematic sectional view showing a first embodiment of the photoelectrode of the present invention. Also, FIG.
[Fig. 2] is a schematic cross-sectional view showing a dye-sensitized solar cell provided with the photoelectrode shown in Fig. 1. Further, FIG. 3 is a schematic cross-sectional view showing another form of the dye-sensitized solar cell shown in FIG.
FIG. 4 is a schematic cross-sectional view showing still another form of the dye-sensitized solar cell shown in FIG.

The photoelectrode 10 shown in FIG. 1 mainly comprises a semiconductor electrode 2 having a light-receiving surface F2, a transparent electrode 1 disposed adjacent to the light-receiving surface F2 of the semiconductor electrode 2, and a back surface of the semiconductor electrode 2. The light reflecting layer 7 is disposed adjacent to F23.

Further, the dye-sensitized solar cell 20 shown in FIG.
Is mainly the photoelectrode 10 shown in FIG.
And the electrolyte E filled in the gap formed between the photoelectrode 10 and the counter electrode CE by the spacer S. The photoelectrode 10 is in contact with the electrolyte E on the back surface F10 opposite to the light receiving surface F1.

The dye-sensitized solar cell 20 generates electrons in the semiconductor electrode 2 by the light L10 which is transmitted through the transparent electrode 1 and is applied to the semiconductor electrode 2. And
The electrons generated in the semiconductor electrode 2 are collected in the transparent electrode 1 and taken out to the outside.

The structure of the transparent electrode 1 is not particularly limited, and a transparent electrode mounted on an ordinary dye-sensitized solar cell can be used. For example, the transparent electrode 1 shown in FIGS. 1 and 2 has a structure in which a so-called transparent conductive film 3 for transmitting light is coated on the semiconductor electrode 2 side of a transparent substrate 4 such as a glass substrate. As the transparent conductive film 3, a transparent electrode used for a liquid crystal panel or the like may be used.

For example, fluorine-doped SnO ₂ coated glass, ITO coated glass, ZnO: Al coated glass and the like can be mentioned. Further, a metal electrode having a structure capable of transmitting light, such as a mesh shape or a stripe shape, may be provided on the substrate 4 such as a glass substrate.

As the transparent substrate 4, a transparent substrate used for a liquid crystal panel or the like may be used. Specific examples of the transparent substrate material include a transparent glass substrate, a glass substrate whose surface is appropriately roughened to prevent light reflection, and a frosted glass-like semitransparent glass substrate which transmits light.
The material need not be glass as long as it transmits light, and may be a transparent plastic plate, a transparent plastic film, an inorganic transparent crystal body, or the like.

The semiconductor electrode 2 shown in FIG. 1 is composed of two layers. That is, the semiconductor electrode 2 includes the innermost layer 21 arranged closest to the transparent electrode 1 and the outermost layer 2 arranged farthest from the transparent electrode 1.
3 and 3.

As described above, the light reflecting layer 7 has a layer thickness adjusted to 3 to 50 μm. Further, the light reflection layer 7 contains the low refractive index particles and the high refractive index particles each having the above-described refractive index, and the high refractive index particles are adjusted to have an average particle diameter of 150 nm or more. Further, the volume ratio of the high refractive index particles in the light reflecting layer 7 is 15 to 4
It is adjusted to 0%. In the photoelectrode 10, the light reflection layer 7 having the above structure is arranged adjacent to the back surface F23 of the semiconductor electrode 2 to improve the absorption efficiency of incident light in the semiconductor electrode 2. ing.

The high refractive index particles have an average particle size of 150 nm.
The above is not particularly limited as long as the refractive index is 2.4 or more, and rutile type titanium oxide particles, anatase type titanium oxide,
Zirconia (ZrO ₂ ) particles and the like can be used, but rutile type titanium oxide particles are particularly preferable.

The low refractive particles have a refractive index of 1.
It is not particularly limited as long as it is 8 or less, and silica (SiO ₂ ) particles, magnesia (MgO) particles, alumina (Al ₂ O ₃ )
Particles and the like can be used, but silica particles are particularly preferable.

As in the dye-sensitized solar cell 20 shown in FIG. 2 which will be described later, the dye-sensitized solar cell including the photoelectrode 10 has a spacer S disposed between the photoelectrode 10 and the counter electrode CE. In the case where the electrolyte E is enclosed in the space formed between the photoelectrode 10 and the counter electrode CE by the above,
The same oxide semiconductor particles and sensitizing dye as those used for the innermost layer 21 described later may be contained.

On the other hand, as in the dye-sensitized solar cell 31 shown in FIG. 4, which will be described later, the dye-sensitized solar cell including the photoelectrode 10 has the counter electrode CE adjacent to the light reflection layer 7 of the photoelectrode 10. In the case of the arrangement, the light reflection layer 7 is required not to have electronic conductivity.

The innermost layer 21 of the semiconductor electrode 2 has the LA layer structure described above, and the outermost layer 23 has the LR layer structure described above. That is, as described above, the innermost layer 21 is adjusted to have a layer thickness of 1 to 5 μm. The average particle diameter of the oxide semiconductor particles contained in the innermost layer 21 is adjusted to 70 nm or less, and the particle diameter of the oxide semiconductor particles is 100 nm.
The ratio of the above particles is adjusted to 5% by mass or less.

The outermost layer 23 has a layer thickness of 5 to 49.
It is adjusted to be μm. Furthermore, the outermost layer 2
The average particle size of the small particles contained in 3 is adjusted to 70 nm or less, and the average particle size of the large particles contained in the outermost layer 23 is adjusted to 150 nm or more.

The innermost layer 21 is mainly composed of oxide semiconductor particles having a size satisfying the above-mentioned conditions, and a sensitizing dye adsorbed on the surface of the oxide semiconductor particles.

The oxide semiconductor particles contained in the innermost layer 21 are not particularly limited, and known oxide semiconductors and the like can be used. As an oxide semiconductor,
For example, TiO ₂ , ZnO, SnO ₂ , Nb ₂ O ₅ , In ₂
O ₃ , WO ₃ , ZrO ₂ , La ₂ O ₃ , Ta ₂ O ₅ , SrTi
O ₃ , BaTiO ₃ or the like can be used.

The sensitizing dye contained in the innermost layer 21 is not particularly limited, and may be in the visible light region or /
Alternatively, a dye having absorption in the infrared light region may be used. As the sensitizing dye P2, a metal complex, an organic dye or the like can be used. Examples of the metal complex include metal phthalocyanines such as copper phthalocyanine and titanyl phthalocyanine, chlorophyll or its derivatives, hemin, ruthenium, osmium, iron and zinc complexes (for example, cis-dicyanate-
Examples thereof include bis (2,2′-bipyridyl-4,4′-dicarboxylate) ruthenium (II)). As the organic dye, metal-free phthalocyanine, cyanine dye, merocyanine dye, xanthene dye, triphenylmethane dye, etc. can be used.

The outermost layer 23 is mainly composed of small-diameter particles having a size satisfying the above-mentioned conditions, large-diameter particles, and sensitizing dyes adsorbed on the surfaces of these small-diameter particles and large-diameter particles. It consists of and.

The oxide semiconductors forming the small particles and the large particles contained in the outermost layer 23 are selected from the group consisting of anatase type titanium oxide, zinc oxide, tin oxide and niobium oxide. At least one kind of particles can be used, but anatase type titanium oxide is preferable. Further, the sensitizing dye contained in the outermost layer 23 is not particularly limited as in the sensitizing dye contained in the innermost layer 21, and is absorbed in the visible light region and / or the infrared light region. Any dye that has For example, a dye similar to the sensitizing dye contained in the innermost layer 21 described above may be used.

The thickness of the semiconductor electrode 2 is 3 to 50 μm.
m is preferable, 5 to 30 μm is more preferable, and 6 to 18 μm is further preferable.
When the thickness of the semiconductor electrode is less than 3 μm, the amount of dye adsorbed decreases and the tendency that light cannot be effectively absorbed increases.

On the other hand, when the thickness of the semiconductor electrode exceeds 50 μm, the electric resistance increases, the loss amount of carriers injected into the semiconductor increases, the ion diffusion resistance increases, and photoexcitation causes electrons to enter the semiconductor. The carry-out of I ₃ ^{− to} the counter electrode, which is caused by the electron injection from I ⁻ into the dye after the injection, is obstructed, and the output characteristics of the battery tend to deteriorate.

The counter electrode CE is not particularly limited and may be the same as the counter electrode normally used for silicon solar cells, liquid crystal panels and the like. For example, it may have the same structure as the above-mentioned transparent electrode 1, a metal thin film electrode such as Pt is formed on the transparent conductive film 3 similar to the transparent electrode 1, and the metal thin film electrode is placed on the electrolyte E side. It may be arranged to face. Further, a small amount of platinum may be attached to the transparent conductive film 3 of the transparent electrode 1, a metal thin film of platinum or the like, a conductive film of carbon or the like may be used.

Further, the composition of the electrolyte E is also photoexcited and the semiconductor
Redox to reduce dye after electron injection into
Although it is not particularly limited as long as it includes the original species, I^-/ I₃ ^-etc
Preferred is an iodine-based redox solution containing a redox species of
Used. Specifically, I ^-/ I₃ ^-The system electrolyte is iodine
Elemental ammonium salt or lithium iodide and iodine
A mixture or the like can be used. Others, Br
^-/ Br₃ ^-System, quinone / hydroquinone system, etc.
Mix electrolyte with acetonitrile, propylene carbonate, ethyl ether
Electrochemically inert solvents such as carbonates (and
And a mixed solvent thereof can also be used.

The constituent material of the spacer S is not particularly limited, and for example, silica beads or the like can be used.

Next, an example of a method for manufacturing the photoelectrode 10 shown in FIG. 1 and the dye-sensitized solar cell 20 shown in FIG. 2 will be described.

First, when the transparent electrode 1 is manufactured, the above-mentioned fluorine-doped SnO _{2 is formed} on the substrate 4 such as a glass substrate.
The transparent conductive film 3 can be formed by a known method such as spray coating.

On the transparent conductive film 3 of the transparent electrode 1, the semiconductor electrode 2 (the innermost layer 21 and the outermost layer 23) and the light reflection layer 7 are provided.
As a method for forming the, for example, there are the following methods.
That is, first, a dispersion liquid for forming the innermost layer 21 in which the oxide semiconductor particles having a size satisfying the above-described condition is dispersed is prepared. The solvent of this dispersion is water,
There is no particular limitation as long as it can disperse the oxide semiconductor particles such as an organic solvent or a mixed solvent of both. Further, a surfactant and a viscosity modifier may be added to the dispersion liquid, if necessary.

Next, the dispersion liquid is applied to the transparent conductive film 3 of the transparent electrode 1.
Apply on top, then dry. As a coating method at this time, a bar coater method, a printing method, or the like can be used. Then, after being dried, it is heated and baked in air, an inert gas or nitrogen to be the innermost layer 21 of the semiconductor electrode 2.
(Porous semiconductor film) is formed. The firing temperature at this time is preferably 300 to 800 ° C. If the firing temperature is less than 300 ° C., the adhesion between the oxide semiconductor particles and the adhesion to the substrate may be weakened, and sufficient strength may not be obtained. If the firing temperature exceeds 800 ° C., the adhesion between the oxide semiconductor particles may proceed, and the surface area of the semiconductor electrode 2 (porous semiconductor film) may be reduced.

Next, the outermost layer 23 is formed on the innermost layer 21.
In the case of forming the above, for example, except that a dispersion liquid having a composition in which a predetermined amount of large diameter particles and small diameter particles are added instead of the oxide semiconductor particles contained in the innermost layer 21 is prepared, The light reflection layer 7 can be formed on the outermost layer 23 in the same manner as the method of forming the innermost layer 21.

Next, when the light reflecting layer 7 is formed on the outermost layer 23, for example, instead of the oxide semiconductor particles contained in the innermost layer 21, a predetermined amount of high refractive index particles and low refractive index particles are used. The light-reflecting layer 7 can be formed in the same manner as the method for forming the innermost layer 21 described above, except that a dispersion liquid having a composition to which refractive index particles are added is prepared.

Next, a sensitizing dye is contained in the innermost layer 21, the outermost layer 23 and the light reflecting layer 7 of the semiconductor electrode 2 by a known method such as an immersion method. The sensitizing dye is the semiconductor electrode 2
It is contained by adhering to it (chemical adsorption, physical adsorption or deposition). As the attachment method, for example, a method of immersing the semiconductor electrode 2 in a solution containing a dye can be used. At this time, the solution can be heated and refluxed to promote the adsorption and deposition of the sensitizing dye. At this time, in addition to the dye, if necessary, a metal such as silver or a metal oxide such as alumina may be contained in the semiconductor electrode 2.

Further, a surface oxidation treatment for removing impurities which hinder the photoelectric conversion reaction contained in the semiconductor electrode 2 is appropriately carried out by a known method each time each layer is formed or when all layers are formed. May be.

As another method for forming the semiconductor electrode 2 on the transparent conductive film 3 of the transparent electrode 1, there are the following methods. That is, TiO _{2 is formed} on the transparent conductive film 3 of the transparent electrode 1.
You may use the method of vapor-depositing semiconductors, such as these. As a method of depositing a semiconductor in a film shape on the transparent conductive film 3, a known method can be used. For example, a physical vapor deposition method such as electron beam vapor deposition, resistance heating vapor deposition, sputter vapor deposition, or cluster ion beam vapor deposition may be used. A metal or the like is vaporized in a reactive gas such as oxygen and the reaction product is used as the transparent conductive film A reactive vapor deposition method that deposits on top may be used. Furthermore, a chemical vapor deposition method such as CVD can be used by controlling the flow of the reaction gas.

After the photoelectrode 10 is manufactured in this manner, the counter electrode CE is manufactured by a known method so that the photoelectrode 10 and the counter electrode CE are opposed to each other via the spacer S as shown in FIG. Build up. At this time, the spacer S fills the space formed between the photoelectrode 10 and the counter electrode CE with the electrolyte E to complete the dye-sensitized solar cell 20.

Hereinafter, the dye-sensitized solar cell 30 shown in FIG.
Will be described. The same elements as those described with respect to the dye-sensitized solar cell 20 shown in FIG. 2 described above are designated by the same reference numerals, and overlapping description will be omitted.

The dye-sensitized solar cell 30 shown in FIG. 3 uses the photoelectrode 10 shown in FIG. 1 and uses the counter CE shown in FIG.
The same counter electrode CE is used. Then, in the dye-sensitized solar cell 20 shown in FIG. 2, the space formed between the photoelectrode 10 and the counter electrode CE by the spacer S is filled with the electrolyte E, as compared with the dye shown in FIG. In the sensitized solar cell 30, the porous layer PS is arranged between the photoelectrode 10 and the counter electrode CE. The transparent substrate 6 is arranged on the surface of the counter electrode CE opposite to the porous layer PS.

The porous body layer PS has a structure having a large number of pores, and the inside of the porous body layer PS is the same as that used in the dye-sensitized solar cell 20 shown in FIG. The same electrolyte E is held by being impregnated.

This electrolyte is used in the semiconductor electrode 2 and in the constituent materials used (for example, a porous conductive film such as carbon).
It is also held in the counter CE. And FIG.
In order to prevent the electrolyte from leaking to the outside from the side surface of the semiconductor electrode 2, the porous body layer PS and the counter electrode CE, the side surfaces of the semiconductor electrode 2, the porous body layer PS and the counter electrode CE of the dye-sensitized solar cell 30 shown in FIG. Is covered with a sealing material 5.

The porous body layer PS is not particularly limited as long as it can hold an electrolyte and does not have electron conductivity. For example, a porous body formed of rutile type titanium oxide particles may be used. Examples of constituent materials other than rutile-type titanium oxide include zirconia, alumina, and silica.

As the sealing material 5, for example, a thermoplastic resin film such as polyethylene or an epoxy adhesive can be used. As the transparent substrate 6 arranged on the side of the counter electrode CE, the same substrate as the transparent substrate 4 used for the transparent electrode 1 of the photoelectrode 10 can be used.

Next, the dye-sensitized solar cell 30 shown in FIG.
An example of the manufacturing method will be described. First, the photoelectrode 10 is prepared in the same manner as the dye-sensitized solar cell 20 shown in FIG. Next, the porous body layer PS is formed on the surface of the light reflection layer 7 of the semiconductor electrode 2 of the photoelectrode 10 by the same procedure as in the case of producing each layer of the semiconductor electrode 2 of the photoelectrode 10. For example, a dispersion liquid (slurry) containing a constituent material of the porous body layer PS such as rutile type titanium oxide is prepared, and the dispersion liquid (slurry) is prepared.
It may be formed by applying it to the surface of the above and drying it.

Regarding the counter electrode CE, for example, when a porous conductive film of carbon or the like is used as the counter electrode CE, for example, a carbon paste is prepared and applied on the surface of the porous body layer PS. It may be formed by drying. Then, the transparent substrate 6 is formed on the surface of the counter electrode CE opposite to the side of the porous body layer PS by a known method, and the side surfaces of the semiconductor electrode 2, the porous body layer PS and the counter electrode CE are covered with the sealing material 5. Then, the dye-sensitized solar cell 30 is completed.

Hereinafter, the dye-sensitized solar cell 31 shown in FIG.
Will be described. The same elements as those described with respect to the dye-sensitized solar cell 20 shown in FIG. 2 described above are designated by the same reference numerals, and overlapping description will be omitted.

The dye-sensitized solar cell 31 shown in FIG. 4 uses the photoelectrode 10 shown in FIG. 1 except that the light reflecting layer 7 of the photoelectrode 10 is used as the porous layer PS. It has the same structure as the dye-sensitized solar cell 30 shown. As shown in FIG. 4, the counter electrode CE is formed on the light reflection layer 7 of the photoelectrode 10.
In the case where the light reflection layers 7 are arranged adjacent to each other, the light reflection layer 7 is required not to have electron conductivity.

The dye-sensitized solar cell 31 can be manufactured by the same method as the dye-sensitized solar cell 30 shown in FIG.

[Second Embodiment] The second embodiment of the photoelectrode of the present invention will be described below with reference to FIG. The same elements as those described in the above-described first embodiment are designated by the same reference numerals, and overlapping description will be omitted.

FIG. 5 is a schematic sectional view showing a second embodiment of the photoelectrode of the present invention. Further, FIG. 6 is a schematic cross-sectional view showing a dye-sensitized solar cell provided with the photoelectrode shown in FIG. Further, FIG. 7 is a schematic cross-sectional view showing another form of the dye-sensitized solar cell shown in FIG. In addition, FIG.
FIG. 6 is a schematic cross-sectional view showing still another form of the dye-sensitized solar cell shown in FIG.

The photoelectrode 12 shown in FIG. 5 has the same structure as the photoelectrode 10 shown in FIG. 1 except that the semiconductor electrode 2 has only the LR layer described above.

The dye-sensitized solar cell 32 shown in FIG. 6 having the photoelectrode 12 has the same structure as the dye-sensitized solar cell 20 shown in FIG. 2 except for the photoelectrode 12. Further, the method for manufacturing the photoelectrode 12 and the dye-sensitized solar cell 32 including the photoelectrode 12 is not particularly limited.
The photoelectrode 10 and the dye-sensitized solar cell 20 described above can be manufactured by the same method.

The dye-sensitized solar cell 33 shown in FIG. 7 has the same structure as the dye-sensitized solar cell 30 shown in FIG. 3 except that the photoelectrode 12 shown in FIG. 5 is used. There is. The method for manufacturing the dye-sensitized solar cell 33 provided with the photoelectrode 12 is not particularly limited, and for example, it can be manufactured by the same method as the dye-sensitized solar cell 30 described above.

The dye-sensitized solar cell 34 shown in FIG. 8 has the same structure as the dye-sensitized solar cell 31 shown in FIG. 4 except that the photoelectrode 12 shown in FIG. 5 is used. There is. The method for manufacturing the dye-sensitized solar cell 34 provided with the photoelectrode 12 is not particularly limited, and for example, it can be manufactured by the same method as the dye-sensitized solar cell 31 described above.

[Third Embodiment] The third embodiment of the photoelectrode of the present invention will be described below. In the third embodiment (not shown) of the photoelectrode of the present invention, the semiconductor electrode 2 is the L described above.
The structure is similar to that of the photoelectrode 10 shown in FIG. 1 except that only the layer A is formed.

A dye-sensitized solar cell (not shown) equipped with this photoelectrode is shown in FIGS.
The dye-sensitized solar cells 32, 33 and 34 shown in FIG. Also,
The method for producing the photoelectrode and the dye-sensitized solar cell provided with the photoelectrode is not particularly limited. For example, the photoelectrode 1 described above is used.
0, 12 and dye-sensitized solar cells 32, 33 and 34
It can be manufactured by a method similar to.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

For example, in the above embodiment, the photoelectrode 10 including the semiconductor electrode 2 having a two-layer structure,
A photoelectrode 12 comprising a semiconductor electrode 2 having a layered structure,
Dye-sensitized solar cells 20, 30, 31, including these
32, 33, and 34 have been described, the photoelectrode and the dye-sensitized solar cell of the present invention are not limited thereto. For example, the photoelectrode of the present invention may have a structure including a semiconductor electrode composed of three or more layers.

The photoelectrode of the present invention is, for example, the semiconductor electrode 2 formed of one LR layer of the photoelectrode 12 shown in FIG.
Instead, it may be a photoelectrode having a configuration including a semiconductor electrode composed of one LA layer.

Furthermore, the dye-sensitized solar cell of the present invention may have the form of a module in which a plurality of cells are provided side by side, such as the dye-sensitized solar cell 40 shown in FIG. However, the dye-sensitized solar cell 40 shown in FIG. 9 shows an example in which a plurality of dye-sensitized solar cells 30 shown in FIG. 3 are arranged in series.

As compared with the dye-sensitized solar cell 30 shown in FIG. 3, the dye-sensitized solar cell 40 shown in FIG. 9 is a sealing material provided between the photocells 10 of single cells of adjacent solar cells. 5, a groove is formed between the photoelectrode 10 of one unit cell (hereinafter referred to as unit cell A). This groove is a single cell A
The semiconductor electrode 2 is formed by shaving the semiconductor electrode 2 by a technique such as laser scribing.

The portion of this groove near the seal member 5 is
The semiconductor electrode 2 is completely removed to reach the depth at which the layer of the transparent conductive film 3 of the transparent electrode 1 appears. Also,
The portion of the groove near the semiconductor electrode 2 of the single cell A is
The portion of the semiconductor electrode 2 and the portion of the transparent conductive film 3 are completely removed to reach the depth at which the layer of the transparent substrate 4 of the transparent electrode 1 appears.

In the vicinity of the sealing material 5 in the groove, the transparent conductive film 3 of the adjacent photoelectrode 10 and the semiconductor electrode 2 on the transparent conductive film 3 are prevented from electrically contacting each other. In addition, the brim-shaped edge portion of the porous body layer PS of the single cell A is inserted between these portions so as to contact the transparent substrate 4 of the transparent electrode 1.

Further, in the portion of the groove near the semiconductor electrode 2 of the unit cell A, that is, between the porous material layer PS of the unit cell A and the sealing material 5, the counter electrode CE of the unit cell A is formed. The brim-shaped edge portion is inserted in contact with the transparent conductive film 3 of the transparent electrode 1 of the other single cell.

[0106]

EXAMPLES The photoelectrode and the dye-sensitized solar cell of the present invention will be described below in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Tables 1 to 4 show the configurations of the semiconductor electrode and the light reflecting layer, which show the characteristics of the photoelectrodes of Examples and Comparative Examples shown below.

(Embodiment 1) FIG.
A photoelectrode having the same structure as that of the photoelectrode 10 shown in FIG. 6 (semiconductor electrode 2 composed of only one LR layer) was prepared, and the dye sensitization shown in FIG. 6 was used except that this photoelectrode was used. A dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same structure as that of the solar cell 32 was produced.

First, commercially available anatase type titanium oxide particles (average particle size: 25 nm, hereinafter referred to as P25),
Using this and anatase type titanium oxide particles having different particle diameters (average particle diameter: 200 nm, hereinafter referred to as P200), the total content of P25 and P200 is 15% by mass.
And the mass ratio of P25 and P200 is P25: P200.
= 70:30, acetylacetone, ion-exchanged water, and a surfactant (manufactured by Tokyo Kasei Co., Ltd., trade name; "Triton-X") are added and kneaded to form a slurry for forming the LR layer (P25. Content: 7.5% by mass, P2
Content of 00; 7.5 mass%, hereinafter referred to as Slurry 1) was prepared.

Next, commercially available silicon dioxide (average particle size:
40 nm, refractive index: 1.45, hereinafter referred to as P1) and commercially available rutile type titanium oxide (average particle diameter: 300 nm,
(Refractive index: 2.7, hereinafter referred to as P2), so that the total content of P1 and P2 is 15 mass% and the mass ratio of P1 and P2 is P1: P2 = 35: 65. A slurry for forming a light-reflecting layer (content of P1; 5.25 mass%, P2
Content of 9.75% by mass, hereinafter referred to as Slurry 2)
Was prepared.

On the other hand, a fluorine-doped SnO ₂ conductive film (film thickness: 700 n) was formed on a glass substrate (transparent conductive glass).
m) formed transparent electrode (thickness: 1.1 mm). Then, the above-mentioned slurry 1 was applied onto this SnO ₂ conductive film using a bar coder, and then dried. Then, it was baked for 30 minutes in the air at 450 ° C. In this way, the LR layer to be the semiconductor electrode was formed on the transparent electrode.

Further, the slurry 2 was used to repeat the same application and firing as described above to form a light reflection layer on the LR layer. Thus, on the SnO ₂ conductive film, a semiconductor electrode having the same structure as the semiconductor electrode 2 shown in FIG. 5 (light receiving surface area: 1.0 cm ² , layer thickness: 17 μm, LR layer thickness: 10 μm, light The thickness of the reflective layer: 7 μm),
A photoelectrode containing no sensitizing dye was prepared.

The volume ratio of the rutile type titanium oxide particles in the light reflecting layer was 23%.

Then, the dye was adsorbed on the back surface of the semiconductor electrode as follows. First, as a sensitizing dye, a ruthenium complex [cis-Di (thiocyanato) -N, N'-bis (2,2'-bipyridy
l-4,4'dicarboxylic acid) -ruthenium (II)], and its ethanol solution (sensitizing dye concentration; 3 × 10 ^-4 mo
1 / L) was prepared.

Next, the semiconductor electrode is immersed in this solution,
It was left for 20 hours under the temperature condition of 0 ° C. As a result, the sensitizing dye is added to the inside of the semiconductor electrode at about 1.0 × 10 ⁻⁷ m
ol / cm ^{2 was} adsorbed. Next, in order to improve the open circuit voltage Voc, the semiconductor electrode after adsorption of the ruthenium complex is changed to 4
After dipping in an acetonitrile solution of -tert-butylpyridine for 15 minutes, it was dried in a nitrogen stream kept at 25 ° C to complete a photoelectrode.

Next, as a counter electrode having the same shape and size as the above-mentioned photoelectrode, a transparent conductive glass electrode (Pt thin film thickness: 3 n, on which Pt was vapor-deposited by an electron beam vapor deposition method) was used.
m) was prepared. Further, as the electrolyte E, an iodine-based redox solution containing iodine, lithium iodide, and an imidazolium salt was prepared.

Further, a spacer S manufactured by Mitsui DuPont Polychemical Co., Ltd. having a shape adapted to the size of the semiconductor electrode is used.
(Product name: “HIMIRAN”) is prepared, and as shown in FIG. 6, the photoelectrode and the counter electrode are opposed to each other via a spacer, and the above electrolyte is filled inside to complete the dye-sensitized solar cell. It was

(Example 2) A photoelectrode having a semiconductor electrode having the same structure as in Example 1 except that an LA layer was arranged instead of the LR layer was prepared, and further, a dye-enhancing method using this photoelectrode was prepared. A sensitive solar cell (light-receiving surface area: 1 cm ² ) was produced.

The LA layer was formed using Slurry 3 prepared by the following procedure. Then, the photoelectrode and the dye-sensitized solar cell were the same as those in Example 1 except that the slurry 3 was used.
It was manufactured by the same procedure as. That is, Example 1 was used except that only P25 which was used as the slurry 3 in Example 1 was used.
It was prepared by the same method as the slurry 1. In P25 used, the proportion of particles having a particle diameter of 100 nm or more was 2% by mass.

Example 3 The innermost layer of the semiconductor electrode (L
A layer), the outermost layer (LR layer), and the light reflection layer have the configurations shown in Tables 3 to 4, except that the photoelectrode 10 shown in FIG. 1 and the dye-sensitized solar cell shown in FIG. A photoelectrode and a dye-sensitized solar cell having the same structure as 20 (area of light receiving surface:
1 cm ² ) was produced.

In this photoelectrode and dye-sensitized solar cell, the slurry 3 was used to form the LA layer (the innermost layer), and the slurry 1 was used to form the LR layer (the outermost layer). The same procedure as in Example 1 was performed except that the light reflecting layer was formed using 2.

(Example 4) A photoelectrode and a dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same structure as in Example 3 except that the light reflecting layer had the structure shown in Table 4 were prepared. It was made.

The photoelectrode and the dye-sensitized solar cell were manufactured by the same procedure as in Example 3 except that the light reflecting layer was formed by using Slurry 4 having the structure shown below. That is, the slurry 4 is the P1 used in the slurry 2.
Instead of commercially available silicon dioxide (average particle size: 100n
m, refractive index: 1.45, hereinafter referred to as P3), and commercially available rutile titanium oxide (average particle diameter: 200 nm, refractive index: 2.7, hereinafter referred to as P4) instead of P2. Use the mass ratio of P3 and P4 in the slurry 4 to P
It was prepared by the same preparation procedure as for Slurry 2 except that 3: P4 = 35: 65.

Example 5 A photoelectrode having the same structure as in Example 1 was used, except that a counter electrode composed of a carbon porous body prepared by the following procedure was used instead of the transparent conductive glass electrode. By the same procedure as in Example 1, a dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same structure as the dye-sensitized solar cell 34 shown in FIG. 8 was produced.

That is, a counter electrode made of a carbon porous material was formed by the following procedure. A commercially available graphite powder, carbon black, and titania (anatase type titanium oxide) particles (particle size: 20 nm) were used as a slurry for forming the counter electrode (hereinafter referred to as slurry 5) to obtain graphite, carbon black and titania. The mass ratio is graphite: carbon black: titania =
It was prepared by the same preparation procedure as the above-mentioned Slurry 1 except that the ratio was set to 100: 20: 15. Next, by repeating the application and sintering of this slurry 5 in the same manner as in the photoelectrode forming procedure shown in Example 1, a counter electrode having a thickness of 50 μm is formed on the surface of the light reflecting layer. The glass substrate used was arranged on the surface opposite to the surface in contact with the porous layer of the counter electrode to prepare a dye-sensitized solar cell.

(Example 6) A photoelectrode having the same structure as in Example 2 was used, and a counter electrode made of a carbon porous material prepared in the same manner as in Example 5 was used in place of the transparent conductive glass electrode. Other than the above, the dye-sensitized solar cell of 5 × 20 mm scale having the same structure as the dye-sensitized solar cell 34 shown in FIG. 8 was prepared by the same procedure as in Example 1 (light-receiving surface area: 1 cm ² ). Was produced.

(Example 7) A photoelectrode having the same structure as in Example 3 was used, and a counter electrode made of a carbon porous material prepared in the same manner as in Example 5 was used in place of the transparent conductive glass electrode. A dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same structure as the dye-sensitized solar cell 31 shown in FIG. 4 except for the above was manufactured.

(Embodiment 8) Using a photoelectrode having the same structure as that of Embodiment 3, a counter electrode composed of a porous body layer prepared by the following procedure and a carbon porous body prepared in the same manner as in Embodiment 5 Is used instead of the transparent conductive glass electrode to form a dye-sensitized solar cell, and a dye-sensitized solar cell having the same structure as the dye-sensitized solar cell 30 shown in FIG. A surface area: 1 cm ² ) was prepared.

That is, the slurry for forming the porous layer (hereinafter referred to as slurry 6) is a commercially available rutile type titanium oxide particle (particle size: 300 nm) and a commercially available zirconia (ZrO ₂ ) particle (particle size: 20 nm), and the mass ratio of the rutile type titanium oxide particles and the zirconia particles is rutile type titanium oxide particles: zirconia particles = 100: 10.
It was prepared by the same preparation procedure as that of the above-mentioned slurry 1 except that the above was adopted. Then, a photoelectrode was prepared in the same manner as in the photoelectrode formation procedure of Example 3, and then the slurry 6 was repeatedly applied and sintered on the back surface of the photoelectrode to form a porous layer having a thickness of 10 μm. Formed.

Next, the slurry 5 was used to repeat the coating and sintering of the slurry 5 in the same manner as in the procedure for forming the photoelectrode described in Example 5, thereby forming a thickness of 50 on the porous layer.
A counter electrode having a thickness of μm was formed, and the glass substrate used for the photoelectrode was further arranged on the surface of the counter electrode opposite to the surface in contact with the porous layer to prepare a dye-sensitized solar cell.

(Example 9) A photoelectrode and a dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same configuration as in Example 1 except that the light reflecting layer had the configuration shown in Table 1. It was made.

That is, the photoelectrode and the dye-sensitized solar cell were manufactured by the same procedure as in Example 1 except that the light reflecting layer was formed by using the slurry 7 having the following structure. As the slurry 7, the P1 used in the slurry 2 was used, and commercially available anatase-type titanium oxide (average particle diameter: 300 nm, refractive index: 2.4, hereinafter referred to as P5) was used instead of P2. It was prepared by the same preparation procedure as for Slurry 2 except that the mass ratio of P1 and P5 therein was P1: P5 = 35: 65.

(Example 10) A photoelectrode and a dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same configuration as in Example 1 except that the light reflecting layer had the configuration shown in Table 1. It was made.

The photoelectrode and the dye-sensitized solar cell were manufactured by the same procedure as in Example 1 except that the light reflecting layer was formed by using the slurry 8 having the structure shown below. That is, the slurry 8 is the P1 used in the slurry 2.
Instead of commercially available magnesia particles (average particle size: 25n
m, refractive index: 1.7, hereafter referred to as P6), and further using P2, except that the mass ratio of P6 and P2 in the slurry 8 was P6: P2 = 45: 55. It was prepared by the preparation procedure of.

(Comparative Example 1) Slurry 3 used in Example 1
Table 2 was prepared in the same manner as in Example 1 except that a semiconductor electrode (light-receiving surface area; 1.0 cm ² , layer thickness: 10 μm) consisting of only one layer (LA layer) was prepared using only
A photoelectrode and a dye-sensitized solar cell having the structure shown in Figure 3 were produced.

(Comparative Example 2) A photoelectrode and a dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same configuration as in Example 2 except that the light-reflecting layer had the configuration shown in Table 2. It was made.

The photoelectrode and the dye-sensitized solar cell were manufactured by the same procedure as in Example 2 except that the light reflecting layer was formed by using the slurry 9 having the structure shown below. That is, the slurry 9 is P1 in the slurry 2.
A slurry 2 was prepared by the same method as the preparation method of the slurry 2, except that the mass ratio of P1 and P2 was changed to P1: P2 = 5: 95.

Comparative Example 3 A photoelectrode and a dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same structure as in Example 2 except that the light reflecting layer had the structure shown in Table 2. It was made.

The photoelectrode and the dye-sensitized solar cell were manufactured by the same procedure as in Example 2 except that the light reflecting layer was formed by using the slurry 10 having the structure shown below. That is, in the slurry 10, instead of P1, commercially available zirconia particles (average particle diameter; 20 nm, refractive index:
2.1, hereinafter referred to as P7), and further using P2, and the mass ratio of P7 and P2 is P7: P2 = 50: 50.
A slurry 2 was prepared by the same method as that of the slurry 2, except that

(Comparative Example 4) Slurry 1 used in Example 1
Table 1 was prepared in the same manner as in Example 1 except that a semiconductor electrode (light-receiving surface area; 1.0 cm ² , layer thickness: 10 μm) consisting of only one layer (LR layer) was prepared using only
A photoelectrode and a dye-sensitized solar cell having the structure shown in Figure 3 were produced.

Comparative Example 5 A photoelectrode and a dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same structure as in Example 1 except that the light reflecting layer had the structure shown in Table 1. It was made.

The photoelectrode and the dye-sensitized solar cell were produced by the same procedure as in Example 1 except that the light reflecting layer was formed by using the slurry 11 having the structure shown below. That is, the slurry 11 is P in the slurry 2.
The slurry 2 was prepared by the same method as the method for preparing the slurry 2 except that the mass ratio of 1 and P2 was changed so that the mass ratio of P1 and P2 was P1: P2 = 10: 90.

Comparative Example 6 A photoelectrode and a dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same structure as in Example 1 except that the light reflecting layer had the structure shown in Table 1. It was made. That is, the photoelectrode and the dye-sensitized solar cell were manufactured by the same procedure as in Example 1 except that the light reflecting layer was formed using the slurry 10 used in Comparative Example 3.

Comparative Example 7 A photoelectrode and a dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same structure as in Example 3 except that the light reflecting layer had the structure shown in Table 4. It was made.

The photoelectrode and the dye-sensitized solar cell were manufactured by the same procedure as in Example 3 except that the light reflecting layer was formed by using the slurry 12 having the following structure. That is, the slurry 12 is the P used in the slurry 2.
1, and commercially available rutile titanium oxide (average particle diameter: 120 nm, refractive index: 2.7, hereinafter referred to as P8) instead of P2, and the mass ratio of P1 and 8 in the slurry 12 was used. Was prepared by the same preparation procedure as for Slurry 2 except that P1: P8 = 35: 65.

Comparative Example 8 A photoelectrode and a dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same structure as in Example 1 except that the light reflecting layer had the structure shown in Table 1. It was made.

The photoelectrode and the dye-sensitized solar cell were manufactured by the same procedure as in Example 1 except that the light reflecting layer was formed by using the slurry 13 having the following structure. That is, the slurry 10 was prepared by changing the mass ratio of P7 and P2 used in the slurry 10 so that the mass ratio of P7 and P2 was P7: P2 = 10: 100. Prepared by a method similar to.

Comparative Example 9 A photoelectrode and a dye-sensitized solar cell (light receiving surface area: 1 cm ² ) having the same structure as in Example 2 except that the light reflecting layer had the structure shown in Table 2. It was made. That is, the photoelectrode and the dye-sensitized solar cell were manufactured by the same procedure as in Example 1 except that the slurry 13 used in Comparative Example 8 was used to form the light reflecting layer.

Comparative Example 10 A photoelectrode and a dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same structure as in Example 2 except that the light reflecting layer had the structure shown in Table 2. It was made.

The photoelectrode and the dye-sensitized solar cell were manufactured by the same procedure as in Example 2 except that the light reflecting layer was formed by using the slurry 14 having the following structure. That is, the slurry 14 uses only P2,
Was prepared by the same method as the method for preparing the slurry 2 except that the content of was adjusted to 15% by mass.

(Comparative Example 11) 1 having the structure shown in Table 1
Photoelectrode and dye-sensitized type having the same configuration as Comparative Example 4 except that a semiconductor electrode (light-receiving surface area; 1.0 cm ² , layer thickness: 10 μm) consisting of only one layer (LR layer) was prepared. A solar cell (light-receiving surface area: 1 cm ² ) was produced.

The photoelectrode and the dye-sensitized solar cell were manufactured by the same procedure as in Comparative Example 4 except that the semiconductor electrode was formed by using the slurry 15 having the following structure. That is, as the slurry 15, P200 used in Slurry 1 was used, and instead of P25, commercially available anatase-type titanium oxide particles (average particle size; 10 nm, hereinafter referred to as P10) were used, and P200 and P10 were used. Was prepared by the same method as the preparation method of Slurry 1 except that the mass ratio of P200: P10 = 80: 20.

Comparative Example 12 A photoelectrode having the same structure as in Comparative Example 2 was used, and a counter electrode made of a carbon porous material prepared in the same manner as in Example 5 was used instead of the transparent conductive glass electrode. A dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same configuration as in Example 6 except for the above was manufactured.

(Comparative Example 13) A photoelectrode having the same structure as in Comparative Example 3 was used, and a counter electrode made of a carbon porous material prepared in the same manner as in Example 5 was used instead of the transparent conductive glass electrode. A dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same configuration as in Example 6 except for the above was manufactured.

Comparative Example 14 A photoelectrode having the same structure as in Comparative Example 5 was used, and a counter electrode made of a carbon porous material prepared in the same manner as in Example 5 was used instead of the transparent conductive glass electrode. A dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same configuration as in Example 5 except for the above was produced.

(Comparative Example 15) A photoelectrode having the same structure as in Comparative Example 6 was used, and a counter electrode made of a carbon porous material prepared in the same manner as in Example 5 was used instead of the transparent conductive glass electrode. A dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same configuration as in Example 5 except for the above was produced.

Comparative Example 16 A photoelectrode having the same structure as in Comparative Example 7 was used, and a counter electrode made of a carbon porous material prepared in the same manner as in Example 5 was used instead of the transparent conductive glass electrode. A dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same configuration as in Example 7 except for the above was manufactured.

Comparative Example 17 A photoelectrode having the same structure as in Comparative Example 8 was used, and a counter electrode made of a carbon porous material prepared in the same manner as in Example 5 was used instead of the transparent conductive glass electrode. A dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same configuration as in Example 5 except for the above was produced.

Comparative Example 18 A photoelectrode having the same structure as in Comparative Example 9 was used, and a counter electrode made of a carbon porous material prepared in the same manner as in Example 5 was used instead of the transparent conductive glass electrode. A dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same configuration as in Example 6 except for the above was manufactured.

Comparative Example 19 A photoelectrode and a dye-sensitized solar cell (light-receiving surface area: 1 cm ² ) having the same structure as in Example 1 except that the light-reflecting layer had the structure shown in Table 1. It was made.

The photoelectrode and the dye-sensitized solar cell were manufactured by the same procedure as in Example 1 except that the light reflecting layer was formed by using the slurry 16 having the structure shown below. That is, in the slurry 16, instead of P2, commercially available zirconia particles (average particle diameter; 320 nm, refractive index:
2.1, hereinafter referred to as P9), P1 is used, and the mass ratio of P7 and P2 is P1: P9 = 30: 70.
A slurry 2 was prepared by the same method as that of the slurry 2, except that

[0161]

[Table 1]

[0162]

[Table 2]

[0163]

[Table 3]

[0164]

[Table 4]

[Battery Characteristic Test] A battery characteristic test is conducted.
The energy conversion efficiency η of the dye-sensitized solar cells of Examples 1 to 8 and Comparative Examples 1 to 19 was measured. Battery characteristics test is performed by a solar simulator (Wacom, trade name;
"WXS-85-H type") using an AM filter (A
M-1.5) through a xenon lamp 100mW /
It was carried out by irradiating with cm ² of pseudo sunlight. I-
Current-voltage characteristics are measured using a V tester, open circuit voltage (Voc / V), short circuit current (Isc / mA · cm ⁻² ),
The fill factor (FF) and energy conversion efficiency (η /%) were obtained.

Examples 1 to 8 and Comparative Examples 1 to 1
Table 5 shows the configuration of the photoelectrode provided in each of the dye-sensitized solar cells of Example 9 and the result of the cell characteristic test.

[0167]

[Table 5]

As is clear from the results shown in Table 5, the energy conversion efficiencies η of the dye-sensitized solar cells of Examples 1 to 8 correspond to Comparative Examples 1 to 19 respectively.
It was confirmed that the value was higher than the energy conversion efficiency η of the dye-sensitized solar cell.

[0169]

As described above, according to the present invention,
Since it is possible to obtain a high light confinement effect in the semiconductor electrode forming the photoelectrode, it is possible to form the photoelectrode having excellent utilization efficiency of incident light. Further, by using this photoelectrode, a dye-sensitized solar cell having excellent energy conversion efficiency can be constructed.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a first embodiment of a photoelectrode of the present invention.

FIG. 2 is a schematic cross-sectional view showing a dye-sensitized solar cell provided with the photoelectrode shown in FIG.

3 is a schematic cross-sectional view showing another form of the dye-sensitized solar cell shown in FIG.

FIG. 4 is a schematic cross-sectional view showing still another form of the dye-sensitized solar cell shown in FIG.

FIG. 5 is a schematic cross-sectional view showing a second embodiment of the photoelectrode of the present invention.

6 is a schematic sectional view showing a dye-sensitized solar cell provided with the photoelectrode shown in FIG.

FIG. 7 is a schematic cross-sectional view showing another form of the dye-sensitized solar cell shown in FIG.

FIG. 8 is a schematic cross-sectional view showing still another form of the dye-sensitized solar cell shown in FIG.

9 is a schematic cross-sectional view showing another form of the dye-sensitized solar cell shown in FIG.

[Explanation of symbols]

1 ... Transparent electrode, 2 ... Semiconductor electrode, 3 ... Transparent conductive film, 4 ...
Transparent substrate, 5 ... Sealing material, 6 ... Transparent substrate, 7 ... Light reflecting layer, 10, 12, ... Photoelectrode, 20 ... Dye-sensitized solar cell, 21 ... Innermost layer, 23 ... Outer layer, 30,3
1, 32, 33, 34, 40 ... Dye-sensitized solar cell, C
E ... Counter electrode, E ... Electrolyte, F1, F2, F3, ... Light receiving surface,
F10 ... Back surface of photoelectrode 10, F23 ... Back surface of semiconductor electrode 2, L10 ... Incident light, S ... Spacer, PS ... Porous body layer.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuo Higuchi             Aichi Prefecture Nagachite Town Aichi District             Ground 1 Toyota Central Research Institute Co., Ltd. (72) Azusa Tsukigase, Inventor             Aichi Prefecture Nagachite Town Aichi District             Ground 1 Toyota Central Research Institute Co., Ltd. (72) Inventor Tomomi Motohiro             Aichi Prefecture Nagachite Town Aichi District             Ground 1 Toyota Central Research Institute Co., Ltd. (72) Inventor Ryusei Toyota             Aichi, 2-chome, Asahi-cho, Kariya city, Aichi prefecture             Within Seiki Co., Ltd. (72) Inventor Toshiyuki Sano             Aichi, 2-chome, Asahi-cho, Kariya city, Aichi prefecture             Within Seiki Co., Ltd. F term (reference) 5F051 AA03 AA14 CB12 CB27 FA02                       GA03                 5H032 AA06 AS16 CC14 EE02 EE07                       EE16 HH00 HH01 HH04

Claims (6)

[Claims] 1. A semiconductor electrode having a light-receiving surface and having at least one layer containing a sensitizing dye and oxide semiconductor particles, and a transparent material disposed adjacent to the light-receiving surface of the semiconductor electrode. An electrode and a light reflecting layer disposed adjacently on a back surface of the semiconductor electrode facing the light receiving surface of the semiconductor electrode, wherein the light reflecting layer has a layer thickness of 3 to 50 μm. The layer contains first particles having a refractive index of 1.8 or less and second particles having an average particle diameter of 150 nm or more and a refractive index of 2.4 or more, and the light reflecting layer In the photoelectrode, the volume ratio of the second particles in 15 to 40%. 2. The photoelectrode according to claim 1, wherein the first particles are silicon dioxide particles and the second particles are rutile type titanium oxide particles. 3. A sensitizing dye having a layer thickness of 5 to 49 μm, and oxide semiconductor particles having an average particle diameter of 70 nm or less,
At least one layer containing oxide semiconductor particles having an average particle diameter of 150 nm or more is disposed between the transparent electrode and the light reflecting layer as a layer forming the semiconductor electrode. Item 3. The photoelectrode according to Item 1 or 2. 4. The oxide semiconductor particles are at least one kind of particles selected from the group consisting of anatase type titanium oxide, zinc oxide, tin oxide and niobium oxide,
The photoelectrode according to claim 3, wherein: 5. A sensitizing dye having a layer thickness of 1 to 5 μm,
An oxide semiconductor particle having an average particle diameter of 70 nm or less is included, and in the oxide semiconductor particle, the particle diameter is 1
At least one layer in which the proportion of particles having a size of 00 nm or more is 5% by mass or less is arranged between the transparent electrode and the light reflecting layer as a layer constituting the semiconductor electrode. Item 5. The photoelectrode according to any one of Items 1 to 4. 6. A semiconductor electrode having a photoelectrode having a semiconductor electrode having a light-receiving surface and a transparent electrode disposed adjacent to the light-receiving surface of the semiconductor electrode, a counter electrode, and an electrolyte. A dye-sensitized solar cell in which the counter electrode and the counter electrode are arranged via the electrolyte, wherein the photoelectrode is the photoelectrode according to any one of claims 1 to 5. Type solar cells.