JP2003142169A - Semiconductor electrode of organic dye sensitized metal oxide and solar cell having the semiconductor electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal oxide conductor film formed simply at a low temperature and having a high energy converting efficiency and also an organic dye sensitized solar cell equipped with such a conductor film. SOLUTION: The organic dye sensitized metal oxide semiconductor electrode 3 is composed of a base board 1 having a transparent electrode 2 on its surface, metal oxide semiconductor film formed on the transparent electrode and organic pigment adsorbed to the surface of the semiconductor film, wherein the semiconductor film is formed through the gas-form film forming method in such a way that the arithmetic mean of the surface roughness Ra is over 2 nm while the rate of voids is over 25%, and using this semiconductor electrode, the intended solar cell is completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic dye-sensitized solar cell, an organic dye-sensitized metal oxide semiconductor electrode which can be advantageously used for the solar cell, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of energy saving, effective use of resources, prevention of environmental pollution, etc., a solar cell which directly converts sunlight into electric energy has been drawing attention and being developed.

Solar cells using crystalline silicon or amorphous silicon as a photoelectric conversion material are mainly used. However, a large amount of energy is required to form such crystalline silicon, and thus the use of silicon conflicts with the original purpose of a solar cell that is an energy-saving battery that uses sunlight. There is. Further, as a result of using a large amount of energy, solar cells using silicon as a photoelectric conversion material have to be expensive.

The photoelectric conversion material is a material which converts light energy into electric energy by utilizing an electrochemical reaction between electrodes. For example, when the photoelectric conversion material is irradiated with light, electrons are generated on one electrode side and move to the counter electrode. The electrons that have moved to the counter electrode move as ions in the electrolyte and return to one electrode. That is, the photoelectric conversion material is a material that can continuously extract light energy as electric energy, and is therefore used in a solar cell.

Silicon is not used as the photoelectric conversion material,
A solar cell using an oxide semiconductor sensitized with an organic dye is known. Nature, 268 (1976), p. 402, a metal oxide semiconductor electrode in which rose bengal is adsorbed as an organic dye on the surface of a sintered disk formed by compression molding zinc oxide powder and sintering at 1300 ° C. for 1 hour. A solar cell using is proposed. The current / voltage curve of this solar cell is
The current value when the electromotive voltage was 0.2 V was about 25 μA, which was extremely low, and it was thought that practical application was almost impossible. However, unlike the solar cells using silicon, the oxide semiconductors and organic dyes used are both mass-produced and relatively inexpensive, so in terms of materials, this solar Clearly, batteries are very advantageous.

As a photoelectric conversion material, as a solar cell using an oxide semiconductor sensitized with an organic dye as described above, in addition to those described above, for example, Japanese Patent Application Laid-Open No. 1-2203
A metal oxide semiconductor having a spectral sensitizing dye layer such as a transition metal complex on the surface of the metal oxide semiconductor described in JP-A-80, and a titanium oxide semiconductor layer doped with a metal ion described in JP-A-5-504023. It is known to have a spectral sensitizing dye layer such as a transition metal complex on its surface.

The above solar cell cannot obtain a practical current / voltage curve. A solar cell having a spectral sensitizing dye layer whose current / voltage curve has reached a practical level is disclosed in Japanese Patent Application Laid-Open No. HEI10-110.
Japanese Patent Publication No.-92477 discloses a solar cell using an oxide semiconductor film made of a fired product of an oxide semiconductor fine particle aggregate. Such a semiconductor film is obtained by applying a slurry of oxide semiconductor fine powder on a transparent electrode, drying the slurry, and then applying 5
It is formed by firing at 00 ° C. for about 1 hour.

[0008]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the solar cell of Japanese Patent No. 477, the oxide semiconductor film of the fired product of the oxide semiconductor fine particle aggregate is formed by the so-called sol-gel method. Since such a forming method requires heating at a high temperature for a long time after coating, the substrate and the transparent electrode are also required to have heat resistance. Since ITO, which is a normal transparent electrode, does not have such heat resistance, it is necessary to use fluorine-doped tin oxide, which is a transparent electrode having particularly excellent heat resistance. It is inferior in properties and is not suitable for applications requiring a large area such as solar cells.

Therefore, an object of the present invention made in view of the above points is to obtain an organic dye-sensitized metal oxide semiconductor electrode having a metal oxide conductor film which is easily obtained at a low temperature and has improved dye adsorption. An object is to provide an organic dye-sensitized solar cell having this.

Another object of the present invention is to provide an organic dye-sensitized metal oxide semiconductor electrode which can be formed at a low temperature and a high speed and has a high energy conversion efficiency of light, and an organic dye-sensitized solar cell having the same. Especially.

A further object of the present invention is to provide a method for advantageously producing the above organic dye-sensitized metal oxide semiconductor electrode.

[0012]

The present invention is directed to a substrate having a transparent electrode on the surface thereof, a metal oxide semiconductor film formed on the transparent electrode, and an organic dye sensitizer containing an organic dye adsorbed on the surface of the semiconductor film. In the sensitive metal oxide semiconductor electrode,
The metal oxide semiconductor film is formed by a vapor deposition method,
And an organic dye-sensitized metal oxide semiconductor electrode having a surface roughness Ra (center line average roughness) of 2 nm or more and a porosity of 25% or more; An organic dye-sensitized solar cell comprising a sensitive metal oxide semiconductor electrode and a counter electrode provided so as to face the electrode, and further a redox electrolyte is injected between the two electrodes.

In the above organic dye-sensitized metal oxide semiconductor electrode and solar cell, the surface roughness Ra is preferably 5 nm or more (particularly 10 nm or more) and the porosity is 30.
% Or more (particularly 35% or more) is preferable. This further increases the amount of organic dye adsorbed and improves the energy conversion efficiency of light. As the vapor deposition method, a physical vapor deposition method,
A vacuum vapor deposition method, a sputtering method, an ion plating method, a CVD method or a plasma CVD method, particularly a facing bipolar target system sputtering method is suitable. A reactive sputtering method is also preferable.

The metal oxide semiconductor film has titanium oxide, zinc oxide, tin oxide, antimony oxide, niobium oxide, tungsten oxide or indium oxide, or these metal oxides doped with another metal or another metal oxide. Of these, titanium oxide is preferable, and anatase-type titanium oxide is particularly preferable. The thickness of the metal oxide semiconductor film is preferably 10 nm or more.

The above metal oxide semiconductor electrode is 2.6 W / cm ² on the transparent electrode of the substrate having the transparent electrode on the surface thereof, using metal and / or metal oxide as a target.
An organic dye-sensitized metal oxide characterized by forming a metal oxide semiconductor film by a sputtering method under the conditions of the above power density and a pressure of 0.6 Pa or more, and adsorbing an organic dye on the surface of the semiconductor film. It can be advantageously obtained by the method of manufacturing a semiconductor electrode.

In the above manufacturing method, the power density is 11
W / cm ² or more is preferable, and pressure is 2.0P
It is preferably a or more. It is preferable to perform sputtering by using titanium metal as a target and supplying oxygen gas. It is preferable to perform sputtering by using conductive titanium oxide as a target and supplying oxygen gas. The metal oxide semiconductor film is preferably titanium oxide, particularly preferably anatase-type titanium oxide. The thickness of the metal oxide semiconductor film is preferably 10 nm or more. As the sputtering method, the opposed bipolar target type sputtering method is particularly preferable, and the reactive sputtering method is also preferable.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a metal oxide semiconductor electrode of the present invention and an organic dye-sensitized solar cell having the same will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing an example of an embodiment of the organic dye-sensitized solar cell of the present invention.

In FIG. 1, a substrate 1 is provided with a transparent electrode 2 thereon, and a metal oxide semiconductor film 3 having a spectral sensitizing dye adsorbed thereon is formed on the substrate 1, and the metal oxide semiconductor film 3 is provided above the transparent electrode to face the transparent electrode. Counter electrode 4 is installed, the side portion is sealed with a sealant 5, and an electrolyte (solution) 6 is sealed between the metal oxide semiconductor film 3 and the counter electrode 4.
The metal oxide semiconductor electrode of the present invention includes the substrate 1,
It is basically composed of a transparent electrode 2 thereon and a metal oxide semiconductor film 3 having a spectral sensitizing dye adsorbed on the transparent electrode.

In the metal oxide semiconductor electrode of the present invention and the organic dye-sensitized solar cell having the same, the metal oxide semiconductor film 3 provided on the transparent electrode on the substrate has various sizes as shown in FIG. It has a shape in which spherical particles are joined together, and has large irregularities on the surface and a large number of voids inside. That is, the metal oxide semiconductor film of the present invention is formed by a vapor deposition method, has a surface roughness (Ra arithmetic average value) of 2 nm or more, and has a porosity of 25% or more. It has a feature. Furthermore, the surface roughness (R
The arithmetic mean value of a) is preferably 5 nm or more, particularly 10 nm or more, and the porosity is preferably 30% or more, particularly 35% or more. There is no particular upper limit to the surface roughness, and as long as the amount of organic dye adsorbed is large, irregularities of 10 mm or more may be present, but the upper limit is actually preferably about 1 mm. Further, the upper limit of the porosity may be close to 100% as long as the adsorption amount of the organic dye is large, but it is preferably about 95% from the viewpoint of maintaining the shape of the film.

As described above, in the metal oxide semiconductor film 3 of the present invention, the surface area of the surface is large, and the surface area of the cavity inside is also large. Therefore, the area where the organic dye is adsorbed is large.
Furthermore, due to such a structure (shape), the organic dye can easily penetrate into the surface and inside, and the dye adsorption can be completed in a short time. Further, since the surface and the inside have a large surface area, the amount of organic dye adsorbed is increased and the energy conversion efficiency of light is improved.

The metal oxide semiconductor film 3 having such a structure can be obtained under various vapor phase film forming conditions, but basically, it is basically formed at a high power for a short time and under a high gas pressure. Film formation is preferable, and further changes in the gas mixture flow rate ratio,
It can be performed by using arc ion sputtering or the like, or by appropriately combining these methods.

A preferred method for forming the metal oxide semiconductor film 3 of the present invention is a sputtering method,
1.3 W / cm ² or more, further 2.6 W / cm ² or more,
In particular, a target input power density of 11 W / cm ² or more, and 0.6 Pa or more, further 2.0 Pa or more, particularly 2.6
It is carried out under the condition of a pressure of Pa or higher, and as the sputtering method, the opposed bipolar target system sputtering method is particularly preferable, and the reactive sputtering method is also preferable. The semiconductor film can be rapidly formed by carrying out under more extreme conditions than the usual sputtering conditions, and as a result, a metal oxide semiconductor film having a specific shape and structure of the present invention can be obtained. it can. As a result, the amount of the organic dye adsorbed can be significantly increased, and a solar cell having high energy conversion efficiency and high efficiency can be obtained.

The substrate 1 may be any transparent substrate and is generally a glass plate, usually silicate glass. However, various plastic substrates and the like can be used as long as the transparency of visible light can be secured. The thickness of the substrate is generally 0.1 to 10 mm,
0.3-5 mm is preferable. The glass plate is preferably chemically or thermally reinforced.

The transparent electrode 2 is made of In_TwoO_ThreeAnd S
nO_TwoFormed with conductive metal oxide thin film, metal, etc.
A substrate made of a conductive material is used. Conductive metal acid
As a preferable example of the compound, In_TwoO_Three: Sn (IT
O), SnO_Two: Sb, SnO _Two: F, ZnO: Al,
ZnO: F, CdSnO_FourCan be mentioned.

A metal oxide semiconductor film for adsorbing a spectral sensitizing dye, which is a semiconductor for photoelectric conversion material, is formed on the transparent electrode. As the metal oxide semiconductor of the present invention,
One or more known semiconductors such as titanium oxide, zinc oxide, tungsten oxide, antimony oxide, niobium oxide, indium oxide, barium titanate, strontium titanate, and cadmium sulfide can be used. In particular, titanium oxide is preferable in terms of stability and safety. Examples of titanium oxide include various titanium oxides such as anatase-type titanium oxide, rutile-type titanium oxide, amorphous titanium oxide, metatitanic acid, orthotitanic acid, titanium hydroxide, and hydrous titanium oxide. In the present invention, anatase type titanium oxide is preferable. The film thickness of the metal oxide semiconductor is generally 10 nm or more,
1000 nm is preferred.

The metal oxide semiconductor film of the present invention uses a metal and / or metal oxide corresponding to the above-mentioned material as a target, and a vapor phase film formation method such as physical vapor deposition method, vacuum vapor deposition method, sputtering method, Ion plating method, CV
D method or plasma CVD method As described above, it can be formed by the sputtering method under the above conditions. A preferred method for forming the metal oxide semiconductor film 3 of the present invention is to use a sputtering method under the conditions of the target input power density and pressure,
As the sputtering method, the opposed bipolar target type sputtering method is particularly preferable, and the reactive sputtering method is also preferable.

In the present invention, as described above, the metal oxide semiconductor film is preferably formed by the opposed bipolar target system sputtering method. A method for forming this metal oxide semiconductor film will be described with reference to FIG. The target electrodes 21a, 21b (having targets on the surface) are arranged facing each other, and a magnet 22 is placed behind them.
a and 22b are installed, and a magnetic field M is formed perpendicularly to the target surface. When a voltage is applied, a plasma is formed in front of the magnetic field and the substrate 23 placed outside the plasma
The sputtered particles adhere to the surface of the semiconductor film to form a semiconductor film. Since the substrate is placed outside the plasma,
A porous film is formed without directly hitting the growth film surface with high-energy particles. For this reason, the dye adsorption performance of the metal oxide semiconductor film is improved, whereby a solar cell having high energy conversion efficiency can be obtained.

Also in the above facing bipolar target type sputtering method, 1.3 W / cm ² or more, and 2.6
Target input power density of W / cm ² or more, particularly 11 W / cm ² or more, and 0.6 Pa or more, further 2.0 Pa
Above, it is also preferable to carry out the sputtering under the condition of a pressure of 2.6 Pa or more. It is considered that a semiconductor film having large irregularities on the surface of the present invention and a high porosity can be obtained by rapidly forming the film without directly hitting the growth film surface.

The opposed bipolar target type sputtering method of the present invention is preferably a reactive sputtering method, that is, sputtering a metal or a metal oxide while introducing a reactive gas such as oxygen gas. In particular, it is preferable to perform sputtering while supplying oxygen gas, using metallic titanium, titanium oxide, particularly conductive titanium oxide as a target.

An organic dye (spectral sensitizing dye) is adsorbed as a monomolecular film on the surface of the oxide semiconductor film on the substrate obtained as described above.

The spectral sensitizing dye has absorption in the visible light region and / or the infrared light region, and in the present invention, one or more kinds of various metal complexes and organic dyes can be used. A spectral sensitizing dye having a carboxyl group, a hydroxyalkyl group, a hydroxyl group, a sulfone group, and a carboxyalkyl group in the molecule is preferable in the present invention because it is adsorbed quickly on the semiconductor. Further, a metal complex is preferable because it is excellent in spectral sensitization effect and durability. Examples of the metal complex include metal phthalocyanines such as copper phthalocyanine and titanyl phthalocyanine, chlorophyll, hemin, ruthenium described in JP-A 1-220380, and JP-A-5-504023.
Complexes of osmium, iron and zinc can be used. As the organic dye, metal-free phthalocyanine, cyanine dye, merocyanine dye, xanthene dye, triphenylmethane dye can be used. Specific examples of cyanine dyes include NK1194 and NK34.
22 (both manufactured by Japan Photosensitive Dye Research Institute Co., Ltd.). Specific examples of the merocyanine dye include NK
2426 and NK2501 (both manufactured by Japan Photosensitive Dye Research Institute). As a xanthene dye,
Specific examples include uranin, eosin, rose bengal, rhodamine B, and dibrom fluorescein. Specific examples of the triphenylmethane dye include malachite green and crystal violet.

In order to adsorb the organic dye (spectral sensitizing dye) on the conductor film, the oxide semiconductor film is placed in an organic dye solution formed by dissolving the organic dye in an organic solvent at room temperature or under heating. It may be dipped with the substrate. The solvent of the above solution may be any solvent that can dissolve the spectral sensitizing dye to be used, and specifically, water, alcohol, toluene or dimethylformamide can be used.

Thus, the organic dye-sensitized metal oxide semiconductor electrode (semiconductor for photoelectric conversion material) of the present invention is obtained.

On the thus obtained substrate, a transparent electrode and an organic dye-sensitized metal oxide semiconductor electrode on which an organic dye-adsorbing metal oxide semiconductor is formed are used to fabricate a solar cell. That is, a semiconductor film for photoelectric conversion material is formed on a substrate such as a glass plate coated with a transparent electrode (transparent conductive film) to form an electrode, and then a glass plate coated with another transparent conductive film as a counter electrode. A substrate such as the above can be bonded with a sealant, and an electrolyte can be enclosed between these electrodes to form a solar cell.

When the spectral sensitizing dye adsorbed on the semiconductor film of the present invention is irradiated with sunlight, the spectral sensitizing dye absorbs and excites light in the visible region. The electrons generated by this excitation move to the semiconductor and then to the counter electrode through the transparent conductive glass electrode. The electrons transferred to the counter electrode reduce the redox system in the electrolyte. On the other hand, the spectral sensitizing dye in which electrons have been transferred to the semiconductor is in an oxidant state. This oxidant is reduced by the redox system in the electrolyte and returns to its original state. In this way, electrons flow and a solar cell using the semiconductor for photoelectric conversion material of the present invention can be constructed.

As the above electrolyte (redox electrolyte)
Is I⁻/ I_Three ⁻System, Br⁻/ Br _Three ⁻System, quinone /
Examples thereof include hydroquinone type. Redock like this
The electrolyte can be obtained by a conventionally known method,
For example, I⁻/ I_Three ⁻The electrolyte of the system is ammonium of iodine.
Can be obtained by mixing um salt and iodine
It The electrolyte includes a liquid electrolyte or a polymer electrolyte containing the liquid electrolyte.
It can be a solid polymer electrolyte. Liquid
Electrolytically inactive as a solvent for degrading
However, for example, acetonitrile, carbonate
Pyrene, ethylene carbonate or the like is used. Opposite
As long as it has conductivity, any conductive
The material used is_Three ⁻Redox of oxidized form such as ions
Catalytic ability to carry out reduction reaction of x ions at a sufficient speed
It is preferable to use one having As something like this
Apply platinum plating or vapor deposition on the surface of the platinum electrode or conductive material.
Applied, rhodium metal, ruthenium metal, ruthenium oxide
Examples include titanium and carbon.

In the solar cell of the present invention, the oxide semiconductor electrode, the electrolyte and the counter electrode are housed and sealed in a case.
All of them may be resin-sealed. In this case, the oxide semiconductor electrode has a structure in which light is applied. In the battery having such a structure, when sunlight or visible light equivalent to sunlight is applied to the oxide semiconductor electrode, a potential difference is generated between the oxide semiconductor electrode and its counter electrode, and a current flows between both electrodes. become.

[0039]

EXAMPLES The present invention will be described in more detail with reference to the following examples.

[Example 1] (1) Preparation of transparent electrode A transparent electrode film was produced using a sputtering device.

5 × 5 cm glass substrate (thickness: 2 mm)
On top, a 100 mmφ ceramic target of ITO (indium-tin oxide) was used, and argon gas was set to 1
While supplying oxygen gas at 0 cc / min and oxygen gas at 1.5 cc / min, the pressure inside the apparatus was set to 5 mTorr, and sputtering was performed for 5 minutes under the condition of a power supply of 500 W.
An ITO film having a thickness of 3000Å was formed. Surface resistance is 10
It was Ω / □.

(2) Preparation of Metal Oxide Semiconductor Film Using a facing target type sputtering apparatus as shown in FIG. 2, a diameter of 1 is formed on the ITO transparent electrode glass.
Two 00 mm metallic titanium targets were placed, oxygen gas was supplied at 5 cc / min, and argon gas was supplied at 5 cc / min. Then, the pressure inside the device was set to 5 mTorr (0.7 Pa), and the supplied power was 3 kW (power). Sputtering was performed for 32 minutes under the condition of a density of 19 W / cm ² ) to form a titanium oxide film having a thickness of 3000 Å.

The surface roughness Ra (center line average roughness) and the porosity of the obtained semiconductor film were measured.

Surface roughness measuring method: The center line average roughness (Ra) of the obtained titanium oxide film was measured using a contact type surface roughness meter (Talystep; manufactured by Taylor Hopson Co., Ltd.).

Measuring method of porosity: The following mass was measured and determined from the following formula (measurement was carried out in accordance with JIS Z8807): w1: sample mass sufficiently containing water (g) w2: sample Absolute dry mass (g) w3: buoyancy of sample (g) porosity = (w1-w2) / w3 × 100 According to the above measurement, the surface roughness Ra (center line average roughness) of the semiconductor film is 5.2 nm. And the porosity was 32%.

(3) Adsorption of spectral sensitizing dye cis-di (thiocyanato) -bis (2,2'-bipyridyl-4-dicarboxylate-4'-tetrabutylammoniumcarboxylate) represented by ruthenium (II). The spectral sensitizing dye was dissolved in an ethanol solution. The concentration of this spectral sensitizing dye was 3 × 10 ⁻⁴ mol / l. next,
The substrate on which the film-shaped titanium oxide was formed was put into this ethanol liquid and immersed at room temperature for 18 hours to obtain a metal oxide semiconductor electrode of the present invention. The adsorption amount of the spectral sensitizing dye of this sample was 1 per 1 cm ² of the specific surface area of the titanium oxide film.
It was 0 μg.

(4) Preparation of solar cell The above metal oxide semiconductor electrode is provided as one electrode,
As the counter electrode, a transparent conductive glass plate coated with fluorine-doped tin oxide and further carrying platinum thereon was used. An electrolyte was put between two electrodes, the side surface was sealed with a resin, and then a lead wire was attached to manufacture a solar cell of the present invention. In addition, as an electrolyte, the concentration of each of lithium iodide, 1,2-dimethyl-3-propylimidazolium iodide, iodine and t-butylpyridine in a solvent of acetonitrile was 0.1 mol / l, 0.3.
What was melt | dissolved so that it might become mol / l, 0.05 mol / l, and 0.5 mol / l was used. When the obtained solar cell was irradiated with light having an intensity of 100 W / m ² with a solar simulator, Voc (voltage in an open circuit state) was 0.58.
V, Joc (density of current flowing when the circuit is short-circuited) is 1.30 mA / cm ² , and FF (fill factor).
Was 0.53 and η (conversion efficiency) was 4.01%. It has been found to be useful as a solar cell.

Example 2 A solar cell was produced in the same manner as in Example 1 except that the production (2) of the metal oxide semiconductor film was carried out as follows.

(2) Preparation of Metal Oxide Semiconductor Film In Example 1, the pressure in the apparatus was 20 mTorr.
After changing to (2.8 Pa), sputtering was performed for 37 minutes under the same conditions except that a titanium oxide film having a thickness of 3000 Å was formed.

The surface roughness (arithmetic average of Ra) of the semiconductor film obtained by the same measurement as in Example 1 was 10.3 nm and the porosity was 38%.

When the obtained solar cell was irradiated with light having an intensity of 100 W / m ² with a solar simulator,
Voc (voltage in open circuit state) is 0.59V, and Jo
c (density of current flowing when the circuit is short-circuited) is 1.31
It was mA / cm ² , FF (fill factor) was 0.53, and η (conversion efficiency) was 4.12%, which proved to be useful as a solar cell.

Comparative Example 1 A solar cell was prepared in the same manner as in Example 1 except that the metal oxide semiconductor film was prepared as follows.

(2) Preparation of metal oxide semiconductor film 6 g of titanium powder (P-25, manufactured by Nippon Aerosil Co., Ltd.)
8 ml of deionized water, 0.2 ml of acetylacetone and 0.2 ml of a surfactant are evenly dispersed, coated on an ITO transparent electrode, and baked at 500 ° C. for 1 hour to obtain a semiconductor electrode having a thickness of 10 μm. It was

The amount of the spectral sensitizing dye adsorbed on this semiconductor was 10 μg per 1 cm ² of the specific surface area of titanium oxide.

The surface roughness (arithmetic mean of Ra) of the semiconductor film obtained by the same measurement as in Example 1 was 10.5 nm and the porosity was 60%.

When the obtained solar cell was irradiated with light having an intensity of 100 W / m ² with a solar simulator,
Voc (voltage in open circuit state) is 0.62V, and Jo
c (density of current flowing when the circuit is short-circuited) is 1.00
It was mA / cm ² , FF (fill factor) was 0.56, and η (conversion efficiency) was 3.50%. This has a lower conversion efficiency than the solar cells of the above-mentioned examples and cannot be said to be useful as a solar cell. It is considered that this is because the transparent electrode deteriorated due to high temperature and long time firing.

Comparative Example 2 A solar cell was produced in the same manner as in Example 1 except that the production (2) of the metal oxide semiconductor film was carried out as follows.

(2) Preparation of metal oxide semiconductor film In Example 1, the power supplied in the device was 0.4 kW (power
Power density 2.5W / cm ^Two) Same as Example 1 except that
Sputtering is performed for 240 minutes under one condition to obtain a thickness of 30.
A titanium oxide film of 00Å was formed.

The semiconductor film obtained by the same measurement as in Example 1 had a surface roughness (Ra arithmetic average) of 1.8 nm and a porosity of 24%.

When the obtained solar cell was irradiated with light having an intensity of 100 W / m ² with a solar simulator,
Voc (voltage in open circuit state) is 0.58V, and Jo
c (density of current flowing when the circuit is short-circuited) is 0.30
It was mA / cm ² , FF (fill factor) was 0.60, and η (conversion efficiency) was 1.05%, which proved to be not useful as a solar cell.

In Comparative Example 2, even if a semiconductor film was formed by sputtering as in Example 1, sufficient performance as a solar cell could not be obtained because the surface roughness and porosity were low.

[0062]

As apparent from the above, the solar cell having the organic dye-sensitized metal oxide semiconductor electrode of the present invention is
It is an organic dye-sensitized solar cell that has a metal oxide conductor film that can be easily obtained at low temperatures, and has a significantly increased amount of dye adsorbed. Therefore, it has high light energy conversion efficiency and sufficient performance as a solar cell. It is equipped with.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an embodiment of a solar cell of the present invention.

FIG. 2 is a cross-sectional view showing an example of a method for forming a metal oxide semiconductor film using a facing bipolar electrode target sputtering method which is preferably used in the present invention.

[Explanation of symbols]

1 substrate 2 transparent electrode 3 Metal oxide semiconductor film with a spectral sensitizing dye 4 counter electrodes 5 Sealant 6 electrolyte 21a, 21b Target electrodes 22a, 22b magnets 23 board

Continued front page    F-term (reference) 5F051 AA14 FA02                 5H032 AA06 AS16 BB05 BB10 CC11                       CC16 EE02 EE16 HH00 HH04                       HH06 HH08

Claims (20)

[Claims] 1. A substrate having a transparent electrode on its surface, a metal oxide semiconductor film formed on the transparent electrode, and an organic dye-sensitized metal oxide semiconductor electrode containing an organic dye adsorbed on the surface of the semiconductor film. The metal oxide semiconductor film is formed by a vapor phase film forming method, has a surface roughness Ra (center line average roughness) of 2 nm or more, and has a porosity of 25% or more. An organic dye-sensitized metal oxide semiconductor electrode. 2. The semiconductor electrode according to claim 1, which has a surface roughness Ra of 5 nm or more. 3. The semiconductor electrode according to claim 1, which has a porosity of 30% or more. 4. The vapor deposition method is a physical vapor deposition method, a vacuum vapor deposition method, a sputtering method, an ion plating method, or a CV.
The semiconductor electrode according to claim 1, which is a D method or a plasma CVD method. 5. The semiconductor electrode according to claim 1, wherein the vapor phase film forming method is a facing bipolar target system sputtering method. 6. The semiconductor electrode according to claim 1, wherein the vapor phase film forming method is a reactive sputtering method. 7. The metal oxide semiconductor film comprises titanium oxide, zinc oxide, tin oxide, antimony oxide, niobium oxide, tungsten oxide or indium oxide, or these metal oxides with another metal or another metal oxide. The semiconductor electrode according to claim 1, which is doped. 8. The semiconductor electrode according to claim 1, wherein the metal oxide semiconductor film is titanium oxide. 9. The semiconductor electrode according to claim 1, wherein the metal oxide semiconductor film is anatase type titanium oxide. 10. The film thickness of the metal oxide semiconductor film is 10 n.
It is m or more, The semiconductor electrode in any one of Claims 1-9. 11. The organic dye-sensitized metal oxide semiconductor electrode according to claim 1 and a counter electrode provided opposite to the electrode, wherein a redox electrolyte is further injected between both electrodes. An organic dye-sensitized solar cell. 12. A substrate having a transparent electrode on the surface thereof, and using a metal and / or a metal oxide as a target on the transparent electrode, a power density of 2.6 W / cm ² or more and 0.6 or more.
A method for producing an organic dye-sensitized metal oxide semiconductor electrode, which comprises forming a metal oxide semiconductor film by a sputtering method under a pressure of Pa or higher and adsorbing an organic dye on the surface of the semiconductor film. 13. The power density during sputtering is set to 1
The manufacturing method according to claim 12, wherein the rate is 1 W / cm ² or more. 14. The pressure during sputtering is 2.0.
The manufacturing method according to claim 12 or 13, wherein Pa or more is used. 15. The manufacturing method according to claim 12, wherein the sputtering is performed by using metallic titanium as a target and supplying oxygen gas. 16. The manufacturing method according to claim 12, wherein the sputtering is performed by using conductive titanium oxide as a target and supplying oxygen gas. 17. The manufacturing method according to claim 12, wherein the vapor phase film forming method is a facing bipolar target system sputtering method. 18. The manufacturing method according to claim 12, wherein the metal oxide semiconductor film is titanium oxide. 19. The manufacturing method according to claim 12, wherein the metal oxide semiconductor film is anatase-type titanium oxide. 20. The thickness of the metal oxide semiconductor film is 10 n.
The manufacturing method according to any one of claims 12 to 19, which is m or more.