JP2002231326A - Photoelectric conversion element and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible, light-weight photoelectric conversion element having high photoelectric conversion efficiency, and to provide its manufacturing method. SOLUTION: This coloring-matter sensitized photoelectric conversion element is composed of an oxide semiconductor electrode 4 formed on a transparent conductor substrate 1, a coloring matter adsorbed on the oxide semiconductor electrode 4, a charge transfer layer, and a counter electrode. The oxide semiconductor electrode 4 is formed, by dissolving a mixture of a metal organic compound and an organic polymer material 8 in a solvent to form a solution, applying the solution onto a polymer film substrate on which a transparent conductive film 2 is stacked, drying, then irradiating ultraviolet rays. Since the oxide semiconductor electrode is formed at a low temperature through irradiating with ultraviolet, flexible, light-weight photoelectric conversion element can be formed on the polymer film substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion element for directly converting light energy into electric energy and a method for manufacturing the same.

[0002]

2. Description of the Related Art There are several types of photoelectric conversion elements or solar cells for converting light energy into electric energy, and most of them are diode type using a junction of a silicon semiconductor or a gallium arsenide semiconductor. Since these photoelectric conversion elements and solar cells are currently expensive, they have become a bottleneck for widespread use in household electric power and the like. Dye-sensitized wet solar cell (Nature 353 (1991) 7) invented in 1991 by Gretzel et al.
37) is operated by a photoelectric conversion mechanism different from that of a silicon semiconductor solar cell, and has a relatively high photoelectric conversion efficiency of about 10%. Therefore, it is expected that the element can be replaced with a silicon solar cell in the future. I have.

FIG. 2 is a sectional view showing the basic structure of a dye-sensitized wet solar cell. According to FIG. 2, this dye-sensitized wet solar cell is configured by laminating two electrodes, an electrode made of a transparent conductive film 2 formed on a transparent substrate 1 and a counter electrode 3 on which platinum or the like is deposited. You.

Normally, a glass having a thickness of about 1 mm is used as a base of the transparent substrate 1 and the counter electrode 3. An oxide semiconductor electrode 4 is formed on the transparent conductive film 2, and a dye 5 is adsorbed on the surface of the oxide semiconductor electrode 4. An electrolyte solution 6 having a redox pair is injected between the two electrodes. As the dye 5, a sensitizing dye capable of efficiently absorbing sunlight, such as a ruthenium (Ru) complex, is used.

When the dye-sensitized wet-type solar cell is irradiated with light, the sensitizing dye 5 is excited and electrons are injected into the oxide semiconductor electrode 4 to generate a current. In addition,
An iodine-based electrolyte is generally used as the electrolyte solution 6 required for electron transfer.

[0006] Dye-sensitized wet-type solar cells based on such a principle have been actively studied even before the invention of Gretzel et al. However, the photoelectric conversion efficiency was generally as low as 1% or less. This was because the probability of light capture at the sensitizing dye 5 portion was low. For this reason, the above solar cell was considered to be a technology with a low possibility of practical use.

On the other hand, Grettzel et al. Made titanium oxide (Ti) having a large surface area by making the oxide semiconductor electrode 4 porous.
O ₂ ) electrodes were used. Accordingly, the amount of the dye adsorbed on the surface of the oxide semiconductor electrode 4 increases, so that the probability of capturing light with the sensitizing dye can be increased. By making such an improvement, a solar cell having a structure as shown in FIG. 2 achieves a photoelectric conversion efficiency of about 10%.

[0008]

As described above, FIG.
In the dye-sensitized wet solar cell shown in (1), the surface area increases by making the oxide semiconductor electrode 4 porous, the amount of the sensitizing dye 5 adsorbed on the surface increases, and the light capture probability of the dye increases. Since it increases, a high photoelectric conversion efficiency of about 10% can be obtained. Normally, a solar cell using single crystal silicon or amorphous silicon uses a high temperature exceeding 1000 ° C. or a vacuum process at the time of manufacturing, and thus has a problem that the cost is high.

However, the solar cell having the structure of FIG. 2 has a process temperature of about 400 to 500 ° C. lower than that of a silicon-based one, does not require a vacuum process, and uses inexpensive titanium oxide as a material. For this reason, it is characterized by being a low-cost solar cell. For this reason, the application range is considered to be very promising not only for residential solar cells but also for mobile terminal batteries.

[0010] However, in consideration of application to portable terminals and the like, the conventional solar cell has a serious problem. That is, in the basic structure shown in FIG. 2, glass is used for the base of the transparent substrate 1 and the counter electrode 3. Generally, a glass having a thickness of about 0.5 to 2 mm is used. As described above, since glass is used for both electrodes, there is a problem that the weight of the solar cell increases. This is a fatal problem for portable terminal applications in which weight reduction in gram units is an important differentiating technology.

Further, since the portion having the highest cost ratio in the solar cell is the transparent substrate 1 on which the transparent conductive film 2 is formed, the cost of this portion is reduced, thereby further reducing the cost of the solar cell. There is expected.

Next, when the above-mentioned solar cell is applied to a portable terminal or the like, if the above-mentioned solar cell is flexible, it can be installed in an arbitrary place having a complicated shape, which is very advantageous. However, it is extremely difficult to achieve flexibility with a conventional solar cell formed on a glass substrate. Therefore, a method of using a polymer film substrate instead of glass, laminating the transparent conductive film 2 thereon, and further forming the oxide semiconductor electrode 4 thereon is conceivable.

In this method, it is necessary to bake at about 400 to 500 ° C. when forming the oxide semiconductor electrode 4. Unless baked at such a temperature, electrical connection between crystal grains of the oxide semiconductor electrode 4 composed of fine crystal grains is deteriorated, and the oxide semiconductor electrode 4 has a very high resistance and cannot be used as an electrode. It is.

However, since the heat resistance of the polymer film substrate is generally about 200 ° C., there is a problem that it is difficult to use this substrate as the transparent substrate 1 of the solar cell.

The present invention has been made in order to solve such problems, and by forming a porous oxide semiconductor electrode on a polymer film substrate at a low temperature, the photoelectric conversion efficiency is high, and It is an object of the present invention to provide a flexible photoelectric conversion element and a method for manufacturing the same.

[0016]

According to a first aspect of the present invention, there is provided an oxide semiconductor electrode formed on a transparent conductive substrate, and a dye adsorbed on the oxide semiconductor electrode. In a dye-sensitized photoelectric conversion device including a charge transfer layer and a counter electrode, the oxide semiconductor electrode is a solution obtained by dissolving a mixture of a metal organic compound and an organic polymer material in a solvent, and forming the solution. A transparent conductive film is laminated on the polymer film substrate, dried, and irradiated with ultraviolet rays.

According to a second aspect of the present invention, in the first aspect, the oxide semiconductor electrode is made of titanium oxide (TiO 2).
₂ ), niobium oxide (Nb ₂ O ₅ ), zinc oxide (Zn
O), tin oxide (SnO ₂ ), or a mixture thereof.

The third aspect of the present invention is the first or second aspect.
In the described invention, the metal organic compound and the organic polymer material
Of titanium oxide having a particle size of 50 nm or more (T
iO _Two), Niobium oxide (Nb_TwoO_Five), Zinc oxide (Zn
O), tin oxide (SnO)_Two)
It is characterized by using.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the metal organic compound is a metal alkoxide or a metal acetylacetonate complex, and titanium (Ti) is used as a metal. Niobium (N
b) any of zinc (Zn) and tin (Sn);
Alternatively, a feature of using these composites is provided.

According to a fifth aspect of the present invention, in the first aspect of the invention, the organic polymer material is polyethylene glycol, or diazoaminobenzene, azodicarbonamide, dinitrosopentamethylene. It is a foaming agent selected from tetramine.

According to a sixth aspect of the present invention, there is provided the method according to any one of the first to fifth aspects, wherein a film coated with a mixture of a metal organic compound and an organic polymer material is applied when irradiating the ultraviolet light. It is characterized by heating to a temperature of not more than ℃.

According to a seventh aspect of the present invention, in the first aspect of the present invention, the transparent conductive film is a tin oxide (SnO ₂ ) thin film or an indium tin oxide (ITO) thin film. There is a feature.

According to an eighth aspect of the present invention, in the first aspect of the present invention, the counter electrode is a platinum (Pt) thin film or palladium (Pd) formed on a polymer film substrate. It is a thin film.

According to a ninth aspect of the present invention, in the first aspect of the present invention, the polymer film substrate is selected from the group consisting of polyester, polycarbonate, polyether sulfone, polyarylate, and polyimide. It is characterized by having been done.

The invention according to claim 10 is the invention according to claims 1 to 9
In the invention according to any one of the above, the dye is a ruthenium (Ru) -based complex dye.

[0026] The eleventh aspect of the present invention is the first aspect of the present invention.
0. The invention according to any one of the items 1 to 3, wherein the charge transfer layer contains an iodine (I ⁻ / I ³⁻ ) ion couple.

According to a twelfth aspect of the present invention, a dye-sensitized dye having an oxide semiconductor electrode formed on a transparent conductive substrate, a dye adsorbed on the oxide semiconductor electrode, a charge transfer layer, and a counter electrode is provided. In the method for manufacturing a photoelectric conversion element, an oxide semiconductor electrode is formed by dissolving a mixture of a metal organic compound and an organic polymer material in a solvent to form a solution, coating the solution on a polymer film substrate on which a transparent conductive film is laminated, and drying. And is formed by irradiating ultraviolet rays.

According to a thirteenth aspect of the present invention, in the twelfth aspect, the oxide semiconductor electrode is made of titanium oxide (T
iO ₂ ), niobium oxide (Nb ₂ O ₅ ), zinc oxide (Zn)
O), tin oxide (SnO ₂ ), or a mixture thereof.

According to a fourteenth aspect of the present invention, in the twelfth or thirteenth aspect, a mixture of a metal organic compound and an organic polymer material is further added to titanium oxide (TiO ₂ ) and niobium oxide (Nb) having a particle size of 50 nm or more. ₂ O ₅ ), zinc oxide (ZnO), and tin oxide (SnO ₂ ).

According to a fifteenth aspect of the present invention, in the invention according to any one of the twelfth to fourteenth aspects, the metal organic compound is a metal alkoxide or a metal acetylacetonate complex, and the metal is titanium (Ti); One of niobium (Nb), zinc (Zn), and tin (Sn), or a composite thereof is used.

The invention according to claim 16 is the invention according to any one of claims 12 to 15, wherein the organic polymer material is polyethylene glycol, diazoaminobenzene, azodicarbonamide, dinitrosopentamethylene. It is a foaming agent selected from tetramine.

According to a seventeenth aspect of the present invention, there is provided the method according to any one of the twelfth to sixteenth aspects, wherein a film coated with a mixture of a metal organic compound and an organic polymer material is applied when irradiating ultraviolet rays. It is characterized by heating to a temperature of not more than ℃.

According to an eighteenth aspect of the present invention, in the first aspect of the present invention, the transparent conductive film is a tin oxide (SnO ₂ ) thin film or an indium tin oxide (ITO) thin film. There is a feature.

According to a nineteenth aspect of the present invention, in the invention according to any one of the twelfth to eighteenth aspects, the counter electrode comprises:
It is a platinum (Pt) thin film or a palladium (Pd) thin film formed on a polymer film substrate.

According to a twentieth aspect of the present invention, in the first aspect of the present invention, the polymer film substrate is selected from the group consisting of polyester, polycarbonate, polyether sulfone, polyarylate, and polyimide. It is characterized by having been done.

According to a twenty-first aspect of the present invention, in any one of the twelfth to twentieth aspects, the dye is a ruthenium (Ru) complex dye.

[0037] The invention of claim 22, wherein, in the invention according to any one of claims 12 to 21, the charge transfer layer, iodine ^- characterized in that it comprises a (I / I ^3-) ions Couples .

[0038]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the present invention, in order to use a flexible polymer film substrate as a base for the transparent substrate 1 and the counter electrode 3 in the solar cell having the basic structure shown in FIG. 2, a manufacturing method based on the schematic diagram shown in FIG. Was invented.

In the present invention, first, a flexible polymer film is used for the transparent substrate 1 shown in FIG.
An electrode made of the transparent conductive film 2 is formed on the film. As the polymer film, a material that is flexible and transmits sunlight, in particular, light having a wavelength of about 400 to 1000 nm is used. Specifically, it is selected from the group consisting of polyester, polycarbonate, polyether sulfone, polyarylate, and polyimide. The thickness of the film is about 0.025 to 0.2 mm, which is very thin and lightweight compared to the conventional glass substrate having a thickness of 0.5 to 2 mm. In addition, these films have heat resistance up to about 200 ° C. The transparent conductive film 2 is formed by sputtering or CV
It is formed by the D method, and has a thickness of 200 to 1,000 nm.
A degree is desirable. Usually, a tin oxide thin film or an indium tin oxide (ITO), preferably a fluorine-doped tin oxide thin film is used for the transparent conductive film 2. The characteristics required for the transparent conductive film 2 are that the visible light transmittance is high and
That is, the sheet resistance is small.

In order to form the porous oxide semiconductor electrode 4 on a flexible polymer film substrate, it is necessary to significantly reduce the temperature in comparison with the conventional firing temperature in consideration of the heat resistance of the polymer film substrate. It is necessary to plan. Therefore, in the present invention, the oxide semiconductor electrode 4 is manufactured in the following order.

First, a mixture of a metal organic compound and an organic polymer material is dissolved in a solvent to form a solution. As the metal organic compound, for example, a metal alkoxide or a metal acetylacetonate complex is used. Any one of Ti, Nb, Zn, and Sn or a composite thereof is used as a metal constituting these metal organic compounds. In addition, tungsten (W), indium (In),
Any of zirconium (Zr), tantalum (Ta), hafnium (Hf), or a composite thereof may be used.

As the organic polymer material, polyethylene glycol or a foaming agent such as diazoaminobenzene, azodicarbonamide, dinitrosopentamethylenetetramine or the like is used. The type and amount of solvent used to dissolve the mixture of these organometallic compounds and organic polymer materials are
A solvent or an amount capable of dissolving them is used. For example, an organic solvent such as toluene, xylene, acetylacetone, ethanol, methanol, or butyl acetate is used.

The mixed solution of the metal organic compound and the organic polymer material prepared as described above is applied on the transparent conductive film 2 as shown in FIG. In this state, the organic polymer material 8 is mixed in the metal organic compound 7 in the applied thin film. The thickness of this thin film finally becomes 1
It is preferable that the distance is about 15 mm. The thin film is irradiated with ultraviolet rays 9. As the ultraviolet light, a strong ultraviolet lamp is used, and further, KrF (248 nm)
Alternatively, an excimer laser beam such as ArF (193 nm) or the like can be used. As an example, ultraviolet rays of several 100 W are irradiated for several hours. By this irradiation, the metal organic compound is decomposed and further crystallized, so that an oxide semiconductor thin film can be obtained at a low temperature. For example, when Ti is used as the metal of the metal organic compound, a titanium oxide (TiO ₂ ) thin film having an anatase or rutile structure can be obtained.

On the other hand, the organic polymer material is decomposed by the irradiation of ultraviolet rays, and becomes a gas such as carbon dioxide and escapes from the inside of the thin film. After this, small holes are formed. As a result, an extremely porous oxide semiconductor electrode 4 having a large surface area can be formed on the transparent conductive film 2 as shown in FIG. Here, when a thin film made of only the metal organic compound 7 without the organic polymer material 8 is used as the thin film applied on the transparent conductive film 2, no fine holes are formed after irradiation. Therefore, the obtained oxide semiconductor thin film has a uniform and dense structure. Therefore, in order to form the porous oxide semiconductor electrode 4 having a large surface area as the object of the present invention, it is essential to use a mixture solution of a metal organic compound and an organic polymer material.

When the irradiation intensity of the ultraviolet light is too low, the oxide semiconductor does not crystallize and the organic polymer material does not decompose. on the other hand,
If the irradiation intensity is too high, ablation occurs and the applied metal organic compound 7 and organic polymer material 8 evaporate. Therefore, the irradiation intensity of the ultraviolet rays needs to be within a certain range suitable for the type of the metal organic compound or the organic polymer material to be used. In the related art, at the time of forming an oxide semiconductor electrode, a sol solution of an oxide semiconductor is applied to a glass substrate and then fired in a temperature range of 400 to 500 ° C. On the other hand, according to the present invention, the porous oxide semiconductor electrode 4 can be formed even at a low temperature near room temperature by the decomposition reaction of the organic component by the irradiation of ultraviolet rays and the subsequent crystallization of the oxide semiconductor thin film. . For this reason, it became possible to manufacture even on a transparent polymer film substrate having lower heat resistance than a glass substrate.

When the oxide semiconductor electrode 4 is manufactured, a solution in which particles such as TiO _{2 having} a particle diameter of 50 nm or more are mixed with a mixed solution of a metal organic compound and an organic polymer material is used. The photoelectric conversion efficiency of the device can be further improved. Oxide semiconductor electrode 4
By dispersing the large particles in the
This is because the light incident on the electrode is efficiently scattered by the particles, the effective optical path length is increased, and the probability of capturing light with the dye is increased.

When irradiating the above ultraviolet rays, the transparent substrate 1 coated with the mixture solution of the metal organic compound 7 and the organic polymer material 8 is heated to a temperature of 200 ° C. or less,
Electric characteristics of the oxide semiconductor thin film can be further improved as compared with the case where irradiation is performed at room temperature. The heating temperature is determined by the heat-resistant temperature of the transparent polymer film used.

The oxide semiconductor electrode 4 manufactured by the above-described manufacturing method receives electrons generated by light irradiation with the dye adsorbed on the electrode surface, and transfers the electrons to the transparent conductive film 2.
It is required to take on the role of communicating to Desirable oxides for this purpose include titanium oxide (TiO ₂ ) and niobium oxide (Nb) having an energy gap of about 3 eV.
₂ O ₅ ), zinc oxide (ZnO), tin oxide (SnO ₂ )
Or a mixture thereof. In addition, tungsten oxide (WO ₃ ), indium oxide (I
n ₂ O ₂ ), zirconium oxide (ZrO ₂ ), tantalum oxide (TaO ₂ ), hafnium oxide (HfO ₂ ), or a mixture thereof.

As the counter electrode 3, a platinum (Pt) thin film or a palladium (Pd) thin film formed on a polymer film substrate is used. In addition to the role of the electrode, the Pt thin film or the Pd thin film also plays a role of efficiently reflecting light that is not absorbed by the dye 5 and has passed through the oxide semiconductor electrode 4 and returns the light into the oxide semiconductor electrode 4 again. . This can contribute to improvement in the photoelectric conversion efficiency of the photoelectric conversion element. The polymer film substrate of the counter electrode 3 may be a flexible one, and examples thereof include those selected from the group consisting of polyester, polycarbonate, polyethersulfone, polyarylate, and polyimide.

The dye 5 used in the present invention preferably has broad absorption in the visible light region, and a ruthenium (Ru) complex dye is used. One type of dye to be adsorbed may be used, or a mixture of two or more types may be used. The dye can be adsorbed to only one surface as shown in FIG. 1C by immersing the oxide semiconductor electrode prepared as described above in an ethanol solution of the dye. Further, the charge transfer layer 6 is composed of a plurality of ion couples in an oxidized state that rapidly perform a reaction of emitting electrons and being oxidized and obtaining and reducing electrons.
Preferably iodine (I ^- / I ^3-) using an electrolyte containing an ion couple.

Hereinafter, the method for manufacturing the photoelectric conversion element of the present invention will be described with reference to specific examples, but the present invention is not limited thereto.

<Embodiment 1> In the first embodiment of the present invention,
The oxide semiconductor electrode 4 was manufactured according to the following procedure. 30
A transparent and flexible polyester having a size of 30 mm × 30 mm and a thickness of 0.05 mm was used as a transparent substrate 1, and a fluorine-doped tin oxide film was formed thereon as a transparent conductive film 2 by a chemical vapor deposition method. Polyester is 400-100
A material capable of transmitting about 90% of light having a wavelength of 0 nm was used. The thickness of the transparent conductive film 2 was about 400 nm. The sheet resistance of the transparent conductive film 2 is 10 W / cm ² ,
The visible light transmittance at a wavelength of 550 nm was 80% or more.

A porous oxide semiconductor electrode 4 was formed on the flexible polyester substrate as follows. First, a mixed solvent was prepared by dissolving Ti tetraisopropoxide as a metal organic compound and polyethylene glycol having a molecular weight of 20,000 in methanol. Polyethylene glycol was mixed with Ti tetraisopropoxide by several percent to about 50%. Next, this mixture solution was applied onto the transparent conductive film 2 by a spin coater, dried at 150 ° C., and this process was repeated three times. As a result, a coating film having a thickness of about 1 to 2 mm and comprising a mixture of a metal organic compound and polyethylene glycol is obtained. This coating film was irradiated with an 8 kW ultraviolet lamp for 3 hours at room temperature in a nitrogen atmosphere. This process is repeated 5 times in total, and the thickness is 5 to 10 m.
m was prepared.

The structure of the thin film obtained by the above steps is represented by X
When evaluated by a line diffraction method, only a diffraction peak corresponding to the anatase type crystal structure was observed, and it was confirmed that the target TiO ₂ thin film could be obtained even at room temperature by the above-described ultraviolet irradiation. In addition, when the surface of the thin film was observed with a scanning electron microscope, fine pores were dispersed in the thin film corresponding to the decomposition and removal of polyethylene glycol, and a very porous thin film was obtained. It was confirmed that. Furthermore, by the specific surface area measuring device,
When the surface area with respect to the area of the TiO ₂ thin film, that is, the specific surface area was measured, a high value of about 1000 was observed. As described above, as a result of using the manufacturing method according to the present invention, it was found that a very porous oxide semiconductor electrode 4 can be formed on a flexible polyester substrate at room temperature.

Next, a dye was adsorbed on the surface of the oxide semiconductor electrode 4 made of the TiO ₂ thin film. As the dye, one obtained by dissolving a Ru bipyridine complex dye having a broad absorption around a wavelength of 550 nm in anhydrous ethanol at a concentration of about 2 × 10 ⁻⁴ M was used. The TiO ₂ thin film was immersed in this dye solution and stored overnight. At the end of dye adsorption,
The TiO ₂ film was removed from the dye solution, rinsed with acetonitrile to remove excess dye, and then dried in air. One drop of an iodine-based electrolyte was dropped as a charge transfer layer 6 on this electrode. As the iodine-based electrolyte, iodine and lithium iodide were used as an ion couple (I ⁻ / I ³⁻ ), and a mixed solution of acetonitrile and ethylene carbonate was used as a solvent. It should be noted that there is no problem even if another combination is used for the ion couple and the solvent.

Next, the electrode fabricated in this manner was used as a counter electrode 3
Then, the end portions were sealed with resin to complete the photoelectric conversion element. The counter electrode 3 was formed by depositing about 100 nm of platinum on a polycarbonate substrate.

The photoelectric conversion element was irradiated with light having an intensity of 100 mW / cm ² under AM 1.5 conditions by a solar simulator, and the generated electricity was measured by a current / voltage measuring device.
The photoelectric conversion characteristics were evaluated. As a result, a photoelectric conversion efficiency of 9.5% was obtained, and it was confirmed that the same level of photoelectric conversion efficiency as that of the amorphous silicon solar cell was obtained. Since this photoelectric conversion element had an electrode portion made of a transparent polymer film, it was very flexible and could be bent at a curvature of 90 degrees or more. It was also confirmed that the photoelectric conversion efficiency hardly changed even in the folded state.

<Second Embodiment> In a second embodiment of the present invention, an oxide semiconductor electrode 4 was manufactured by the following procedure.
First, a transparent and flexible polyimide having a size of 20 mm × 20 mm and a thickness of 0.02 mm was used as a transparent substrate 1, and a fluorine-doped tin oxide film was formed thereon as a transparent conductive film 2 by a chemical vapor deposition method. Polyimide is 400-
A material capable of transmitting about 90% of light having a wavelength of 1000 nm was used. The thickness of the transparent conductive film 2 was about 500 nm. The sheet resistance of the transparent conductive film 2 was 15 W / cm ² , and the visible light transmittance at a wavelength of 550 nm was 80% or more. A porous oxide semiconductor electrode 4 was formed on this flexible polyimide substrate as follows.

First, Ti acetylacetonate as a metal organic compound and a blowing agent diazoaminobenzene are dissolved in xylene, and a small amount of rutile-type TiO ₂ powder having a particle size of about 50 nm is added and sufficiently dispersed. Produced. Diazoaminobenzene was mixed with Ti acetylacetonate in an amount of about several to 50%. Next, this mixture solution was applied on the transparent conductive film 2 by a spin coater, dried at 150 ° C., and this process was repeated twice.
As a result, a coating film having a thickness of about 1 to 2 mm and comprising a mixture of a metal organic compound and diazoaminobenzene is obtained.
This coating film was irradiated with an 8 kW ultraviolet lamp in dry air at 150 ° C. for 3 hours. This process was repeated a total of 5 times to produce a thin film having a thickness of 5 to 10 mm.

In the thin film obtained by the above steps, diffraction peaks of anatase and rutile were observed to be mixed, and a TiO ₂ thin film could be obtained by irradiation with ultraviolet rays. In this case, since the temperature at the time of irradiation was increased to 150 ° C., the intensity of the diffraction peak was stronger than that of the first embodiment,
₍₂₎ The crystallinity of the thin film was improved. As a result of observation with a scanning electron microscope, it was confirmed that diazoaminobenzene was decomposed by ultraviolet rays and escaped, so that fine pores were dispersed in the thin film to form a very porous thin film.
The TiO ₂ thin film had a structure in which relatively large crystal grains having a particle size of about 50 nm were dispersed in fine crystal grains having a particle size of 10 to 30 nm. It is considered that the fine crystal grains are TiO ₂ particles crystallized by ultraviolet irradiation, and the large crystal grains are rutile TiO ₂ particles added to the solution. When the specific surface area of this TiO ₂ thin film was measured by a specific surface area measuring device, it was a high value of about 1,200.

Next, a dye was adsorbed on the surface of the oxide semiconductor electrode 4 made of the TiO ₂ thin film. As the dye, a solution obtained by dissolving a Ru terpyridine complex dye having a broad absorption around a wavelength of 550 nm in anhydrous ethanol at a concentration of about 2 × 10 ⁻⁴ M was used. The TiO ₂ thin film was immersed in this dye solution and stored overnight. When the adsorption of the dye was completed, the TiO ₂ thin film was removed from the dye solution, rinsed with acetonitrile to remove excess dye, and then dried in air. One drop of an iodine-based electrolyte was dropped as a charge transfer layer 6 on this electrode. As the iodine-based electrolyte, iodine and lithium iodide were used as an ion couple (I ⁻ / I ³⁻ ), and a mixed solution of acetonitrile and ethylene carbonate was used as a solvent. It should be noted that there is no problem even if another combination is used for the ion couple and the solvent.

Next, the electrode fabricated in this manner was used as a counter electrode 3
Then, the end portions were sealed with resin to complete the photoelectric conversion element. The counter electrode 3 was formed by depositing platinum on a polyarylate substrate to a thickness of about 100 nm.

The photoelectric conversion element was irradiated with light having an intensity of 100 mW / cm ² under AM 1.5 conditions by a solar simulator, and the generated electricity was measured by a current / voltage measuring device.
The photoelectric conversion characteristics were evaluated. As a result, a photoelectric conversion efficiency of 10.2% was obtained. Even after the photoelectric conversion element was bent at a curvature of 90 degrees or more, the photoelectric conversion efficiency hardly changed, and it was confirmed that the photoelectric conversion element can be used as a flexible solar cell.

<Third Embodiment> In a third embodiment of the present invention, the oxide semiconductor electrode 4 was manufactured by the following procedure.
First, a transparent conductive film 2 was formed on a polyarylate transparent substrate 1 having a size of 30 mm × 30 mm and a thickness of 0.05 mm.
A porous oxide semiconductor electrode 4 was formed on this flexible polyarylate substrate as follows.

First, as a metal organic compound, Ti tetri
Sobutoxide and azodicarbonamide blowing agent
Dissolved in water and a small amount of rutile with a particle size of about 50 nm
Type TiO_TwoAdd powder and disperse thoroughly to form a mixed solvent.
Made. Azodicarbonamide is Ti tetraisobutoki
The mixture was mixed at a ratio of several% to 50% with respect to SID. Then this
Apply the mixture solution on the transparent conductive film 2 with a spin coater
And dried at 150 ° C., and this step was repeated twice.
As a result, a metal organic compound having a thickness of about 1 to 2 mm
A coating film comprising a mixture of dicarbonamide is obtained.
This coating film is exposed to K
rF excimer laser beam at 50 mJ / cm ^Two, 25H
Irradiation for 15 minutes at z. This process is repeated a total of 5 times,
A thin film having a thickness of 5 to 10 mm was produced.

In the thin film obtained by the above steps, diffraction peaks of anatase and rutile were observed to be mixed, and a TiO ₂ thin film could be obtained by irradiation with ultraviolet rays. As a result of observation with a scanning electron microscope, as in the second embodiment, azodicarbonamide was decomposed by ultraviolet light and escaped, so that fine pores were dispersed in the thin film, and a very porous thin film was obtained. It was confirmed that it was. Also, Ti
The O ₂ thin film has fine crystal grains with a particle size of 10 to 30 nm.
Relatively large crystal grains having a particle size of about 50 nm were dispersed. When the specific surface area of this TiO ₂ thin film was measured by a specific surface area measuring device, it was a high value of about 1,200.

Next, a dye was adsorbed on the surface of the oxide semiconductor electrode 4 made of the TiO ₂ thin film in the same manner as in the second embodiment, and then a drop of an iodine-based electrolyte was dropped. Further, the photoelectric conversion element was completed by laminating the counter electrode 3 as shown in FIG. The counter electrode 3 was formed by depositing platinum of about 100 nm on a polyimide substrate.

[0068] by irradiation with light having an intensity of 100 mW / cm ² of AM1.5 conditions by a solar simulator to the photoelectric conversion element was evaluated photoelectric conversion characteristics. As a result, 10.
A photoelectric conversion efficiency of 5% was obtained. This photoelectric conversion element
Even after bending at a curvature of 90 degrees or more, little change was observed in the photoelectric conversion efficiency, and it was confirmed that the photoelectric conversion efficiency could be used as a flexible solar cell.

The embodiments described above are preferred embodiments of the present invention, and various modifications can be made within the scope of the technical concept of the present invention.

[0070]

As is clear from the above description, according to the photoelectric conversion element and the method for manufacturing the same of the present invention, the oxide semiconductor electrode is formed at a low temperature by the ultraviolet irradiation method, thereby forming A flexible and lightweight photoelectric conversion element can be manufactured, and application to a portable terminal or the like as a flexible solar cell becomes possible.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a photoelectric conversion element according to an embodiment of the present invention and a method for manufacturing the same.

FIG. 2 is a sectional view showing a basic structure of a dye-sensitized solar cell.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transparent substrate 2 transparent conductive film 3 counter electrode 4 oxide semiconductor electrode 5 dye 6 electrolyte solution having redox couple 7 metal organic compound 8 organic polymer material 9 ultraviolet ray

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Sadanori Kuroshima 5-7-1 Shiba, Minato-ku, Tokyo F-term within NEC Corporation 5F051 AA14 5H032 AA06 AS16 BB02 BB05 BB10 CC11 CC16 EE01 EE04 EE03 EE04 EE06 EE07 EE11 EE17 HH06

Claims (22)

[Claims] 1. A dye-sensitized photoelectric conversion element comprising: an oxide semiconductor electrode formed on a transparent conductive substrate; a dye adsorbed on the oxide semiconductor electrode; a charge transfer layer; and a counter electrode. In the oxide semiconductor electrode, a mixture of a metal organic compound and an organic polymer material is dissolved in a solvent to form a solution, and the solution is applied to a polymer film substrate on which a transparent conductive film is laminated and dried, A photoelectric conversion element formed by irradiating ultraviolet rays. 2. An oxide semiconductor electrode comprising: titanium oxide (TiO ₂ ), niobium oxide (Nb ₂ O ₅ ),
Zinc oxide (ZnO), or the tin oxide (SnO _2), or, the photoelectric conversion element according to claim 1, wherein the mixtures thereof. 3. A mixture of the metal organic compound and the organic polymer material, further comprising titanium oxide (TiO ₂ ), niobium oxide (Nb ₂ O ₅ ), zinc oxide (ZnO), tin oxide (50 nm or more) having a particle size of 50 nm or more. The photoelectric conversion device according to claim 1, wherein a solution in which particles of SnO ₂ ) are mixed is used. 4. The metal organic compound is a metal alkoxide or a metal acetylacetonate complex, and titanium (Ti), niobium (Nb), zinc (Z
The photoelectric conversion element according to any one of claims 1 to 3, wherein any one of n) and tin (Sn), or a composite thereof is used. 5. The organic polymer material is polyethylene glycol or a blowing agent selected from diazoaminobenzene, azodicarbonamide, and dinitrosopentamethylenetetramine. The photoelectric conversion element according to any one of the above. 6. The method according to claim 1, wherein, when irradiating the ultraviolet rays, the film coated with the mixture of the metal organic compound and the organic polymer material is heated to a temperature of 200 ° C. or less. 2. The photoelectric conversion element according to claim 1. 7. The photoelectric conversion device according to claim 1, wherein the transparent conductive film is a tin oxide (SnO ₂ ) thin film or an indium tin oxide (ITO) thin film. element. 8. The device according to claim 1, wherein the counter electrode is a platinum (Pt) thin film or a palladium (Pd) thin film formed on the polymer film substrate. Photoelectric conversion element. 9. The method according to claim 1, wherein said polymer film substrate is selected from the group consisting of polyester, polycarbonate, polyethersulfone, polyarylate, and polyimide. The photoelectric conversion device according to any one of the preceding claims. 10. The photoelectric conversion device according to claim 1, wherein the dye is a ruthenium (Ru) -based complex dye. Wherein said charge transport layer, iodine (I ^- / I ^3-) The photoelectric conversion device according to any one of claims 1 to 11, characterized in that it comprises an ion couples. 12. A method for manufacturing a dye-sensitized photoelectric conversion element having an oxide semiconductor electrode formed on a transparent conductive substrate, a dye adsorbed on the oxide semiconductor electrode, a charge transfer layer, and a counter electrode. In the above, the oxide semiconductor electrode is formed by dissolving a mixture of a metal organic compound and an organic polymer material in a solvent to form a solution, applying the solution on a polymer film substrate on which a transparent conductive film is laminated, drying the film, and irradiating with ultraviolet light. A method for manufacturing a photoelectric conversion element, characterized by being formed by: 13. An oxide semiconductor electrode comprising: titanium oxide (TiO ₂ ), niobium oxide (Nb ₂ O ₅ ),
Zinc oxide (ZnO), or, or, a method for manufacturing a photoelectric conversion element according to claim 12, wherein the mixtures thereof of tin oxide (SnO _2). 14. A mixture of the metal organic compound and the organic polymer material, further comprising titanium oxide (TiO ₂ ), niobium oxide (Nb ₂ O ₅ ), zinc oxide (ZnO), tin oxide (50 nm or more) having a particle size of 50 nm or more. 14. The method for manufacturing a photoelectric conversion element according to claim 12, wherein a solution in which particles of SnO ₂ ) are mixed is used. 15. The metal organic compound is a metal alkoxide or a metal acetylacetonate complex, and titanium (Ti), niobium (Nb), zinc (Z
15. Any one of n) and tin (Sn), or a composite thereof is used.
The method for manufacturing a photoelectric conversion element according to any one of the above. 16. The organic polymer material is polyethylene glycol or a blowing agent selected from diazoaminobenzene, azodicarbonamide, and dinitrosopentamethylenetetramine. The method for producing a photoelectric conversion element according to any one of the above. 17. The method according to claim 12, wherein, when irradiating the ultraviolet rays, the film coated with the mixture of the metal organic compound and the organic polymer material is heated to a temperature of 200 ° C. or less. 2. The method for producing a photoelectric conversion element according to claim 1. 18. The photoelectric conversion device according to claim 12, wherein the transparent conductive film is a tin oxide (SnO ₂ ) thin film or an indium tin oxide (ITO) thin film. Device manufacturing method. 19. The device according to claim 12, wherein the counter electrode is a platinum (Pt) thin film or a palladium (Pd) thin film formed on the polymer film substrate. A method for manufacturing a photoelectric conversion element. 20. The polymer film substrate according to claim 12, wherein the polymer film substrate is selected from the group consisting of polyester, polycarbonate, polyether sulfone, polyarylate, and polyimide.
The method for producing a photoelectric conversion element according to any one of the above. 21. The method according to claim 12, wherein the dye is a ruthenium (Ru) -based complex dye. 22. The method according to claim 12, wherein the charge transfer layer contains an iodine (I ⁻ / I ^{3 −} ) ion couple.